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diff --git a/old/67222-0.txt b/old/67222-0.txt deleted file mode 100644 index 5c1bd6b..0000000 --- a/old/67222-0.txt +++ /dev/null @@ -1,28906 +0,0 @@ -The Project Gutenberg eBook of Harvard Psychological Studies, Volume -II, by Various - -This eBook is for the use of anyone anywhere in the United States and -most other parts of the world at no cost and with almost no restrictions -whatsoever. You may copy it, give it away or re-use it under the terms -of the Project Gutenberg License included with this eBook or online at -www.gutenberg.org. If you are not located in the United States, you -will have to check the laws of the country where you are located before -using this eBook. - -Title: Harvard Psychological Studies, Volume II - -Author: Various - -Editor: Hugo Münsterberg - -Release Date: January 22, 2022 [eBook #67222] - -Language: English - -Produced by: Clare Boothby, Jane Robins and the Online Distributed - Proofreading Team at https://www.pgdp.net (This file was - produced from images generously made available by The - Internet Archive) - -*** START OF THE PROJECT GUTENBERG EBOOK HARVARD PSYCHOLOGICAL -STUDIES, VOLUME II *** - - - +-------------------------------------------+ - | Note: | - | | - | = around word indicates bold =CAPSULE.= | - | _ around word indicated italics _Erebus_ | - +-------------------------------------------+ - - - - - - HARVARD PSYCHOLOGICAL - STUDIES - - EDITED BY - - HUGO MÜNSTERBERG - - Volume II - - BOSTON AND NEW YORK - HOUGHTON, MIFFLIN AND COMPANY - The Riverside Press, Cambridge - 1906 - - - COPYRIGHT 1906 - BY THE PRESIDENT AND FELLOWS OF HARVARD COLLEGE - ALL RIGHTS RESERVED - - _Published June 1906_ - - - - -CONTENTS - - - EMERSON HALL: Hugo Münsterberg. - - I. Experimental Psychology in Harvard 3 - II. The Need for Emerson Hall 8 - III. Emerson as Philosopher 16 - IV. The Place of Experimental Psychology 31 - V. The Psychological Laboratory in Emerson Hall 34 - - OPTICAL STUDIES. - - Stereoscopic Vision and the Difference of Retinal Images: G. V. - Hamilton 43 - Eye-Movements during Dizziness: E. B. Holt 57 - Vision during Dizziness: E. B. Holt 67 - Visual Irradiation: Foster Partridge Boswell 75 - - FEELING. - - The Expression of Feelings: F. M. Urban 111 - The Mutual Influence of Feelings: John A. H. Keith 141 - The Combination of Feelings: C. H. Johnston 159 - The Æsthetics of Repeated Space Forms: Eleanor Harris Rowland 193 - The Feeling-Value of Unmusical Tone-Intervals: L. E. Emerson 269 - - ASSOCIATION, APPERCEPTION, ATTENTION. - - Certainty and Attention: Frances H. Rousmaniere 277 - Inhibition and Reënforcement: Louis A. Turley 293 - The Interference of Optical Stimuli: H. Kleinknecht 299 - Subjective and Objective Simultaneity: Thomas H. Haines 309 - The Estimation of Number: C. T. Burnett 349 - Time-Estimation in its Relations to Sex, Age, and Physiological - Rhythms: - Robert M. Yerkes and F. M. Urban 405 - Associations under the Influence of Different Ideas: Bird T. - Baldwin 431 - Dissociation: C. H. Toll 475 - - MOTOR IMPULSES. - - The Accuracy of Linear Movement: B. A. Lenfest 485 - The Motor Power of Complexity: C. L. Vaughan 527 - - ANIMAL PSYCHOLOGY. - - The Mutual Relations of Stimuli in the Frog _Rana Clamata_ Daudin: - Robert M. Yerkes 545 - The Temporal Relations of Neural Processes: Robert M. Yerkes 575 - The Mental Life of the Domestic Pigeon: John E. Rouse 581 - Reactions of the Crayfish: J. Carleton Bell 615 - - - - -PLATES - - - _Frontispiece_ 3 - I 60 - II 64 - III 78 - IV 80 - V 269 - VI 271 - VII 273 - VIII 293 - IX 295 - - - - -EMERSON HALL - -[Illustration: HARVARD PSYCHOLOGICAL LABORATORY] - - - - -EMERSON HALL - -BY HUGO MÜNSTERBERG - - -I. EXPERIMENTAL PSYCHOLOGY IN HARVARD - -On the 27th of December, 1905, Harvard University opened its new house -of philosophy, Emerson Hall. The presence of the American Philosophical -and Psychological Associations gave national significance to the -completion of this building. - -The psychologist will find quarters in all parts of Emerson Hall. The -general courses in psychology will be held on the first floor in the -large lecture-room, which has nearly four hundred seats; and close by -are the psychological seminary-room and smaller lecture-rooms for the -advanced psychological courses. On the second floor the psychologist -finds his special library as a wing of the large library hall. But -the exclusive domain of the psychologist is the third floor,--a -psychological laboratory with twenty-five rooms. A large attic hall for -laboratory purposes on the fourth floor completes the psychologist's -allotment. - -The work to be reported in future in the Harvard Psychological Studies -will be work done in this new building, and while the researches -reported in the following pages were completed in the smaller quarters -of the old laboratory, it seems natural that this volume, which appears -at this new epoch of our work, should give an account both of our -psychological past and of the development and purpose of Emerson Hall. - -The Harvard Psychological Laboratory was founded in 1891 by Professor -William James, who had introduced some experimental features into his -psychological lecture courses for some time before the formal opening -of a regular workshop. Professor James started with two large rooms -on the second floor of Dane Hall, and secured an excellent equipment, -especially for the study of the psychology of the senses. He was -assisted by Dr. Herbert Nichols, and at once gathered a number of -graduate students for research. - -In the following year Professor James withdrew from the experimental -work, and the conduct of the laboratory was given over to me. In the -years which followed, Dr. Arthur Pierce, Dr. J. E. Lough, and Dr. -Robert MacDougall were the assistants until three years ago, when the -development of the laboratory demanded a division of the assistant -functions; since that time Dr. E. B. Holt has been the assistant for -the work in human psychology, while Dr. R. M. Yerkes has had charge -of the work in comparative psychology. Since from the first I laid -special emphasis on research work, a greater number of small rooms -was soon needed. In the year 1893, we divided a part of the adjacent -lecture-room into four rooms for special investigations, and two years -later the larger of the two original rooms was divided into five. As -the lecture-room also was finally made part of the research laboratory, -we had at last eleven rooms in Dane Hall. The activities of the -laboratory, however, went far beyond the research work. We had regular -training-courses in experimental practice, and the lecture courses in -human and in comparative psychology drew largely on the resources of -our instrument cases. Yet the original investigations absorbed the -main energy of the laboratory, and demanded a steady expansion of -its apparatus. An illustrated catalogue of the instruments has been -published as part of the Harvard Exhibition at the Chicago World's Fair. - -The participation of the students has been controlled by a principle -which has characterized our Harvard work through all these years, -and distinguished it from the methods of most other institutions. I -insist that no student shall engage in one investigation only, but -that every one who has charge of a special problem shall give to -it only half of his working time, while in the other half he is to -be subject in four, five, or more investigations by other members -of the laboratory. In this way each research is provided with the -desirable number of subjects, and all one-sidedness is avoided. Every -experimenter thus comes in contact with a large range of problems and -gets a fair training in manifold observations, besides the opportunity -for concentration on a special research. It is true that this demands -a complicated schedule and careful consideration of the special needs -of every research, but it gives to the work a certain freshness and -vividness, and banishes entirely the depression which is unavoidable -whenever a student is for any length of time a passive subject in one -psychological enquiry only. In both capacities, as experimenter and -as observing subject, only graduate students have been acceptable. In -this way about _one hundred investigations_ on human psychology have -been carried on, for most of which I have proposed the problems and -the special lines of work, taking care that the research of succeeding -years and of succeeding generations of graduate students should show -a certain internal continuity. Whenever the results seemed fit for -publication, the papers have been published under the names of the -students who had the responsibility for the conduct of the experiments. -Until three years ago the publication was scattered; most of the -papers, however, appeared in the Psychological Review. The Harvard -Psychological Studies, beginning in 1903, are to gather the bulk of our -material, although not a few of the researches of recent years have -been published in other places. - -The laboratory has always sought to avoid one-sidedness, and this the -more as it was my special aim to adjust the selection of topics to the -personal equations of the students, many of whom came with the special -interests of the physician, the zoölogist, the artist, the pedagogue, -and so on. My own special interests may have emphasized those problems -which refer to the motor functions and their relations to attention, -apperception, space-sense, time-sense, feeling, etc. At the same time -I have tried to develop the psychological-æsthetic work, which has -become more and more a special branch of our laboratory, and there has -been no year in which I have not insisted on some investigations in the -fields of association, memory, and educational psychology. On the other -hand, in a happy supplementation of interests, Dr. Holt has emphasized -the physiological psychology of the senses, and Dr. Yerkes has quickly -developed a most efficient experimental department of animal psychology. - -As the work thus became more manifold, the old quarters in Dane Hall -appeared less and less sufficient. And yet this laboratory development -has been merely parallel to the growth of general philosophical studies -in the whole University. The demand for a new hall, exclusively devoted -to philosophy, was thus suggested from many sides. The idea of linking -it with the name of Ralph Waldo Emerson has been for years a cherished -plan of Professor Palmer. - -An especially appropriate time for the realization of such a plan came -in the approach of the hundredth anniversary of Emerson's birthday. -Almost two years before this date the Department took the first steps -in seeking to interest the members of the Visiting Committee for the -collection of the necessary funds. This Committee, consisting of Mr. -G. B. Dorr, chairman, Mr. R. H. Dana, Dr. R. Cabot, Mr. J. Lee, Mr. -D. Ward, and Mr. R. C. Robbins, showed not only warm interest, but -lent itself to the furtherance of the plans with such an energy and -devotion that the Philosophical Department owes to these friends of -philosophy in Harvard the most lasting gratitude. Various means were -taken by the Committee and by the Department to stir the interest of -the public, and soon the gifts began to come in, gifts of which some -were clearly given from sympathy with the work of the Philosophical -Department, some evidently in memory of Emerson. The original plans -of the architect called for $150,000 for the building. When, on the -25th of May, 1903, the hundredth anniversary of Emerson's birthday was -celebrated, the University had contributions amounting to more than -this sum, and given by one hundred and seventy persons. - -It was soon found, however, that this sum was inadequate; yet we never -asked in vain. Additional gifts came in for the building fund, just as -later the generosity of several friends furnished the building with a -handsome equipment and the laboratory with new instruments. Mr. R. C. -Robbins gave the books for a philosophical library to be placed in the -new Hall. - -The architect chosen was Mr. Guy Lowell, who has had to labor under the -difficulties involved in the fact that the best and quietest available -place was on Quincy Street opposite Robinson Hall. This spot demanded -that the new building be harmonized with Robinson and Sever Halls, two -structures most unlike in their architectural style. There was not -even the possibility of making it a companion to Robinson Hall, since -the latter has but two stories, while it was evident that Emerson -Hall needed three stories. The plan finally accepted, a Greek, brick -building with brick columns and rich limestone trimmings, provided for -the work of the whole Philosophical Division with the exception of -education. The Education Department, with its large library, will soon -need a whole building of its own, and has thus had no interest in being -housed under the roof of Emerson Hall. On the other hand, the building -was to give full space to that part of our Philosophical Division which -now forms, like education, an administrative unity,--the Department of -Social Ethics. A special library, museum rooms, etc., for social ethics -were planned for the second floor by the munificence of an anonymous -benefactor. Altogether we have six large lecture-rooms, two library -halls, two collection-rooms, a department-room, a seminary-room, -two studies and conference-rooms, twenty-five laboratory-rooms, all -connected by very spacious, well-lighted halls and broad, imposing -stairways. Surely never before in the history of scholarship has such -a stately house been built for philosophy. And while the nature of the -work is certainly not determined by the luxury of stone and carved -wood, teachers and students alike must feel these superb surroundings -as a daily stimulus to their best efforts. - -At Christmas, 1905, the building stood ready for use, and Duveneck's -bronze statue of Emerson was unveiled in the entrance hall. At the -opening meeting, after short dedicatory orations by President Eliot -and Dr. Edward Emerson, a real exchange of ideas in a joint debate -of the Philosophical and Psychological Associations was substituted -for the usual formal exercises. The question debated was suggested by -the fact that Emerson Hall was to house the psychological laboratory. -Does psychology really belong to philosophy or rather to the natural -sciences? As the representative of Harvard, it was my part to open the -debate and to characterize the attitude of the Harvard laboratory. - -My remarks on that occasion may thus serve as the most direct -introduction to our work. They are printed here, together with a short -sketch of the equipment of the laboratory. I venture to add also two -other papers, one of which points to the administrative, the other and -longer one to the philosophical background of Emerson Hall. Inasmuch -as I was Chairman of the Philosophical Department throughout the five -years in which the plan for Emerson Hall was growing and became finally -realized, it has been my official duty repeatedly to express our hopes -and ideals. Thus I had to formulate the wishes of the Department at -the outset in a letter to the Visiting Committee, a letter which was -used as a circular in asking the public for funds. Two years later when -Harvard celebrated the Emerson anniversary, I delivered an address on -Emerson as philosopher. This epistemological paper may seem far removed -from the interests of the Harvard Psychological Studies, and yet I am -glad to print it in this laboratory volume, and thus emphatically to -indicate that I for one consider philosophy the true basis for the -psychologist. - -There follow thus, first, the letter to the Visiting Committee, with -which the Emerson Hall movement took its official inception in 1901; -secondly, the address delivered at Harvard on the celebration of the -Emerson anniversary in May, 1903; thirdly, the paper contributed to the -debate of the philosophers at the opening meeting in December, 1905; -and, finally, a description of the present status of the laboratory in -January, 1906. - - -II. THE NEED FOR EMERSON HALL - - [The letter addressed to the Visiting Committee of the Overseers of - Harvard University, in 1901, reads as follows:] - -Gentlemen,--The philosophical work in Harvard has in the last twenty -years gone through an inner development which has met with a hearty -response alike on the part of the University and of the students. The -students have attended the courses in constantly growing numbers, the -Governing Boards have provided the Division amply with new teachers, -steadily increasing the number of professors, instructors, and -assistants. The outer growth of the Division has thus corresponded -most fortunately to the internal development, by an harmonious -coöperation of the administration, the teachers, and the students of -the University. And yet there remains one other factor as an essential -condition for the healthy life of the Department, a factor which cannot -be provided by the University itself and for which the help must come -from without. Our work needs a dignified home where under one roof all -the varied philosophical work now carried on at Harvard may be united. -The need has been urgently felt for many years, but only with the -recent growth has the situation become intolerable. It is therefore the -unanimous opinion of the Department that we must ask the public for the -funds to build at Harvard a "School of Philosophy," in the interest of -the students and of the teachers, in the interest of the Department and -of the University, in the interest of culture and of scholarship. - -The present work of the Division of Philosophy can be indicated by -a few figures. We entered the current year with a teaching-staff of -six full professors, two assistant professors, four instructors, two -teaching-fellows, and six assistants. The instruction of these twenty -men covers the ground of history of philosophy, metaphysics, theory -of knowledge, psychology, logic, ethics, æsthetics, philosophy of -religion, philosophy of science and sociology. Thirty-two courses -have been offered. These courses are grouped in three classes: the -introductory courses, intended primarily for Sophomores and Juniors; -the systematic and historic courses, planned for Juniors, Seniors, -and Graduates; and the research courses for Graduates only. But -the students whom we try to reach differ not only with regard to -their classes, their corresponding maturity, and their degree of -philosophical preparation, but also with regard to the aims and -interests for which they elect philosophical studies in the University. -The one group seeks in our field liberal education. The fundamental -problems of life and reality, and the historic solutions of them -which the great thinkers developed, the values of truth and beauty -and morality, the laws of the mental mechanism and of the social -consciousness, all these promise and prove to be incomparable agencies -for widening the soul and giving to our young men depth, strength, and -ideals. Not a few of the students who belong to this group remain loyal -to philosophy through three or four years. A second group of students -need our courses as preparation for divers scholarly or practical -aims. The future lawyer, teacher, physician, minister, scientist, or -philanthropist knows that certain courses in ethics or psychology, in -education or logic afford the most solid foundations for his later -work; there is hardly a course in our Division which is not adjusted to -some kind of professional study. The third group finally, naturally the -smallest, but to the teachers the most important, consists of those to -whom philosophy itself becomes a life's work. The Harvard Department -believes that there is nowhere else in this country or abroad such -an opportunity for systematic and all-round training for an advanced -student of philosophy as is offered here, covering easily a man's full -work for six years, advancing from the introductory courses of the -Sophomore year to the six seminaries of the graduate years and finally -reaching the doctor's thesis in the third year after graduation. - -The extent to which the Harvard students make use of these -opportunities is to be inferred from the figures which the last Annual -Report of the President offers. These refer to the year 1899-1900; the -current year will show somewhat the same proportions, perhaps even -an increase of graduate work. The figures are necessarily too low, -inasmuch as they refer merely to those students who take examinations -in the courses and omit those who merely attend the lectures. The -attendance in the philosophical courses was last year over one thousand -students. They belonged to all parts of the University, 188 Graduates, -210 Seniors, 218 Juniors, 175 Sophomores, 59 Specials, 57 Scientifics, -55 Divinity students, and the rest from the Freshman class, the Law -School, and the Medical School. The introductory courses were attended -by almost four hundred students, that is, by a number corresponding to -the size of the Junior class. As, in spite of natural fluctuations, -this figure is pretty constant,--in 1897 reaching its maximum with -427,--it can be said that in Harvard under the system of absolutely -free election practically every student who passes through Harvard -required of himself at least a year of solid philosophical study. - -An even higher interest, however, belongs to the figures which refer -to the most advanced courses offered, especially to the courses of -research. It has always been the most characteristic feature of the -Harvard Philosophical Department to consider the advancement of -knowledge as its noblest function. The productive scholarship of the -Department is shown by the fact that the last two years alone brought -before the public eight compendious scholarly works from members of our -Department, besides a large number of smaller contributions to science. -To train also in the students this highest scholarly attitude, that -of the critical investigator as contrasted with that of the merely -receptive hearer of lectures, is thus the natural aim of our most -advanced work; it is this spirit which has given to the Department its -position in the University and in the whole country. This prevalence -of the spirit of research is the reason why, as the Report of the Dean -of the Graduate School points out, the Philosophical Department has a -larger number of graduate students who have carried on graduate studies -elsewhere than any other Department of the University. The table of -the Dean which records these migrating graduate students who come to -us for advanced work after graduate studies at other universities, -is as follows: Mathematics 6, Natural History 7, Political Science -7, Modern Languages 11, Classics 14, History 15, English Literature -16, Philosophy 20. If we consider the whole advanced work of the -University, that is the totality of those courses which are announced -as "primarily for Graduates," we find that the following number of -graduate students, including the graduate members of the professional -schools, have taken part: Classics 103, Philosophy 96, English 75, -German 61, History and Government 52, Romance Languages 45, Mathematics -39, Economics 23, Chemistry 21, in the other departments less than -twenty. But this situation turns still more strongly in favor of -philosophy as soon as we consider the technical research courses, those -which in the language of the catalogue are known as the 20-courses, and -omit those graduate courses which are essentially lecture courses. In -these research courses the number of Graduate Students is: Philosophy -71, History and Government 34, Chemistry 13, Zoölogy 12, Geology 10, -and in the other departments less than ten. - -These few figures may be sufficient to indicate not only the extent -of the Department and its influence, but above all the harmonious -character of this development. The most elementary courses, the solid -routine courses, and the most advanced courses, show equal signs of -growth and progress, and the whole work with its many side branches -remains a well-connected unity with a clear systematic plan. All this -must be understood before one can appreciate the striking contrast -between the work and the workshop. It is of course easy to say at once -that the truth of a metaphysical thought does not depend upon the -room in which it is taught, and that the philosopher is not, like a -physicist or chemist, dependent upon outer equipments. Yet, this is but -half true, and the half of the statement which is false is of great -importance. - -The dependence upon outer conditions is perhaps clearest in the case -of psychology, which has been for the last twenty-five years an -objective science with all the paraphernalia of an experimental study: -the psychologist of to-day needs a well-equipped laboratory no less -than the physicist. Harvard has given the fullest acknowledgment to -this modern demand and has spent large sums to provide the University -with the instruments of an excellent psychological laboratory; the -one thing which we miss is room, simply elbow-room. Our apparatus is -crowded in the upper story of Dane Hall, and even that small story -must give its largest room for the lectures of other departments and -another room to a philosophical reading-room. The space which remains -for the psychological work is so absolutely out of proportion to the -amount of work going on that the problem how to bring all the men into -those few rooms has become the most difficult of all our laboratory -problems. During the current year, besides the training-courses, -twenty-three men are engaged there in original research, each one with -a special investigation and each one anxious to devote as much time as -possible to his research; only the most complicated adjustment makes -it possible at all, and yet the mutual disturbance, the necessity of -passing through rooms in which other men are working, and of stopping -the work when other men need the place interfere every day with the -success of the instruction. A mechanical workshop is an urgent need of -our laboratory, and yet we cannot afford the room; and while the only -desirable arrangement would be to have the psychological lectures in -the same building where the apparatus is stored,--as the instruments -are necessary for the experimental demonstrations,--there is no room -for the lectures under the roof of Dane Hall, which houses the Bursar's -Office and Coöperative Stores. The result is that the instruments -must be carried through the yard in rain or shine, an effective way -to damage our valuable equipment. But the evils connected with the -present locality of the psychological laboratory are not only such -as result from its narrowness. Its position on Harvard Square, with -the continuous noise and the vibration of the ground, is perfectly -prohibitory for large groups of psychological studies and disturbing -for every kind of work for which concentration of attention is a -fundamental condition. Finally a psychological laboratory, perhaps -still more than a physical one, needs in its whole construction a -perfect adaptation to its special purpose; the walls, the shape, and -the connection of the rooms, everything must be built, as has been -done in other universities, for the special end. We have merely the -rooms of the old Law School with thin partitions dividing them. In -short everything is in a state which was tolerable during the last few -years only because it was felt as provisional, but the time when the -psychological laboratory must have really adequate quarters cannot be -postponed much longer. - -The needs of the psychological work can thus be easily demonstrated to -every beholder; but while perhaps less offensive on the surface, the -outer conditions of the other branches of the Philosophical Department -are not therefore less unsatisfactory. The advanced student of logic -or ethics does not need a laboratory, but he needs seminary-rooms with -a working library where his work may have a local centre, where he -can meet his instructors and his fellow students engaged in related -researches, where he may leave his books and papers. To-day all this -theoretical work has no home at all; the seminaries seek refuge in -an empty room of the laboratory at a late evening hour, in a chance -lecture-room, or in private homes; there is nowhere continuity, no -place to collect or to deposit, no opportunity to meet beyond official -hours, no feeling of coherence suggested by surroundings. The most -advanced research work of the country is thus done under external -conditions which suggest the spirit of a schoolroom, conditions which -deprive students and instructors equally of the chance to make our -seminaries the fitting forms for their rich content. But if all this is -most deeply felt by the advanced students, it is not less true and not -less deplorable for the undergraduate courses. There is nowhere fixity -of association between the work and the room. The philosophy courses -are scattered over the whole yard, wandering each year from one quarter -to the other, creeping in wherever a vacant room can be found, not even -the instructors knowing where their nearest colleagues are meeting -students. The dignity and the unity of the work are equally threatened -by such a state of affairs. There remains not even a possibility for -the instructor to meet his students before or after the lecture; his -room is filled up to the time when he begins and a new class rushes -in before he has answered questions. A business-like restlessness -intrudes into the instruction, and yet philosophy above all needs a -certain repose and dignity. - -Thus what we need is clear. We need a worthy monumental building at a -quiet central spot of the Harvard yard, a building which shall contain -large and small lecture-rooms, seminary-rooms, a reading-room, and -one whose upper story shall be built for a psychological laboratory, -so that under one roof all the philosophical work, metaphysical -and ethical, psychological and logical, may be combined. Here the -elementary and the advanced work, the lecture courses and the -researches, the seminaries and the experiments, the private studies in -the reading-room and the conferences and meetings of the assistants -would go on side by side. Here would be a real school of philosophy -where all Harvard men interested in philosophy might find each other -and where the students might meet the instructors. - -Such a home would give us first, of course, the room and the -external opportunities for work on every plane; it would give us -also the dignity and the repose, the unity and the comradeship of a -philosophical academy. It would give us the inspiration resulting from -the mutual assistance of the different parts of philosophy, which -in spite of their apparent separation are still to-day parts of one -philosophy only. All this would benefit the students of philosophy -themselves, but not less good would come to the University as a -whole. The specialization of our age has brought it about that in -the organization of a university, even philosophy, or rather each of -the philosophical branches, has become an isolated study coördinated -with others. The average student looks to psychology as to physics -or botany; he thinks of ethics as he thinks of economics or history; -he hears about logic as coördinated with mathematics, and so on. The -University has somewhat lost sight of the unity of all philosophical -subjects and has above all forgotten that this united philosophy is -more than one science among other sciences, that it is indeed the -central science which alone has the power to give inner unity to the -whole university work. Every year our universities reward our most -advanced young scholars of philology and history, of literature and -economics, of physics and chemistry, of mathematics and biology with -the degree of Ph.D., that is of Doctor Philosophiae, thus symbolically -expressing that all the special sciences are ultimately only branches -of philosophy; but the truth of this symbol has faded away from the -consciousness of the academic community. All knowledge appears there as -a multitude of scattered sciences and the fact that they all have once -been parts of philosophy, till one after the other has been dismissed -from the mother arms, has been forgotten. A school of philosophy as a -visible unity in the midst of the yard will renew this truth and thus -give once more to the overwhelming manifoldness of intellectual efforts -of our University a real unity and interconnection; the external -connection of administration will be reënforced by the inner unity of -logical interdependence. - -The time is ripe for a school of philosophy to play this rôle and to -fulfil again its old historical mission, to be the unifying principle -of human knowledge and life. The second half of the nineteenth century -was essentially controlled by realistic energies, by the spirit of -analysis, by the triumph of natural science and technique. But a long -time before the century came to an end a reaction started throughout -the whole intellectual globe; the synthetic energies again came to -the foreground, the idealistic interests were emphasized in the most -different quarters; the historical and social sciences make to-day the -same rapid progress which fifty years ago characterized the natural -sciences, and everywhere in the midst of the empirical sciences -there is awakening again the interest in philosophy. In the days of -anti-philosophical naturalism scientists believed that philosophy -had come to an end and that an unphilosophical positivism might -be substituted for real philosophy; to-day the mathematicians and -physicists, the chemists and biologists, the historians and economists -eagerly turn again and again to philosophy, and on the borderland -between philosophy and the empirical sciences they seek their most -important problems and discussions. The world begins to feel once more -that all knowledge is empty if it has no inner unity, and that the -inner unity can be brought about only by that science which enquires -into the fundamental conceptions and methods of thought with which the -special sciences work, into the presuppositions and ultimate axioms -with which they begin, into the laws of mental life which lie at the -basis of every experience, into the ways of teaching the truth, and -above all into the value of human knowledge, its absolute meaning and -its relation to all the other human values--those of morality, beauty, -and religion. The most advanced thinkers of our time are working to-day -in all fields of knowledge to restore such a unity of human life -through philosophy. To foster this spirit of the twentieth century in -the life of our University there is no more direct way possible than to -give a dignified home to the philosophical work. Such a building ought -to be a Harvard Union for scholarly life. - -The beautiful building which we see in our minds should not be -devoted to a single system of philosophy. In its hall we hope to see -as greeting for every student the busts of Plato the Idealist and -Aristotle the Realist, of Descartes and Spinoza, of Bacon and Hobbes, -of Locke and Hume and Berkeley, of Kant and Fichte and Hegel, of Comte -and Spencer, of Helmholtz and Darwin. The School of Philosophy will -be wide open to all serious thought, as indeed the members of the -Department to-day represent the most various opinions and convictions. -This ought never to be changed; it is the life-condition of true -philosophy. Yet there is one keynote in all our work: a serious, -critical, lofty idealism which forms the background of the whole -Department and colors our teaching from the elementary introductions -to the researches of our candidates for the doctor's degree. All the -public utterances which have come from the Department in recent years -are filled with this idealism, in spite of the greatest possible -variety of special subjects and special modes of treatment. Here belong -The Will to Believe and the Talks to Teachers, by William James, the -Noble Lectures and the Glory of the Imperfect, by George Herbert -Palmer, Poetry and Religion, by George Santayana, The Principles of -Psychology, and Psychology and Life, by Hugo Münsterberg, Jesus Christ -and the Social Question, by Francis Peabody, Educational Aims and -Educational Values, by Paul Hanus, Shaftesbury, by Benjamin Rand, the -Conception of God, and The World and the Individual, by Josiah Royce. - -We have sought a name which might give symbolic expression to this -underlying sentiment of idealism and might thus properly be connected -with the whole building. It cannot be that of a technical philosopher. -Such a name would indicate a prejudice for a special system of -philosophy, while we want above all freedom of thought. It ought to be -an American, to remind the young generation that they do not live up -to the hopes of the School of Philosophy if they simply learn thoughts -imported from other parts of the world, but that they themselves as -young Americans ought to help the growth of philosophical thought. It -ought to be a Harvard man--a man whose memory deserves that his name -be daily on the lips of our students, and whose character and whose -writing will remain a fountain of inspiration. Only one man fulfils all -these demands perfectly: Ralph Waldo Emerson. It is our wish and hope -that the new, dignified, beautiful home of philosophy may soon rise as -the moral and intellectual centre of Harvard University and that over -its doors we shall see the name: Emerson Hall--School of Philosophy. - - -III. EMERSON AS PHILOSOPHER - - [The following address was delivered at Harvard University, May, - 1903, as part of the Emerson Celebration:] - -At the hundredth anniversary of Emerson's birthday, Harvard University -is to take a noble share in the celebration. For years it has been one -of the deepest desires of the Harvard community to erect in the college -yard a building devoted to philosophy only. To-day this building is -secured. To be sure, the good-will of the community must still do much -before the funds allow the erection of a building spacious enough to -fulfil our hopes; but whether the hall shall be small or large, we know -to-day that it will soon stand under the Harvard elms and that over -its door will be inscribed the name: Ralph Waldo Emerson. No worthier -memorial could have been selected. Orations may be helpful, but the -living word flows away; a statue may be lasting, but it does not awaken -new thought. We shall have orations and we shall have a statue, but -we shall have now, above all, a memorial which will last longer than -a monument and speak louder than an oration: Emerson Hall will be a -fountain of inspiration forever. The philosophical work of Harvard -has been too long scattered in scores of places; there was no unity, -philosophy had no real home. But Emerson Hall will be not only the -workshop of the professional students of philosophy, will be not only -the background for all that manifold activity in ethics and psychology, -in logic and metaphysics, in æsthetics and sociology, it will become -a new centre for the whole University, embodying in outer form the -mission of philosophy to connect the scattered specialistic knowledge -of the sciences. Harvard could not have offered a more glorious gift to -Emerson's memorial. - -But the spirit of such a memorial hour demands, more than all, -sincerity. Can we sincerely say that the choice was wise, when we look -at it from the point of view of the philosophical interests? It was -beautiful to devote the building to Emerson. Was it wise, yes, was it -morally right to devote Emerson's name to the Philosophy Building? -Again and again has such a doubt found expression. Your building, we -have heard from some of the best, belongs to scientific philosophy; the -men who are to teach under its roof are known in the world as serious -scholars, who have no sympathy with the vague pseudo-philosophy of -popular sentimentalists; between the walls of your hall you will have -the apparatus of experimental psychology, and you will be expected to -do there the most critical and most consistent work in methodology -and epistemology. Is it not irony to put over the door, through which -daily hundreds of students are to enter, the name of a man who may be -a poet and a prophet, a leader in literature and a leader in life, -but who certainly was a mystic and not a thinker, an enthusiast but -not a philosopher? Not only those who belittle him to-day and who -short-sightedly deny even his immense religious influence, but even -many of Emerson's warmest admirers hold such an opinion. They love -him, they are inspired by the superb beauty of his intuitions, but -they cannot respect the content of his ideas, if they do not wish to -deny all their modern knowledge and scientific insight. Yes, for the -most part they deny that his ideas form at all a connected whole; -they are aphorisms, beautiful sparks. Did he not himself say: "With -consistency a great soul has simply nothing to do. He may as well -concern himself with his shadow on the wall." And yet how can there -be philosophy without consistency; how can we interpret reality if we -contradict ourselves? If Emerson's views of the world did really not -aim at consistency and did really ignore our modern knowledge, then -it would be better to go on with our philosophical work in Harvard -without shelter and roof than to have a hall whose name symbolizes both -the greatest foe of philosophy, the spirit of inconsistency, and the -greatest danger for philosophy, the mystic vagueness which ignores real -science. - -But Emerson stands smiling behind this group of admirers and says, -"To be great is to be misunderstood." Yes, he did say, "A foolish -consistency is the hobgoblin of little minds, adored by little -statesmen and philosophers and divines;" but he soon adds, "Of one -will the actions will be harmonious however unlike they seem." Emerson -despises the consistency of the surface because he holds to the -consistency of the depths, and every sentence he speaks is an action of -the one will, and however unlike they seem they are harmonious, and, we -can add, they are philosophical; and, what may seem to these anxious -friends more daring, they are not only in harmony with each other, -they are in deepest harmony with the spirit of modern philosophy, with -a creed which ought to be taught by the most critical scholars of -Harvard's Philosophy Hall. - -What is the essence of Emerson's doctrine in the realm of philosophy? -It seems like sacrilege to formulate anything he said in the dry terms -of technical philosophy. We must tear from it all the richness and -splendor of his style, we must throw off the glory of his metaphor, and -we must leave out his practical wisdom and his religious emotion. It -seems as if we must lose all we love. It is as if we were to take a -painting of Raphael and abstract not only from the richly colored gowns -of the persons in it, but from their flesh and blood, till only the -skeletons of the figures remained. All beauty would be gone, and yet we -know that Raphael himself drew at first the skeletons of his figures, -knowing too well that no pose and no gesture is convincing, and no -drapery beautiful if the bones and joints fit not correctly together. -And such a skeleton of theoretical ideas appears not only without -charm, it appears necessarily also uninteresting, without originality, -commonplace. All the philosophies, from Plato to Hegel, brought down to -their technical formulas, sound merely like new combinations of trivial -elements, and yet they have made the world, have made revolutions and -wars, have led to freedom and peace, have been mightier than traditions -and customs; and it is true for every one of them that, as Emerson -said, "A philosopher must be more than a philosopher." - -There are, it seems, three principles of a philosophical character -without which Emerson's life-work cannot be conceived. To bring -them to the shortest expression we might say, Nature speaks to us; -Freedom speaks in us; the Oversoul speaks through us. There is no -word in Emerson's twelve volumes which is inconsistent with this -threefold conviction, and everything else in his system either follows -immediately from this belief or is a non-essential supplement. But -that threefold faith is a courageous creed indeed. The first, we said, -refers to Nature; he knew Nature in its intimacy, he knew Nature in -its glory; "Give me health and a day and I will make the pomp of -emperors ridiculous." And this Nature, that is the assertion, is not -what natural sciences teach it to be. The Nature of the physicist, the -dead world of atoms controlled by the laws of a dead causality, is not -really the Nature we live in; the reality of Nature cannot be expressed -by the record of its phenomena, but merely by the understanding of its -meaning. Natural science leads us away from Nature as it really is. We -must try to understand the thoughts of Nature. "Nature stretches out -her arms to embrace man; only let his thoughts be of equal greatness;" -and again Emerson says, "All the facts of natural history taken by -themselves have no value, but are barren like a single sex; but -marry it to human history and it is full of life;" and finally, "The -philosopher postpones the apparent order of things to the empire of -Thought." - -And in the midst of Nature, of the living Nature, we breathe in -freedom; man is free. Take that away and Emerson is not. Man is free. -He does not mean the freedom of the Declaration of Independence, a -document so anti-Emersonian in its conception of man; and he does not -mean the liberty after which, as he says, the slaves are crowing while -most men are slaves. No, we are free as responsible agents of our -morality. We are free with that freedom which annuls fate; and if there -is fate, then freedom is its most necessary part. "Forever wells up the -impulse of choosing and acting in the soul." "So far as man thinks he -is free." "Before the revelations of the soul, time, space, and nature -shrink away." "Events are grown on the same stem with the personality; -they are sub-personalities." "We are not built like a ship to be -tossed, but like a house to stand." This freedom alone gives meaning to -our life with its duties, and puts the accent of the world's history on -the individual, on the personality: "All history resolves itself very -easily into the biography of a few stout and earnest persons," and "An -institution is the lengthened shadow of a man." - -Nature speaks to us, Freedom speaks in us, but through us speaks a Soul -that is more than individual, an over-individual soul, an "Oversoul, -within which every man is contained and made one with all others." -Now even "Nature is a great shadow, pointing always to the sun behind -her." Every one of us belongs to an absolute consciousness which in us -and through us wills its will; "Men descend to meet" and "Jove nods to -Jove from behind each of us." Yes, "Man is conscious of a universal -soul within or behind his individual life, wherein as in a firmament -justice, truth, love, freedom arise and shine." The ideals, the duties, -the obligations, are not man's will but the will of an Absolute. - -Does not all this sound like a wilful denial of all that has been fixed -by the sciences of our time? Does not every Sophomore who has had his -courses in Physics, Psychology, and Sociology know better? He knows, -we all know, that the processes of Nature stand under physical laws, -that the will of man is the necessary outcome of psychological laws, -that the ideals of man are the products of human civilization and -sociological laws. And if every atom in the universe moves according -to the laws which physics and chemistry, astronomy and geology, have -discovered, is it not anti-scientific sentimentality to seek a meaning -and thoughts in the mechanical motions of the dead world of substance? -So the poet may speak, but we ought not to say that his fanciful dreams -have value for scholarly philosophers. The philosophy of the scientist -ought to be the acknowledgment that matter and energy, and space and -time are eternal, and that the smallest grain of sand and the largest -solar system move meaningless by blind causality. - -And emptier still is the naïve belief that man is free. Do we not -profit from decades of psychological labor, whereby the finest -structure of the brain has been discovered, wherein the psychological -laws have been studied with the exactitude of a natural science, -wherein we have studied the mental life of animals and children, and -have observed the illusions of freedom in the hypnotized man and in -the insane? Yes, we know to-day that every mental act, that every -psychological process is the absolutely necessary outcome of the given -circumstances; that the functions of the cells in the cortex of the -brain determine every decision and volition, and that man's deed is as -necessary as the falling of the stone when its support is taken away. -Yes, modern psychology does not even allow the will as an experience of -its own kind; it has shown with all the means of its subtle analysis -that all which we feel as our will is only a special combination of -sensations which accompany certain movement-impulses in our body. Can -we still take it seriously, when the philosopher steps in and pushes -sovereignly aside all the exact knowledge of mankind, and declares -simply "Man's will is free!" - -Finally, the claim for the over-personal, absolute consciousness in -man. It is a triumph of modern science to understand how the duties and -ideals have grown up in the history of civilization. What one nation -calls moral is perhaps indifferent or immoral for another people or -for another time; what the one calls beautiful is ugly for the other; -what one period admires as truth is absurdity for another; there is no -absolute truth, no absolute beauty, no absolute religion, no absolute -morality; and sociology shows how it was necessary that just these -ideals and just these obligations should have grown up under a given -climate and soil, a given temperament of the race, a given set of -economical conditions, a given accumulation of technical achievements. -Man has made his Absolute, not the Absolute made man, and whatever -hopes and fears make men believe, the scholarly mind cannot doubt that -these beliefs and idealizations are merely the products of the feelings -and emotions of individuals bound together by equal conditions of life. -Leave it to the raptures of the mystic to ignore all scientific truth, -to get over-soul connection beyond all experience. In short, to accept -Emerson's philosophy, the scientist would say, means to be a poet where -Nature is concerned, means to be ignorant where man is concerned, and -means to be a mystic where moral and religious, aesthetic and logical -ideals are concerned. Can such be the herald of modern philosophy? - -But those who are so proud and so quick are not aware that the times -have changed and that their speech is the wisdom of yesterday. In the -history of human knowledge the periods alternate. Great waves follow -each other, and while one tendency of scientific thought is ebbing, -another is rising; and there is no greater alternation than that -between positivism and idealism. The positivistic period of natural -science has ebbed for ten or fifteen years; an idealistic one is -rising. Emerson once said here in Harvard that the Church has periods -when it has wooden chalices and golden priests, and others when it -has golden chalices and wooden priests. That is true for the churches -of human knowledge too, and for knowledge of all denominations. -Forty, fifty years ago, in the great period when Helmholtz discovered -the conservation of energy and Darwin the origin of species, one -naturalistic triumph followed the other, golden high priests of -natural science were working with wooden chalices in narrow, awkward -laboratories; to-day natural science has golden chalices provided -in luxurious institutions, but there are too many wooden priests. -The fullest energies of our time are pressing on to an idealistic -revival, are bringing about a new idealistic view of the world, and -turning in sympathy to that last foregoing period of idealism of -which Ralph Waldo Emerson was perhaps the last original exponent. -But also with his period idealism was not new. When he came to speak -on the Transcendentalist, he began, "The first thing we have to say -respecting the new views here in New England is that they are not new." -Yes, indeed; since the beginnings of Greek philosophy, more than two -thousand years ago, the two great tendencies have constantly followed -each other. Each one must have its time of development, must reach its -climax, must go over into undue exaggeration, and thus destroy itself -to make room for the other, which then begins in its turn to grow, to -win, to overdo, and to be defeated. - -Glorious had been the triumph of Positivism in the middle of the -eighteenth century when the French encyclopædists were at work, those -men who wrote the decrees for the French Revolution. But before the -last consequences of the Positivism of the eighteenth century were -drawn, the idealistic counter-movement had started. Immanuel Kant -gave the signal, he fired the shot heard round the world; and Fichte -followed, whose ethical Idealism changed the map of Europe, and his -spirit went over the Channel to Carlyle, and finally over the ocean to -these shores of New England and spoke with the lips of Emerson. It is -unimportant whether Emerson studied the great transcendental systems -in the original; he knew Kant and Schelling probably at first through -Coleridge, and Fichte through Carlyle. But in the mean time Idealism -too had exaggerated its claims, it had gone forward to Hegel, and -while Hegelian thought, about 1830, held in an iron grasp the deepest -knowledge of his time, his neglect of positive experience demanded -reaction, a counter-movement became necessary, and in the midst of -the nineteenth century the great idealistic movement with all its -philosophical and historical energies went down, and a new Positivism, -full of enthusiasm for natural science and technique and full of -contempt for philosophy, gained the day. With logical consistency, -the spirit of empiricism went from realm to realm. It began with the -inorganic world, passed into physics, then forward to chemistry, became -more ambitious and conquered the world of organisms, and when biology -had said its positivistic say, turned from the outer nature of being -to the inner nature. The mind of man was scrutinized with positivistic -methods; we came to experimental psychology, and finally, as the -highest possible aim of naturalism, to the positivistic treatment of -society as a whole, to sociology. But naturalism again has overdone its -mission, the world has begun to feel that all the technique and all the -naturalistic knowledge makes life not more worth living, that comfort -and bigness do not really mean progress, that naturalism cannot give -us an ultimate view of the world. And above all, the reaction has come -from the midst of the sciences themselves. Twenty years ago scientific -work received its fullest applause for the neglect of philosophical -demands. Ten years ago the feeling came up that there are after all -problems which need philosophy, and to-day philosophers, with good or -bad philosophy, are at work everywhere. The physicists, the chemists -and the biologists, the astronomers and the mathematicians, the -psychologists and the sociologists, the historians and the economists, -the linguists and the jurists, all are to-day busily engaged in -philosophical enquiries, in enquiries into the conditions of their -knowledge, into the presuppositions and methods of their sciences, into -their ultimate principles and conceptions; in short, without a word -of sudden command, the front has changed its direction. We are moving -again towards philosophy, towards Idealism, towards Emerson. - -Does all this mean that we are to forget the achievements of natural -science, and ignore the results of empirical labor, of labor which has -given us an invincible mastery of stubborn nature and an undreamed-of -power to calculate all processes of the physical and of the psychical -world? No sane man can entertain such a notion. Yes, such ideas -would contradict the laws which have controlled the alternation -of Idealism and Positivism through the ages of the past. Whenever -Positivism returned, it always showed a new face, and the teaching of -the intervening period of Idealism was never lost. The naturalism of -the middle of the nineteenth century was not at all identical with the -naturalism of the middle of the eighteenth; and so Idealism too, as -often as it returned to mankind after periods of neglect and contempt, -had every time gained in meaning, had every time found increased -responsibilities, had every time to do justice to the new problems -which the preceding period of Positivism had raised. If Idealism -to-day wants to gain new strength, nothing must be lost of all that -the last fifty years have brought us, no step must be taken backward, -the careful scientific work of the specialists must be encouraged and -strengthened, and yet the totality of this work must be brought under -new aspects which allow a higher synthesis; yes, a higher synthesis -is the problem of the philosopher of to-day. He does not want to be -ignorant of natural science and simply to substitute idealistic demands -in the place of solid, substantial facts; and he should feel ashamed -of the foul compromise with which half-thinkers are easily satisfied, -a compromise which allows science its own way till it comes over -the boundaries of human emotions, a compromise which accepts rigid -causality but pierces little holes in the causal world, making little -exceptions here and there that human freedom may be saved in the midst -of a world-machinery; a compromise which accepts the social origin -of ideals, but claims a mystic knowledge that just our own private -pattern will remain in fashion for eternity. No philosophy can live -by compromises. If natural science is to be accepted and Idealism is -to hold its own, they must be combined, they must form a synthesis in -which the one no longer contradicts the other. Just such synthetic -harmonization, and not at all a stubborn ignorance of the other side -or a compromise with cheap concessions, was the aim of the period from -Kant to Emerson. It is merely the naturalistic period which ignores its -idealistic counterpart, which delights in its one-sidedness, which is -afraid of harmony because it is suspicious of demands for concessions. -It is naturalism only which thinks that mankind can walk on one leg. - -If we ask where such harmonization can be found, where the great -Idealists of the beginning of the last century have sought it, and -where our modern philosophy is seeking it again, well aware that by -the progress of science in the mean time the difficulties have been -multiplied, the logical responsibilities have become gigantic, we -cannot do more here than to point out the direction; we cannot go -the way. And it is clear, of course, too, that such an answer has its -individual shape, and that no one can promise to give a bird's-eye -view of the marching movement while he is himself marching among his -comrades. But the individual differences are non-essential. The one -great tendency, the Emersonian spirit, if it is rightly understood, -is common to them all. What has modern philosophy all over the world -to say about that threefold claim concerning Nature, Freedom, and -Oversoul? What has it to say when natural science has fully said its -say and had its fair hearing, and has been approved as sound and -welcome? - -A philosopher might answer, perhaps, as follows: You Positivists have -done wonderfully with your microscopes and your telescopes, with your -chronoscopes and spectroscopes; you have measured and weighed and -analyzed and described, and finally explained the whole world which you -perceive, and there is nothing in space and time and causality which -can escape your search. But did not all that work of yours involve -certain presuppositions which you had accepted and which it was not -your business to look on critically, but which, nevertheless, may be -open to enquiry? Your first claims granted, all may follow; but how is -it with the first claims? You examine all that is in space and time, -but what are space and time? You examine the material substances and -the contents of consciousness, but what is consciousness, and what is -matter? You seek the special applications of causality, but what is -causality? Well, you reply, you give the facts just as you find them; -but do you do that really? And what do you mean by saying that you find -the facts? Let us look, at least for a moment, at the very simplest -facts with which your work begins. You say there are physical objects -made up of atoms, and you describe them as a physicist; and there are -mental ideas in consciousness made up of sensations, and you describe -them as a psychologist; and both, you say, you are finding. But what -does it mean, that you find the physical object outside there and the -mental idea of the object inside in you; is that really a statement -of your immediate experience? The physicist speaks of this table here -before me, outside of me; and the psychologist speaks of my idea of -this table, enclosed in my consciousness. Both may do well to speak -so; but will you make me believe that I find that doubleness in my -experience? If I see this table and want to use it, I am not aware -of one table of wooden stuff and another in me of mental stuff. I am -not aware of a two-ness at all, and if the physicist says that this -wooden table is made up of molecules and has in itself no color and -no continuity, and that the mental idea in me furnishes all those -qualities of color and smoothness, but has no solidity, then they -speak of two interesting worlds about which I am anxious to know, but -certainly neither of them is the world I live in. If I lean on this -table I am not aware of a table in my mind at all. I know the one table -only, and this one table has its color and its smoothness. - -I know what you will answer. You will say, in your immediate experience -there are indeed not two worlds of objects, a physical and a -psychical; the real thing to which our interests in life refer is not -differentiated into a molecular object outside of us and a sensational -object in us, but it is clear that every real thing allows a kind of -double aspect; we can consider this table in so far as it is common to -all of us, in so far as it is a possible object for every one of us, -and in so far as it becomes an object for the individual, and we can -then call the objects, in so far as they are common property, physical; -and in so far as we take the aspect of individual relations, psychical; -and as it must be of the highest importance for our practical purposes -to discriminate between those two aspects, we have clearly the right -to consider the world from the point of view of both the physicist -and the psychologist. It is, of course, an abstraction if we leave -out in the one case the one side, in the other case the other side -of our objective experience; but we gain by that the possibility of -constructing two closed causal systems of which each one must have its -special conditions of existence, inasmuch as the one is conceived as -related to individuals and the other as independent of individuals. - -Very true, we should answer. Something like that saves you completely, -justifies fully your claim to separate the physical and the psychical -worlds of objects, the world of matter and the world of ideas; but -can you deny that you have lost your case, are you not now yourself -in the midst of philosophical, methodological discussions, which your -physics and psychology themselves cannot settle, yet which must be -settled before they can enter into their rights; and above all, do you -not yourself see now that your whole physics, for instance, is not at -all an account of reality, but merely a certain logical transformation -of reality; that you do not find the world of physics at all, just as -little as you find the psychical ideas, but that you can merely work -over and reshape the reality which you find till you construct out -of it your world of matter and your world of consciousness? What you -believed you would find you have never found, while your construction -of physical things may have been most necessary for your purposes; but -do not deny that you have left reality far behind you. - -And so it is with all your doings. You tell us proudly, for instance, -that you show us the deepest nature of the world by showing us the -elements which the object contains, and that you thus bring us at least -nearer to the essence of things; and yet if we begin to look into your -real achievements, we are disappointed again to find that you are far -away from even attempting anything of the kind. You tell us that water -is hydrogen and oxygen, and if we say "Prove it," you show us simply -that you can transform the water into hydrogen and oxygen, and that -you can transform these two elements again into water. Is that really -what you promise? We want to know what the thing is, and you show us -simply how the one thing can be transformed into another thing; and -whenever we turn to your wisdom, it is always the same story. You show -us always, and most nicely, how the one goes over into the other, but -you never show us what the one or the other really is in itself. For -your practical purposes the first may be the most important aspect, -but do not make us believe, therefore, that it is the only possible -aspect. In short, whether science describes or explains, it never -gives us what we find in reality, but makes out of reality a new ideal -construction in the service of certain purposes, and never gives us -the things as they are, but merely the effects and changes which they -produce. Are we still, then, to be deeply impressed with the claim -of the naturalist that he alone has the monopoly of knowing reality, -while we see now that every step of his leads us away from reality? And -have we still to be afraid to raise the voice as philosophers with the -claim that reality itself must find its expression, that there must be -a science which shall give account of reality as we really find it, -of nature before it is made up and repolished for the purposes of the -physicist? Only if we have such other account of nature, then only -do we speak of that nature in which we live and in which we act, and -compared with such an account of the fuller reality, the constructed -schematism of the physicist must appear, indeed, as Emerson said, -"barren like a single sex." Not the slightest result of natural science -is depreciated, not the slightest discovery ignored, if we insist that -all these so-called facts have a meaning only under certain artificial -conditions which set them apart from the reality of our life; and in -this reality lies the interest of the philosopher. We have thus no -reason to reproach the scientist so long as the scientist does not -fancy that his science gives an account of nature as it really is. Both -kinds of work are necessary, and the scientist may well speak, as the -squirrel in Emerson's poem: - - "Talents differ, - All is well and wisely put; - If I cannot carry forests on my back, - Neither can you crack a nut." - -Natural science has to crack our nuts, but philosophy has to carry -on its back the flourishing forests of life, in which we wander and -breathe. And if Emerson is right, to-day and forever, in claiming that -the facts of natural science are not expressions of reality, it is only -a small step to see that he was not less right in saying that man is -free. Consider man as a particle in the physical universe, consider his -actions from the point of view of a causal science, and there is no -possibility of escaping materialism and fatalism. We must understand -every activity as a necessary outcome of foregoing conditions. -Psychology must do so, and physics must do the same. The empirical -sciences would be disloyal to their own principles if they allowed -the slightest exception. The noblest gesture, the greatest word, the -bravest action, must be considered by them under the category of -causality. They are necessary effects of all the preceding causes. It -may be interesting, it may be fascinating to follow such lines with the -enthusiastic energy of scholarly research. But are we really obliged -to accept the outcome as an ultimate word concerning the meaning of -our freedom? "Forever wells up the impulse of choosing and acting in -the soul." Is it really merely an illusion? Has responsibility still -its moral value, are we the actors of our actions, are we still good, -are we still guilty, when every deed follows as necessary effect? Is -not, then, the whole constitution of the world, which has made us, -responsible whenever we move our hand for good or for bad? - -But we know now where we are standing; we know now that the world -of objects, of psychical as well as of physical, is a constructed -world, constructed for the purpose of satisfying our demand for causal -connection; for that world holds causality because it is the world -seen from the point of view of causality; and just as there cannot be -anything in that world of physical and psychical objects which is not -causally connected, just so it cannot have any meaning at all to ask -for causal connection before the world is conceived in the service of -this artificial construction. Reality in itself is not causal, and to -ask for the causes of the real experience of our inner life has not -more meaning than to ask how many pounds is the weight of a virtue, and -how many inches is the length of our hopes. But we must go farther. -To apply the question of cause and effect to our real will means not -only that we apply to the real object a standard which belongs to -the artificial or constructed object, but it means above all that we -consider as an object something which in reality is not an object at -all. The will which the psychologist describes and must describe, the -will which has causes and which is thus not free, is a will conceived -as an object found in our mind like an idea, something of which we are -aware, something whose happening we perceive, and yet if anything is -sure it is the immediate experience that we are aware of our will in -a way which is absolutely different from the way in which we perceive -objects. We do not perceive our will at all, we will it, we strive -it, we fight it; yes, we feel ourselves, only in so far as we are the -subjects of will. Our will is our personality, which we do not find but -which we are, and which stands opposed and separated by the deepest -gulf from the world of objects. Those objects are means and purposes of -our will, are ends and aims and instruments; but they come in question -for us only as we will them, as we like and dislike them, as we approve -and reject them. And if we take this world of objects and reconstruct -it into the artificial world of physical and psychical things connected -by causality, in this very act of reconstruction we feel ourselves as -willing, deciding, approving, aiming personalities, whose wills decide, -who think the world as causally connected, whose freedom guarantees -the value of our conception of a world not free. There is no knowledge -but in our judgments; there is no judgment but in our affirming and -denying; there is no affirming and denying but in our will. Our will -chooses for its purposes to conceive reality as if it were unfree. -What a climax of confusion to think that this conception of an unfree -world, the conception of science, can itself now condemn the freedom -of the will which has chosen. "Freedom is necessary," said Emerson. We -can add, necessity itself is merely a purpose determined by freedom. -"Intellect annuls fate," Emerson says. We may add, fate is merely an -idea of intellect. Let us be psychologists if we want to analyze, to -calculate, to explain the unfree man; but let us be philosophers to -understand what it means to be a psychologist. Now the synthesis is -reached; the real world is free, but we choose for our purposes to -conceive the world as unfree, and thus to construct causal sciences. - -And if we understand that in reality man is free and that the -psychological aspect of man as unfree is a special way of looking on -man for special purposes, then suddenly there opens itself before -us the vast field of history, and the historical life, which seemed -deprived of all interest by the psychological, iconoclastic mood, -suddenly wins again a new importance. We feel instinctively that -this free man of reality, this man who is a responsible actor of his -actions, he only is the agent of history; and history is falsified -and cheapened when it is brought down to a causal explanation of -psychological man instead of real man. History had become an appendix -of sociology, and what great historians aimed at in the interpretation -of the few "stout and earnest personalities" seemed lost in favor of a -construction in which the great man and the genius rank with the fool -as mere extreme variations of psychological averages. Now suddenly do -we understand that history has to deal with the world of freedom, that -it has not to explain, but to interpret, that it has not to connect -the facts by linking causes and effects, but by understanding the -meaning of purposes, their agreement and disagreement, their growth -and liberty. Now we understand why Fichte, why Carlyle, why Emerson -believes in heroes and hero-worship, why Idealism has been at all -times the fertile ground for writing history and for making history, -while Naturalism has made technique, and thought in an anti-historical -spirit. Our time begins again to think historically. It can do so -because it again begins to emancipate itself from its positivistic -disbelief in man's freedom and from its unphilosophic superstition that -causal science alone is science, that we know only when we explain. - -And when we at last stand man to man in full freedom, no longer as -psycho-physical constructions but as free personalities, and when we -debate and try to convince each other, will you deny that Jove stands -behind each of us and Jove nods to Jove when we meet? Would it even -have a meaning for us to go on with our talk, should we try at all -to convince each other if you thought and I thought, each one for -himself, that our will is only our personal will, that there is no -over-individual will, no Oversoul behind us? Can we discuss at all if -we do not presuppose that there is really a truth which we are seeking -in common, that there are certain judgments which we are bound to will, -which we are obliged to affirm, which we will, but not as individuals, -and of which we take for granted that every one whom we acknowledge -at all as a personality must will them too; and if you come with the -flippant air of the sceptic and tell me, "No, there is no truth, all -is only as it appears to me, there is no objective truth," do you not -contradict yourself, are you not saying that at least this, your own -statement, expresses objective truth; that you will this with a faith -and belief that this will of yours is an over-individual will which -is, as such, a duty, an obligation for every one who thinks? Every -escape is futile. And all the over-individuality that lives in our -will towards truth comes to us again in our will towards morality. Do -not say sceptically that there is no absolute obligation, that you do -not feel bound by an over-individual will in your action, that you -will do in every moment what pleases you individually. You cannot even -speak this sceptical word without contradicting yourself again, as you -demand through the fact of your saying it that we believe that you -speak the truth and that you thus feel yourself bound not to lie. If -you leave us doubtful whether your word was not a lie, the word itself -cannot have any meaning. Do not try to dodge the Oversoul. Men live -and fight in its purposes, and men descend to meet. It is as Emerson -said, "At first delighted with the triumph of the intellect, we are -like hunters on the scent and soldiers who rush to battle; but when the -game is run down, when the enemy lies cold in his blood at our feet, -we are alarmed at our solitude." Let the sociologists triumphantly -reduce the ideals to necessary social products of evolution in the -same spirit in which the psychologist eliminates the freedom of the -individual; but let us never forget that such a social mechanism is as -much an artificial construction necessary for its purposes as is the -psycho-physical mechanism of individuality. In that reality with which -history deals, in which our freedom lies, there our over-individual -will comes from deeper ground than from the soil and the food and the -climate. Our logical obligations, our ethical duties, our æsthetic -appreciations, our religious revelations, in reality they do not come -from without, they come from within; but from within as far as we are -souls in the Oversoul. There is no duty in the world but the duty -which we will ourselves; no outer force, no training, no custom, no -punishment can make us have duties. Duty is our will, it may be the -duty to think for the ideal of truth, the duty to feel for the ideal -of æsthetics, the duty to act for the idea of morality, the duty to -have faith in the ideal of religion; but it is always our own will, -and yet not our fanciful, personal, individual will. It is a system -of purposes upon whose reality all knowledge of the world, and thus -the world as we know it, is dependent forever. The wave of Idealism -is rising. The short-sighted superstition of Positivism will not lurk -under the roof of a new hall of philosophy. To be a true student of -the most scientific, of the most scholarly, of the most insistent -philosophy means to respect and to study the sciences, the physical and -the psychical sciences, but at the same time to understand that natural -science is not the science of reality, that psychology does not touch -the freedom of man, that no life has a meaning without the relation to -the Oversoul. We cannot write a whole system and a whole text-book -on the front of the new building. It must be enough to write there a -symbolic word; happy, forever happy, the university which can write -over the door of its temple of philosophy the name: Ralph Waldo Emerson. - - -IV. THE PLACE OF EXPERIMENTAL PSYCHOLOGY - - [At the opening of Emerson Hall, December 27, 1905, the American - Psychological Association discussed the relation of psychology to - philosophy; I opened the discussion with the following remarks:] - -From the whole set of problems which cluster about psychology and its -relation to neighboring sciences, this hour, in which Emerson Hall is -completed, and this room, in which I hope to teach psychology to the -end of my life, suggest to me most forcibly to-day the one question: -Have I been right in housing psychology under this roof? I might have -gone to the avenue yonder and might have begged for a psychological -laboratory in the spacious quarters of the Agassiz Museum, to live -there in peaceful company with the biologists; or I might have -persuaded our benefactors to build for me a new wing of the physical -laboratory. But I insisted that the experimental psychologists feel at -home only where logic and ethics, metaphysics and epistemology keep -house on the next floor. - -I certainly do not mean that the psychologist ought to mix the records -of his instruments with the demands of his speculations, and that he -may seek help from the Absolute when the figures of the chronoscope -or the curves of the kymograph are doubtful. Experimental psychology -is certainly to-day and will be for all future an independent exact -discipline with its own problems and methods. No one can insist more -earnestly than I do on the demarcation line between the empirical study -of mental phenomena and the logical enquiry into the values of life. - -Yet I deny that it is a personal idiosyncrasy of mine to try to combine -vivid interest in both. There is no antagonism between them; a man may -love both his mother and his bride. I am devoted to philosophy, just -as I love my native country; and I am devoted to psychology, just as I -love the country in which I do my daily work; I feel sure there is no -reason for any friction between them. - -Of course, on the surface a psychological laboratory has much more -likeness to the workshop of the physicist. But that has to do with -externalities only. The psychologist and the physicist alike use subtle -instruments, need dark rooms and sound-proof rooms, and are spun -into a web of electric wires. And yet the physicist has never done -anything else than to measure his objects, while I feel sure that no -psychologist has ever measured a psychical state. Psychical states are -not quantities, and every so-called measurement thereof refers merely -to their physical accompaniments and conditions. The world of mental -phenomena is a world of qualities, in which one is never a multiple of -the other, and the deepest tendencies of physics and psychology are -thus utterly divergent. - -The complicated apparatus is therefore not an essential for -the psychologist. Of course, we shall use every corner of our -twenty-four laboratory-rooms upstairs, and every instrument in the -new cases--and yet much of our most interesting work is done without -any paraphernalia. Three of the doctor-dissertations which our -psychological laboratory completed last year consisted of original -research in which no instruments were involved; they dealt with -memory-images, with associations, with æsthetic feeling, and so -on. Yes, when, a short time ago, a Western university asked me how -much it would cost to introduce a good practical training-course in -experimental psychology, I replied that it would cost them the salary -of a really good psychologist, and besides, perhaps, one dollar for -cardboard, strings, rulers, colored paper, wire, and similar fancy -articles at five cents apiece. - -On the other hand, I do not know a psychological experiment which -does not need a philosophical background to bring its results into -sharp relief. Of course, you will say, the psychologist deals with -facts, not with theories, and has to analyze and to describe and to -explain those facts. Certainly he has to do all that; only he must -not forget that the so-called "fact" in psychology is the product of -complex transformations of reality. A will, an emotion, a memory-image, -a feeling, an act of attention, of judgment, of decision--these are -not found in the way in which stones and stars are noticed. Even if -I choose perceptions or sensations as material for my psychological -study, and still more when I call them _my_ perceptions and _my_ -sensations, I mean something which I have found at the end of a long -logical road, not at its starting-point, and that road certainly leads -through philosophy. Emerson said wisely, "A philosopher must be more -than a philosopher;" we can add: A psychologist must be more than a -psychologist. First of all, he must be a philosopher. - -What would be the result if our laboratory had moved to the -naturalistic headquarters? It would be the beginning of a complete -separation from philosophy. Our graduate students would flock to -psychological research work without even being aware that without -philosophical training they are mere dilettantes. And soon enough a -merely psychological doctorate would be demanded. I do not deny at -all that such pure psychologists would find enough to do; I should -doubt only whether they know what they are doing. There are too many -psychologists already who go their way so undisturbed only because they -walk like somnambulists on the edge of the roof; they do not even see -the real problem; they do not see the depths to which they may fall. - -But does the laboratory itself gain from such divorce? Just the -contrary. It is evident that everywhere in the world where the -psychological laboratory turns to natural science, the experiments -deal mostly with sensation, perception, and reaction; while those -laboratories which keep their friendship with epistemology emphasize -the higher mental functions, experimenting on attention, memory, -association, feeling, emotion, thought, and so on. But is it not clear -that only the latter work gives to the psychological laboratory a real -right to existence, as the former is almost completely overlapped by -the well-established interests of the physiologists? If psychology -cannot do anything else than that which physiologists like Helmholtz, -Hering, Kries, Mach, Bowditch, and the rest have always done so -successfully, then experimental psychology had better give up the trade -and leave the study of the mind to the students of the organism. - -I have said that we ought not to depend on authorities here. Yet -one name, I think, ought to be mentioned gratefully in this hour in -which the new psychological laboratory is opened for work. I think -of Professor Wundt of Leipzig. The directors of the psychological -laboratories in Columbia, and Yale, in Clark and Chicago, in -Pennsylvania and Cornell, in Johns Hopkins and Washington, in Leland -Stanford and Harvard, and many more are his pupils. Some weeks ago, -when I did not foresee our present discussion, I told him of Emerson -Hall; and a few days ago I got an answer from which, as my closing -word, I may quote in translation. Professor Wundt writes to me: "I am -especially glad that you affiliated your new psychological laboratory -to philosophy, and that you did not migrate to the naturalists. -There seems to be here and there a tendency to such migration, yet I -believe that psychology not only now, but for all time, belongs to -philosophy: only then can psychology keep its necessary independence." -Mr. Chairman, these are the words of the father of experimental -psychology. I hope they indicate the policy to which Harvard University -will adhere forever. - - -V. THE PSYCHOLOGICAL LABORATORY IN EMERSON HALL - -A monumental staircase leads from the first--the lecture-room--floor -of Emerson Hall to the second, the library floor; at the two ends of -its broad corridor smaller staircases lead to the third floor, the -laboratory. Its general division of space is seen at a glance from the -sketch of the ground plan (opposite page 1). Eighteen rooms of various -sizes with outside windows form a circle around the central hall -which is well lighted by large skylights; but at each end of the hall -itself two large windowless spaces are cut off and each of these is -divided into three dark rooms. We have thus twenty-four rooms, besides -coat-room, toilet-rooms, etc. A further stair leads to the wide attic -which is mainly a store-room for the institution. - -In order that the laboratory should be adaptable to the most diverse -purposes, the permanent differentiation of the rooms has been kept in -narrow limits. It seemed unwise to give from the first every room to a -special line of research, as the preponderance of special interests may -frequently shift; there are years when perhaps studies in physiological -and comparative psychology make the largest demand and others in -which studies in æsthetical and educational psychology stand in the -foreground. A thorough-going specialization, by which special rooms -are reserved for tactual studies and others for chronoscope work or -for kymograph researches, allows of course certain conveniences in the -fixed arrangement of instruments and a certain elaboration of equipment -that is built in, but it very much impairs the flexibility of the -whole laboratory, and has thus not seemed advisable for an institution -whose catholic attitude welcomes investigations as different as those -contained in this volume. - -To be sure certain constant requirements have demanded a special -fitting up of one room as a workshop, one room for the more -delicate instruments, one for the beginning course in experimental -work, a lecture-room for the courses in comparative psychology, a -photography-room, a battery-room, a sound-proof room, the chief animal -rooms, and the dark rooms. We have seven light-proof rooms, finished -in black, of which two have outside windows for heliostats; of the -others, four can be used for optical research; the longest one contains -the photometer. Six other rooms, including the lecture-room, may be -darkened by opaque blinds. One contains a partition with door and a -grooved window-frame fitted with screens in which openings of any -desired size and shape may be cut. This window is opposite the main -door of the room, and opposite this, across the central hall, some -sixty feet away, is the door of another dark room; optical stimuli can -thus be given from this window to a subject over seventy feet away. - -Several rooms are fitted up with special reference to the investigation -of the various forms of organic movement, animal behavior and -intelligence. As one result of several investigations in animal -psychology already pursued here, the laboratory has a considerable -number of devices for testing and making statistical studies of the -senses and intelligence, methods of learning and emotional reactions of -animals. - -Adequate provision is made for the keeping of animals in a large, -well-lighted, and well-ventilated corner room. Instead of having -aquaria built into the room, an aquarium-table eighteen feet long has -been constructed to support moveable aquaria of various sizes. Whenever -it is desirable for the purposes of an investigation, any of these -aquaria may be moved to the research-room of the investigator or to -such quarters as the special conditions of the experiment demand. - -The vivarium-room contains, in addition to provisions for -water-inhabiting animals, cages of a variety of forms and sizes. The -largest of these cages, six and a half feet high, six feet wide, -and four feet deep, may be used for birds, monkeys, or any of the -medium-sized mammals. Cages for rabbits, guinea-pigs, and other small -animals are arranged in frames which support four double compartments. -Similarly, small cages suitable for mice, rats, and other small rodents -are in supporting frames which carry four of the double cages, each of -which is removeable and may be carried to the experimenting-room at the -convenience of the experimenter. - -In a large unheated room above the main laboratory are tanks for -amphibians and reptiles. These tanks, since they can be kept at a low -temperature during the winter, are very convenient and useful for -frogs, tortoises, and similar hibernating animals. - -In view of the prime importance of electricity to a modern -psychological laboratory, a rather elaborate system of wiring has -been designed and built in. The unit of this system is a small -delivery-board six inches wide by eight inches high, which carries -the following five circuits: _a_, a time-circuit for running magnetic -signals; _bb_, two low-tension circuits for chronoscope, bells, -signals, etc.; _c_, a high-tension alternating current (110 v. and 60 -phases) for alt. current motors, to be used where great constancy of -speed is desired; _d_, a high-tension direct current (110 v.) for dir. -current motors, where it is desired to vary the speed continuously (by -the introduction of resistance). Two such delivery-boards have been -set on opposite walls of all except the smallest rooms, which have -but one board. Circuits _a_ and _b_ are represented on the board by -binding-posts, while the high-tension currents, _c_ and _d_, appear as -flush, protected sockets that take a double-pole plug. - -Circuit _a_ is a single circuit led from a time-pendulum permanently -set in the battery-room, and carried once around the laboratory. It is -connected with the _a_ binding-posts of the individual delivery-boards -in parallel. It follows that the time-circuit is alike for all the -rooms at any one time; but in different hours the pendulum can be -adjusted to give various impulse-rates. If an investigation requires -some special rate of impulse, the special time-apparatus is set up in -the investigator's room and current for it taken from one of the _b_ -pairs of posts. - -Each _b_ pair goes directly from the delivery-board to the battery-room -and ends at a double-pole (telephone type) socket on a large -switch-board. Thus every room has two or four direct and independent -connections with the battery-room. - -The _c_ and _d_ circuits do not come from the battery-room, but from -their respective generators that are stationed outside of the building. -They are of course connected at the delivery-boards in parallel. - -The large switch-board in the battery-room consists of an upper and a -lower part. The upper part bears the double-pole sockets from the _b_ -posts in all the rooms; the lower part carries some fifty pairs of -single-pole sockets that are connected with the batteries stationed -near by. These pairs are labelled, and some give a current from cells -of the Leclanché type, others of a gravity type. The student has merely -to choose the kind and number of cells that he needs, from the lower -part, and connect them with one of the double-pole sockets of the -upper part which runs to a _b_ pair in his own room. By connecting -two double-pole sockets with each other, the student can establish a -circuit between any two rooms of the laboratory,--this for purposes of -telephonic or other communication. Since every room has two, and most -of the rooms have four of the _b_ circuits, the greatest variety and -elasticity of service is attained. - -The large switch-board further carries a voltmetre and an ammetre, -both of the Weston make, which are reached (electrically) from -double-pole jacks (sockets) on the upper part of the board. Thus -before connecting the current with his room, the student can in a -moment measure its amount and intensity. These instruments are of the -flushface type, and dead-beat. - -All of the rooms are lighted by electricity, and the lighting system -is independent of the delivery-boards. Nine of the rooms are provided -with soapstone sinks, and six (not including the lavatories and -service-room) with enamelled iron or porcelain sinks. All the sinks -have two taps and each of these ends with a screw-thread so as to take -a tip and rubber hose. The soapstone sinks were specially designed -with soapstone drip-boards. This is probably the best material for a -research-room, and the porcelain and enamel sinks were put only where a -neater appearance was desired, or where chemicals were to be frequently -used--as for instance in the battery and photographic rooms. Gas is not -used for illumination, but six rooms are provided with jets for the -smoking of drums, soldering, brazing, etc. - -The instrument-room is equipped with large dust-proof cases for holding -the more delicate and valuable instruments. The larger unused pieces -are stored, out of sight but readily accessible, in an attic which has -a clear floor-space of something more than half the total area of the -laboratory. Dust-proof cases for demonstration and class-work material -are provided in the lecture- and class-rooms. - -The shop contains a wood-working bench with two vices, tool-racks, -shelves, drawers, cupboards, and stock-racks, for the use of students; -and a 9-in. lathe, circular saw, grinding- and buffing-machine, -separate bench, vice, racks, and drawers for the use of the mechanic. -The machinery is run by a 5 h.p. electric motor suspended from one of -the outside brick walls, on brackets. One who selects the equipment of -such a shop has to weigh carefully the respective merits of circular -and band saws; the latter undoubtedly lends itself to a greater variety -of uses, but it is also a far more dangerous machine to have running -in a room to which students are to be given access. This latter -consideration determined in the present case the choice of a circular -saw. It is quite dangerous enough, and may be used only by, or under -the supervision of, the mechanic. - -It has been stated on competent authority that a truly sound-proof -room cannot be built except under ground. This has not been -attempted, but the laboratory contains one room (no. 17) which is -virtually sound-proof. A double door separates it from the adjoining -experimenter's room, and double doors also separate this from the -main hall. The wall between these two rooms consists of two layers of -plaster with special deadening material inserted between. Two small -tubes, ordinarily stuffed with felt, connect these rooms. When the -acoustical stimulus is a tuning-fork, it is placed in a distant room, -connected with one of the _b_ circuits of the sound-proof room, and -then with a telephone receiver near the subject's ear. - -The photographic-room contains the ordinary sink, red lights, shelves, -etc. The indirect entrance is light-tight when the door is not closed, -so that the experimenter may pass in and out even when developing is -going on. This room, like all the others which have no window (except -the sound-proof room), has forced ventilation. - -The class-room is designed for the experimental training-courses. It -has eight of the regular delivery-boards, ten tables, instrument-case, -blackboard, and sink. - -The lecture-room for specialized courses in comparative and -experimental psychology seats eighty students. It is provided with -two Bausch and Lomb electric projection-lanterns, horizontal and -vertical microscope attachments, and attachment for the projection of -opaque objects. On the lecturer's platform, besides the blackboard, -projection-screen, and chart-racks (capable of holding twenty charts), -is a large demonstration-table provided with a delivery-board, water, -gas, sixteen chart-drawers, two other drawers, and three cupboards. - -As has been said before, the general psychology course of the -University is not given on the laboratory floor, but downstairs -in the large lecture-hall with about 400 seats. A number of large -demonstration instruments of the laboratory serve the special purpose -of this course; this hall too has its own stereopticons. - -Our instrumentarium is, of course, in first line, the collection of -apparatus bought and constructed through the fourteen years of work. -Yet with the new expansion of the institute a considerable number of -psychological, physical, and physiological well-tested instruments has -been added. Especially in the departments of kymographic, chronoscopic, -and optical apparatus the equipment presents a satisfactory -completeness; its total value may be estimated to represent about -twelve thousand dollars. Yet the place of the laboratory which we -appreciate most highly is not the instrument-room but the workshop, -in which every new experimental idea can find at once its technical -shape and form. Whether those experimental ideas will be original and -productive, whether their elaboration will be helpful for the progress -of our young science, in short, whether the work in the new laboratory -will fulfil the hopes with which we entered it, may be better decided -as soon as a few further volumes of the Harvard Psychological Studies -shall have followed the present one, which is still from cover to cover -a product of Harvard's pre-Emerson-Hall period. - - - - -OPTICAL STUDIES - - - - -STEREOSCOPIC VISION AND THE DIFFERENCE OF RETINAL IMAGES - -BY G. V. HAMILTON - - -The question which the Laboratory proposed to me for experimental -enquiry was one which demanded a definite reply of yes or no. The -positive answer seemed a necessary consequence of the traditional -psycho-physiological theories, while a certain practical consideration -seemed to suggest the negative solution. The question which seems -to have been overlooked so far was this: According to the theory of -stereoscopic vision two points of light which are seen by each of the -two eyes under the same angle appear to lie in the same plane; as soon -as the angle for the right eye is larger than that for the left, that -is, as soon as the two stimulated retinal points in the right eye are -more distant than the two retinal points stimulated in the left eye, -the right light-point seems to be farther away than the left one. If we -relate them to planes vertical on the ideal binocular fixation-line, -the right point lies in a more distant plane. This principle, which, of -course, controls all arrangements for stereoscopic effect, is deduced -from experiences in which the fixation-line is vertical to the line -that connects the nodal points of the two eyes; the plane in which -the equally distant points lie is then parallel to the forehead. If, -on the other hand, the eyes are turned to the side, that is, if the -ideal fixation-line forms an acute angle with the line connecting -the eyeballs, the two fixated light-points, which lie in a plane -perpendicular to the fixation-line, cannot be seen by the two eyes -under the same angle. Any object on my right side is somewhat nearer -to my right eye than to my left, and therefore must throw a larger -image on my right retina. The two light-points of a plane vertical -to the fixation-line give thus with the eyes turned to the right two -unequal pairs of retinal stimuli; and the difference of the retinal -stimulations is evidently just the same as if the eyes were looking -straight forward but the two lights were at different distances. If -difference of retinal images really produces the conscious experience -of seeing the lights in differently distant planes, vertical to the -fixation-line, it follows that with the eyes turned to the right, -lights which objectively lie in the same plane must appear subjectively -to lie in different distances. The question arises whether the facts -correspond to this conclusion. If we look with eyes turned sidewise -towards a plane vertical to the direction of seeing, do the points -of that plane remain in it for consciousness or do we see them in -different planes? We see that practical considerations suggest a "No" -to this question, because it would mean that everything which does -not lie exactly in front of us must change its plastic form, and -this the more strongly the more we see it on our right or our left, -and this of course again the more strongly the nearer it is to the -eyes, inasmuch as the relative difference of the retinal images must -increase with the nearness of the object. If a short-sighted person -fixates an object a few centimetres from the eyes strongly turned to -the side, the distances in the retinal image of the one eye may be -almost the double of those in the other. Under normal conditions the -differences would be smaller, but yet everything would be necessarily -distorted in its three-dimension shape as soon as it is seen in -indirect vision or with sidewise fixation. On the other hand, if the -objects keep their three-dimensional relations in spite of sidewise -movements, it is evident that the accepted psycho-physiological theory -of stereoscopic vision is incomplete and must be revised in a very -essential way. The experiment had to decide. Of course the question -might be approached experimentally in different ways. It would have -been possible, for instance, to study the stereoscopic synthesis of two -separate flat pictures seen with the eyeballs in different positions. -But we preferred the simplest possible way, seeking the threshold of -distance for two parallel vertical edges with eyes turned forward and -to the side. We chose edges instead of hanging threads for the purpose -of avoiding the possible influence of the apparent thickness of the -threads on the judgment of distance. Of course, distance is here never -distance from the one or the other eye, but from the centre of the -line which connects the two nodal points of the eyes; the two vertical -planes whose edges were to be compared stood always vertical on the -ideal line of fixation which starts from that central point between the -two eyeballs. - -The apparatus used in these experiments consists of three parts, viz.: - -(1) A plank 2.5 metres x 9.5 centimetres x 4 centimetres, set on edge -and screwed to a table at either end. - -(2) A head-rest 45 centimetres high, 35 centimetres broad and 15 -centimetres deep. Attached to the centre of the lower strip of the -frame is a concave trough for the chin. Another trough, shaped to -fit over the vertex and with a strip of wood fastened to the front -of it for the forehead, slides up or down within the frame. The -attachment for the forehead can be moved and fixed at various positions -antero-posteriorly. By means of these devices the head can be securely -fixed in any position desired without discomfort to the subject. - -In order to have the eyes always in the same plane and at a known -distance from the apparatus at the other end of the plank, a hole was -made in either side of the frame with its centre at a level of the -eyes. Extending through the vertical diameter of each hole is a fine -wire. Fitted into the inner portion of each hole is a cardboard tube 10 -centimetres long: the inner end of each tube contains a vertical wire -so arranged that the four wires all fall into a plane at right angles -to the long direction of the plank. A mirror at the outer exit of -either hole enables the experimenter to align the tips of the subject's -corneæ with the wires. - -Two parallel strips of wood are so attached to the "head-rest" end of -the plank--one below and the other above it--that they can be rotated -laterally upon the plank, with the bolt which secures them to it for a -centre of rotation. Opposite this centre, and attached to the anterior -surface of the upper parallel strip is a wire needle 25 centimetres -long. By means of a quadricircular piece of cardboard attached to the -plank at the end of the needle, the extent of rotation to the right -or left can be read off in degrees. (The point midway between the two -corneal tips when they are aligned with the wires is in the same axis -of rotation as the head-rest.) - -A vertical iron rod 50 centimetres long extends upwards from either end -of the parallel strips, and upon these rods the frame of the head-rest -can be moved up or down by means of thumb-screws upon which it rests. - -(3) At the opposite end of the plank there is attached a flat board, -35 centimetres long and 30 centimetres wide. Attached to the edge of -the board which faces the head-rest is a piece of black cardboard -40 centimetres long by 35 centimetres broad. In the centre of the -cardboard is a rectangular aperture, 7 centimetres by 14 centimetres. -On the upper surface of the board are two slots, one at either side. -Sliding within each of these slots is a block of wood to which is -attached an upright sheet of black-painted tin, 15 centimetres wide and -20 centimetres high. The surfaces of these tins lie in planes parallel -to the plane of the four wires in the head-rest, when the latter is -at right angles to the plank. When their surfaces are equidistant -from the wires, the inner vertical edges of the tins are separated -from each other by 3 centimetres. The sides of the slots, in which -the blocks with their tins slide, are fitted with millimetre scales, -thus enabling the experimenter to determine the distance of the edges -from the corneæ. The point on the scale at which an edge was exactly 2 -metres from the vertical plane of the wires was chosen as the "zero" -point, and if this distance was decreased by moving an edge forward, -the latter was said to stand at "minus" one, two, or more millimetres, -as the case might be. Likewise, an edge was said to stand at "plus" -the number of millimetres' distance beyond the zero point if it had -been moved at a greater distance than 2 metres from the wires. A piece -of ground glass attached to the distal end of apparatus enabled the -experimenter to secure a uniform illumination, the room being darkened -and the light coming from a 32-candle-power electric lamp set about a -metre and a half behind and on a slightly lower level than the glass. - -It was found that by shading the lamp itself and admitting a dim -light to the room by means of drawing down only the ordinary thin -window-shades, the edges could be made to seem almost isolated in space -and to stand out in clear relief. - -The subjects of the experiment were Messrs. Bell, Flexner, and Tait. -Each subject determined the equality-point and the threshold for the -normal primary position of the eyes, for the eyes in a lateral position -of 15° and in a lateral position of 30°, both to the left and to the -right. - -Eyes at 0° means the following: that the most anterior part of the two -corneæ lies in a plane parallel to and two metres' distance from the -plane in which the two parallel edges lie at 0. Eyes at 30° to the left -means that a line drawn in front of the two corneæ intersects such a -line at an angle of 30°, the left eye being at the distal end of the -line. In calculating the visual angles 7.4 mm. are added in order to -compensate for the distance from the extreme anterior portion of the -cornea to the nodal point of the eye. - -The results for Mr. Tait are as follows: - -The position of eyes 0°. The right edge was moved, at first from an -evident + position to equality, then from equality to the - threshold, -then from an evident - position to equality, then from equality to -the + threshold. These four points were determined each fifteen times -and the average taken. Then exactly the same fifteen sets of four -determinations with the left edge moved. The averages of these 120 -experiments are these: When the left edge is moved from + to =:-2.77, -from = to -:-6.97, from - to =:+0.77, from = to +5.93. When the right -edge is moved from + to =: +2.83, from = to -:-1.6, from - to =:+5.9, -from = to +:+10.53. The first equality-point appears thus when the left -edge is moved at -0.76, when the right edge is moved at +4.41, with a -threshold of about 5 in either case. With the normal eye-position the -edges must thus not be exactly in the same plane to appear equally -distant; at a distance of 2000 mm. the left must be about 2 mm. nearer -than the right to appear in the same plane, vertical to the line of -regard. - -If the position of the eyes is 15° to the left, we have the following -results: When the left edge is moved from + to =:-4.17, from = to --:-8.5, from - to =:-1.33, from = to +:+1; when the right edge is moved -from + to =:+4.17, from = to -:+1.17, from - to =:+4.5, from = to -+:+8.67. - -If the position of the eyes is 30° to the left, we find when the left -edge is moved from + to =:-2.67, from = to -:-6.67, from - to =:+0.5, -from = to +:+3.33. When the right edge is moved from + to =:+2.33, from -= to -:-0.02, from - to =:+9., from = to +:+12.33. - -If we take again the general averages, we have for the eye-position of -15° to the left an equality-point of -3.25 if the left edge is moved -and judged and +4.63 if the right edge is moved and judged. That is, -if the right edge stands at 2000 mm. the left edge must be moved to -1996.75, and if the left stands at 2000, the right must be moved to -2004.63. For the eye-position of 30° to the left, the equality-point -lies at -1.49 if the left edge is moved and judged, and at +5.91 if -the right edge is the variable. The threshold lies in all three cases, -for eyes at 0°, at 15°, and at 30°, at about ±5 mm.; the position of -the eyes has thus no influence on the threshold for the perception of -distance in the direction of regard. - -But the point essential for our investigation is of course not -the threshold but the equality-point. To take the extremes of the -eye-positions 0° and 30° we find the equality when the left edge is -judged, at -0.76 for 0° and -1.49 for 30°, and when the right edge is -moved, at +4.41 at 0° and +5.91 at 30°; the middle is thus +1.82 for 0° -and +2.21 for 30°, that is a difference of less than 0.4 mm. - -To understand this figure we must enter into the calculation of the -angles. We have an eye-distance of 60 mm., a distance of the edges from -the cornea 2000 mm., from the nodal points 2007.4 mm., the distance of -each edge from the median line 15 mm., the distance of the two edges -from each other thus 30 mm. as long as they are in the same plane. We -have to determine the angle under which each eye sees the distance of -the two edges. A simple trigonometric calculation gives the following -figures: If both eyes are in normal position, at 0°, and both edges -are in the same plane, 2000 mm. from the corneæ, the angle for each -eye is 51' 22". If the left edge is now moved to +5, the left eye sees -the distance of the edges at an angle of 51' 25", the right eye under -51' 10", the difference is thus 15"; if the left edge is at +10 mm., -the left eye's angle is 51' 29", the right eye's angle 50' 59", the -difference 30". If the left edge is moved to -5 mm., the left eye's -angle is 51' 18", the right eye's angle 51' 33", the difference 15"; -if the left edge is moved to -10 mm., the left eye's angle is 51' 14", -the right eye's angle 51' 45", the difference 31". Now we saw that with -normal eye-position when the left edge was moved the threshold was -+5.93 and -6.97; a difference of 15" to 20" between the visual angles -of the two eyes was thus amply sufficient to give a distinct experience -of different distance. When the left eye's angle was about 15" smaller -than the angle of the right eye, the difference of the retinal images -gave a sure impression of the greater nearness of the left edge. - -If we now bring the eyes into the position of 30°, the angles are of -course different when both edges are in the same plane vertical to -the direction of regard. If the two edges are in the same plane, the -left eye's angle is 50' 59" and the right eye's angle 51' 45", the -difference thus 46". If we move the left edge to +5, the left angle -becomes 51' 1", the right angle 51' 34", the difference 33". If we move -the left to +10, the left angle becomes 51' 4", the right 51' 24"; the -difference is thus still 20", and we must move the left edge to +17 mm. -to get an equal angle for the left and the right eye. If we move the -left to -5, the difference becomes of course larger, the left eye sees -under 50' 56", the right eye 51' 55", the difference 59"; and at -10, -the left eye has the angle 50' 53", the right eye 52' 6", difference 1' -13". It is hardly necessary to state here the angles for the changes of -the right edge or for an eye-position of 15°, inasmuch as the maximum -differences bring out our case most clearly. With an eye-position of -15°, the edges at the same plane give angles of 51' 10" and 51'34", -that is, a difference of 24"; if the left edge is moved to -5 mm. the -difference becomes 38"; if it is moved to -10 mm. the difference is -54"; if the left edge is moved to +5 the difference decreases to 10" -and at +10 mm. to 6". - -We have thus the following fundamental result: If the eyes are in -normal primary position, a movement of the left edge to ±6 mm. is -constantly apperceived at threshold of distance and this corresponds to -retinal images whose visual angles differ by about 17". A difference -of 17" in the visual angles of the two eyes produces thus under the -conditions of this experiment for this subject a strong stereoscopic -effect when the eyes are in primary position. If the eyes are in the -position of the head 30° to the left, the left eye thus much further -from the edges than the right eye, the visual angle of the left image -thus much smaller than that of the right image, we find the same -equality-point with the same threshold. We saw that in this position -the two visual angles would be equal if the left edge were moved to -+17 mm.; instead of at +17, the equality-point--when the left edge is -judged--lies at -1.49, that is, at a point at which the visual angle -of the left eye is more than 46" smaller than the angle of the right -eye. While in normal position a difference of the two retinal images of -17" constitutes a distinct threshold value; at a lateral position of -the eyes of 30° the great difference of 46" becomes necessary to give -the impression of equal plane, while a decrease of that difference to -30" gives a distinct feeling of greater distance. Equal retinal images -produce for the lateral eyes thus the same effect which for the normal -position very different images produce; and to get for the lateral eyes -the effect which equal images produce for the normal position, the -angles of the images must differ by 46". - -The results for the second subject, Mr. Flexner, are practically the -same. With the position of the eyes at 0°, when the left edge is judged -and moved, we find the following averages: from + to =: +0.03, from = -to -:-3.8, from - to =:-0.7, from = to +:+3.93; when the right edge is -moved from + to =:-0.08, from = to -:-4.29, from - to =:+1.21, from = -to +:+4.08. It is evident that the difference between right and left -which existed for Mr. Tait does not enter into Mr. Flexner's results. -The equality-point as average of 120 experiments lies for normal -eye-position practically at zero, and the threshold is ±4 mm.; his -sensibility for differences of retinal images is thus still finer than -for Mr. Tait, as we saw that the threshold of ±4 mm. means a difference -of visual angles of less than 15". If Mr. Flexner's head is turned 15° -to the left, his left eye thus considerably farther away from the edges -than the right eye, the results are these: If the left edge is moved -and judged, we find from + to =:-0.02, from = to -:-3.17, from - to -=:0, from = to +:+4.67; if the right edge is moved from + to =:-0.01, -from = to -:-2.5, from - to =:-0.8, from = to +:+3.33. Experiments -with lateral movement of 30° were not carried through, as the subject, -accustomed to eye-glasses, became less accurate in the judgments; but -the experiments with the position of 0° and of 15° are unequivocal. -They show that the equality-point and the thresholds are exactly the -same for 15´ as for 0°. For the lateral position of 15° again the -average equality-point is exactly at 0° and the threshold at less than -±4 mm. We saw that for a lateral movement of 15° the difference of -the angles at the equality-point is 24". We find thus for Mr. Flexner -that with primary eye-position a difference of angles of less than 15" -gives a distinct stereoscopic effect, while with a lateral position of -the eyes a plane effect demands a difference of 24" for the two visual -angles. - -Experiments with Dr. Bell finally showed a rather strong fluctuation -of judgments and the determination of the equality-point for normal -eye-position has not only too large a middle variation to be a reliable -basis, but is influenced by a constant tendency to underestimate the -distance of the edge moved. Yet the general result is the same as with -the other two subjects, that is, the equality-point is with him, too, -practically the same for the eyes in normal and in lateral position. - -The general conclusion from the results of all three subjects is thus -evidently that the traditional physiological theory is untenable, the -stereoscopic effect cannot be simply a function of the difference -of the two retinal images. The same pair of unequal retinal images -which gives a most striking stereoscopic effect for eyes in primary -position, has no stereoscopic effect for eyes in lateral position and -_vice versa_. The stereoscopic interpretation is thus the function -of both the difference of the retinal images and the position of the -eyeballs. Of course the two retinal images are in any case never -felt as two pictures if they are not different enough to produce a -double image. With the primary position of the eyes as long as the -two different retinal views are sufficiently similar to allow a -synthesis in a three-dimensional impression of our object, we perceive -every point of the object not as double image but as one point of -a given distance. The distance feeling of the normal stereoscopic -vision demands thus itself more than the reference to the different -retinal images, and the only factor which can explain the phenomena -is the response of the eye-muscles which react on the double images -by increase or decrease of convergence. The distance of a point in a -stereoscopic image is determined by the impulse necessary for that -particular act of convergence of the eyeballs by which the two retinal -images on non-cor-responding points would be changed into images on -corresponding points. The different retinal images are thus ever for -the normal eye-position merely the stimuli for the production of that -process which really determines the experience of distance, that is, -the motor impulse to a change in convergence. - -If thus the stereoscopic vision under normal conditions is ultimately -dependent upon the central motor impulses, it is not surprising that -a change in the psycho-physical conditions of movement produces a -change in the resulting impulses. Such a change in the conditions is -given indeed whenever the eyes are in a lateral position. Just as -the same stimulus produces a different response when the arm or leg -is in a flexed or an extended position, so the retinal double images -stimulate different responses according to the particular position -of the eyeballs. That pair of unequal retinal images that in primary -eye-position produce in going from one end of the object to the other a -strong increase of convergence and thus a feeling of greater nearness, -may produce with the lateral eye-position no increase of convergence -and thus a feeling of equal distance or even a decrease of convergence -and thus a feeling of removal. The psycho-physical system upon which -our three-dimensional visual perception depends is then much more -complex than the usual theory teaches; it is not the retinal image of -the double eye, but this image together with the whole distribution -of contractions in the eye-muscles, which determines the stereoscopic -vision: the same retinal images may give very different plastic -perceptions for different positions of the eyeballs. - -The experiments point thus to the same complex connection which -Professor Münsterberg emphasized in his studies of the "Perception of -distance."[1] I may quote the closing part of his article to bring -out the intimate connection of the two problems. He reports his -observations on the so-called verant and insists that the monocular -verant almost as little as the ordinary binocular stereoscope can give -the impression of normal distance of nature. Professor Münsterberg -writes: "Whoever is able to separate seeing in three dimensions from -seeing in natural distance cannot doubt that in both cases alike we -reach the first end, the plastic interpretation, but are just as far -removed from the other, the feeling of natural distance, as in the -ordinary vision of pictures. The new instrument is thus in no way a -real 'verant.' - -"The question arises, Why is that so? If I bring my landscape picture -on a transparent glass plate into such a distance from my one eye -that every point of this transparent photograph covers for my resting -eye exactly the corresponding point of the real landscape and yet -accommodation is excluded, as, for instance, in the case of the -short-sighted eye, or in the case of the normal eye with the verant -lenses, then we have exactly the retinal images of the real view of -nature and the same repose of the lens. Why are we, nevertheless, -absolutely unable to substitute the near object for the far one? This -problem exists in spite of all the theoretical assurances that the one -ought to appear exactly like the other, and I think that it is not -impossible to furnish an answer to it. - -"If I am not mistaken, there is one point of difference between seeing -the mere picture and seeing the far landscape, which has been neglected -in the usual discussions. Every one knows, of course, that we see the -picture and the landscape normally with the help of eye-movements. The -eye moves from point to point; but psychologists have neglected the -consideration that the relation between eye-movement and retinal image -must be quite a different one for the landscape and for its photograph. -Let us consider the simplest possible case, the case of the myopic eye -without any lenses whatever, and without any need of accommodation for -a picture as near to the eye as 10 cm. If I take a small landscape -picture made with a camera whose distance from lens to plate is 10 -cm., I have a splendid plastic view if I see it at a distance of about -10 cm. from my eye. I have before me just such a picture in which two -mountain peaks are, in the photograph, 1 cm. distant from each other. -If I now have my little picture at the distance of 10 cm. from the -eye, these two mountain tops correspond in their distance of 1 cm. -exactly to the retinal image which the two real mountains, which are -ten miles away and one mile distant from each other, produce in my -retina. The retinal image of the two mountain peaks in the photograph -is thus for my resting eye indeed identical with that of real nature. -Does that mean that I have to make the same eye-movement to go from -the left to the right mountain in the landscape as in the picture? Of -course, that would be so, the movement would be just as identical as -the retinal images if the nodal point of the light-rays were identical -with the rotation-point of the eyeball. But everybody knows that this -is not at all the case. The light-rays cross in the lens. The angle -of vision, and thus the size of the retinal image, are thus dependent -upon the distance of the lens from the retina. But the movement of the -eye is related to a rotation-point which lies about 13 mm. behind the -cornea, roughly speaking 1 cm. behind the nodal point of the rays. This -additional centimetre plays, of course, no rôle whatever, if I look at -my mountains in the real landscape; following with my eyeball from the -fixation-point of the left mountain to the fixation-point of the right -mountain, I make a movement whose angle can be declared identical with -the angle under which I saw the two mountains with the resting eye in -the first position. This angle of vision was determined by the distance -of the nodal point, which was in our case ten miles, while the angle -of eye-movement was determined by the distance of the rotation-point, -which would be ten miles plus one centimetre, and there is of course -no possible difference for practical discrimination between these two -distances. - -"But the situation is completely changed if I turn to my little -picture 10 cm. distant from my eye. The angle under which I see my -two peaks is, of course, again the same under which I saw them in the -real landscape. It is determined by the distance of the picture from -the nodal point, which is in this case 10 cm. But the angle of the -eye-movement necessary to fixate first the left and then the right -peak is now a much smaller one because it is again determined by the -distance from the rotation-point, and that is in this case 10 cm. -plus 1 cm. With this short distance of the picture from the eye this -one additional centimetre is not at all the negligible quantity which -it was in addition to ten miles in the landscape. For the two real -mountains the angle of the eye-movement had a tangent of one tenth; -for the photograph mountains, in spite of their equal size of retinal -image, the angle of necessary movement would of course have a tangent -of one eleventh. Roughly speaking, we could say that the photograph, -in order to produce the same eye-movement which the mountains in the -landscape excited, would need a pictorial distance between the two -photograph mountains of 11 mm. instead of 10 mm. Of course if the -distance in the picture were made 11 mm. instead of 10, it would not -cover any more the mountains of the landscape. The retinal image would -thus be relatively too large and would not give us any longer the true -landscape. On the other hand, if we tried to correct it by bringing the -picture one centimetre nearer to the eye, then of course every retinal -image would be enlarged by that necessary tenth, and yet there would be -no help for the situation, as now again the eye-movement demanded by -the retinal image would be relatively increased too. - -"We can put it in this way: _my real landscape demands a relation -between retinal image and movement which my picture cannot produce -under any circumstances whatever_. That which would be needed to -imitate the relations would be realized only if I had my retinal -images from the picture at a distance of 10 cm., and at the same time -the movements belonging to the same picture seen at a distance of 9 -cm. That is of course unrealizable. We cannot see a picture without -having our movements constantly controlled by the size of the real -retinal images, as it is necessary that the distance seen in indirect -vision is the distance covered by the fixation-point during the -eye-movement. That demands, as we have seen, a different relation -between retinal image and eye-movement for near and far, and no verant -and no stereoscope can eliminate this factor. If a 10-mm. object in the -photograph demands an 11-mm. movement to give the impression of real -natural distance, then we have a condition which cannot be fulfilled. - -"If we remember how extremely delicate is our normal sensitiveness for -retinal distances and how the newer studies in stereoscopic vision have -demonstrated an unsuspected delicacy of adjustment between retinal -images and motor responses, it is evident that this so far always -neglected relation must be an extremely important one. If we have -one adjustment of central reaction in which a certain eye-movement -corresponds to retinal images of one size, and another adjustment in -which the same movements correspond to retinal images which are ten -per cent larger, we can really not expect our judgment of distance -to neglect the difference between these two systems of relations. Of -course they represent two extreme cases. Every distance beyond 10 cm. -demands its special adjustment up to the point where the distance -becomes too large to be influenced by the distance from the nodal point -to the rotation-point. We must thus presuppose a sliding scale of ever -new adjustments for the different distances at which we see any object, -and we have, in this relation, probably not the least important factor -in the judgment of the third dimension for relatively near objects, and -probably even more important than the irradiation circles which control -the accommodation, as these circles must be the same for objects which -lie before and behind the fixation-point. Of course the whole system -of our localizing reactions becomes through these considerations more -complex by far than the schematizations of the text-books propose. But -physiological optics has shown at every point in its development that -mere simplification has not always meant a deeper insight into the real -relations." - -It is evident that our studies in stereoscopic vision with lateral -eye-position involve exactly the same principle and reaffirm completely -Professor Münsterberg's theoretical views. In both cases, in the -monocular of the verant as in the binocular of our experiments, the -same retinal image has different psycho-physiological space-value on -account of the different motor situation. - -FOOTNOTE: - -[Footnote 1: Münsterberg: Perception of Distance, The Journal of -Philosophy, Psychology and Scientific Methods, vol. 1, p. 617, 1904.] - - - - -EYE-MOVEMENTS DURING DIZZINESS - -BY E. B. HOLT - - -It is a familiar fact that when the head is passively turned about -its vertical axis, the eyes do not move with the head but lag behind, -keeping their fixation on that object toward which they were directed -before the head moved. The eyes move in their sockets in a direction -opposite to that in which the head has moved. Now it has been proved -beyond a doubt by the experiments of Mach,[2] Crum Brown,[3] and -Breuer,[4] that these lagging movements of the eyes are reflex and are -governed by the semi-circular canals, which are stimulated directly by -the motion of the head. Similar reflex eye-movements are found when the -head is turned about some other than its vertical axis, the direction -of such movements being always in confirmation of the theory. All -these movements, together with the theory, are well described in the -summaries of Peters[5] and Nagel.[6] The present paper deals solely -with the eye-movements that occur after rotation of the head about its -vertical axis. - -The mechanism of these lagging, reflex movements is not, then, -identical with that which enables us, when the head is at rest, to -fix on and follow a luminous moving object,--the "pursuit movements" -of Dodge.[7] It is, however, identical with that of Dodge's "fourth -type"[8] and that of the compensatory eye-movements described -by Brown,[9] Nagel,[10] and Delage,[11] and recently studied by -Angier.[12] This function of the semi-circular canals was first -suggested by Goltz in 1870. Now if the rotary movement of the head is -prolonged, the eyes lag for a while on their first fixation-point, and -then dart suddenly forward to a new fixation-point on which they rest -for a while as before, until they dart forward again. Therefore if the -head continues to rotate, the eyes fall into a regular and well-marked -nystagmus. In this the lagging movements, or those opposite to the -direction of the head, are called "compensatory," and are relatively -slow and long. Their rate coincides closely if not exactly with that -of the head-movement. But the movements forward, in the direction of -the head-movement, are short and swift. Such are the facts during the -rotation of the head. - -But if this rotation has been somewhat prolonged, the ocular nystagmus -continues after the head and body are brought to rest. But now its -phases are reversed, and the slower eye-movements are in that direction -in which the head has moved; while the swifter are in what before -was the lagging direction. These observations are in accord with -the semicircular canal theory, and are well established by various -investigators.[13] - -This paper presents the results of a photographic study of the reflex -eye-movements following after rotation of the head (and body) about the -vertical axis. - -The subject whose eyes were to be photographed sat in a chair placed -on a rotating platform, in such a position that the vertical axis of -rotation passed through, or just posterior to the nose. Rays from an -arc-lamp of 6 amperes, placed about 60 cm. from the subject's face, -were so converged by a lens that when the subject came to rest, after -the rotation, his two eyes were brightly illuminated. An adiathermal -screen consisting of a dilute solution of copper ammonium sulphate -kept the heat from being painfully intense on the eyes. The light fell -slightly from one side on the subject's face, when he was brought to -rest; and directly in front of him, at a distance of about 40 cm., was -a camera of which the lens was on a level with his eyes. The ordinary -ground-glass screen at the back of this camera was replaced by a -light-proof box, in the front of which, and in the plane which should -have been that of the ground glass, was a slit 55 mm. broad and 5 mm. -high. Inside the box was a Ludwig kymograph of which the drum rotated -on a horizontal axis: the circumference of the drum lay tangentially -to the front of the box, and the line of tangency passed horizontally -through the long axis of the slit. For each photograph a photographic -film of sensitometer 40 was fixed to the drum, as paper is ordinarily -fastened, and in moving, the drum carried this film upwards past the -slit. It follows from this arrangement that 5 mm. along the length of -this film were always exposed at once. The camera was so focused that -the images of both eyes were sent through the slit, and fell on the -film. - -[Illustration: Figs. 1 and 2] - -The subject's head was rigidly held by a rest: this rest was adjusted, -and the camera focused, before the rotation. The adjustment of the -head was greatly facilitated by fastening a fine black thread to pegs -that projected forward from the head-rest, on either side; the thread -was stretched horizontally, and at such a height that its image in the -camera coincided with the middle of the long (horizontal) axis of the -open slit. If then the subject, on seating himself in the chair, had -his head so adjusted that each eye was directly behind the thread, -each eye would certainly be imaged on the sensitive film. Neither the -shadow of this thread on the subject's face, nor its image on the film, -interfered in the least with the exposure that was made after rotation. -This thread was further found very useful by the subject himself, -who, after the rotation and just before the exposure was made, could -make sure by sighting on the thread that his eyes had not slightly -changed position during the rather protracted rotation. The subject was -ordinarily turned twenty-five times at about the rate of one turn in -two seconds. The kymograph was set in motion and the exposure commenced -as soon as the whirling chair was brought to a dead stop. This stopping -always took two or three seconds, at the very time when the nystagmus -was most pronounced, so that the photographs do not show the maximum -eye-movements. The exposure lasted through one rotation of the drum, -nine seconds. - -In the strongest negatives the movements of the eyes can be fairly -well made out from the undulatory curve generated on the film by the -dark image of the iris as it oscillated from side to side. But this is -true only of the best negatives, and almost never of these if the eyes -photographed had the iris blue. In order to obtain better definition -in the photographs of the eye-movements, small flecks of Chinese white -were tried, as invented and described by Judd.[14] A small square of -white was laid with a brush on each cornea, on the side toward the -lamp, so that its image on the film should be as bright as possible. -The flecks were found to adhere to the eyeball even more perfectly than -Judd himself has claimed; and they produced so little discomfort that -the subject ordinarily forgot their presence on the eyes. Nevertheless -their image as produced on the negatives, although much better than -that of the iris, was generally not clearly readable, owing to the -brief exposure and the illumination by electric light. This light seems -not to be well reflected by the Chinese white: but in all cases where -daylight can be employed the use of these flecks must be eminently -satisfactory. - -Thus it was found necessary to fall back on the image of the arc as -reflected from the cornea. This corneal image invariably traced a -clear, strong curve on the negative, and would have been appropriated -at the outset, were it not that its movements are not, as is well -known, a true register of the _amplitude_ of the corresponding -eye-movements; a fact that was shown clearly from a comparison in -these negatives of the curves produced respectively by the flecks -of Chinese white and by the corneal image. The former showed a much -greater amplitude of movement. But the corneal reflection is a perfect -register of the _time_ and _direction_ of the eye-movements; and in -the following tables these features alone are studied. This reflection -traced on the film a perfectly readable curve, although in some of the -films, owing to a shifting of the carbons in the lamp taking place -during the rotation, one of the eyes would be badly illuminated and a -good record would be obtained from the other eye alone. - -The arc ran on an alternating circuit of 60 phases per second, and -owing to these interruptions of the illumination the curve of the -corneal image showed on the negative as a dotted line in which the -distance between any two dots represented one sixtieth of a second. -Since the constancy of this alternation in the current has been -measured in the Jefferson Physical Laboratory (of Harvard), and found -to vary within a few tenths of one per cent only, the spacing of the -dots on the negatives formed the most convenient possible means for -determining the durations of the nystagmiform movements. These dots are -shown in Figs. 3, 4, and 5 (Plates I and II). - -[Illustration: PLATE I. - -Fig. 3 - -(By an error Fig. 4 is shown reversed; the lettering is correct.) - -Fig. 4] - -Fig. 3 shows a portion of one of the films. The two curves are to be -read from below upwards; but at the bottom is a photograph of the slit -(showing a part of the subject's face) taken when the drum had made -a little over one revolution and had come back to rest. Hence below -the image of the slit, the curve of corneal reflection is doubled. -"Right" and "Left" refer to the subject's right and left sides, so -that the reader looks into the subject's face from in front. In the -picture of the slit, the place on the cornea of the corneal reflection -is shown; and also a minor reflection, which as may be seen traced no -curve, from some other source of light. The fine line that crosses -the slit horizontally is the image of the thread, above mentioned, -which was used in adjusting the head. The time-dots are seen to be -perfectly distinct, so that they could be accurately read with the -help of a jeweller's eyeglass. Fig. 4 shows another part of the same -negative, a portion subsequent to the single eye-curves of Fig. 3, -that is, a continuation vertically upwards of Fig. 3. The rotation -had been from the subject's left to his right, a direction that will -be termed "clockwise" throughout this paper, and it can be seen that -the quick eye-movements are toward the subject's _left_, while the -slow are towards his right: had the photograph been taken _during_ the -rotation, the directions of the quick and slow movements would have -been reversed. Two points may be observed in this figure which the -tables will also bring out,--that the two eyes move together, and that -as the nystagmus subsides the quick eye-movements become less frequent -but endure no longer, or in other words, the slow movements alone -increase in duration. The corneal reflection does not accurately show -the amplitude of the movements; but direct inspection of a subject's -eyes, as the nystagmus dies away, shows that generally (but perhaps -not always) the amplitudes of both quick and slow movements decrease -together. When this is the case, it follows that at the end of the -nystagmus the _rate_ of the slow movements decreases very much faster -than that of the rapid movements. - -Readable negatives were obtained from four, out of six subjects. Of -such negatives there are fourteen, ten of which are of eye-movements -after rotation clockwise, and four after rotation anti-clockwise. -This distribution is accidental, for the rotations in each direction -were about equal in number. With the exceptions to be noted later all -the negatives exhibit the same features, so that of the fourteen only -four examples are given in full in the tables; while for the others -merely the averages of the duration of quick and slow eye-movements -respectively are given. - - -TABLE I - - KEY: - 1: Subject - 2: Film - 3: Eye - 4: Direction of the rotation. - 5: Slow movements toward Subject's - 6: Rapid movements toward Subject's - 7: Average duration in seconds of slow movements - 8: Average duration in seconds of rapid movements - - 1 2 3 4 5 6 7 8 - - C 1 left clockwise right left .32 .05 - " 2 " " " " .36 .06 - " 3 right anti-clock left right .26 .08 - H 1 " clockwise right left .54 .07 - " 2 " " " " .45 .07 } - " " left " " " .45 .07 } - " 3 " " " " .50 .08} - " " right " " " .49 .08} - " 4 " anti-clock left right .49 .07 - " 5 left clockwise right left .53 .06 - Ta 1 right " " " .73 .07 - " 2 " anti-clock left right .48 .10 - Tu 1 " clockwise right left .50 .06 } - " " left " " " .49 .07 } - " 2 " " " " .49 .12} - " " right " " " .49 .12} - " 3 left " " " .40 .07 - " 4 right anti-clock left right .58 .08 - - Av. .48 .08 - -Table I gives these averages for all the fourteen negatives. In four -of these (H 2, H 3, Tu 1, Tu 2) simultaneous curves for both eyes -were obtained. In every curve the slow eye-movements were in the -same direction as the previous rotation; the rapid in the opposite -direction. The very few single movements that are exceptions to this -are noted under Table II. Had the photographs been taken during -(instead of after) the rotation, the directions of rapid and slow -movements would undoubtedly have been reversed. It is to be noted -that when both eyes were recorded, their movements were generally -identical, within the accuracy of measurement (one sixtieth of a -second). There are a few exceptions to this. The averages of all slow -and all rapid movements merely show that in general, and for that part -of the nystagmus that was photographed, the slow eye-movements lasted -six times as long as the rapid ones. This ratio varies considerably -from one case to another, and at best throws little light on the whole -nystagmiform series, since during the very first instants after the -rotation the ratio of quick to slow movements would be less than one -sixth, and at the very end of the series would be considerably more; -this because toward the end the slow movements become much slower, -while the rapid seem to change very little. The variations from case -to case arise, at least partly, because in some cases the picture was -taken more promptly, after the rotation stopped, than in others. - - -TABLE II - - All records in seconds. - Subject C. Subject H. Subject H. Subject Tu. - Film 3. Film 2. Film 3. Film 4. - anti-clockwise. clockwise. clockwise. anti-clockwise. - right eye. left eye. right eye. left eye. right eye. right eye. - - slow fast slow fast slow fast slow fast slow fast slow fast - m. m. m. m. m. m. m. m. m. m. m. m. - to to to to to to to to to to to to - lft. rt. lft. rt. lft. rt. lft. rt. lft. rt. lft. rt. - - .26 - .08 .03 .05 .06 .08 .06 - .2 .51 .58 .1 .1 .45 - .06 .06 .06 .06 .05 .08 - .05 .16 .16 .13 .13 .75 - .08 .05 .06 .1 .13 .06 - .19 1.01 1.05 .36 .33 .36 - .05 .06 .06 .1 .06 .13 - .02 .26 .26 .28 .3 .48 - .05 .05 .06 .13 .13 .05 - .21 .26 .26 .28 .23 .61 - (.19) .06 .06 .11 .13 .1 - .16 .55 .6 .35 .35 .41 - .05 .1 .1 .08 .1 .05 - .03 .25 .25 .33 .3 .65 - .05 .06 .05 .06 .11 .06 - .18 .33 .33 .25 .2 .51 - .06 .1 .1 .1 .1 .05 - .03 1.65 1.65 .83 .83 .66 - .05 .06 .06 .1 .13 .16 - .29 .26 .26 .63 .61 .66 - .11 .06 .08 .06 .06 .08 - - -TABLE II, _continued_. - - All records in seconds. - Subject C. Subject H. Subject H. Subject Tu. - Film 3. Film 2. Film 3. Film 4. - anti-clockwise. clockwise. clockwise. anti-clockwise. - right eye. left eye. right eye. left eye. right eye. right eye. - - slow fast fast slow fast slow fast slow fast slow slow fast - m. to m. to m. to m. to m. to m. to m. to m. to m. to m. to m. to m. to - lft. rt. lft. rt. lft. rt. lft. rt. lft. rt. lft. rt. - .29 .78 .76 .45 .43 .68 - .03 .06 .06 .05 .1 .15 - .04 .16 .2 .45 .43 .23 - .05 .1 .1 .06 .1 .11 - .25 .38 .33 .4 .38 .36 - .15 .08 .11 .08 .06 .08 - .3 .58 .56 .58 .56 .35 - .05 .06 .06 .06 .06 .06 - .33 .78 .78 .58 .56 .38 - .05 .08 .1 .08 .08 .05 - .28 .71 .71 .35 .35 1.78 - .11 .08 .06 .05 .06 .06 - .41 .46 .45 .51 .5 - .06 .05 .06 .06 .05 - .43 .56 .58 .6 .61 - .11 .06 .06 .08 .1 - .35 .33 .31 .73 .68 - .05 .1 .1 .06 .06 - .23 .86 .86 - .15 .08 .08 - .38 .21 .21 - .1 .06 .05 - .43 .8 .81 - .11 .08 .08 - .38 1.53 1.58 - .03 .06 .05 - .53 - .2 - .23 - (.18) - .36 - .03 - .23 - .06 - .45 - .11 - .25 - - Averages - .26 .08 .07 .45 .07 .45 .08 .50 .08 .49 .58 .08 - -Parentheses indicate time during which the eye did not move at all. - -[Illustration: PLATE II. - -Fig. 5] - -Table II gives in detail the data yielded by four of the most -instructive films. C 3 is the longest record that was obtained; Tu 4 -is among the shortest, though it is not the very shortest. H 2 and -H 3 show how nearly alike are the simultaneous movements of the two -eyes: .07 sec. is the greatest difference recorded on any film between -simultaneous movements. All four records show how much less the -duration of the slow movements is at the beginning of the record than -at the end, and how little the fast movements vary in this respect. - -H 2 is given because it is not typical; and about one half of the film -itself is reproduced in Fig. 5 (Plate II). It will be seen that at four -points there intervened between slow movements (toward the right) a -rapid one that was also toward the right. This is the only record in -which such a thing happened: and its explanation is problematical. With -the subjects C and H, and only very rarely with these, a rapid movement -sometimes took the place of a slow one, that is, occurred in the same -direction as the slow movements (_e. g._, Table II, C 3). And a trifle -more often, yet very seldom, a rapid movement was relatively slow (_e. -g._, _ibid._). With every subject there are a few cases in which the -eyes stood still for a small part of a second (_e. g._, _ibid._), and -these moments of rest seem to come after a rapid or a slow movement -indifferently. - -McAllister[15] and others have shown that the eyes are seldom at rest -even when voluntary fixation is attempted, and these anomalies in the -nystagmiform series may well be the result of such random factors, -which instead of being always inhibited by the afferent impulses from -the semicircular canals, which govern the nystagmus, operate along with -these latter, and sometimes even inhibit them. With the exception of -these anomalies, the movements recorded in the photographs confirm the -observations of Purkinje, Mach, Breuer, Delage, and other investigators. - -In conclusion, the sensations of vertigo and of nausea seem not to be -essentially connected with the nystagmus. Several subjects were so -disagreeably affected by a preliminary rotation that it seemed best not -to continue the experiment with them. With those, however, whose eyes -were photographed, while they experienced a mild degree of vertigo and -nausea during and after the first few rotations, these sensations soon -wore off with further practice, while so far as could be observed their -eye-movements were as ample and rapid as at first. The introspection -of these subjects was that after the rotation the body seemed at rest -and the stomach quite settled, while the visual field alone whirled -rapidly in the direction opposite to that of the previous rotation. - -FOOTNOTES: - -[Footnote 2: E. Mach: Sitzungsb. d. k. Akad. d. Wissensch., Wien, 1874.] - -[Footnote 3: A. Crum Brown: Proceedings of the Royal Soc., Edinburgh, -1874.] - -[Footnote 4: J. Breuer: Med. Jahrb., Wien, 1874-75.] - -[Footnote 5: W. Peters: Arch. f. d. ges. Psych., vol. 5, p. 42, 1905.] - -[Footnote 6: W. Nagel: Handbuch d. Physiol. des Menschen, vol. 3, p. -762, 1905.] - -[Footnote 7: R. Dodge: Amer. Jour. of Physiol., vol. 8, p. 317, 1903.] - -[Footnote 8: _Ibid._ p. 327.] - -[Footnote 9: A. Crum Brown: Proceedings of the Royal Soc., Edinburgh, -1895.] - -[Footnote 10: W. Nagel: Zeitsch. f. Psych. u. Physiol., vol. 12, p. -331, 1896.] - -[Footnote 11: Yves Delage: Arch. de Zoöl. expér. et générale, vol. 1, -1903.] - -[Footnote 12: R. P. Angier: Zeitsch. f. Psych. u. Physiol., vol. 37, p. -235, 1905.] - -[Footnote 13: See the summaries of Nagel and Peters, above referred to.] - -[Footnote 14: C. H. Judd: Yale Psych. Studies, Psych. Rev., Mon. -Supplements, vol. 7, no. 1, p. 7, 1905.] - -[Footnote 15: C. N. McAllister: Yale Psych. Studies, Psych. Rev. Mon. -Supplements, vol. 7, no. 1, p. 17, 1905.] - - - - -VISION DURING DIZZINESS - -BY E. B. HOLT - - -During and after a prolonged rotation of the head, the visual field -seems to spin around before one's eyes,--a phenomenon that is -ordinarily called the "dizziness of Purkinje." Delage describes it as -follows:[16] "In the experiment of Purkinje, while we are rotating in -a positive sense, space seems possessed of a motion in the opposite -direction.... This phenomenon is explained _by the direction of the -nystagmus_." - -"In the nystagmus," he continues, "the eyeballs execute two -well-differentiated motions: one, a compensatory, _relatively_ slow -motion, during which images pass across the retina so as to give the -appearance of a movement of space in the opposite direction; two, a -swift motion opposite to the slow one, and so rapid that the images -passing across the retina leave no sensation of their movement." - -Now, in a previous paper[17] I have shown that there is a central -anæsthesia, or central inhibition of visual sensations, during about -the latter two thirds of the time occupied by every voluntary eye-jump; -and in view of this I was led to enquire whether in fact, as Delage so -confidently asserts, it is the _speed_ of these more rapid movements, -or some other factor, that causes them to leave no visual sensations. -There can be no doubt that they do leave none, since, aside from the -statement of Delage, in dizziness the visual field whirls always in -only one direction; whereas it should otherwise appear to swing now -to one side, now to the other, as the eyes move back and forth across -the objects. I have found but one other mention of this point in the -literature. In his Analyse,[18] Mach says, parenthetically, "(the -jerky eye-movement leaves no optical impression)"; but he does not -suggest that this is because of its greater speed. - -In order to test this point, a 2 c. p. incandescent lamp was so -arranged that it could be moved vertically in front of, and about four -metres distant from, a rotating chair. Since after a rotation the eyes -are oscillating from side to side, if the lamp is moved up and down an -obliquely inclined after-image streak must be generated on the retina; -and clearly there are four possible positions in which this may lie, as -shown in Fig. 1. - -The results were absolutely uniform (the author alone as subject); -the after-image streak always lay on that side of the moving light -_toward_ which the _slow_ eye-movements were directed, that is, the -lamp appeared to drift obliquely up or down and in a lateral direction -_opposite_ to that of the slow eye-movements. Apart from its vertical -displacement, then, the lamp behaved like the less intensely illumined -parts of the visual field, seeming to be totally invisible during the -swifter eye-movements. Now since the experiment was done in a partially -darkened room and the eyes were partly adapted to darkness, the lamp -should have been intense enough adequately to stimulate the retina -even during the more rapid movements, and might be expected to leave -an after-image streak on that side toward which these rapid movements -were directed, and differing only from the streaks seen during the slow -eye-movements in being inclined at a less angle from the horizontal. -Yet no such streaks were visible. - -These observations were made at about the same number of seconds after -the rotation stopped, as the photographs were taken that are recorded -in the preceding paper of this volume. The rapid movements were -therefore about one sixth as long in duration as the slower ones. Since -the respective amplitudes of rapid and slow must average very nearly -the same, the rapid movements must have been about six times as swift -as the slow movements. It needs therefore to be shown beyond a doubt -that the 2 c. p. lamp _was_ bright enough, in view of the briefness of -stimulation of any one retinal element during the rapid eye-movement, -to be above the threshold of perception. For this reason the experiment -was not continued with other subjects. - -The certainly adequate degree of illumination was realized during the -photography of the eyes described in the preceding paper. Here during -the post-rotary dizziness an arc lamp (of 6 amp.) was in front of -the face and but a little to one side of the primary line of regard; -it was 60 cm. distant from the eyes and on a level with them; a lens -condensed the rays on the two eyes, and the light was diminished -only just enough as not to be painful, by a dilute screen of copper -ammonium sulphate about 3 cm. thick. Of course such an illumination -must adequately stimulate each retinal element even during the most -rapid eye-movements. Nevertheless with the four subjects that were -photographed the arc lamp, like the rest of the visual field, seemed -always to swim in one direction, and that opposite to the slower -eye-movements. In one case where the eyes were photographed without the -adiathermal screen, and the light was rather painfully intense, the -lamp was still seen to drift in one and the same direction. There was -never any trace of its moving to and fro, as there should have been had -it been visible during both phases of the nystagmiform movements. - -[Illustration: Fig. 1] - -This absence of visual sensation during the more rapid eye-movements -might conceivably depend on either peripheral or central inhibitory -factors. But the anatomy and physiology of the eye offer no point of -support for the supposition that during such movements the irritability -of the rods and cones is momentarily reduced, or that the retinal -layers posterior to the rods and cones suffer an interruption of -function during a movement of the eyeball in its socket. Indeed, during -some such movements, the "pursuit" movements (Dodge's second type), -vision is unimpaired.[19] In view of these facts, and of the many known -cases of the mutual inhibition of sensations where undoubtedly the -process is a central one, it is by far most probable that this visual -inhibition is also a central process; as was certainly the visual -inhibition during voluntary eye-jumps, previously reported by me.[20] - -The conclusion above reported that the visual inhibition during the -more rapid phase of the nystagmus in no wise depends on an inadequate -stimulation of the retina, due to the greater speed of the rapid -movements, and that the inhibitory process is purely central, is -further supported by the following phenomenon. If before the rotation -has commenced, the eyes are so strongly stimulated that a lasting -after-image is obtained, this after-image will, during the rotation, -always be seen to swim in the direction opposite to the rotation, that -is, _with_ the _slow_ eye-movements; but when the rate of rotation -begins to decrease, and as Mach, Breuer, and Delage have shown, the -slow eye-movements reverse their direction, the after-image also -reverses its direction, and now swims in the direction of rotation, -that is, _still with_ the _slow_ eye-movements. If the after-image -persists long enough, it may still be observed, after the rotation -has ceased, swimming in the same direction as the surviving slow -eye-movements. If, for instance, the slow movements are from left to -right, the after-image (best seen with the eyes closed) swims from the -left to the right hand side of the field and disappears, reappears at -the left and swims again toward the right, and continues to do this -until the nystagmus entirely ceases. - -This experiment was repeated several times, with four subjects, and -with both clockwise and anti-clockwise rotations, and the results were -uniformly as described above. In order to see whether this motion of -the after-image really depended on the slower nystagmiform movements, -the following variation was tried. It will be recalled that if the -head is rotated not about a vertical (longitudinal) axis, but about a -transverse axis, as, say, one passing through the ears, a nystagmus -is produced in which during the rotation the slower eye-movements are -opposite to the direction of rotation, while when the rotation is -checked or stopped, the nystagmus, as before, reverses. The same is -true if the rotation is about a sagittal axis. These conditions were -approximately realized by having the subject sit as before on the -rotary chair, but during the rotation hold his head horizontally to -the right or left, forward or back. With any of these positions of the -head, however, the rotation produced, on all of the subjects tried, -extreme dizziness and a feeling of nausea that lasted in some cases -for several hours. This fact made it impossible to ask for a set of -the four possible positions of the head from any of the subjects. The -following are the records that were obtained: - - Subject Fl. Head horizontally to left; rot. anti-clockwise. - During rot.; after-im. moved clockwise, _i. e._, from - subject's brow to chin. - Eye-mov. not observable during rot. - After rot.; after-im. moved anti-clockwise, chin to brow. - Slow eye-mov. anti-clockwise, chin to brow. - Vis. field clockwise, brow to chin. - - Subject H. Head horizontally to right; rot. anti-clockwise. - During rot.; after-im. clockwise, chin to brow. - Eye-mov. not observable. - After rot.; after-im. anti-clockwise, brow to chin. - Slow eye-mov. anti-clockwise, brow to chin. - Vis. field clockwise, chin to brow. - - Subject H. Same repeated, with same results. - Subject H. Same as case of Fl., with identical results. - - Subject K. Head horizontally to left; rot. anti-clockwise. - During rot.; after-im. not observed. - After rot.; after-im. anti-clockwise, chin to brow. - Slow eye-mov. anti-clockwise, chin to brow. - Vis. field not observed. - -So far as these records go, they entirely confirm the results of other -investigators as to the direction and the reversal of the nystagmus. In -each of the cases the after-image moved with the slow eye-movements, -reversing its direction with these slow movements, while the visual -field whenever it was observed (the eyes were kept closed during the -rotation) moved in the opposite direction to that of the after-image -and the slow eye-movement. It is well known that after-images move -_with_ every involuntary eye-movement, and although they disappear -during voluntary eye-jumps,[21] they reappear at the end of the jump in -a position that is related to the new fixation-point exactly as the old -position was to the former fixation-point. These after-images, then, -are seen during the slow eye-movements whose direction they follow; -but are not seen during the quick movements, when they must naturally -move in the direction of these quick movements. And aside from this it -is possible to observe introspectively that the after-image disappears -at that side of the visual field toward which the slow eye-movements -tend, and is for a moment invisible before it reappears on the other -side of the field. As was shown above, the visual field always moves -opposite to the direction of the slow eye-movements, as must of course -be the case if there is no inhibition of vision during these movements. -The simultaneous appearance of the after-image moving with, and the -rest of the visual field moving contrary to, the direction of the slow -eye-movements, with a uniform absence of the converse phenomena, seems -to prove that vision is unimpaired during these slow movements, while -it is completely inhibited during the rapid phases of the nystagmus. - -Purkinje himself[22] called the slower phases "involuntary and -unconscious," meaning by "unconscious" not that the visual field was -not seen (for it just then is seen), but that the movement of the -eyeball during the slow phases was not felt. I have observed, with -the confirmation of several subjects, that _this_ movement can also -not voluntarily be inhibited; whereas the swift movement is so far -voluntary that it can be inhibited at pleasure. It is possible, that -is, to fix the eyes on that side of the field toward which the slow -movements are directed, but not on any point at the other side of the -field. The slow movements, then, during which vision is possible, are -purely reflex. These slow movements, purely reflex and yielding clear -vision, with the rapid movements, partly under voluntary control and -attended by an inhibition of vision, present a parallelism, that may -be not without significance, to the "pursuit" eye-movements (Dodge's -"second type"), that are likewise relatively slow, are reflex, and -yield remarkably clear vision, and the ordinary voluntary eye-jumps -(Dodge's "first type"), that are relatively rapid, and are, like the -rapid nystagmiform movements, attended by a central inhibition of -vision. - -FOOTNOTES: - -[Footnote 16: Yves Delage: Physiol. Studien über d. Orientirung -(Aubert's transl.), p. 100, Tübingen, 1888.] - -[Footnote 17: E. B. Holt: Harvard Psych. Studies, Psych. Rev. Mon. -Supplements, vol. 4, p. 1, 1903.] - -[Footnote 18: E. Mach: Analyse der Empfindungen, 2d ed., p. 98, Jena, -1900.] - -[Footnote 19: R. Dodge: Amer. Jour. of Physiology, vol. 8, p. 317, -1903.] - -[Footnote 20: E. B. Holt: Harvard Psych. Studies, Psych. Rev. Mon. -Supplements, vol. 4, p. 42, 1903.] - -[Footnote 21: S. Exner: Zeitschrift für Psych. u. Physiol., vol. 1, p. -46, 1890; E. Fick and A. Gürber: Berichte d. ophth. Gesellschaft in -Heidelberg, 1889; E. B. Holt: _op. cit._ p. 4.] - -[Footnote 22: Purkinje, 1825; reprinted in Aubert's Physiol. Stud. über -d. Orientirung, p. 117, Tübingen, 1888.] - - - - -VISUAL IRRADIATION - -BY FOSTER PARTRIDGE BOSWELL - - -There are various kinds of visual irradiation, of which perhaps the -best-known variety is that which appears as the enlargement of a -brightly illuminated surface at the expense of a contiguous one of less -intensity. This has been until recently the only form recognized, and -until very lately the greater part of the literature has dealt with it -alone. - -The whole subject was carefully investigated by Plateau in 1831, -and retinal irradiation extricated from phenomena which very often -accompany it. He showed that the extent of irradiation varies with -the intensity of the stimulating light and the time during which it -is allowed to act. He was also the first to call attention to the -phenomenon of so-called negative irradiation. - -Somewhat later Volkman again called attention to negative irradiation, -while Aubert, in opposing the explanation advanced by Volkman, first -showed the relations existing between irradiation and contrast. - -Dove was the first to investigate the influence of irradiation on -stereoscopic pictures, thus calling attention to the question of -binocular irradiation. Experiments in this direction, however, have -in general given negative results in so far as any enlargement of the -binocular portion is concerned. - -Helmholtz examined the manner in which the stimulation at the -border-line between a light and dark field changes in intensity, -and drew a curve showing these modifications of intensity due to -irradiation. Hering showed that the form of the Helmholtz intensity -curve would be modified by the presence of other phenomena not strictly -those of irradiation. - -De Roux demonstrated the difference in the extent of a real induction -on the foveal and the extra-foveal parts of the retina. - -Charpentier has attempted to carry forward the general explanation -by saying that this spreading of neural excitation, the existence of -which he proves to be beyond question, takes the form of an undulatory -excitation in the free nerve-endings of the retina. Bidwell has -investigated more thoroughly in some respects than Charpentier the -phenomena of the after-images of moving sources of light, which have -bearing upon irradiation. The same is true with regard to McDougall, -von Kries, Hess, and others. Burch has instituted investigations -along these lines, especially concerning the inhibition of stimuli -on contiguous portions of the retina. Hess has worked carefully -upon the different phases of the stimulation derived from a moving -source of light, the differences in functioning of the foveal and -extra-foveal parts of the retina, the respective functions of the -rods and cones, and in connection with this, made investigations in -the visual perception of color-blind subjects. All these observations -have important bearing on irradiation, contrast, and theories of -color-vision. - -In connection with some work which was being done upon the after-images -of moving sources of light in the Harvard laboratory in the early -winter of 1903, some phenomena were observed which I believe are due to -one form or other of visual irradiation. They can be seen in various -ways, perhaps most advantageously by observing with fixed eyes the -passage of a luminous image over the retina. What one sees as such a -figure moves by is a travelling band of light, its forefront somewhat -like that of the stimulating source, the rest composed of a long -train of after-images which differ very decidedly from one another -in intensity and color. The advantage of this well-known method of -observation lies in the fact that it enables one to translate the -temporal relations between the different phases of the stimulation -into spatial relations between the different portions of the moving -band of light. For since the figure moves across in a plane before the -observer, that which appears in his consciousness first in time will -likewise appear as foremost on the plane in space. Thus by observing -the train of images one practically sees the different phases of -the stimulation spread out in order before one. The new phenomena -we observed, however, have to do with but a single phase of the -stimulation, the extreme front of the stimulating image. - -The intensity of light used varied considerably with the differently -colored images, and was regulated so as to give as well as possible -the phenomena we wished to study. With white light the intensity was -less than that of an eight-candle-power electric lamp placed about ten -feet distant from the observer. When colored light was employed it was -necessary to use a very much stronger source of illumination, since -the colored glass which was used absorbed a great deal of light and -in case of colors lying toward the violet end of the spectrum greater -luminosity seemed demanded. - -The apparatus used consisted of a three-foot pendulum with a screen -attached. This screen swung with the pendulum. In the screen was an -opening about four inches wide and three inches high, into which -strips of cardboard or tin backed by a piece of ground glass could be -slipped. In these strips differently shaped holes were made through -which the light passed. In this manner an image of any desired form -might be used. Behind the screen, between it and the lamp, was a frame -in which other pieces of ground or colored glass were placed. These -pieces of ground glass would reduce the intensity of the light and -diffuse it evenly over the image. The observer sat ten feet away. When -the pendulum was set in motion, the image would appear moving back and -forth in an arc. In order to shorten this arc and to aid the observer -in keeping his gaze perfectly fixed, a second screen was placed before -and very close to the pendulum, between it and the observer. This -screen was stationary. In it was a hole six inches long and two inches -wide. The top and bottom of this hole were arcs of circles parallel -with the arc in which the pendulum swung. The ends were radii. - -The screen was so placed with reference to the observer that the moving -image would pass directly across the middle of the opening, appearing -from behind one side and disappearing behind the other. In the centre -of the opening, directly in front of the place occupied by the moving -image when the pendulum was at rest, were two luminous fixation-points, -one above the other, below the path of the moving light. In order -to measure apparent spatial differences between the phases of the -stimulation, two wires were stretched vertically across the opening -in the stationary screen. These wires could be moved nearer together -or farther apart. Thus by measuring the apparent distances in space -between the different parts of the moving figure a measure could be -had of their temporal differences in coming into consciousness. The -luminous image moved, during the time it was visible, at a velocity of -about one and a quarter feet per second. Since the observer sat about -ten feet from the instrument, this would be at an angular velocity of -about seven degrees per second. In one experiment a higher and a lower -velocity were also employed. - -It was of course very easy to change the figures and vary them widely -in form, color, and intensity. Most of those employed, however, were -rather small, subtending an angular distance of not more than one -degree. Since the whole opening did not subtend an angle of more than -three degrees or so, nearly all the phases of the stimulation occurred -at the fovea. - -We noticed that the form of the stimulating images themselves seemed -to suffer modification as the light swung by, not only because of the -train of after-images which dragged behind them over the retina, but -in other ways as well. For instance, a circular image (Plate III, Fig. -1) appeared crescent-shaped, and its forward edge possessed greater -curvature than the segment of the circle which produced it. It was -longer also from horn to horn than the diameter of the generating -circle, and a faint haze surrounded the points extending outward and -backward until lost in the blackness of the background. Von Kries -remarks that a circular moving image appears cylindrical in form with -a concave edge behind. By using a little higher speed we observed this -phenomenon. At first we thought the crescent-shaped image to be due -merely to an intensely black after-process, which Bidwell describes -as following the positive image of a bright white light. This, taking -place before the circular disc of light had gone forward a distance -equal to its own diameter, would overlap the bright image from behind -and a crescent-shaped figure would result, but the increase in width -and convexity of the stimulating image as well as the laterally -trailing clouds of light remained to be explained, and as this could -not be done in terms of anything which might happen to the back of the -image, another explanation had to be sought. In order to determine -the effect of the form of the figure used as a source of light on the -form of the apparent image, several differently shaped figures were -employed. In place of the original circle, an oblong pointed at both -ends was tried (Plate III, Fig. 2). The front of this figure appeared -very convex indeed, while the ends, which, owing to the shape of the -figure, were very much less effective as a stimulating source, trailed -far behind the centre. - -A crescent-shaped figure (Plate III, Fig. 4) gave rise to a very pretty -phenomenon. When it moved toward its concave side, it appeared very -much less concave on that side than the real figure, but when it moved -the other way, toward its convex side, it seemed very much more curved -than it was in reality.[23] - -[Illustration: PLATE III.] - -No. 3, a simple oblong figure, appeared curved like the others, almost -as perfect a crescent as any of them. - -The idea occurred to me that perhaps all these modifications in the -curvature of the figures could be explained if we assumed two things: -First: that there is a spreading of excitation from one portion of the -retina to another. Each point will therefore be stimulated not only by -the light falling directly upon it, but it will also derive a certain -reënforcement of its stimulation from the points surrounding it. Thus -a point lying toward the centre of one of these figures would be more -favorably situated for receiving reënforcement than one located toward -the periphery, where there are few neighboring points, and those lying -mostly in one direction, namely, toward the centre. - -This may be represented diagramatically, as in the illustration -(Plate IV, Fig. 10), where the horizontal coördinates represent the -spatial dimensions of an oblong image and the vertical coördinates -the intensity of the excitation due to direct stimulation and its -reënforcement by surrounding points at various portions of the -figure.[24] Secondly I assumed that the stimulation at one part of the -figure being thus rendered more intense, that part would appear in -consciousness more quickly than the others and cause a modification -in the form of the figure.[25] For example, in the case of the oblong -figure, the light would be rendered most intense at the centre and -less and less intense toward the ends, for the points in the centre of -the figure will have their intensity increased by nervous excitation -spreading to them from points lying toward the ends. Those toward the -ends will be reënforced by light coming only from toward the centre. -Thus the intensity of the centre of the figure will be increased, and -as the figure moves across before the observer, the centre, appearing -first in consciousness, would likewise appear foremost in space, the -points near the centre a little later and so on, until finally, the -ends being the last to appear, the whole front of the figure would take -the form of a convex curve, after the manner in which it was observed. -The back of the figure also appears curved, probably because of the -fact that the front of the negative after-image, which closely follows -it, is of the same shape as the front of the positive image, as was -shown in the case of the circular figure.[26] - -It is of course a well-known psychological fact that a light of -greater intensity will take less time in coming into consciousness -than one of less intensity. In this case, however, it was necessary to -find some way of showing such differences between lights which were -very little different in intensity. For one is practically unable to -see any difference in intensity between the parts of a stationary -image. So unless it could be shown that a difference in intensity -between two sources of illumination, so small as to be imperceptible -to the observer, will nevertheless make its presence known by the -appearance of the brighter light in consciousness before the other, -the explanation which I have suggested for the curvature of the images -would have to be abandoned. - -The following experiments do show, as I believe, that of two sources -of light not perceptibly different in intensity, the brighter will -appear in consciousness before the other, and that in the case of these -figures the curvature of the image is due to a heightened intensity of -the light in the centre through reënforcement of the excitation there -present by stimulation spreading from the ends. - - -EXPERIMENT I - -In the first of these experiments three dots of about three sixteenths -of an inch were placed in a vertical row about three eighths of an inch -apart (Plate IV, Fig. 1). No change was then observed in the form of -the figure. The row of dots swung across the opening in a perfectly -vertical line one directly above the other (Plate IV, Fig. 2). They -were presumably too far apart for irradiation to take place between -them. When, however, another dot was interposed between each end dot -and the centre dot (Plate IV, Fig. 3), so that the excitement could -extend from one dot to the next, the front of the line of dots no -longer appeared vertical, but decidedly convex, the centre dot being -perhaps three eighths of an inch before the dots on the ends (Plate IV, -Fig. 4). - -[Illustration: PLATE IV.] - -Absolutely the only difference between the two cases was that in the -one, irradiation presumably could not occur, while in the other it -conceivably could. - - -EXPERIMENT II - -In the second of these experiments the curvature of a line of dots was -observed and measured. Then the centre dots were slightly darkened -(Plate IV, Fig. 5) by shading lightly with a lead pencil the ground -glass which travelled with the pendulum and held in place the card -from which the dots were cut, until the front of the image lost its -curvature and appeared vertical (Plate IV, Fig. 6). The pendulum was -then stopped and the row of dots observed closely, in order to see -whether the dots in the centre were perceptibly of less intensity than -those on the ends. No perceptible difference was found. - - -EXPERIMENT III - -All the dots were covered, except the shaded central and the two -unshaded end dots, in order that no irradiation might take place -between them (Plate IV, Fig. 7). The pendulum was again set in motion, -and the centre dot, instead of remaining co-linear with the dots on the -ends, appeared considerably behind them (Plate IV, Fig. 3). This would -show that irradiation must heighten the intensity of the excitation in -the centre of the figure--for the two cases just mentioned are alike in -every respect except that in the first (Fig. 6), where the dots were -near enough together so that irradiation might occur between them, the -intensity of the centre dot, which was objectively fainter than the -end dots, was heightened enough by this induced excitation to appear -in consciousness as soon as the two end dots, which were objectively -of greater intensity; whereas in the second case (Fig. 7), where the -dots were too far apart for irradiation to take place between them, -the centre dot, being objectively of less intensity than the end dots, -appeared behind them. - -These experiments show that of two sources of light very little -different in intensity the brighter will appear in consciousness -before the other. Other things being equal, the difference in -intensity may even be so small as to be imperceptible by direct -comparison; it is able nevertheless to make its presence known by -the order in which the lights appear. Exner made some experiments in -1868 to determine the time necessary for the perception of lights of -different intensity. He used, however, stationary images of brief -duration and tried to eliminate the effects of the after-image -by flooding the visual field with light. This method has its -disadvantages. It is incapable of measuring the minute temporal -differences in latent perception of sources of light very slightly -different in intensity. - -While my method does not give the absolute time taken by any one light -to enter consciousness, it is a very much more delicate method than -Exner's for measuring _differences_ in time of latent perception of -sources of light very close to one another in intensity. It would be -a very easy matter, having found the time of latent perception for a -light of standard intensity, to determine by this method the time of -lights of greater or less intensity. - -These experiments also show that when irradiation is absent, the -curvature of the images is absent; when irradiation is presumably -present, curvature is present. For I find, not only in these, but also -in a number of other experiments, that under all conditions in which -the presence of irradiation is to be expected, the form of the images -tends to be modified in precisely the manner that the assumption of its -presence would lead one to anticipate. In all cases where irradiation -is presumably absent, the contour of the front of the moving figure -depends entirely on the amount of light proceeding from its different -parts. - -It is next in order to say something of the physiological causes of the -phenomena we have been considering. - -It is probable from what has been observed that in the case of the -curved figures we are dealing with a form of visual irradiation which -is due to the spreading of neural excitation over or through the layers -of the retina. It is also evident from the close connection between -irradiation and intensity that it must be of such a kind that the -excitation produced in one part of the retina may communicate itself -readily to another part. We have also seen in the case of the moving -line of dots that the several dots could remain distinct from one -another and yet could reënforce each other by means of communicated -excitation. It must also be a very rapid form of irradiation, for the -curvature of the figures does not increase very much during the time -they are visible. - -I think that the demands made by these different facts are best met -by assuming that the spread of the nervous excitation which gives the -reënforcement takes place in one of the interconnecting layers of nerve -cells and fibres underlying the rods and cones. The line of dots which -appeared curved and yet perfectly distinct from one another could -very well communicate excitation to one another along these fibrils, -and the intensity of one part be raised by the excitation of the -near-lying parts. The fact that the dots remain distinct would not be -contradictory. For in that case very near-lying parts might communicate -excitation to one another without arousing to any very great activity -the nerves that lead to the brain from the small unstimulated portions -which lie between them. In this manner the intensity of the centre dots -could be heightened enough to make the row appear convex, without any -merging into one another on the part of the several dots. The fact that -the dots do not fuse shows that the curvature is not due merely to a -forward-spreading of the excitation in the retina. However, there is -always a certain amount of light visible between the dots, with all the -colors. This is especially noticeable with green light. - -The fact that the elements of the retina form a kind of concatenated -series from without inwards, a number of rods and cones corresponding -to but one ganglion cell, furnishes a further bit of evidence in -support of the explanation just advocated, since the irradiated -excitation would tend to be "drained off" through the group of ganglion -cells corresponding to the most highly stimulated portions and leave -the intervening spaces comparatively free from centrally proceeding -excitation. Thus also the individual dots in the five-dot figures may -appear entirely distinct from one another and yet the centre ones be -reënforced enough by irradiation to appear in consciousness in advance -of the others. - - -SUBSIDIARY EXPERIMENTS - -A number of other observations were made which present various -exemplifications of the principles we have considered. - - -EXPERIMENT IV - -An oblong figure, all its parts objectively of the same intensity, -had its ends slightly darkened. When this was done the curvature had -increased from twelve sixteenths to fourteen sixteenths of an inch. - -The pendulum was stopped, and a very slight difference was perceived -between the ends and the centre of the figure. This difference in -intensity was greater than in the dot experiment, when the image had -been darkened enough in the centre to make it appear vertical, because -in this case, when the ends were darkened the centre would still be -reënforced by irradiation from a considerable space which intervened -between the shading and the centre. - - -EXPERIMENT V - -The centre of the oblong figure was considerably darkened so as to -counteract the effect of induction. By properly varying the amount -of shading, one may make the front of the figure appear less convex, -vertical, or even concave. This shows perfectly the effect of -differences in intensity upon the curvature of the figure, but does not -show so neatly as the similar experiments performed with the dots, the -influence of the presence or absence of irradiation upon the intensity -of the centre of the figure and so upon the curvature. - -The illustration shows a case where the centre was too much darkened. - -[Illustration] - -The two ends were comparatively free from shading. In each end-part -irradiation took place. The points lying toward the centres of these -ends received reënforcement, both from points lying toward the centre -of the figure and from the extreme ends, and so the centres of the ends -of the image were considerably brighter than either the extreme ends -of the figure itself, or the sides of the end-parts toward the heavily -shaded centre of the figure. Accordingly each end appeared convex for a -short distance. The whole figure, however, being considerably brighter -at the two ends than at the centre, on account of the heavy shading, -the ends appeared in consciousness first and the centre afterwards, so -that the figure as a whole seemed concave. - - -EXPERIMENT VI - -An oblong figure was shaded rather heavily at one end, gradually -becoming lighter toward the other, while about a third of the figure -was free from shading. The shaded end always seemed to lag behind. The -extreme front of the figure was at a point a little distance from the -other end, before the shaded portion began. So that the front of the -whole figure appeared, not like a segment of a circle, but like part of -an oval with the bulge toward the brighter end. - -Beyond the ends of all these images faint clouds of light were seen, as -has been mentioned before, extending outward and backward, gradually -decreasing in intensity, until lost in the surrounding blackness of the -background. - -Charpentier's bands, sometimes more and sometimes less in number, were -observable in all of my figures and with all colors. Very often they -appeared to be parallel to the forefront of the image, or even of a -slightly greater degree of curvature. - - -EXPERIMENT VII - -It is a well-known fact that a rotating color-disc, having colors which -just fuse at a certain intensity, will show flicker at a slightly less -intensity. - -A color-disc was set in motion and the speed found where the colors -were on the point of fusing. A piece of black cardboard, with a hole -about an inch in diameter, was held close to the screen. - -Around the periphery of the hole flickering appeared, while at the -centre there was fusion. (The cardboard was held very close to the -disc, so that there would be no shadows on the disc near its edges.) -This fusion at the centre of the disc is probably due to the fact that -the centre of the field is of slightly greater intensity than the -edges, owing to irradiation. This difference in intensity makes the -difference between the fusion at the centre and the slight flicker seen -at the periphery. - -Karl Marbe in a recent article mentions the difference in fusion -between a point in the centre of the disc and a point near its border, -and he thinks the increase of flickering in the latter is due to -some influence on the part of the moving edge which separates the -different parts of the disc. It would seem more probable from this -last experiment that the fusion at the centre of the field of view -was due to reënforcement of intensity by irradiation, and that the -flicker about the periphery of the field was due to the lack of such -reënforcement. - - -EXPERIMENT VIII - -Three large dots were used and the centre one covered with tissue -paper. The two end dots then appeared ahead of the centre dots. They -were larger than the centre dot, due to irradiation over their borders. -But this increase in size did not account for their position ahead in -space. The centres of all the dots were not co-linear, but the middle -dot was behind the others, thus, of course, showing the greater time -necessary for the perception of the less luminous object. - - -EXPERIMENT IX - -This was exactly similar to the preceding, except that the intensities -of the various dots were reversed. The end dots were covered with -tissue paper, instead of the centre one. Then the centre dot appeared -first and the end dots after it. - - -EXPERIMENT X - -Professor Hess finds that an image which, compared to those we -used, was very long, subtending an angular distance of about thirty -degrees, and which extends entirely across the fovea and overlaps the -surrounding parts of the retina will appear curved backwards at the -fovea, owing to the longer time of latent perception of the fovea and -the macula. The accompanying illustration shows a modification of one -of Hess's figures, in which the presence of this phenomenon and that -of the convex image are both shown. The two phenomena were observed -when a two-inch image was observed at a distance of about fourteen -inches. The intensity of the light was that of an eight-candle-power -lamp with three pieces of ground glass in front of it. (Very many of -Hess's intensities are too great to give convex images.) Thus the image -would be about 12° in height. About 5/12 of the figure would then fall -on the macula and fovea and appear curved backwards in relation to the -ends. The ends where they fell on the extra foveal parts of the retina -appeared convex in front and concave at the rear as any small image -of the right intensity does which falls on a homogeneous part of the -retina. - -[Illustration: Figure observed with centre curved backward at the -fovea, and ends curved forward owing to irradiation.] - - -EXPERIMENT XI - -Charpentier, Bidwell, and others have made the observation that if -a small source of light be exposed for a brief interval, excitation -will proceed out in all directions over the retina, but if the light -be exposed for a slightly longer period, the excitation will contract -again and the light appear nearly its proper size and in its proper -location at the stimulated portion of the retina. Using variously -shaped figures we obtained analogous results, and the additional fact -appeared that the outgoing excitation proceeds from the borders of the -figures and that its form is somewhat determined by the form of the -figure. An oblong image appeared vaguely elliptical, a diamond-shaped -figure in the form of a more pointed ellipse, etc. These images were -exposed for only a small fraction of a second, by means of a shutter. -As the exposure grew longer the true form of the figures came out more -and more clearly. There thus seems to be a general spreading of the -stimulation in all directions over the retina from the borders of the -images. Then, upon a slightly longer duration of the stimulus, this -very rapid irradiation of excitation contracts and the irradiation -becomes confined within the borders of the stimulated portion and -affects the intensity of the different portions of the image. With -strong intensities and certain colors it is, however, never wholly -confined to the stimulated portion even of moving images. Charpentier -speaks of "clouds of light accompanying his figures." With green light -these clouds are especially noticeable. His "palm branch" phenomenon is -a good instance of the irradiation of stimulation. - -Besides these experiments which I have just described, several -phenomena of a like sort were observed in connection with other -experiments which were being performed in the laboratory at the same -time. Dr. Holt was experimenting with a bright circular spot of light -about one half inch in diameter, surrounded by a very faint ring about -one half inch wide. When the whole image was moved about, the spot -would seem to go back and forth across the less intense part so that -the whole image looked like a jelly-fish swimming about in the water. - -When the figure was allowed to remain stationary for a few moments it -would resume its natural shape. Otherwise the bright part would seem to -advance faster than the rest, sometimes even overlapping the border. -This phenomenon was due to the fact that a bright light requires less -time in coming into consciousness than a less intense one, and is, of -course, the same in principle as those which were performed with dots -when the bright dot moved ahead of the rest. - -Another one of these phenomena occurred when an isosceles triangle -was moved in a direction parallel to its base. The side toward which -it moved appeared curved forward, with the apex bent backward. Toward -the bottom, where there was the best chance for irradiation to have -its effect, appeared the most advanced portion of the figure, while -the bottom corner, although objectively the most advanced part of the -figure, appeared rounded off and somewhat behind the part just above. - -A narrow, vertical image with a large bulge behind the central part -appeared with a large portion of this bulge in advance of the centre of -the figure. - -All these experiments show that a more intense object is, other things -being equal, always located ahead of other objects co-linear with it. -And I assume irradiation to account for the priority in localization -of parts of the figure which are not objectively of greater intensity -than others, but whose position makes them subject to reënforcement. -The localization itself may be a function of more central organs, and -not directly a question of the coming into consciousness more quickly -of a more intense stimulation, although that seems to be the simplest -explanation, but in any case priority of localization varies directly -with the degree of intensity. - -If the light is not bright enough to produce much irradiation the image -will lose its curvature. If the light is too bright, although there -may be a maximum of irradiation aroused and the absolute difference in -intensity between the ends and centre of the image be at its greatest, -yet this difference may not be great enough in proportion to the -absolute intensity of the light to make the centre of the image appear -in advance of the rest. - -The curvature also varies with the angle subtended by the image and the -portion of the retina upon which the image falls. If the image were too -long, although all the processes which produce curvature be present, -yet the front of the image would still appear vertical, because of the -fact that each point in this long line would not derive reënforcement -sensibly greater than that of the neighboring points. The best one -could expect would be that these long figures should have their ends -rounded off, which is usually the case. Most of the images which -Professor Hess used in his experiments were too long to appear curved. -All the images whose curvature we measured did not subtend an angle -greater than 1° 10´, and were all seen on the fovea. - -An image which subtends an angle of more than about 2° will hardly -appear curved when it passes over the fovea. - -We were sometimes able to see the curvature reversed. This happened in -my own case about once in a hundred times, usually when my eyes were -fatigued by the repeated passing of the moving light back and forth -over the same portion of the retina. With other observers it occurred -more often. - -Slight vertical differences in fixation would cause the central part -of the path taken by the moving light to become more fatigued than the -edges and so to respond more slowly to the stimulation and reverse -the curvature. It may be that some brain process which has to do with -the apperception of the form and movement of visual objects becomes -fatigued or does not always function properly, and so the curvature -of the image may sometimes appear reversed. At any rate the more -usual cases are those in which the convexity is present. The others, -owing to the number of factors involved, and the vast majority of the -opposite cases, may be regarded as due to temporary defects in the -psycho-physical mechanism, which when properly working would give the -more usual result. - - -QUANTITATIVE EXPERIMENTS - -The object of the following experiments was to measure the amount -of curvature produced by differing degrees of intensity of light at -different speeds. An oblong figure was employed one fourth inch wide -and two inches long. As has been mentioned, two vertical wires were -stretched across the path in which the light moved. As the light swung -by, it was attempted to get the wires at such a distance from one -another that when one appeared tangent to the curve at the front of -the figure the other would seem to cross the image at the point of -intersection of the curve with the rest of the figure, as indicated in -the diagram. (Plate IV, Fig. 9.) - -The distance between the wires was then read off on a scale. Thus one -was able to obtain a measure of the curvature of the figure when it was -moving at different speeds and illuminated by different intensities of -light, and to compare the observations of different subjects. The mean -error in this work is surprisingly little, considering the difficulties -in making the judgment as the light passed rapidly by the wires. -Usually the moving light had to be observed several times before the -curvature of the front of the moving image could be measured exactly. -It would be perfectly obvious that the front was considerably curved, -but it would often be wholly impossible to tell just how much it was -curved, until the pendulum had swung back and forth four or five times. -Fatigue and darkness adaptation modify the judgments considerably. If -one's eyes were partially adapted to darkness some little difficulty -was experienced in seeing clearly the curvature of the image. Fatigue -comes on very rapidly indeed. Usually it was impossible to get more -than four judgments without resting, and often only two could be made. -It was sometimes impossible to measure the curvature at the exact point -when the light passed under the cross-wires, so the curvature had to be -observed carefully and compared with the distance between the wires, -and a judgment made when the wires were not superimposed upon the -image. With each intensity of light two judgments were taken, one when -the cross-wires had to be brought nearer together, the other when they -had to be moved farther apart. Several series of measurements were made -by different observers, and the results averaged up and compared. - -The following curves and tables give the different observations for the -nine different intensities of white light,[27] and the three speeds -which were used. In the case of the high speed the light moved across -the opening in the screen placed before the pendulum at a velocity of -about 1.5 ft. per sec. The middle speed was about 1.27 ft. per sec. and -the low speed about .917 feet per sec. In all cases an oblong image was -used, 1/4 inch wide and 2 inches long. The numerals on the left of the -plotted curves give the apparent curvature of the image in sixteenths -of an inch, and were obtained by measuring the distance between the -cross-wires when this distance measured the apparent curvature of the -image in the way described above. The figures at the bottom designate -the different intensities of light which were used. Number one is the -greatest intensity, number nine the least; the others those in between. - -_High Speed._ This curve shows very well indeed what seems to be -typical of the relations between the intensity of the moving light -and the apparent curvature of the front edge of the image. With the -lowest degrees of intensity the amount of the curvature is very little. -Sometimes it was difficult to measure it at all. The light was so -faint and the speed so rapid that probably very little reënforcement -or irradiation took place, although what did occur would show its -presence most prominently, since, on account of the high speed at -which the pendulum moved, any part of the image which should come -into consciousness ahead of the rest, even by a very little time, -would appear considerably in advance of the rest of the image in -space. Of course a certain amount of time would be required for the -stimulus to spread itself over the retina, since it has to overcome -a certain amount of resistance in the nerve-layers, and if this time -were not given, the curvature of the resulting image would be of course -decreased. As the light brightened, however, the curvature increased -rapidly, until finally, when the intensity of the light neared its -highest point, the curvature ceased becoming greater, and finally -decreased. The mean error in eight judgments taken by two people for -each intensity of light was about .099 in. - -[Illustration: High Speed] - -[Illustration: Middle Speed] - -[Illustration: Low Speed] - -The measurements with the middle speed were very similar. The curvature -with the lowest intensity of light was somewhat greater than when this -same light moved with the highest speed. The maximum point of curvature -was reached with a light of less intensity, and the curvature was less. -When yet higher intensities were used, the curve decreased rapidly. The -amount of curvature was also much less with the brightest light than -with the higher speed. The following table shows the judgments of three -observers for this speed: - - -MIDDLE SPEED - - Intensities. 1 2 3 4 5 6 7 8 9 - - First Subject. 8 10 9 11 10 9 9 7 8 - 10 11 13 13 10 11 10 9 8 - 10 10 11 11 9 8 8 7 7 - 10 11 11 14 10 12 8 9 9 - 10 11 10 11 9 9 7 10 7 - 11 11 11 13 10 10 9 10 7 - - Second Subject. 10 9 11 11 12 8 11 7 8 - 12 14 13 14 15 14 10 9 9 - 10 14 13 13 12 11 11 10 9 - 11 14 13 13 13 12 12 10 9 - 13 11 13 14 12 12 10 9 9 - 13 12 13 14 12 12 11 11 9 - - Third Subject. 7 10 9 13 10 9 9 7 8 - 8 12 12 13 12 10 10 8 7 - 7 11 10 10 11 10 10 8 8 - 9 11 13 11 12 10 11 8 8 - 9 11 11 10 10 9 10 9 7 - 9 11 12 12 11 10 10 8 8 - - Average. 9-15/16 11-1/3 11-1/2 12-5/18 11-1/9 10-1/3 9-7/8 8-5/8 8-1/9 - - Mean Error, .075 in. - -The low-speed measurements show the same general tendencies except -that the curvature is smaller with this speed when the faintest lights -were used than with any of the others. The maximum curvature is also -less and occurs with a more intense light than with the middle speed. -These modifications offer no special difficulties. Since the light -moves slowly, although the centre of the image, which is reënforced -by induced excitation from the ends, does appear in consciousness in -time ahead of the rest of the image, yet it does not appear so far in -advance of the rest of the figure in space as it would if the light -moved with a higher speed. While the same difference in brightness -between the centre and the ends of the image should make one part -appear in consciousness just as far ahead of the rest in time with -this speed as with any other, yet since the speed is slow it would not -appear to be so far ahead in space. The fact that the maximum amount of -apparent curvature is less would also be explained in the same manner. - -When the high and middle speeds were used the results were surprisingly -consistent and the variations between the observers not very great. -With the low speed the individual differences are very much more -prominent. Uncertainties and variations between observers and between -different observations of the same observer became greater and greater -as the intensity of the light decreased. One seemed to be approaching -the lower limit of induction, below which, even if the spreading of -light stimuli through the retina took place at all, it was to such a -slight extent that it made no very marked difference in the appearance -of the moving image. Individual differences are very great in this -respect. For instance, my own average measurement was 15/64 in. of -curvature for the image produced when a light of the lowest intensity -moved at the lowest speed. Mr. Vaughan's measurements averaged 30/64 -in., a measurement of just twice as much for the same light at the same -speed. - -So far there has been given only a general view of what happens when an -oblong moving image appears convexly curved. It may be well to consider -the different causes which determine a certain curvature of the image -and see how they are related. - -As we have seen, the curvature is a function of the difference in -intensity of various excitations between the centre and the ends of the -retinal area excited. This difference is modified both by the objective -intensity of the light and by the speed at which the light moves. Its -efficiency to produce curvature is also modified by both these factors, -since it requires a certain small amount of time for the irradiation to -take place. If this time is not given by the too rapid passage of the -image over a certain part of the retina, the difference in intensity -will be lessened and the curvature therefore be decreased. On the other -hand, if the figure moves too slowly, although this difference in -intensity may be as great as possible for the brightness of the light -which is acting, yet the curvature may be lessened on account of the -fact that, although the centre of the image does appear ahead of the -ends in time, yet it does not appear so far ahead of the ends of the -image in space as it would if the same difference in intensity were -present and the image moved more rapidly. - -It will be remembered that the intensity of the centre of the figure -owes its increase to reënforcement by excitation irradiating from the -surrounding points. It seems only reasonable to suppose that this added -intensity due to irradiation does not increase without limit, or with -exactly the required ratio to produce a curvature of the front of the -image which becomes continuously greater as the intensity of the light -increases, indefinitely. - -If this be so, then, at a certain brightness, the difference in -intensity between the ends and the centre of the image will have -reached a maximum, and a further increase in brightness of the light -will not serve to increase the apparent curvature of the image, but -rather to decrease it. - - -COLOR IRRADIATION - -The color of the image has a decided influence upon the amount of -perceived curvature, independently of the intensity. - -The following experiments were performed with lights of different -colors, in order to investigate the relations between the kinds and -amounts of irradiation of the different colors by comparing the amounts -of the curvatures obtained. We encountered a good deal of difficulty in -fixing upon a proper method of comparison between the different colors. -Finally it was decided to use such intensities of light as would give -a maximum amount of curvature with each of the four primary colors, -to measure this amount in each case, and also to measure the amount -obtained when the intensity of the light was greater and less than that -required to give the maximum. - -It was found that very different objective intensities of light were -required to give a maximum amount of curvature with the different -colors. The colored images were obtained by placing colored pieces of -glass in a frame which stood before the source of light. The intensity -of the light could be regulated by interposing or taking away pieces -of ground glass which rested in the frame between the light and the -colored glass. - -The red glass gave a nearly saturated color, but its place in the -spectrum was rather nearer the orange than I could have wished. It -was a thick piece of glass and absorbed a great deal of light. A -32-candle-power light with four pieces of ground glass in front of it -gave a maximum curve for most observers. - -The yellow gave a very well-saturated color with light from the -incandescent lamps which we used. The glass was thinner and absorbed -less light than the red. A 32-candle-power lamp with three pieces of -ground glass usually gave the maximum. - -Two 32-candle-power lamps and one of 24-candle-power were required with -the green. - -The green glass was not quite so saturated in color as the red or -yellow. It was a slightly yellowish green. Red and yellow rays were -visible through it to some extent when it was examined through the -spectroscope. It absorbed somewhat less light than the red and -decidedly more than the yellow. The maximum curvature was obtained when -the source of light was screened with four pieces of ground glass. - -The blue glass was a bluish violet, very heavy, and absorbed a great -deal of light; it allowed many red and violet rays to pass through. It -was necessary to use with this glass two 32-candle-power lamps and one -100-candle-power. When the combined light of these lamps was reduced by -interposing three thicknesses of ground glass, the maximum curvature -was observed. The light which then appeared, however, seemed of greater -intensity than any other which gave a maximum. - -The curvature of the white light was measured again in order to compare -it with the colored lights. This was necessary, since the work was done -with a different set of subjects and the former work showed individual -variations. An 8-candle-power light was used as before. This, reduced -by four pieces of ground glass, gave the maximum in most cases. - -The following curves and tables show the average of the observations of -four subjects. In the table the figures under the columns numbered 1 -and 2 represent the amount of curvature perceived when the intensity of -light was greater than that required to give a maximum under 4 and 5, -when the light was not strong enough to produce a maximum of curvature. -The columns numbered 3 represent the greatest amount of curvature -perceptible with each color. - -The curves shown in the diagram represent these measurements plotted -out. - - -TABLE - - Intensities. 1 2 3 4 5 - - Red. 13.50 15.20 16.85 14.06 13.46 - Yellow. 13.90 15.46 18.00 16.40 15.85 - Green. 15.66 18.00 19.86 18.32 18.00 - Blue. 13.00 14.15 16.85 15.50 14.09 - - Average for all - the colors. 14.00 15.70 17.90 15.90 15.35 - -The measurements were made in the same way as before, and are given in -sixteenths of an inch. - -In the diagram the abscissas represent the different intensities, the -ordinates the amount of the curvature. To avoid confusion, the curve of -the average of all the colors is left out of this diagram. - -[Illustration] - -It will be noticed in these records that the different colors give very -different measurements of curvature. Green gives by far the largest, -being greater than any of the others at every point. Since the process -of obtaining the curvature was the same with all the colors, these -differences in curvature can only be due to inherent differences in -the processes which give the sensations of the different colors. -It cannot be due simply to one sort of intensity process, the same -for all the colors, otherwise the curvature of all the colors would -be the same. At the same time the curvature of the image is due to -differences in intensity of excitation between one part of the image -and another. There must be, therefore, a retinal excitation in some -respects different for each color, capable of its different degrees -of intensity. Of course these individual differences would have a -decidedly limited range, for, as every one knows, if the intensity of -a color be increased sufficiently its saturation vanishes and white -appears in its place, while if the intensity be decreased without -limit, black appears. It may be that different degrees of excitation in -the different processes have different rates of time in coming into -consciousness, so that an equal degree of difference in excitation -between the ends and centre of the green image and the ends and centre -of the red image would give decidedly different amounts of curvature, -if it took a longer time after the centre of the green image had -appeared in consciousness for the ends to appear than it did in the -case of the red. - -The time-differences might be greater with the same differences in -intensities of excitation with one color and another. Or it may be -that the excitation spreads in a different manner with each one of the -colors, and therefore gives differing degrees of reënforcement with the -different colors, and thus produces different amounts of curvature. - -It is noticeable also that the amounts of curvature are related to one -another in a peculiar way. Green has the greatest amount of curvature, -yellow the next. Red is greater than blue with the higher intensities, -they are equal at the maximum, and blue is greater than red when the -lower intensities are used. - -When a spectrum showing a fair degree of saturation is observed, it is -seen that the point of greatest brightness lies in the yellows. As the -intensity is heightened, this point moves toward the red end, and as it -is lowered, it moves toward the blue. - -It will be seen that the relation between the different amounts of -curvature for the different colors is the same as that between the -different degrees of apparent brightness when the intensity of the -colors in the spectrum is decreased. It is not that of the extreme case -of the phenomenon of Purkinje, but when the point of brightness has -moved from the yellow into the yellowish greens or decidedly to the -right of the place it occupies in the normal spectrum. In that case -yellow would be the color second in brightness. In our measurements -the amounts of curvature obtained from yellow images were next in size -to those of green. The red and the violet-blue which we used would -therefore be about equal. It is a noteworthy fact, however, that when -the intensities of light (1) and (2) are too great to give a maximum of -curvature the amount of curvature obtained with the red is greater than -that of the blue, while with the intensities which are too small (4) -and (5) to give a maximum the blue curve is greater than the red. - -As yet it has not been possible for me to find an interpretation of -these facts which would seem to meet all the requirements, and I -should not wish to offer any explanation at present. The question -of the possible connection of this phenomenon with Purkinje's is -probably important for any explanation, though it is possible that the -arrangement of the curves is merely a coincidence, yet this hardly -seems likely, and it would seem as if an explanation of the connection -would involve an attempt at explanation of Purkinje's phenomenon, and -lead at once into the most doubtful problems of the theory of visual -sensations. - -It is also noticed that the series of numbers obtained when the -amounts of curvature of the different colored images, at the different -intensities given in the foregoing table, are averaged up, and the -curve of the average of all colors is thus obtained, that this average -curve is very like that obtained for the white light. These curves and -the series of numbers which they represent are here given. - -[Illustration] - - Average for all colors. 14.00 15.70 17.90 15.90 15.35 - Curve for white light. 11.50 15.00 17.80 15.75 14.25 - -It will be noticed, however, that the curve for the white light, while -nearly equal to that of the average for the colored lights at the -maximum point, nevertheless falls considerably below it at each end. -This may possibly be due to the fact that with white light it was only -necessary to use an 8-candle-power lamp as a source of light, so that -when pieces of ground glass were interposed in order to reduce the -intensity of this light, very much greater reduction would occur with -this comparatively weak source than would take place with an objective -source of light of far greater brilliancy, as was the case with the -colored lights. Hence there would be a greater difference in absolute -intensity between intensities 1 and 3 with the white light than between -intensities 1 and 3 with any of the colored lights, or that represented -by their average. Thus the falling of the curve of the white light -at each end may possibly be due to the fact that there is a greater -difference in intensity represented by these parts of the curve in the -case of the white light than is represented by the analogous portions -of the curve of the average of the colored lights. - -It will be remembered that these measurements were obtained when -the image was upon the fovea, so that the white obtained was "cone -white," and not due in any way to the functioning of the rods. It is -interesting to note that the curve of the white is very near that of -the average curve of all the colors, though I should hesitate to draw -the conclusion from this that "cone white" is due to a mixture or -fusion of all the excitations corresponding to the different colors. - -In regard, however, to relations of the amounts of curvature of the -images, there are several further considerations which ought to be -noted. In the first place all three measurements were made when the -images were entirely on the fovea. In the fovea there are no rods, so, -whatever the connection of these facts with Purkinje's phenomenon, it -is one which has to do with the functions of the cones alone. - -Professor Hess, in his experiments upon totally color-blind subjects, -found that exactly the same oscillatory processes in the course of the -stimulation occurred with them as with normal subjects. He also found -that the difference in the time of latent perception between the foveal -and extra-foveal parts was the same for one set of subjects as for the -other. The sole difference seemed to be in the one fact of not being -able to perceive colors. From these facts it does not look as if the -difference between seeing colors and color-blindness were by any means -always due to the absence of cones in the color-blind eye. It may of -course be true that an eye which is deficient in cones or which has -a lesion of the fovea would have poor color perception. But it seems -also true that an eye which, in so far as the rods and cones and their -purely retinal processes were concerned, seems to be normal in every -way, except perhaps that somewhat different intensities were required -to give the same reactions (which might be explained by different -central processes), may nevertheless belong to a person who is totally -color-blind or totally unable to perceive colors with that eye. - -If this should prove true, the cones would still be regarded as the end -organs of color perception, but the cones would only give sensations -of color when functioning in conjunction with some other more central -process. The usual cases of color-blindness would be attributable, not -to any deficiency in the cones or any other retinal process, but to a -defect in this more central process, which, working in conjunction with -the cones, gives us our sensations of color. - -The usual views of the functions of the rods would not be affected by -these considerations. They would continue to be regarded as end organs -whose main business it is to deal with weak stimulations and to notice -movement in objects whose images fall upon the periphery of the retina. - -But the main difference would be that all cases of partial -color-blindness and most cases of total color-blindness would be -explained by lesions in the brain rather than abnormalities of retinal -structure. - - -VARIOUS FORMS OF IRRADIATION - -The endeavor to explain these phenomena of moving images which we -have been considering and an examination of the literature of the -subject have led me to conclude that there are five distinct types of -irradiation. These are: - -1. Irradiation α. The very rapid spreading of the nervous excitation -over the retina, which extends far beyond the borders of the image -and which occurs immediately upon stimulation. It is most distinctly -observed with stationary sources of illumination of the briefest -duration perceptible. This kind of irradiation has been discussed at -length by Charpentier and Bidwell. - -2. Irradiation β. As the apparent form of the moving image becomes -distinctly perceptible, such irradiation takes place within the -confines of the stimulated portion of the retina, so as to make the -excitation present at favorably situated localities more intense than -that of other places. The portions which are so situated as to receive -this reënforcement are the first to enter consciousness. The various -phenomena discussed earlier in this paper furnish examples of this -process, as well as the phenomenon of the curved image. - -3. Irradiation γ. After, and in part during, the rise and development -of the reënforcing irradiation, emanations of nervous excitation of -small intensity proceed from the borders of the stimulated portions -and from the after-images, rapidly extending themselves over the retina -and gradually decreasing in intensity. - -4. Irradiation δ. When two fields of different intensities are brought -into juxtaposition, the field having the greater intensity will enlarge -itself at the expense of the other. This constitutes what has been -usually termed irradiation, and is observable with stationary objects. -This enlargement varies with the time during which it is observed, the -absolute intensity of the light employed, and the relative differences -in intensity of the two fields. Its angular extent under determinable -conditions is constant, although it varies considerably from one -observer to another, and with the same observer at different times. -Its physiological explanation is probably similar to that of the -other kinds of irradiation, viz., the spreading of nervous excitation -over or through the layers of the retina, although various factors of -accommodation, dispersion, achromatism, astigmatism, etc., enter in -and modify the totality of the phenomenon. It will be noticed that -reënforcement occurs in this kind of irradiation as well as in certain -of the other forms. The sides of the dark fields upon which this -form of irradiation shows itself appear curved inward at the centre, -apparently showing the presence of a greater excitation in the lighter -fields next to the centre of the darker ones. - -5. Irradiation ε. When a luminous object has been observed for a long -time (from thirty seconds to several minutes), the whole surrounding -field will be flooded by a faint haze of light, which within certain -limits increases in intensity the longer the stimulation is present. -This phase has many characteristics of the first and most rapid kind of -irradiation, and possibly represents a discontinuance of functioning, -through fatigue of certain nervous mechanisms which prevent the -spreading, or inhibit the perception, of this irradiatory excitation -after the form of the object is distinguished clearly. It is probably -largely due to such a mechanism that we are enabled to perceive as -clearly and sharply as we do the outlines of objects which differ -greatly in intensity from their backgrounds. - -W. McDougall has developed a theory of inhibition[28] which he uses -to explain the more usual kinds of irradiation. This explanation -harmonizes very well with the results of my own experiments and helps -to explain all the kinds of irradiation we have distinguished. Briefly -stated the theory of inhibition is this: there is a transference of -nervous excitation or energy through the nerves and from one neurone to -another. This living nervous energy he calls neurin. The place where -it crosses from one neurone to another he calls the synapse. - -Of course these conceptions are not to be taken too literally. They -seem to be rather, if they are to be of any value at all, a convenient -way of handling certain neurological processes of which at present we -know very little, but whose grosser modes of action are comprehended -more easily by the use of such terms as "resistance," "neurin," etc. It -is in this manner that I wish to be understood in the use I have made -of Dr. McDougall's valuable contributions to the methodology of the -subject. - -Neurin is generated when a stimulus is applied to the afferent nerves. -When a strong stimulus is applied, neurin is generated rapidly, and -discharges across the synapse to the efferent neurone in a series of -very rapid discharges like the multiple discharge of a Leyden jar. -When the stimulus is weak the discharges take place more slowly. -Consciousness occurs at the time of the discharges and occurs in -pulses. When these pulses occur in very rapid succession we experience -a continuous sensation, when the discharges take place at a lower rate -we are conscious of a pulsative sensation, as for instance, in the -visual phenomenon of Charpentier's bands. - -Continuance of stimulation continues to produce neurin, but the -multiple discharges caused by the incoming neurin cause fatigue in -the synapses, and the neurin seeks new paths of discharge through -unfatigued synapses. - -The resistance of the synapses is first lowered by the incoming neurin, -then raised again through fatigue. When the resistance is first lowered -upon application of the stimulus, the neurin which might go through -other channels of discharge is "drained off" through the synapses which -have their resistance thus lowered, then as the resistance is again -raised through fatigue, it again seeks discharge through synapses which -are unfatigued. - -Applying these conceptions to the different kinds of irradiation we -have distinguished, we can bring them all under one category. One -might remark in passing that, in so far as our purposes are concerned, -it makes very little difference whether we regard consciousness as -occurring upon the crossing of neurin from one neurone to another, or -upon the charging and discharging of a cortical cell, so long as the -conditions already referred to are maintained, viz., first, a lowering -of resistance as the incoming nervous excitation finds its way through -the cell or across the synapse, and then the gradual rise of resistance -and its conduction into new channels by fatigue of the synapse, or -exhaustion of the cell and a consequent turning of the excitation -through fresh cells across fresh synapses before its passage into the -efferent nerves. - -When a light stimulation falls upon the retina, during the first one -hundredth or one fiftieth of a second the nervous excitation of neurin -will spread about generally through the retina for a considerable -distance from the point immediately excited. Thus by means of the -fibres of the retina faint excitations will go to the brain from all -these different points, so that one will perceive a faint cloud of -light, similar to that described under the first kind of irradiation. -Moreover, since the portion of the retina directly stimulated by the -light will have the most intense stimulation, this part will come to -consciousness somewhat more quickly than the outlying parts, so that -the cloud of light will first seem to spread outward from its source, -and then, as the resistance in the synapses is lowered through the more -intense stimulation of the part of the retina upon which the light -directly falls, the outrunning excitation will be "drained off" from -these portions of the retina outside of the borders of the image, and -the halo or cloud of light will appear to contract again. This was -observed by Charpentier and Bidwell, and in our own experiments. - -Moreover, in case the synapses corresponding to the portions of -the retina indirectly stimulated should have themselves periods of -discharge and periods of charging, we might expect to see dark rings -upon this halo, this was also first observed by Charpentier and Bidwell. - -Secondly, as the resistance is lowered in the central organs -corresponding to the end organs of the retina upon which the -stimulation falls, the image tends to assume its true form, but -irradiation has been, and probably still is, present through the layers -of the retina, so that certain favorably located portions of the image -secure reënforcement by means of this irradiation, in the manner -described, and these portions appear in consciousness sooner than -the others. This reënforcement, in the case of the travelling oblong -image, will make it appear convex. Moreover, since the resistance of -the synapses corresponding to the centre of the oblong images will be -less than those corresponding to the ends, there will be a certain -tendency to "drain off" the stimulation from the rest of the image, a -sort of reënforcement of the reënforcement, which will also help in -making the image appear curved. Of course all the conditions which we -found to modify the curvature of the images will still hold good, these -conceptions being used only to describe the course of events which -causes the image to appear convex. Thus a very weak or a very intense -or a very long or an excessively short image will not appear curved, -owing to a lack of difference in intensity between the ends and the -centre great enough to produce perceptible curvature. - -As to the third kind of irradiation, that which proceeds from the ends -of the moving image over the unstimulated portions of the retina, -and which has the appearance of long streamers of light extending -outward and backward from the moving image, this may be regarded as -being in certain respects a form of the first and very rapid kind -of excitation. It may well be that all the outrunning excitation -which occurs immediately upon stimulation does not find its way to -the central organs through those nerve-paths which correspond to the -directly stimulated portions of the retina, even after the form of -the image may be very clearly determined, but that some excitation -proceeds outward from one retinal element to another, arousing fainter -and fainter excitation as it proceeds. This being the case, we should -expect to find these streamers of light from the ends of the image -extending outward and backward over the retina. Of course the faster -the image moved and the more intense it was, the longer then would be -these streamers. For if the image moved very fast, very much less of -the excitation would be "drained off" through the directly stimulated -portion, and thus more of the excitation would be left behind, so to -speak, by the image when it moved along rapidly, and this would appear -to drag farther and farther behind. Of course these streamers being -curved backward would appear more curved the faster the image moved, -and if the pulsative processes occurred with these stimulations which -occur in the course of other retinal stimulations, we should have -Charpentier's "palm-branch" phenomenon. - -The fourth kind of irradiation which we have defined is of course -the best-known form, and is that which has been the most discussed -by the many writers on the subject. It will be remembered that this -form appears in stationary objects which have been observed for some -little time (from four to ten seconds), and consists in the apparent -enlargement of a more intensely illuminated portion at the expense of -a less illuminated one. This enlargement occurs after all trace of -the first kind of irradiation has vanished, and of course no trace of -the third kind comes in, since the object is stationary. The course -of events may then be somewhat as follows. In the first perception -of the object we have the wide-spreading irradiation described. Then -way is made through the synapses corresponding to the stimulated -portion of the retina, and the wide-spreading irradiation is drained -off through these open channels, so that the image contracts again to -its proper size. But at the same time it is not likely that there -will not be a slight irradiatory enlargement of the borders of the -image. For irradiation is present within the confines of the image. -This is shown not only in the case of moving images, but also in the -fact that the edges of the less intensely illuminated portions of the -field are curved inward, this being most probably due to the fact that -the centres of the contiguous luminous portions are reënforced by -irradiation proceeding from the direction of both the ends. - -Not all of the excitation proceeds to the brain from the directly -stimulated portions of the image merely, but a little irradiates -over the borders and causes an apparent enlargement of the brighter -field. It has also been shown by Plateau and others that the amount -of irradiation increases both with the intensity of the stimulation -and with the time during which it acts. Of course, as to the intensity -there is no question. As to the time-element, it may be that the -excitation at the border spreads rather slowly outward after the -previous contraction of the image to its proper dimensions, which takes -place within a very short time after stimulation, until a sort of -balance is reached between the tendency of the image to enlarge itself -through irradiation and the tendency for this irradiatory excitation -to be drained off through the nerves corresponding to the stimulated -portion of the retina, after which no further apparent enlargement -takes place. - -In some of our experiments with dots we found that after a dot of the -proper intensity of illumination had been steadily gazed at for some -time the centre would appear dark. This seems to be due to the fact -that the centre of such an image was reënforced by irradiation, so -that the nervous mechanism corresponding to it became fatigued more -quickly and the stimulation at the centre no longer gave such intense -sensations as the rest of the figure, but appeared darker. - -Passing to the fifth and last variety of irradiation, this seems due -to fatigue in the inhibiting apparatus which reduced the spread of the -first kind of irradiation. Following out the scheme we have applied, -it would seem as if the channels which were first opened by the direct -stimulation became blocked through fatigue, and, therefore, the -excitation produced in the retina were forced to seek new paths through -to the brain by means of the nerves which proceed from the unstimulated -portions of the retina. Thus if the resistance through fatigue occurs -slowly, the excitation which spreads may increase in intensity and in -extent. So, as the resistance increased, a portion corresponding to the -directly stimulated portion and its slight irradiatory enlargement of -the borders would be surrounded by a cloud of light growing in size and -intensity. - -Of course the limiting case would be when the external cloud of light -attained as great or even greater intensity as the stimulated portion, -but such a case would probably be impossible to realize because of -other conditions which would prevent. - -It may be that this fifth variety is caused partly at least by a -cortical spreading of the excitation. But it seems to me more likely, -in view of the fact that we could find no irradiatory enlargement of -the binocular portions of stereoscopic images and for a number of other -reasons, that the induction is retinal in character and that after -the resistance through fatigue has arisen in the central organs the -stimulation spreads out over the retina to the unstimulated portions -of the field and proceeds from thence to the brain. This seems more -probable than that the stimulation continues to be confined merely -to the stimulated portion of the retina, but seeks passage from one -portion to another of the brain through fresh neurones which branch -only from those nerve-tracts which proceed from the directly stimulated -portions of the retina. - -To conclude; we have seen that there are various forms of irradiation -which take place during the perception of stationary and moving sources -of illumination. - -That there are certain modifications in the form of a moving image -which are probably due to one of these processes. - -Concerning color irradiation it was found that the curvature of the -images varied with the color of the light, so that a figure illuminated -by a colored light of one intensity would not have the same curvature -as one illuminated by a light of the same intensity but of another -color. Green gives the greatest curvature, yellow the next, red and -blue about the same. In other words the differences in curvature of the -images follow the order of the brightness of the colors in a spectrum -the intensity of which is much reduced. - -From a consideration of these phenomena we were led to discuss the -functions of the rods and cones in the retina of the eye, and the -suggestion was made that differences in color-vision were due to -central rather than retinal processes, and that in many cases of -partial or total color-blindness the retina would be found normal and -the defect in vision due to a lesion in some more central structure. - -The various forms of visual irradiation which have been described -by a number of different writers we found to be all forms of one -rather simple process. Resistance, removal of resistance upon further -stimulation, and recurrence of resistance through fatigue in some part -of the optic tract, together with the spreading of stimulation over the -retina (probably through the molecular layers) from one afferent nerve -to another are assumed as the minimal requirements which are sufficient -to explain the five forms of irradiation which have been considered in -this paper. - -FOOTNOTES: - -[Footnote 23: Image no. 5 appeared with the concavity in front. In the -centre of the figure appeared a dark grayish splotch of light, very -much darker than the rest of the image. This is due, most probably, to -the presence of Charpentier's phenomenon of recurrent bands. If this -happens in this figure the ends of the recurrent bright images would -overlap while the centres would not, so that the black bands appearing, -as it were, through interstices in the central part of the figure, -would seem like a dark splotch, especially since the outlines of the -bands are vague and hazy. The back end of the figure had the effect of -being vertical or nearly so. This is probably due to the same cause as -that which made the circular figure to appear as it did, namely, the -negative after-image overlapping the positive after-image. The front -of this black image is usually of about the same shape as the front of -the real figure which it follows. If this is so, then, in this case, it -would make the back part of the image pretty nearly vertical.] - -[Footnote 24: The intensity of the objective stimulation may be -represented by the line _AB_. If there were no reënforcement of -stimulation the whole figure would be flat on top and of this height. -The difference between _AB_ and _AC_, or _BC_, represents the increase -of intensity due to irradiation at the most favorably situated portion -of the figure. The other portions receive increments proportional to -their location, as indicated in the diagram.] - -[Footnote 25: Favorable localization will of course depend largely on -the shape of the figure in which the point is situated. Thus one in the -angle of a triangle or at the horn of a crescent would have much less -reënforcement of excitation than another point, say halfway down the -side.] - -[Footnote 26: Bidwell describes this "black process" or "negative -after-image" of a bright, white light as being of a blackness more -intense than the ordinary blackness of an entirely dark room. This is -perfectly true. The black image, however, lasts for a very much longer -time than the recurrent images of the same light. Often this velvety -black band would trail along behind the moving light for the distance -of a foot or more, gradually lightening into the darkness of the -background.] - -[Footnote 27: The intensities used with white light are all less than -an eight-candle-power electric lamp placed at about a foot behind the -opening and covered with two pieces of ground glass.] - -[Footnote 28: McDougall, 1901, 1903.] - - - - -FEELING - - - - -THE EXPRESSION OF FEELINGS - -BY F. M. URBAN - - -The material of this paper was obtained by an experimental -investigation which was carried on in the Harvard laboratory from -February, 1904, till June, 1905. The immediate purpose of these -experiments was a study in the expression of the feeling-tone of -simple sense-stimuli. Breathing and circulation were the functions the -changes of which were observed by tracing the curves of thoracal and -of abdominal breathing and the sphygmographic curves simultaneously. -Acoustical, tactual, pain, and smell sensations were studied in this -way, special attention being devoted to the smell and pain sensations. -These stimuli have the advantage that the physiological reactions of -the subject are more uniform than the reactions to other stimuli. -The number of experiments performed in this investigation was large, -although a subject was never experimented on for more than forty -minutes, because the facilities of the laboratory allowed a continuous -experimenting for several hours a day on different subjects. All the -experiments were performed on trained subjects. Only the changes in -the form of the sphygmographic curve will be discussed in this paper. -The results of this observation confirm the observations of previous -investigators in so far as the same changes in the curves were observed -and the introspections of the subject were, on the whole, similar to -those obtained by other observers. It does not seem probable, however, -that a satisfactory discussion of the results can be given on the basis -of merely mechanical measurements of the curves, and it, therefore, -seemed necessary to reconsider the principles of the theory of the -sphygmographic curves. - -There are two methods which can be applied to the study of the -psychology of feelings. They are called the method of impression and -the method of expression. The first is a purely psychological method, -while the latter is confined by its definition to the study of the -physiological changes which are the accompaniments of feelings. The -method of expression is never used as a pure method in investigations -which are carried on for psychological purposes, because the -introspections of the subject must be compared with the physiological -results. It therefore has the character of a mixed method. The first -experimental investigations into the psychology of feelings were -started by Fechner, who employed the pure method of impression. At -this time, however, the apparatus for studying the circulation had -been greatly improved and sooner or later these instruments were sure -to be used for a more exact study of the influence of feelings on -circulation. It was to be hoped that the crude observations on the -changes of the heart-beats and of the circulation under the influence -of feelings might be followed up in detail. - -Darwin laid stress on the importance of certain bodily accompaniments -of feelings, and he inaugurated the genetic explanation in this -field. But even if the genetic explanation is successfully carried -through, human psychology remains unexplained, and, furthermore, those -emotional expressions which Darwin described form only a part of the -physiological accompaniments which may be observed with the instruments -now in use. The invention or at least the great improvement of these -instruments is due to the investigators in the middle of the last -century, and a more thorough understanding of the delicate changes of -respiration, circulation, and of temperature was not possible before -the construction of these sensitive recorders. It seems that Mosso was -the first to observe these small changes under the influence of mental -activity in general, and feelings in special; in this sense it may -be said that Mosso started the experimental physiology of feelings. -The discovery of the influence of feelings on circulation is very -important, and it is to be appreciated that Mosso saw these slight -changes which escaped an observer like Marey. In the Mémoire offered -to the Academy[29] on March 26, 1860, Marey gives a great number of -circumstances which influence the sphygmographic curve, but feelings -or mental phenomena are not mentioned in this list. It is true that he -speaks in a later publication[30] of the influence of "moral ideas" on -the circulation and makes the hypothesis that these ideas influence the -circulation in the same way as other disturbing influences, _i. e._, by -changing the peripheral resistance. At this time Marey was already in -possession of his sphygmograph, but nothing in this passage indicates -that he saw the influence of feelings on the tracings. On the contrary, -the words "Sans rien livrer à l'hypothèse" seem to indicate that Marey -had no other facts in mind than those commonly known. He certainly did -not follow up his observation, and his statement at this point does not -differ very much from the observations of the old psychologists, that -emotions change certain physiological functions, of which a more or -less complete list is frequently given.[31] - -It certainly is a long step from this vague statement to Mosso's -experimental investigations. His new instruments, the plethysmograph, -and the balance, enabled him to study the distribution of the -blood,[32] and he observed the influence of mental phenomena on the -circulation,[33] on the bladder,[34] and on the temperature of the -brain.[35] His work, "La Paura," describes the physiological effects of -emotions somewhat in detail. - -The way toward applying the method of expression to the study -of emotions was shown by the results of previous physiological -investigations. Casual observations of the influence of certain -sense-stimuli on respiration and circulation were made by Naumann, -Couty and Charpentier, Thanhoffer, Dogiel, Gley, Mays, Istomanow and -Tarchanoff, Féré, Delabarre, and others.[36] The changes of breathing -seem to be of greater importance, and some writers account breathing -the most delicate physiological index of feelings.[37] It seems, -however, that a satisfactory treatment can be obtained only by direct -comparison of the respiration and circulation, and it now but seldom -occurs that circulation is observed exclusively. - -There are three different instruments for observing the circulation: -the plethysmograph, the sphygmomanometer, and the sphygmograph. Each -of these instruments allows one to observe a different feature of the -circulation. The sphygmomanometer records the pressure in the artery; -the plethysmograph records the volume of a certain part of the body; -and the sphygmograph records the movement of a certain part of the -arterial wall. The curves traced with the sphygmograph indicate to a -certain extent the pressure of the blood, and sometimes they are called -curves of blood-pressure to distinguish them from the plethysmographic -curves which are called curves of pulse-volume. - -The invention of these instruments is due to physiological -investigations of the pulse. The problem of studying the pulse -by graphic, or at least experimental methods, begins with the -investigations of Hales and Poiseuille. The first great success in -this line was the construction of the "Kymographion" of Ludwig, but -this instrument had the disadvantage that it could be applied only -by scission of an artery. This circumstance, of course, confined the -application of the instrument to the study of the pulse of animals. -After several attempts by Hérisson, Chelius, and others, Vierordt -succeeded in constructing his sphygmograph, by which curves of the -normal human pulse could be obtained. Some years afterwards Marey -constructed his much more sensitive instrument, which was made still -handier by the use of air transmission. Buisson was the first to use -air transmission for sphygmography, but Upham had used it before for -similar purposes. A considerable number of sphygmographs has been -constructed since, and though they may show some improvements in -detail, the technique of the sphygmograph has made no marked progress -since Marey, and his instrument has been found by experimental tests -remarkably exact. - -The curves traced with the sphygmograph are extremely variable in shape -and size. In almost every normal curve, however, a steep ascent may be -seen; it is called the up-stroke or percussion stroke, and this part -of the sphygmographic curve has the name of the anacrotic phase. This -line of ascent ends abruptly and within the limits of the usual speed -of the recording drum it goes over into the descent by a sharp angle. -The descending part of the curve is called the catacrotic phase. The -descent is not so abrupt and is not a more or less straight line, but -is interrupted by secondary elevations. The first secondary elevation -is the largest and is called the dicrotic.[38] - -These secondary elevations were seen first by Chelius and Vierordt, -and from the beginning they aroused considerable interest. It was -known that sometimes during fever the pulse takes an abnormal form, -where two beats of the pulse, a strong one and a weaker one, may be -felt for every heart-beat (pulsus bis feriens). This form of the pulse -was thought to be entirely abnormal and it was therefore a great -surprise for the first modern investigators to find these secondary -elevations in tracings of the normal pulse curve. The conviction of -the abnormality of the dicrotic pulse form was so firm that Vierordt -always applied his instrument in such a way that it did not trace the -dicrotic elevation, although it was sensitive enough to trace the exact -form of the pulse curve. Marey, however, used his much more delicate -instrument and found the dicrotic elevation in most of the normal -pulse curves.[39] For this reason Marey's sphygmograph met at first -with considerable criticism (Meissner), but the critical examinations -by v. Wittich, Buisson, and Mach showed that the dicrotic elevation -could not be due to an error of the instrument, for so great an error -was out of question, and there no longer remained a doubt as to the -genuine existence of the dicrotic elevation in the normal pulse curve. -The sphygmograph, thus, had revealed two new and surprising features of -the pulse; (1) The ascent and the descent do not take place with equal -rapidity, the ascent being steep, the descent gradual; - -(2) the descent is interrupted by secondary elevations. Neither of -these facts could be observed by applying the finger and it seemed -important to explain them. The explanation of the dicrotic promised to -be of special interest, as it was shown that abnormal dicrotism is in -close relation to the normal form of the pulse curve. - -This caused considerable interest in the observation of the pulse, -and the sphygmograph was supposed to be of the greatest importance -for medical diagnosis. Burdon Sanderson,[40] Landois, Lorain,[41] -Ozanam,[42] Pfungen,[43] Riegel,[44] Roy and Adami,[45] and others -have studied the sphygmographic curve under abnormal conditions, and -wellnigh all diseases have been studied by these observers with the -sphygmograph. The results were ambiguous and did not seem to justify -the amount of work spent on these observations. The enthusiasm for -the sphygmograph subsided, and it was no longer expected to obtain -a diagnosis, or even, indeed, a prognosis of a disease from mere -inspection of a pulse curve. Later investigators, in fact, confined -their research to the proof of the ambiguity of the sphygmograms, -which could be valuable only in connection with other observations. -It could not be hoped that an explanation of the abnormalities of the -pulse curve would be found before an understanding of the normal form -was attained. It, therefore, seemed necessary to decide between two -theories of the origin of the normal pulse curve, which had opposed -each other almost since the discovery of the existence of the dicrotic -elevation. Both theories chiefly refer to the origin of the dicrotic, -and they agree on this, that the dicrotic elevation is due to a wave -travelling in the blood, but they disagree on the direction in which -this wave is moving. These two theories may be called the theory of the -peripheral, and the theory of the central origin of the dicrotic wave. - -The theory of the peripheral origin of the dicrotic wave assumes that -the change of pressure which is indicated by the dicrotic elevation -originates somewhere at the periphery and travels through the arteries -towards the heart.[46] Commonly it is assumed that the dicrotic -originates in the arterioles. This theory has been mentioned first, -because it is the simpler in every respect, though the less probable. -The origin of the dicrotic wave according to this theory is similar to -the origin of the echo. - -Buisson was the first who gave an explanation of the dicrotic elevation -by assuming a central origin of this wave. His theory was adopted by -Marey, who stated it in this way. The action of the heart causes the -blood to be pumped into the aorta with considerable strength. The blood -leaves the aorta by its inertia and expands the arterial system. In -the arterioles it finds an obstacle and being reflected it flows back -to the aorta. But there it finds the semilunar valves closed and a new -wave is produced by reflection. This wave has an effect similar to the -first, and this reflection of waves lasts until the valves are thrown -open again. The existence of several secondary waves is explained by -the great velocity with which the blood travels through the arterial -system.[47] - -This theory is open to many objections. First, there is no reason why -the blood wave should not produce a dicrotic elevation when it flows -back to the aorta. Second, the narrow lumen of the arterioles cannot -be an obstacle to the flowing blood, because if an artery splits up -into small branches, the sum of the lumina of the branches is greater -than the lumen of the artery. Lack of space, therefore, cannot be the -cause of the reflection of the pulse wave. Marey, finally, is mistaken -in his conception of the effect of the blood pumped into the aorta by -the action of the left ventricle. He supposes that the entering blood -pushes before it the whole column of blood in the arteries. This view -is refuted by the actual measurements of the velocity of the pulse -wave, because if it were true the pulse would appear at the same moment -in every part of the body.[48] - -These are the more obvious of the arguments against Marey's theory. -Other investigators have tried to state a more correct theory of the -central origin of the dicrotic wave. Landois's theory belongs to this -type of improved theories of the central origin. The action of the -left ventricle, according to Landois, causes the primary pulse wave -which travels down the arterial system, until it is extinguished in -the arterioles. The walls of the arteries are expanded by the arriving -blood wave, and, when the valves close, they force the blood onward by -their elasticity. There is a free way to the periphery, but the blood -pushed towards the heart finds the semilunar valves closed and is -reflected. In this way a new positive wave originates which may produce -in the same way a secondary or tertiary wave.[49] - -It seemed necessary first to decide between the theories of the central -and of the peripheral origin of the dicrotic wave. Many investigations -have been carried on for this purpose, and some of them bear witness -to the high ability of the investigators. It is, however, remarkable -that the arguments which have been brought forward in favor of one -hypothesis chiefly consist in reasons why the other hypothesis should -not be accepted. These experiments can be divided into two classes. -The first class comprises all the experiments which study the relation -of the pulse curve to other functions, or its dependence on various -conditions. The above mentioned observations of the pathological -changes of the pulse curve belong to this class. The object of frequent -studies of this type has been the relation of the sphygmographic -curve to the curve of the apex beat. The papers of Otto and Haas,[50] -Garrod,[51] Traube,[52] Rosenstein,[53] - -Maurer,[54] Gibson,[55] François Frank,[56] and Edgren[57] deal -with this problem. The curve of intraventricular pressure cannot be -studied in man for obvious reasons, and only in some cases has an -attempt been made to compare the sphygmographic curve with the curve -of intraventricular pressure obtained from animals. One of the most -interesting attempts in this line will be mentioned later. - -To the second class belong all those investigations, by which -experimental evidence in favor of one or the other hypothesis has been -collected. The experiments which belong to this class are in so far -more decisive as the conditions of the experiments are better known -and, therefore, easier to interpret. Von Kries proved the existence of -the dicrotic in the femoral artery of an animal after having replaced -the heart by a bag filled with liquid.[58] Grashey[59] and Hoorweg[60] -have demonstrated the existence of secondary waves in models, on which -peripheral reflection was impossible. To the same type of experiments -belong Marey's[61] and Grashey's registration of the waves in elastic -tubes, and Mach's[62] tracings from a mechanical model on which the -resulting movement of two simple components could be registered. -Without giving any physiological theory Mach showed how curves similar -to the pulse curves can be obtained by the registration of a movement, -the mechanical conditions of which are known. - -As the results of these investigations, we may state the following -facts as arguments against any hypothesis of the peripheral origin of -the dicrotic elevation. - -(1) Automatic registration of the pulse wave shows that the dicrotic -appears sooner in the regions nearer to the heart than in regions -which are more distant. The opposite would be the case if the dicrotic -elevation were due to a wave travelling from the periphery to the heart. - -(2) The dicrotic appears at the same time after the primary wave in a -dwarf as in a tall man. This would be impossible if the wave had to -travel so much farther. - -(3) Inhalation of amyl nitrite makes the dicrotic almost disappear. The -adherents of the theory of the peripheral origin of the dicrotic wave -explain this fact by supposing that this drug dilates the arterioles -and makes little reflection possible. Their opponents say that the -action of the heart and the resistance of the system are so enfeebled -that the backward flow is slight and gives rise only to a small wave. - -(4) If an artery is opened and the blood allowed to spurt on a -revolving drum of white paper a curve is obtained which shows the -dicrotic elevation (the hemautographic curve of Landois). The -resistance of the periphery is totally lacking in this case and the -dicrotic elevation could not appear if it were due to a wave reflected -at the periphery. - -(5) The appearance of the dicrotic is not retarded if an elastic tube -is placed between the periphery and the place where the instrument is -adjusted. If the dicrotic were due to a wave reflected at the periphery -it would be retarded because the wave would have to travel a distance -so much greater. - -These arguments prove the impossibility of the theory of the peripheral -origin of the dicrotic wave. Also the other hypothesis meets with a -number of serious difficulties, and we mention the following facts -which are arguments not against any special form of this theory, but -against any hypothesis which starts from the assumption that the -dicrotic elevation is due to a wave travelling from the heart to the -periphery. - -(1) The descent of the catacrotic phase ought to be a succession of -diminishing waves, but not a slow descent with merely small elevations. - -(2) This hypothesis accounts for none of the abnormal pulse forms. - -(3) The blood ought to push against the semilunar valves with a -force not less than 1/2 - 2/3 of the force of the contraction of the -ventricle, because this is about the relative height of the first -secondary elevation with regard to the primary wave, which is due to -the contraction of the ventricle. - -(4) It does not account for the disappearance of the dicrotic -elevation through lack of elasticity of the arterial wall: for the -dicrotic elevation is most marked in youth, becomes lower in old age, -and disappears in diseases like atheroma and arteriosclerosis, which -impair the elasticity of the arterial wall. Landois's theory overcomes -this theory only apparently, although the dicrotic would be absent, yet -in that case the descent of the primary wave ought to be as steep as -its ascent. - -(5) This theory is refuted by the experiment of v. Kries, who proved -the existence of the dicrotic if the heart is replaced by a valveless -bag. - -The obvious impossibility of making the theories agree with the facts -does not permit one to accept any of them. All of them are based on the -supposition that the dicrotic elevation is due to a wave travelling in -the blood, and this belief is founded on the following argument: If a -wave travels in the blood the sphygmographic curve shows an elevation; -the dicrotic elevation is an elevation in the sphygmographic curve. -Therefore, the dicrotic elevation is due to a wave travelling in the -blood. This fallacy is responsible for the astonishing fact that the -refutation of one of two apparently contradictory statements does not -prove the other. It is characteristic of the present state of the -problem concerning the origin of the dicrotic elevation, that a modern -writer[63] calls it "inextricably complicated." - -The contradiction between the theories of the peripheral and of the -central origin of the dicrotic, however, is only apparent, and neither -may be true, because it might be that this elevation is not due to -a wave which travels in the blood. The experiments of the previous -investigators seem to point in this direction. The disappearance of the -secondary elevations when the arterial wall has lost the properties -of an elastic body, the above-mentioned experiments of v. Kries, and -the observations of Grashey and Marey on the movements of the walls -of an elastic tube indicate clearly that nothing but elasticity is -needed to produce these secondary or dicrotic elevations, for, in the -different experiments, they are produced as well when the heart and -its valves are replaced by a valveless bag as when the function of -the valves is unimpaired; as well with resistance at the periphery as -without, the only condition being that the walls are elastic. This -proves the importance of the elasticity of the arterial wall. The -experiments of the graphic registration of the movements of the walls -of an elastic tube, furthermore, indicate that the conditions of this -experiment are a close imitation of the mechanical conditions which -prevail in the arteries. It may be expected that the analysis of the -conditions of the experiment will give an insight into the origin of -the sphygmographic curves, because the tracings which Grashey and Marey -took from the walls of a rubber tube resemble closely the tracings of -the human pulse. This experiment, first, proves that the form of the -curve depends merely on physical conditions. The movement of a point -of the wall of the tube depends on the following four factors: (1) The -elasticity of the wall; (2) the incompressibility of the liquid; (3) -the form of the original wave, _i. e._, the way in which the liquid -is pumped into the tube; (4) the rate of outflow. If the process of -pressing liquid into the tube is repeated regularly, a stationary form -of movement will be obtained eventually; the amount of outflow for one -interval is constant in this case. This means that eventually a state -is attained where the same quantity of liquid which is pumped into the -tube at one end flows out from the tube at the other. The physiological -bearing of this result is that the turgor of an artery does not change -without a cause. Such a change would be indicated by the going up or -down of the base-line of the tracing. - -The first two factors are, in physiology, studied with relative -ease. The elastic qualities of the arteries have been studied since -Poiseuille and John Hunter by Wertheim, Zwardemaaker, Marey, and -others, and they are more or less well known. The physical properties -of the blood are very nearly those of an incompressible liquid, and -this is certainly true for the small pressure to which the blood is -exposed in the arteries. - -As to the initial form of the wave which the action of the left -ventricle produces in the arterial system, we get a hint from the -experiments of Grashey, v. Kries, and Marey, where the sudden -compression of a bag furnished the initial shock.[64] These changes of -pressure can be represented by a curve like that in Fig. 1. - -So long as the contraction of the left ventricle lasts and the valves -are open, the action of the heart produces a certain pressure in the -aorta, but the influence of the intraventricular pressure is zero when -the valves are closed. The second phase of the curve Fig. 1, where the -pressure is zero, certainly gives the influence of the intraventricular -pressure during the diastole, because there is no communication between -the ventricle and the arterial system when the valves are closed. The -question is whether the rest of the curve can represent the changes of -the intraventricular pressure when the valves are open. - -[Illustration: Fig. 1. Changes of pressure produced in a bag by sudden -compression.] - -[Illustration: Fig 2. Decreasing amount of liquid in a tube when the -outflow is uniform.] - -The first curves of intraventricular pressure were traced by Chauveau -and Marey. These experiments were made on a horse, and they have been -repeated since it was discovered that they can be performed also on -smaller animals. Besides Chauveau and Marey may be mentioned the names -of Fick, Huerthle, v. Frey, Rolleston, Bayliss and Starling. The curves -obtained by various observers belong to two types; one shows the so -called "plateau," the other does not. Recent experiments have proved -that this difference of results is due to a difference in methods. This -also is suggested by the fact that different curves have been obtained -from animals of the same species. Two methods have been applied lately -for testing these curves of intraventricular pressure. The first -was devised by Bayliss and Starling. It consisted chiefly in the -photographic registration of the movement of the liquid in a manometer -tube. The photographic registration is frictionless, and the mass of -the moving liquid was so small that vibrations by inertia were fairly -excluded for pressures which are not greater than the intraventricular -pressure.[65] The second method was used by Porter. The idea of this -method was to trace only a part of the curve, not the whole. The -writing lever, thus, has in the beginning of the tracing no inertia at -all, and the tracing may be overdrawn but is certainly correct in form -up to the next point of inflexion of the curve.[66] These tests and -the repeated experiments of Chauveau leave no doubt as to the existence -of the plateau. - -The varying pressure from the heart which produces the pulse wave may -be described in this way: The pressure suddenly rises to a maximum -and maintains it for a certain time; when the semilunar valves close, -the pressure drops as suddenly as it rose, and remains at zero until -the valves open again. Such a function can be represented by a curve -like Fig. 1, and this is the reason why the complicated action of the -heart can be superseded by the compression of a bag without changing -the mechanical conditions of the problem. Of course it can not be -expected that a schematic curve will show all the details of the real -tracing. It is suggested, however, by Frank[67] that many of the small -irregularities of the curve of intraventricular pressure are due to -vibrations caused by the inertia of the apparatus and that the true -form of the curve of intraventricular pressure is very simple. This -remark is supported by Huerthle,[68] who tested the apparatus of Marey, -Knoll and Grunmach. Marey's tambour was found to be the most exact, -but even this instrument produces deformities in the tracings, though -the general outlines are exact. This would indicate that the schematic -representation of Fig. 1 is a very close imitation of the real form of -the curve of intraventricular pressure, although empirical tracings do -not show right angles and straight lines. It seems, however, that the -undulations of the plateau are genuine, since they are found in the -most reliable tracings, and it may be possible to explain them merely -on the basis of the physical conditions of the experiment. - -The fourth factor of importance is the rate of outflow. We may -introduce the following assumption as to the rate of outflow of the -blood through the capillaries: The outflow through the capillaries -is uniform in the short time of one heart-beat. The fact has been -mentioned above that the quantity of outflowing blood must be equal -to the quantity of incoming, for any stationary form of the pulse -movement; this new hypothesis means that the velocity of the outflow -is constant. One might think that this assumption is warranted by the -law of Poiseuille that the amount of outflow through a horizontal -capillary filled with liquid under constant pressure depends on -the fourth power of the radius and on the difference of pressure -at the two ends of the tube, and is inversely proportional to the -constant of friction and to the length of the tube. This law has -been proved mathematically and tested physically only for horizontal -tubes and constant pressure. Neither of these suppositions holds for -the capillaries of the arterial system. The connection between the -hypothesis in question and Poiseuille's law is this. Let us suppose -that an artery splits up in a great number of arterioles which go -off in every direction. The amount of outflow is then a complicated -function, because the law of Poiseuille does not hold for every -direction of the capillaries; but it will be equal to the outflow -through a tube of certain radius and certain direction in the same -time. Our assumption says that the law of Poiseuille holds for this -typical but imaginary tube. The essential point of this hypothesis -is merely the supposition that the outflow of blood through the -capillaries follows α law.[69] - -It is possible to show that the graphic registration of a movement -under these four conditions must give curves which correspond to -the pulse curves in every respect. The action of the left ventricle -causes the pulse wave which travels through the arterial system with -considerable velocity. This wave expands the arteries and the whole -system is filled with blood because the wave arrives by its great -velocity at the periphery before the contraction of the ventricle -is finished. The increased pressure forces the blood to enter the -arterioles, through which it passes at a constant rate. When the valves -are closed, the amount of blood decreases uniformly and the volume of -the blood contained in an artery can be represented graphically by a -straight line of more or less steep descent, as is shown in Fig. 2. -Now the walls of an artery have to a high degree the qualities of an -elastic body, and, therefore, they are forced back by elasticity after -being displaced from the position of equilibrium by the shock of the -arriving pulse wave. The movement of a point of the arterial wall, -therefore, results from two components: (1) From the movement which it -would perform if it were merely forced to remain on the surface of the -blood in the artery, and (2) from the movement due to the elasticity of -the arterial wall. Both movements have the same direction, because the -column of blood is enclosed in a cylinder the radius of which decreases -regularly, and the elastic force of the arterial wall is directed -towards the centre. The direction of both forces is in the line of the -radius, and the resulting movement of these two components, therefore, -can be found by simple superposition. Of the first component we know -that it can be represented graphically by a straight line. - -An elastic force tends always to bring the body back to the position -of equilibrium; if the distance is not too great, the force is -proportional to the elongation. A physical body is always under the -influence of friction, the acceleration of which is opposite to the -direction of the movement, and therefore diminishes the velocity. The -form of the resulting movement depends on the amount of friction, -and, roughly speaking, we may distinguish two types of elastic -movements:[70] the first type is a periodic movement, the second an -aperiodic. Let us suppose that a body is carried from its position of -equilibrium by a sudden impulse, which transmits a certain velocity to -the body. Friction and elasticity diminish this velocity, and after a -certain time the body attains a maximum elongation, where the velocity -is zero. Then the body returns under the influence of elasticity and -under the retardation of friction. There are two cases possible, either -the elastic force is strong enough to overcome friction and to carry -the body over the position of equilibrium, or it is not strong enough. -In the first case, it is easy to see, the body repeats the same form -of movement on the other side of the position of equilibrium, and -the conditions being constant a vibratory movement results as the -stationary form. In the second case the body approaches the position -of equilibrium asymptotically. The first case may be illustrated by -the vibrations of a magnet needle suspended with little friction, the -second by the movement of a door which is regulated by a well-working -shutter. - -These forms of the movement of a body under the influence of elasticity -and friction are illustrated in Fig. 3. - -Curve 1 shows a movement where friction is so small that it can be -neglected; it is, of course, a simple sine curve. Curve 2 shows the -effect of friction on vibrations. The period of damped vibrations is -greater than in the frictionless movement, but the amplitudes are -smaller. The amplitudes of a damped vibration decrease constantly and -there is a simple relation between two subsequent amplitudes. The ratio -between them is constant, and, therefore, if one amplitude and this -constant ratio are known, all the other amplitudes can be calculated. -The amplitudes of such a movement decrease as the terms of a geometric -series. The dotted line in Fig. 4 represents the rapidity of this -decrease. It is obvious that the smaller the constant ratio of two -subsequent terms is, the more rapidly will the amplitudes decrease. -This ratio depends on friction, and becomes smaller when friction -becomes greater. A vibration under heavy friction dies out quickly. -Curve 3 shows a movement where friction is too great to allow any -vibrations. The body does not acquire a velocity which can carry it -over the position of equilibrium, but it approaches this position with -ever diminishing velocity. - -[Illustration: Figs. 3 and 4] - -These are the types of movement which the arterial wall can perform by -its elasticity in consequence of the shock of the arriving pulse wave. -The mechanical nature of the components on which depends the form of -the sphygmographic curve is, therefore, known. The constructions in -Fig. 5 show how the resulting movement can be found. - -[Illustration: Fig. 5] - -These curves are constructed in this way. The lines _AB_ represent -the time of the interval of one heart-beat. The straight line _EB_ -represents the decreasing volume of the artery and the curves on -_AB_ represent the elastic movement of the arterial wall. Both are -synchronous movements, and a line perpendicular to _AB_ gives the -corresponding points. The points of the resulting movement are found -by arithmetical addition of the two ordinates. The results of these -constructions prove that the curves show the dicrotic elevation only -if the elastic force is great enough to make a vibratory movement -possible. Aperiodic movements do not produce this elevation. The -friction is always great for the movement of the walls of an artery, -and there are only the two possibilities, of a vibratory movement which -dies out quickly, and of an aperiodic movement. This accounts for the -fact that the dicrotic elevation may be missing sometimes, and that in -other cases several secondary elevations may be seen, the number of -which, however, is always limited, and their relative height rapidly -diminishing. It may be remarked that the length of the lines _AB_ seems -essential to the form of the resulting curve. Curves I and III differ -very much in the length of the lines _AB_, while the lines _AE_ are -equal and the vibratory movements are only slightly different. The -resultants, nevertheless, seem to differ very much. It is easy to see -that a different speed of the recording drum will have an effect on -the tracings which is similar to that of a change in the length of -the lines _AB_ in the constructions. This is one more reason why mere -inspection of the curves cannot give a satisfactory result. - -These constructions show that the sphygmographic curves must show -great variations, since the amount of blood pumped into the system, -the elasticity of the arteries and friction of the surrounding tissues -are subjected very likely not only to individual but also to local and -temporal variations. But under given conditions only a certain form of -the pulse wave is possible, and this form does not change so long as -these conditions do not change. The sphygmograms in Fig. 6 show some of -the typical forms of the pulse curve. - -[Illustration: Fig. 6] - -No. I shows the influence of high arterial tension, and No. II of low -tension. The first corresponds to No. II in Fig. 5, the second to Nos. -I and III. Nos. IV and V of Fig. 5 show the effect of great friction -and small elasticity. The constructions differ in the form of the -elastic movement; the position of equilibrium is reached with different -velocity in both cases. The resulting movements differ slightly in the -form of the catacrotic phase. Both forms may be seen in No. III of Fig. -6. This sphygmogram was taken from an artery with low tension, and this -form of the sphygmographic curve is well known as characteristic of the -"soft" pulse. If the artery has lost to a large extent the qualities -of an elastic body, and if the outflow is very rapid, the pulse curve -shows nothing but the slight elevation of the travelling wave; No. IV -in Fig. 6 shows a curve of this character. - -This theory explains many surprising facts which resisted every attempt -at explanation. The anacrotic part shows a steep ascent, because it -is due to the sudden arrival of the blood wave. It seems that an -interruption in the descent may be seen only in abnormal cases. The -sphygmograms of twelve normal individuals were observed regularly by me -during more than a year without once discovering an anacrotic elevation. - -The hemautographic curve of Landois is produced in this way. The form -of this curve depends on the velocity of the escaping jet of blood. The -velocity of the blood flow depends on the resistance of the arterial -system in the sense that the velocity decreases when the resistance -increases. When the arterial wall is in the negative phase of vibration -the lumen of the artery is smaller, and, therefore, the velocity -smaller. This is confirmed by the actual tracings of the velocity of -the circulation by Marey. - -It is also obvious that the dicrotic elevation never can arrive before -the primary wave, because the arterial wall cannot perform elastic -vibrations before it is expanded by the impulse of the arriving blood -wave. Neither is it surprising that the "dicrotic wave" seems to travel -in the same direction and with a velocity equal or almost equal to the -velocity of the pulse wave. Such a difference can be produced only by a -difference in the time of the vibrations of the arteries at different -points of the body. The time of one vibration is necessarily very -short, and the length of this interval depends on the circumstances -which determine the elasticity of the arterial wall and the friction. -These conditions may be subjected to local variations. If, therefore, -the time-interval between the primary and the secondary elevation -is measured at two different points (_e. g._, at the carotid and at -the radialis) a difference of time may be found. Starting from the -supposition that the dicrotic elevation is due to a wave travelling in -the blood, one could attribute this difference of time to a velocity of -the "dicrotic wave" which is slightly different from the velocity of -the primary wave. The fact that the dicrotic elevation appears later in -places farther from the heart was interpreted as a proof that the wave -travelled out from the heart. No theory which assumes that the dicrotic -elevation is due to a wave travelling in the blood can give a reason -why two waves of the same form and origin should travel through the -same liquid at different velocities. - -At this point a theory must be mentioned, which was brought forward -recently, because it is based on measurements of the velocity of -propagation of the dicrotic wave. This theory is connected with Krehl's -theory of the function of the valves. The blood, according to Krehl, -enters the aorta through a small opening, and expanding in a large -space it produces fluctuations and eddies, which would close the valves -if they were not kept open by the blood which streams through under -high pressure. They must, therefore, close at the moment when the -aortic pressure is equal to the intraventricular pressure. This occurs -shortly after the moment indicated by the beginning of the decline of -the intraventricular pressure curve. Now the second sound of the heart -is heard somewhere in the descending part of the cardiogram[71] and -the measurements of Huerthle[72] have shown that the second sound is -heard 0.02" after the beginning of the descent of the cardiogram. This -seems to indicate that the second sound of the heart is in a temporal -relation to the closure of the valves. Many theories of the origin of -the sounds of the heart agree on this one point that the second sound -is due to a noise in the muscles. It therefore may be supposed that -the second sound is due to the tension of the valves when they close -or shortly afterwards. The problem now would seem to be to find an -elevation in the descending branch of the curve of intraventricular -pressure, or in the tracings of the apex beat, which could be -attributed to the closure of the valves. It was taken for granted that -the curves of intraventricular pressure and those of the apex beat -were identical. In many of these tracings an elevation was found which -may be called "the wave _f_." This elevation is not found in all the -tracings, and its position seems to be rather variable. Edgren[73] -remarks that the wave _f_ was always found near the abscissa no matter -whether the preceding decline of the curve was great or small. In some -of Chauveau's tracings the wave _f_ is missing or indistinct,[74] in -others it is very well marked and approximately in the middle of the -descending branch of the curve.[75] - -Edgren made experiments on the temporal relation of the wave _f_ and -of the dicrotic wave, which to avoid misunderstandings he calls the -"wave _f_´." His experiments were made as follows. A sphygmogram from -the carotid and a cardiogram were taken simultaneously, the points -of the writing-levers being in the same vertical line. The wave _f_´ -appeared a little after the wave _f_. The length of this interval -could be calculated by measuring the distance between these waves, as -the speed of the drum was known. From this was subtracted the time -of propagation of the dicrotic from the heart to the point where the -instrument was fixed. In this way it was found that the time between -the appearance of the wave _f_ and of the wave _f_´ was equal to -the time of propagation of the dicrotic wave from the heart. Edgren -concluded that the dicrotic wave is in close temporal relation to the -closure of the valves.[76] To this comes the supposition that the wave -_f_´ is due to a change of pressure proceeding from the heart. The wave -_f_´, therefore, could be attributed to the tension of the valves.[77] -Edgren and Tigerstedt are the chief exponents of this theory. - -In so far as this theory assumes that the dicrotic elevation is due -to a wave travelling from the heart to the periphery,[78] it is -open to all the arguments against a theory of the central origin -of the dicrotic wave. Against the more special assertion that the -dicrotic elevation is in connection with the closure of the valves, -the following facts must be mentioned. We grant that the tracings -of the apex beat may be directly substituted for the curves of -intraventricular pressure, although this is by no means obvious, since -one tracing gives the form of the pressure changes and the other the -effect of the shock of the heart against the wall of the chest. It is, -furthermore, not proved that the wave _f_ is due to the closure of the -valves and that the waves _f_ and _f_´ correspond to each other so -closely as Edgren's experiments seem to indicate. His measurements of -the length of lines were made with an exactitude of 0.1 mm., but his -computations were carried to the third decimal place of a second. The -third decimal is generally inexact and the second in a large number of -cases. Experimental evidence, furthermore, directly contradicts the -statement that the dicrotic elevation corresponds to the wave _f_. -Fredericq[79] traced pressure curves in the ventricle and in the aorta, -and determined the points of equal pressure in both curves. He thus -found that a point near the beginning of the descent of the curve of -intraventricular pressure corresponds to the dicrotic. His experiments -are rather conclusive against the theory in question, since the wave -_f_ is very well marked in these tracings of Fredericq. The following -facts, however, are fatal for the theory that the closure of the valves -causes the dicrotic elevation: The dicrotic wave disappears in diseases -like atheroma and arteriosclerosis which do not impair the function -of the valves, but affect the elasticity of the arterial wall, and it -is not affected by valvular insufficiency. The independence of the -dicrotic from the function of the valves is conclusively proved by v. -Kries, who found the dicrotic elevation in the femoral artery of an -animal whose heart was replaced by a valveless bag. - -All these facts, on the contrary, can be understood easily in the light -of the theory that the sphygmographic curve gives the movements of the -arterial wall, which movement is conditioned by the decreasing amount -of blood in the artery, and the elastic vibrations of the wall around -a variable position of equilibrium. In some cases the conditions of -the problem are rather simple, and admit an analytic treatment, the -results of which fit closely to the experimental facts. This part of -the theory, however, has merely physiological interest, and therefore -is discussed in a separate paper. It may be mentioned at this point -that this theory of normal dicrotism is essentially identical with the -theory of abnormal dicrotism as stated by Galen. He believed that the -second beat of the pulsus bis feriens was due to an elastic vibration -of the arterial wall. "Ex eodem genere sunt dicroti; nam arteria in -occursu quasi repellitur, moxque redit.... Neque enim tum arteria -contrahitur, sed quasi concuteretur, occidit; cuius delapsum a primae -distentionis termino nulla dirimit manifesta quies, ut animadvertitur -in contractione: sed simulatque attolli destitit, recidit atque ita -paulisper vibrata, mox occurrit iterum."[80] Galen, however, is -mistaken in his view, and in his observation that sometimes three or -more pulse-beats may be felt with the finger. No form of the pulse is -known where three or more beats may be felt for every heart-beat, and -the actual tracings exclude the possibility of this observation for -the pulsus bis feriens. The pulsus bis feriens is due to an increase of -the frequency of the heart-beats. If the new pulse wave arrives before -the vibrations of the arterial wall have had time to subside, the new -wave and the already existing vibration may interfere in such a way as -to produce this abnormal pulse form. - -The form of a single wave of the sphygmographic curve may be influenced -by changes in the following conditions: - -(1) The pulse wave may have an initial form which cannot be represented -by the schematic curve in Fig. 1. This may be due to an irregularity of -the function of the ventricle. The action of the heart has an influence -on the length of the waves, which length is determined by the rapidity -of the heart-beats. This influence has been mentioned before. A change -in the rapidity of the heart-beats has no great influence on the form -of the catacrotic part of the curve so long as the impact of the new -pulse wave does not arrive before the vibrations of the arterial wall -have had time to subside. - -(2) Differences of the elasticity of the arterial wall affect -materially the form of the catacrotic part of the sphygmographic curve. -It has also some influence on the height of the curves, because the -amplitude of elastic vibrations depends on the elastic force for a -given force of the shock. The degree of elasticity of the arterial -wall is subjected to individual variations, and it depends in a given -subject on the state of innervation of the wall. - -(3) The surrounding tissues have a certain influence, since their -resistance determines the friction opposing the vibration. This -accounts for the fact that merely local conditions, such as a change -of the position of the arm or the adjustment of the instrument, may -change the form of the pulse curve. For instance, if the sphygmogram is -taken from the a. radialis the instrument is placed between the styloid -process of the radius and the tendon of the flexor carpi radialis. In -the neighborhood of this place are two venae comites and a superficial -branch of the median or radial vein. A change in the position of the -arm will have a certain influence on the circulation in the veins, and -influence the turgor of these vessels. Increased turgor increases the -friction, and thus produces the different forms of the tracings. - -(4) The changes of the turgor of the artery, moreover, cause a general -rise or lowering of the curve. This symptom is essentially ambiguous -for the turgor of the artery may be changed as well by an increase or -decrease of the amount of blood pumped into the arterial system as by -a decrease or increase of the amount of blood which passes through the -capillaries. - -The influences mentioned under (1) may be seen in tracings taken from -cases of cardiac insufficiency, and have merely pathological interest. -All the other influences, however, can be observed in the curves which -are traced for psychological purposes. The changes in the general rise -or fall of the curves are not so very hard to observe,[81] and for the -observation of the rapidity of the heart-beats it is only necessary to -trace a time-curve and count the number of beats or measure the length -of every single beat. Also the changes of the height of the waves can -easily be measured. This has been done conscientiously by several -observers. It is by far harder to see the changes in the form of the -catacrotic branch, and only a few keen observers have seen them. These -changes of the pulse curve under the influence of feelings were proved -as facts by experiments, but their interpretation was doubtful. With -the exception of the rapidity of the heart-beats, which could easily -be observed in some other way, all the symptoms of the influence of -feelings on circulation are ambiguous. A difference in height of the -single waves may be due to a change in the amount of blood which is -pumped into the artery, but it also may be due to a change in the -amplitude of the vibrations of the artery. The form of the catacrotic -part of the sphygmographic curve may be changed by a different state of -innervation of the arterial wall, but it also may be due to an increase -or decrease of the friction of the surrounding tissues. The general -rise or fall of the curve may indicate a change in the amount of blood -which leaves the left ventricle, but it also may indicate a change in -the amount of the capillary outflow. - -The problem, nevertheless, is fully determined, and a solution is -suggested by the constructions in Fig. 5. The form of the resulting -movement depends, first, on the length of the line _AB_, secondly, on -the length of the line _AE_, and thirdly, on the nature of the elastic -movement. An elastic movement is determined if three constants are -known, one of which is the amplitude, the second the friction, and the -third the elasticity. Only _AB_ can be measured directly, and there -remain four unknown quantities to be determined. Four measurements -must be sufficient for this purpose. It is obvious, however, that not -any four measurements will do, but a method can be devised by which -it is possible to determine each one of these four quantities. The -problem can be solved in every case provided that the sphygmogram is -trustworthy enough to justify the work. The length _AB_ is proportional -to the time of one heart-beat, and the length of the line _AE_ is -proportional to the amount of blood pumped into the arteries. The -successful analysis of the pulse curves, therefore, shows changes of -the action of the heart and makes it possible to distinguish them from -the changes at the periphery. - -Besides the length of the heart-beats there are invariably these -four quantities which must be determined by the analysis of the -pulse curves: Amount of incoming blood, amount of outflowing blood, -elasticity of the artery, and friction of the tissues. These quantities -depend on the action of the heart, the peripheral resistance, and the -state of innervation of the artery. It is not possible to discuss here -the bearing of this theory and of the facts which may be connected with -it, on the different views of the localization and operation of the -centres which control these functions. Anatomical and physiological -evidence, however, leaves no doubt that the function of the heart and -the innervation of the arteries and capillaries _are_ under the control -of nervous centres. It may be supposed, therefore, that changes of -the pulse curve like those due to the influence of feelings are the -effect of the function of these centres. It is to be expected that the -detailed analysis of the pulse curves may give some indications as to -the nature of this influence, for it may be observed how the function -of these centres changes under the influence of mental processes. - -A complete analysis of the physiological accompaniments of a -feeling process must give a description of the changes in the -function of the heart and the system, besides a description or at -least enumeration of the other changes which can be observed. By -a number of such investigations material for a general theory of -physiological accompaniments of feelings may be obtained, which -would not be void of interest for the psychology of feelings. Such -a theory must contain the answers to the following questions: (1) -How do the physiological reactions depend on the sense-stimulus? (2) -How many possible circulatory reactions are there? (3) What is the -location and interdependence of the respective physiological centres? -The first question cannot so far be answered in general, but it -will be possible to give a general answer when a greater number of -systematic investigations on the effect of sense-stimuli have been -carried on. Papers like those of Mentz may settle the question for -certain sense-stimuli. From the results which have been obtained so -far it comes out clearly that the reaction does not depend merely -on the nature of the stimulus, but that it depends largely on the -psychical and physiological state of the subject. The answer to the -second question may be given readily, but it seems advisable to give -it in connection with an experimental investigation. It may be said, -nevertheless, that the number of typical reactions is rather limited. -The third problem, by its nature, cannot be definitely answered before -the location of the respective centres is ascertained and their -interdependence explained. - -It is, finally, a merit of this theory of the pulse curves that it -shows how the form of this curve may depend on central processes. The -problem of the mysterious influence of mental processes is thus reduced -to the analysis of merely physiological conditions. The theories on the -nature of this influence are so numerous that they may well be called -innumerable, and they vary from accepting a direct influence of ideas -on the circulation to considering the body as a sounding-board which by -every sensation is shaken in all its parts. Each one of these theories -is also a theory of feelings, and a more or less exact description of -these changes has been often taken for a descriptive psychology of -feelings. The example of the sounding-board is taken from one of those -papers which expound the theory that bodily changes follow directly -on the perception, and that our sensation of these facts is the -emotion. Every one of these bodily changes, whatsoever, is perceived, -acutely or obscurely, the moment it occurs. This theory is defended -by the argument that if we try to abstract from consciousness all the -sensations of our bodily symptoms, we find we have nothing left behind. -This argument, which may be found in almost every paper that deals -with this theory, is remarkable, because it sometimes is referred to -processes of every description, and thus comes into contradiction with -psychophysical parallelism which excludes the acceptance of psychical -states which have no physical correlate. This theory, as will have been -noticed, is the theory of feelings expounded by James, Lange, Ribot, -and others. It is widely accepted, and may be found also in books of -popular or semi-popular nature. Two observations must be made against -this view: - -First, a perception of a bodily change which is felt in the moment -the change occurs exists only in the theory, every real process -needing a certain time. This point of the theory may be improved by -admitting that the afferent process lasts as long as any other of the -physiological processes of this kind. Either assumption, however, is -contradicted by the experimental evidence supplied by Lehmann that the -physiological changes occur after the beginning of an emotional state. - -Secondly, if the theory refers only to those bodily changes which we -know, it certainly is not true, for emotional states are sometimes -observed without it being possible to find with modern instruments any -bodily accompaniments. If the theory refers to bodily changes of every -description, it is certainly true, or, better, it is beyond all attack -because it becomes identical with psychophysical parallelism. In this -general form this theory of feelings is as good as no theory at all, -because it refers to mental states of every description.[82] - -This conception of emotional states of mind as perceptions of bodily -sensations would hardly have been promulgated, if the authors had tried -to base it on experiments performed in the laboratory. An emotion -but not the feeling-tone of a simple sensation may be mistaken for -the sum of bodily sensations. It is, furthermore, remarkable that -the promoters of this theory do not make a clear distinction between -sensation and feeling. They introduce an emotional element by calling -the perception of bodily changes a feeling of these changes. Only in -this way do they succeed in building up emotional states of mind out -of elements which are seemingly sensational. This does not succeed if -the word feeling is replaced by the word sensation. The failure of this -theory is due to two facts, first to the starting from a philosophical -doctrine, and second to the lack of a precise distinction between -feeling and sensation. It cannot be doubted after the above discussion -how a definition of this difference may be given which holds for every -empirical investigation. - -A sense-stimulus produces a complex of nervous and central processes. -Among these is a certain group of processes which manifest themselves -by changing the innervation of the heart, the blood-vessels, the -lungs, and certain muscles. Another group is formed by those nervous -and central processes which are more or less immediate effects of -the sense-stimulation. The first group of processes is referred -subjectively to an emotional state of mind, and the second to a -cognitive process; the first group of processes is the physiological -accompaniment of feelings, the second that of sensations. The relative -independence of the first group from the second group is warranted -by the fact that the same processes are observed as accompaniments -of ideational processes. A strict limit between these two groups of -processes can be drawn when the central processes are better known, -because to the first group belong all those processes which are found -to be accompaniments as well of sensational as of ideational processes. -In different sensations the emotional process may be more or less -marked, and in others the cognitive process may be prominent, but it -seems that feelings are an invariable accompaniment of the sensation. -This suggests the definition of feelings as psychic processes, the -physiological accompaniment of which are central processes which depend -largely on the state of the organism, and which manifest themselves by -changes in the innervation of the heart, the blood-vessels, the lungs, -and muscles. The impossibility of directly comparing the sensations -of different subjects is recognized, and it is also impossible to -compare feelings, because in either case we are dealing with psychic -processes. - -FOOTNOTES: - -[Footnote 29: Comptes Rendus, vol. 50, p. 637, 1860.] - -[Footnote 30: Comptes Rendus, vol. 53, p. 98, 1861. "Sans rien livrer à -l'hypothèse il est bien certain que des changements dans la circulation -périphérique arrivent souvent sous l'influence d'émotions morales.... -En résumé d'après ce qui précède il nous semblerait illogique de faire -une exception pour les actions que les causes morales exercent sur les -battements du cœur, et nous pensons qu'elles doivent agir comme toutes -les autres influences, c'est à dire à la périphérie primitivement."] - -[Footnote 31: We quote as an instance Lotze: Medicinische Psychologie, -p. 257, 1852: "Es ist wahr, dass Gefühle sehr lebhafte motorische -Ruckwirkungen äussern; wir sehen die Respiration in Unordnung gerathen, -den Druck der Arterienwandung auf das Blut bei heftigen Schmerzen -zunehmen, Erbrechen auf widrige Geschmackseindrücke, allgemeine -Muskelkrämpfe bei physischen Martern eintreten." All the principal -physiological features of feelings are enumerated here, but one hardly -will give any great credit for priority to Lotze. Such a general -statement, in fact, belongs to the class of easy observations from -which philosophical speculation often starts. G. L. Duprat shows -that the same "observations" underlie the theories of Aristotle, -Hippocrates, and Plato. (Duprat: La psycho-physiologie des passions -dans la philosophie ancienne, Archiv f. Geschichte d. Philosophie, vol. -18 (N. F. 11), pp. 395-412, 1905.)] - -[Footnote 32: Application de la balance à l'étude de la circulation du -sang chez l'homme, Archives Italiennes de Biologie, pp. 130-143, 1884.] - -[Footnote 33: Ueber den Kreislauf des Blutes im menschlichen Gehirn, -1880.] - -[Footnote 34: Mosso et Pellacani: Sur les fonctions de la vessie, -Archives Italiennes de Biologie, vol. 1, pp. 97-127, 1882.] - -[Footnote 35: La température du cerveau, Arch. Ital. de Biol., vol. 22, -pp. 264-311.] - -[Footnote 36: For the literature, see P. Menz: Die Wirkung akustischer -Sinnesreize auf Puls und Athmung, Phil. Stud., vol. 11, p. 61, 1895.] - -[Footnote 37: Meumann und Zoneff: Ueber Begleiterscheinungen -psychischer Vorgänge in Athem und Puls, Phil. Stud., vol. 18, p. 3, -1901; and Wundt: Physiologische Psychologie (5th ed.); vol. 2, p. 298.] - -[Footnote 38: It has been pointed out that this terminology, which -is due to a large extent to Landois, presupposes a certain theory of -the origin of the secondary elevations. (Edgren: Cardiographische -und sphygmographische Untersuchungen, Skandinavisches Archiv. f. -Physiologie, vol. 1, p. 92, 1889.) It is not easy to change a -terminology, and the Greek terms, some of which were used by and -before Galen, are so indifferently connotative that they can be kept -without inconvenience. If one were to be rigorous, one would change -the name of the sphygmograph into palmograph, because this instrument -does not serve exclusively for the registration of the abnormal -pulse. It does seem, however, advisable to drop the terms recoil wave -(Rückstosselevation, Landois), and "onde de rebondissement" (Marey), -because they are taken from modern languages and directly suggest a -certain theory with which they are intimately connected.] - -[Footnote 39: Recherches sur l'état de la circulation d'après les -caractères du pouls, Journal de Physiologie de l'Homme, vol. 3, p. -249, 1860; and La circulation du sang, p. 264, 1863. "Le dicrotisme du -pouls est un phénomène physiologique, on l'observe presque chez tous -les sujets; seulement il n'est sensible au doigt que dans les cas où -il est extrêmement prononcé." References for previous observations of -the slow descent of the pulse curve are given by Landois, Die Lehre vom -Arterienpuls, p. 36, 1872.] - -[Footnote 40: Burdon Sanderson: Handbook of the Sphygmograph, 1867.] - -[Footnote 41: Lorain: Études de médecine clinique; Le Pouls, 1870.] - -[Footnote 42: Ozanam: La circulation et le pouls, 1886.] - -[Footnote 43: Pfungen: Pulscurve der Arterien in Gad's Lexicon der -medicinischen Propaedeutik, vol. 3, pp. 544-642, 1895.] - -[Footnote 44: Riegel: Ueber die Bedeutung der Pulsuntersuchung in -Volkmann's Sammlung klinischer Vortraege, Nos. 144, 145, 1878.] - -[Footnote 45: Roy and Adami: Heartbeat and Pulsewave, The Practitioner, -vol. 1, pp. 81-94, 161-177, 241-253, 347-361, 412-425, 1890.] - -[Footnote 46: Cf. Howell: American Text-book of Physiology, p. 436, -1897. Marey's first explanation of the dicrotic belongs to this type -(Comptes Rendus, vol. 47, p. 826, 22 Nov., 1858.) He supposed that -the dicrotic elevation was due to a wave reflected from the Iliacae -communes. He was led to this theory by the erroneous observation of -Beau, that abnormal dicrotism never occurs in the lower extremities. -Marey's own observations refuted this theory, since they show that the -dicrotic elevation is found also in the sphygmograms of the arteries of -the leg. (Marey, La circulation du sang, p. 274, 1863.)] - -[Footnote 47: Marey, La circulation du sang, pp. 271, 272, 1863. "Dans -ces conditions, l'ondée lancée par les ventricules se porte vers la -périphérie, et par suite de la vitesse acquise, abandonne les régions -initiales de l'aorte pour distendre les extrémités du système artériel. -Arrêtée en ce dernier point par l'étroitesse des artères qui lui fait -obstacle, elle reflue vers l'origine de l'aorte; mais cette voie est -fermée par les valvules sygmoïdes. Nouvel obstacle, nouveau reflux, et -par suite nouvelle ondulation (où rebondissement). Ces oscillations -alternatives se produisent jusqu'à ce qu'une nouvelle contraction du -ventricule vienne y mettre fin en produisant une onde nouvelle."] - -[Footnote 48: This view was held by Haller, Bichat, and Bourgelat and -goes back to Galen ("Omnes enim clare cernunt, omnes partes arteriarum -eodem distendi tempore," De causis pulsi, book 2, c. 8). The first who -saw that the pulse did not appear at the same time in all the parts of -the body was Josias Weitbrecht, but his observations were neglected -until E. H. Weber actually measured the velocity of the propagation of -the pulse wave. (His famous thesis of 1827,--"Pulsum arteriarum non in -omnibus arteriis simul, sed in arteriis a corde valde remotis serius -quam in corde et in arteriis cordi vicinis fieri.") For the results of -other measurements see Tigerstedt: Physiologie des Kreislaufes, p. 385, -1894. Some use of these measurements is made in the present writer's -L'Analyse des Sphygmogrammes, which is to appear in the Journal de -Physiologie et de Pathologie Générale for May, 1906.] - -[Footnote 49: Landois: Human Physiology (English translation), p. 145, -1889, and Die Lehre vom Arterienpuls, p. 188, 1872.] - -[Footnote 50: Otto und Haas: Vierteljahrsschrift f. praktische -Heilkunde, vol. 34, p. 41, 1877.] - -[Footnote 51: Garrod: Journal of Anatomy and Physiology, vol. 5, pp. -17-27, 1870.] - -[Footnote 52: Traube: Gesammelte Beiträge, vol. 3, p. 595, 1878.] - -[Footnote 53: Rosenstein: Deutsches Archiv f. klinische Medicin, vol. -23, pp. 75-97, 1879.] - -[Footnote 54: Maurer: Deutsches Archiv f. klinische Medicin, vol. 24, -pp. 291-341.] - -[Footnote 55: Gibson: Journal of Anatomy and Physiology, vol. 14, pp. -234-240, 1879.] - -[Footnote 56: Fr. Frank: Travaux du laboratoire Marey, pp. 301-327, -1877.] - -[Footnote 57: I. G. Edgren: Skandinavisches Archiv f. Physiologie, vol. -1, pp. 67-152, 1889.] - -[Footnote 58: v. Kries: Studien zur Pulslehre, p. 62, and M. v. Frey, -Die Untersuchung des Pulses, p. 164.] - -[Footnote 59: Grashey: Die Wellenbewegung elastischer Röhren, p. 166, -1881.] - -[Footnote 60: Hoorweg: Archiv f. d. ges. Physiologie, vol. 46, p. 143, -1890.] - -[Footnote 61: Marey, _loc. cit._, pp. 267-271, and Traité de Physique -Biologique (publié par d'Arsonval, Chauveau, Gariel, Marey), vol. 1, -p. 390, 1901; these tracings are reproduced rather frequently; _e.g._, -Pfungen, _loc. cit._, p. 563, and Chapman: Human Physiology (2d ed.), -p. 270, 1899.] - -[Footnote 62: E. Mach: Sitzungsberichte der K. Akademie der -Wissenschaften, vol. 47 (2), p. 43, 1863; and in the tables, figs. -48-53.] - -[Footnote 63: L. Hill, in Schaefer's Text-book of Physiology, vol. 2, -p. 111, 1902. The same opinion maybe found in Hermann's Lehrbuch der -Physiologie (12th ed.), p. 79, 1900. "Ihre (der dicrotischen Wellen) -Erklärung ist noch nicht widerspruchsfrei gestellt." In the previous -editions different views were given, and this critical doubt may be -regarded as the final outcome of the investigations of almost half a -century.] - -[Footnote 64: Sudden compression is the most convenient way of -producing a wave in a liquid which is enclosed in an elastic tube. -It was used already in the first experiments on the propagation of -these waves. (E. H. Weber: Anwendung der Wellenlehre auf die Lehre vom -Kreislaufe des Blutes und insbesondere auf die Pulslehre, Berichte -d. Kgl. Sächsischen Ges. d. Wissenschaften, Math.-Phys. Cl., p. 177, -1850.)] - -[Footnote 65: Bayliss and Starling: On the form of the intraventricular -and aortic pressure curves obtained by a new method, Intern. -Monatsschrift f. Anatomie u. Physiologie, vol. 11, pp. 426-435, 1894.] - -[Footnote 66: W. T. Porter: A new method for the study of the -intraventricular pressure curve, Journal of Experimental Medicine, -vol. 1, pp. 296-303, 1896. A similar method was used by O. Frank: Ein -experimentelles Hülfsmittel für die Kritik der Kammerdruckkurven, -Zeitschrift f. Biologie, vol. 35, pp. 478-480, 1897.] - -[Footnote 67: O. Frank, _loc. cit._, p. 480.] - -[Footnote 68: Huerthle: Beiträge zur Hämodynamik, VIII, Zur Kritik des -Lufttransmissionsverfahrens, Arch. f. d. ges. Physiologie, vol 53, pp. -281-331, 1892.] - -[Footnote 69: The special assumption on the rate of outflow -is by no means essential for the following theory. Two other -possible assumptions are mentioned in the author's "L'Analyse des -Sphygmogrammes," and others may be found easily. Every one of these -theories is equally probable as long as no experimental evidence can be -brought forward. The assumption that the rate of outflow through the -arterioles is uniform has the merit that it is the simplest and that it -can be deduced from considerations of the average directions of tubes -which split up in "every" direction.] - -[Footnote 70: A detailed discussion shows that four different cases are -possible, but this distinction is of minor importance for the purpose -of this paper. The distinction holds that the movement is either -periodic or aperiodic.] - -[Footnote 71: Edgren: Kardiographische und sphygmographische -Untersuchungen, Skandinavisches Archiv f. Physiologie, vol. 1, pp. -88-91, 1889; Fredericq: Vergleich der Stoss und Druckcurven der rechten -Herzkammer des Hundes, Centralblatt f. Physiologie, vol. 7, p. 770, -1893; Einthoven und Geluk: Die Registrierung der Herztöne, Archiv f. d. -Ges. Physiologie, vol. 57, p. 631, 1894.] - -[Footnote 72: K. Huerthle: Beiträge zur Hämodynamik, Archiv f. d. Ges. -Physiologie, vol. 60, p. 281, 1895.] - -[Footnote 73: Edgren: _loc. cit._ p. 87.] - -[Footnote 74: A. Chauveau: Inscription électrique des mouvements -valvulaires, Journal de Physiologie et de Pathologie Générale, vol. 1, -p. 388, fig. 4, 1899.] - -[Footnote 75: _Ibid._ p. 391, fig. 6 (curve 5); and the same author's -La pulsation cardiaque, in the same Journal, vol. 1, p. 795, fig. 5, -and p. 796, 1899.] - -[Footnote 76: Edgren: _loc. cit._ p. 114.] - -[Footnote 77: The exposition of this theory may be found in R. -Tigerstedt: Intracardialer Druck und Herzstoss, Ergebnisse der -Physiologie, vol. 1, pp. 258-262, 1902. This theory, equally -remarkable for its logical beauty and for its confirmation by Edgren's -experiments, has not found its way into recently published text-books -of physiology, though Edgren's paper belongs to the most frequently -quoted publications on sphygmography and cardiography.] - -[Footnote 78: Tigerstedt: _loc. cit._ p. 261.] - -[Footnote 79: Fredericq: La pulsation du cœur chez le chien, no. 5. -La comparaison du tracé du choc du cœur avec celui de la pression -intraventriculaire, Travaux du Laboratoire de Liège, vol. 5, p. 67, -1896.] - -[Footnote 80: Galenus: De pulsuum differentiis, lib. 1. c. 16.] - -[Footnote 81: The amount of change in the base-line is the chief -difference between the sphygmograms and the plethysmograms. It was -stated recently that for this reason the plethysmograph could not be -used for psychological experiments. An analysis of the mechanical -conditions of these two instruments shows that also the sphygmogram -must show some plethysmographic influences, and the author supplied -experimental evidence for this result.] - -[Footnote 82: More recent publications have taken this view. Cohn -speaks of "Organgefühle des Gehirns," approaching Meynert's view on -the causes of pleasure and pain. (P. Cohn: Gemüthserregungen und -Krankheiten, pp. 23 and 50, 1903.) Cohn's book shows clearly that -this theory belongs to the type of philosophical explanations. This -is also suggested by Duprat who remarked the parallelism between the -theories of James, Lange and Ribot, and the theories of certain Greek -philosophers. (Duprat: "La psycho-physiologie des sentiments dans la -philosophie ancienne," Archiv f. Geschichte d. Philosophie, vol. 18 -(3), p. 395, 1905.)] - - - - -THE MUTUAL INFLUENCE OF FEELINGS - -BY JOHN A. H. KEITH - - -The object of this investigation was to ascertain the mutual influence -of simultaneous stimuli that appealed to different senses with regard -to the _intensity_ of their feeling values. The investigation covers -combinations: (1) of colors and active touches, (2) of colors and -passive touches, (3) of tones and active touches, (4) of tones and -passive touches, (5) of colors and tones. - -The basis of appreciation was a numerical scale[83] as follows: - - 1. Very disagreeable. - 2. Disagreeable. - 3. Slightly disagreeable. - 4. Indifferent. - 5. Slightly agreeable. - 6. Agreeable. - 7. Very agreeable. - -The color series began with the one hundred thirty-six colors as put -out by the Milton Bradley Co. This series consists of ninety pure -spectrum colors, ten whites, blacks, and grays, and thirty-six broken -spectrum colors. The colors were exposed at the back of a semicircular -black-lined box for about two seconds. The subject was seated at a -convenient distance, about three and a half feet, from the colors. In -order to have a constant light, all experiments were conducted in a -dark room with an electric light suspended over the subject's head. -The whole series was used for ten times in order to get the range of -judgments. Then twenty-eight colors, covering as fully as possible the -range from 1 to 7, were selected for further experiment in combination. - -At the same time a series of thirty-six touches, from velvet to -sandpaper, was being employed as the colors were. From this number -fourteen were finally selected. - -Similarly, by using a reed box, with reeds ranging from 128 to 1024 -vibrations per second and separated from each other by four vibrations, -from a much larger series twenty-seven tone-combinations were finally -selected. - -Moreover, from time to time, each selected series was given alone; and -on the basis of these readings, averaging from thirty to forty, the -"standard" for each stimulus was made. Tables I to III give a brief -description of the stimuli and also the "standards" for each of two -subjects, F. and M. - - -TABLE I. COLORS - - _No. of_ _Description._ _Standard_ _Standard_ - _Color._ _for F._ _for M._ - - 1 Violet Red. Tint no. 1 5.90 4.00 - 2 Red. Tint no. 1 6.00 6.00 - 3 Red 6.00 5.40 - 4 Orange Red 5.60 6.20 - 5 Red Orange 4.20 5.20 - 6 Yellow Orange. Tint no. 1 3.10 4.50 - 7 Yellow. Tint no. 1 2.30 5.20 - 8 Yellow. Shade no. 2 2.00 4.00 - 9 Green Yellow 2.80 5.60 - 10 Yellow Green 4.45 6.20 - 11 Green. Shade no. 1 5.70 4.40 - 12 Blue Green. Tint no. 1 3.40 6.00 - 13 Green Blue 5.00 3.50 - 14 Blue. Shade no. 1 5.40 2.10 - 15 Blue Violet 5.10 5.00 - 16 Violet. Tint no. 2 4.20 5.30 - 17 Violet. Shade no. 2 5.50 3.50 - 18 Red Violet 5.65 3.70 - 19 Black 4.00 4.00 - 20 Green Gray. no. 1 2.20 4.20 - 21 Green Gray. no. 2 2.00 4.00 - 22 A-Red. Light 3.70 3.70 - 23 A-Red. Dark 2.10 2.70 - 24 A-Orange. Dark 2.00 3.00 - 25 A-Yellow Orange. Light 3.10 4.30 - 26 A-Green Yellow. Dark 2.50 4.00 - 27 A-Blue Green. Medium 2.40 4.30 - 28 A-Violet. Medium 4.10 4.50 - - Totals 110.40 124.50 - Average 3.94 4.44 - -In connection with this table it may be noted that the subjects agree -regarding 2, 19, and 22, red tint no. 1, black, and A-red light; -that M. estimates the colors higher than F. in seventeen cases; and -that F. estimates 1, 3, 11, 13, 14, 15, 17, 18, higher than M. does. -These individual differences are probably explicable on grounds -of association; they are not, however, connected with the problem -under consideration here, for we are concerned with the effect of -combinations with other stimuli. - - -TABLE II. TOUCHES - -The various articles were fastened to small pieces of wood and placed -in small cardboard boxes. In active touch, the subjects were allowed -to stroke the object gently twice, always with a contracting movement -of the forefinger of the right hand. In passive touch, the operator -stroked the subject's forefinger with the object, twice as before. The -table explains itself. - - _Standards._ - _No. of_ _Active._ _Passive._ - _Touch._ _Description._ _F._ _M._ _F._ _M._ - - 1 Thick napped velvet 6.90 6.60 7.00 7.00 - 2 Thin stretched rubber, such as is - used on tambours 5.70 5.40 6.00 6.00 - 3 Glazed thin cardboard 5.80 5.50 5.50 6.00 - 4 White silk ribbon--always stroked - with the ribs 5.80 5.70 5.40 5.00 - 5 Soft, split, rough leather 5.50 5.50 5.00 6.00 - 6 Smooth polished cork 5.70 5.10 5.40 6.00 - 7 Glazed tin 5.00 4.50 6.00 6.00 - 8 Rough, tarred paper 4.30 4.60 4.00 5.00 - 9 Blue blotting paper 4.50 5.10 4.20 5.00 - 10 Sand paper no. 1, fine grained 2.20 3.50 2.00 4.00 - 11 Shot no. 3, set in paraffine 2.70 4.90 3.00 3.50 - 12 Sandpaper no. 2-1/2, coarse-grained 1.40 2.00 1.50 3.00 - 13 A coarse, rough, ridged cotton cloth, - always stroked across the ridges 4.00 2.40 4.70 3.50 - 14 A thin, closely woven white muslin 4.20 4.60 4.20 5.00 - - Totals 63.70 65.40 63.90 71.00 - Average 4.55 4.67 4.56 5.14 - - -TABLE III. TONES - -The table of tone-combinations shows that some are simply repetitions -of the same chord in a higher octave, as 1 and 9, 5 and 13, 15 and 14. -The first sixteen are harmonious; so also the twenty-sixth; the others -introduce beats and discords, some of which are agreeable, as 20 and -21, while others are disagreeable, as 19 and 27. Individual differences -appear in this as in the previous series. The totals introduced into -the tables simply go to show that in each series the total judgments -are not widely diverse. - - _No of_ _Standards._ - _Tones._ _Description._ _F._ _M._ - - 1 256, 320 4.25 3.25 - 2 256, 384 4.25 3.00 - 3 256, 320, 384 5.60 3.00 - 4 320, 384 4.30 3.50 - 5 256, 512 4.65 5.50 - 6 320, 512 4.10 5.00 - 7 384, 512 4.90 5.00 - 8 512, 640 5.40 5.30 - 9 512, 768 5.50 5.80 - 10 640, 768 4.40 5.00 - 11 640, 1024 4.25 3.40 - 12 768, 1024 4.80 5.50 - 13 512, 1024 5.60 5.80 - 14 512, 640, 768, 1024 6.30 5.90 - 15 256, 320, 384, 512 6.50 4.00 - 16 320, 512, 768 5.00 4.70 - 17 136, 144 2.00 2.50 - 18 156, 160 3.80 4.00 - 19 136, 140 2.70 3.50 - 20 440, 444 6.81 6.00 - 21 504, 508 6.70 6.40 - 22 148, 152, 156 1.70 2.50 - 23 172, 296, 452 3.00 2.50 - 24 180, 480, 768 3.40 2.50 - 25 232, 328, 492 3.20 2.50 - 26 256, 512, 768 5.00 5.50 - 27 256, 240, 384 2.00 1.70 - - Totals 120.11 113.25 - Average 4.45 4.19 - -The following tables deal with the combined series. - -Table IV shows that the appreciation of the colors was, in general, -lowered slightly by the combinations with the tones; and, also, that -the appreciation of the tones was lowered more than one point by the -combinations with the colors. By referring to Tables I and III, M.'s -average for the colors is 4.44 and for the tones 4.20. - - -TABLE IV. COLOR-TONE RESULTS. M. - - _No. of times color was_ _Total No. of points_ - _No. of_ _Not_ _color was_ _Net result_ - _Color_ _Raised_ _Lowered_ _Affected_ _Raised_+ _Lowered_- + - - 1 3 15 9 3 15 12 - 2 0 22 5 0 23 23 - 3 0 27 0 0 32.2 32.2 - 4 0 27 0 0 20.4 20.4 - 5 0 27 0 0 8.2 8.2 - 6 23 4 0 12.5 2 10.5 - 7 14 13 0 11.2 2.6 8.6 - 8 6 5 16 6 5 1 - 9 16 11 0 6.4 6.6 .2 - 10 1 26 0 .8 20.2 19.4 - 11 0 27 0 0 36.8 36.8 - 12 0 23 4 0 23 23 - 13 2 25 0 1 18.5 17.5 - 14 9 18 0 8.1 9 .9 - 15 1 12 15 1 14 13 - 16 1 26 0 .7 16.8 16.1 - 17 7 20 0 6.5 12 5.5 - 18 13 14 0 4.9 10.8 5.9 - 19 0 0 27 0 0 - 20 1 26 0 .8 9.2 8.4 - 21 0 6 21 0 6 6 - 22 7 20 0 3.1 16 12.9 - 23 21 6 0 9.3 4.2 5.1 - 24 12 2 13 17 3 14 - 25 8 19 0 5 7.7 2.7 - 26 1 4 22 1 4 3 - 27 16 11 0 12 3.3 8.7 - 28 13 14 0 6 10 4 - - Totals 175 450 132 47.9 271.1 - - Grand Total (28 × 27) 756. Net lowered 223.2 - - Average lowering of each color judgment, 223.2/756 = .295 - % of judgments of color lowered, 450/756 = 59+ - % of judgments of color raised, 175/756 = 23+ - % of judgments of color not affected, 132/756 = 17+ - - - _No. of times tone was_ _Total No. of points_ - _No. of_ _Not_ _tone was_ _Net result_ - _Tone_ _Raised_ _Lowered_ _Affected_ _Raised_+ _Lowered_- + - - 1 0 28 0 0 29 29 - 2 4 9 15 4 9 5 - 3 2 22 4 2 28 26 - 4 7 21 0 4.5 17.5 13 - 5 0 28 0 0 32 32 - 6 0 24 4 0 35 35 - 7 0 22 6 0 32 32 - 8 4 24 0 2.8 11.2 8.4 - 9 3 25 0 .6 37 36.4 - 10 0 17 11 0 25 25 - 11 15 13 0 16 7.2 8.8 - 12 6 22 0 3 20 17 - 13 10 18 0 2 22.4 20.4 - 14 3 25 0 .3 37.5 37.2 - 15 0 27 1 0 55 55 - 16 4 24 0 1.2 38.8 37.6 - 17 2 26 0 1 22 21 - 18 0 27 1 0 66 66 - 19 0 28 0 0 56 56 - 20 1 19 8 1 23 22 - 21 6 22 0 3.6 13.8 10.2 - 22 0 28 0 0 37 37 - 23 1 27 0 .5 33.5 33 - 24 10 18 0 5 13 8 - 25 7 21 0 3.5 24.5 21 - 26 5 23 0 2.5 50.5 48 - 27 1 27 0 .3 18.9 18.6 - - Totals 91 615 50 8.8 749.8 - - Grand Total (27 × 28), 756. Net lowered 741 - - Average lowering of each tone judgment, .98+ - % of judgments of tones lowered, 615/756 = 81+ - % of judgments of tones raised, 91/756 = 12+ - % of judgments of tones not affected, 50/756 = 6+ - - -TABLE V. COLOR-TONE RESULTS. F. - - _No. of times color was_ _No. of points color was_ _Net result_ - _No. of_ _Not_ - _Color_ _Raised_ _Lowered_ _Affected_ _Raised_ + _Lowered_ - + - - 1 9 18 0 10 19.2 9.2 - 2 0 24 3 0 38 38 - 3 0 26 1 0 31 31 - 4 1 26 0 0.4 33.6 33.2 - 5 9 18 0 7.2 16.6 9.4 - 6 3 24 0 3.7 12.4 8.7 - 7 13 14 0 9.1 4.2 4.9 - 8 9 4 13 9 4 5 - 9 21 6 0 12.4 5.8 6.6 - 10 18 9 0 15.90 12 3.9 - 11 19 8 0 10.7 5.6 5.1 - 12 9 18 0 7.4 13.2 5.8 - 13 5 7 15 6 7 1 - 14 7 20 0 6.2 4 2.2 - 15 5 22 0 6.5 5.1 1.4 - 16 1 26 0 .8 17.2 16.4 - 17 2 25 0 1 13.5 12.5 - 18 3 24 0 1.35 18.6 17.25 - 19 0 3 24 0 3 3 - 20 18 9 0 14.4 2.8 11.6 - 21 9 0 18 9 0 9 - 22 5 22 0 4.5 26.2 21.7 - 23 2 25 0 1.8 5.5 3.7 - 24 5 7 15 6 7 1 - 25 1 26 0 .9 28.4 27.5 - 26 16 11 0 8 5.5 2.5 - 27 19 8 0 14.4 3.2 11.2 - 28 7 20 0 6.3 4 2.3 - - Totals 215 451 90 54.1 250.95 - Grand Total 756 Net lowered 196.85 - - Average lowering of each color judgment, .26+ - % of judgments of color lowered, 451/756 = 59.6+ - % of judgments of color raised, 215/756 = 28+ - % of judgments of color not affected, 90/756 = 11.9+ - - - _No. of times tone was_ _No. of points tone was_ _Net result_ - _No. of_ Not - _Tone_ _Raised_ _Lowered_ _Affected_ _Raised_ + _Lowered_- + - - 1 6 22 0 3 20.5 17.5 - 2 2 26 0 1.5 22.5 21 - 3 2 26 0 .8 24.6 23.8 - 4 2 26 0 1.4 16.8 15.4 - 5 4 24 0 1.4 27.6 26.2 - 6 3 25 0 6.7 26.5 19.8 - 7 4 24 0 1.4 40.6 39.2 - 8 1 27 0 .6 32.8 32.2 - 9 1 27 0 .5 34.5 34 - 10 8 20 0 5.8 25 19.2 - 11 3 25 0 2.25 33.25 31 - 12 4 24 0 .8 38.2 37.4 - 13 2 26 0 .8 23.6 22.8 - 14 2 26 0 1.4 25.8 24.4 - 15 1 27 0 .5 32.5 32 - 16 0 21 7 0 40 40 - 17 4 10 14 4 10 6 - 18 18 10 0 22.6 14 8.6 - 19 17 11 0 22.1 13.7 8.4 - 20 6 22 0 4.8 22.6 17.8 - 21 10 18 0 3 17.6 14.6 - 22 18 10 0 10.4 7 3.4 - 23 1 20 7 2 21 19 - 24 0 28 0 0 20.4 20.4 - 25 3 25 0 2.4 21 18.6 - 26 0 22 6 0 39 39 - 27 1 11 16 1 11 10 - - Totals 123 583 50 20.4 581.3 - Grand Total 756 Net lowered, 560.9 - - Average lowering of each tone judgment, .742+ - % of judgments of tones lowered, 583/756 = 77+ - % of judgments of tones raised, 123/756 = 16+ - % of judgments of tones not affected, 50/756 = 6+ - - -Table VI. Tone-Active Touch Results. M. - - _No. of times tone was_ _No. of points tone was_ _Net result_ - _No. of_ _Not_ - _Tone_ _Raised_ _Lowered_ _affected_ _Raised_ + _Lowered_ - + - - 1 14 0 0 31.5 0 31.5 - 2 14 0 0 29 0 29 - 3 14 0 0 30 0 30 - 4 14 0 0 32 0 32 - 5 9 5 0 9.5 4.5 5 - 6 14 0 0 25 0 25 - 7 14 0 0 22 0 22 - 8 14 0 0 22.8 0 22.8 - 9 14 0 0 16.8 0 16.8 - 10 14 0 0 25 0 25 - 11 14 0 0 46.8 0 46.8 - 12 14 0 0 21 0 21 - 13 14 0 0 13.8 0 13.8 - 14 13 1 0 13.4 .9 12.5 - 15 13 0 1 23 0 23 - 16 14 0 0 24.2 0 24.2 - 17 14 0 0 25 0 25 - 18 13 0 1 28 0 28 - 19 14 0 0 30 0 30 - 20 13 1 0 13 0 13 - 21 13 1 0 7.8 0 7.8 - 22 14 0 0 24 0 24 - 23 14 0 0 21 0 21 - 24 14 0 0 42 0 42 - 25 14 0 0 38 0 38 - 26 12 2 0 11 2 9 - 27 13 1 0 22.9 .6 22.3 - - Totals, 365 11 2 640.5 - Grand Total, 378. Net raised, 640.5 - - Average raising of each tone judgment, 1.69+ - % of judgments of tones lowered, 11/378 = .2+ - % of judgments of tones raised, 365/378 = 97+ - % of judgments of tones not affected, 2/378 = .5+ - - - _No. of times touch was_ _No. of points touch_ - _No. of_ _Not_ _was_ _Net result_ - _Touch_ _Raised_ _Lowered_ _affected_ _Raised_ + _Lowered_ - + - - 1 27 0 0 10.8 0 10.8 - 2 6 21 0 3.6 12.4 8.8 - 3 10 17 0 5.8 8.5 3.5 - 4 6 21 0 2.8 16.7 13.9 - 5 14 13 0 8 6.5 1.5 - 6 8 19 0 7.2 6.9 .3 - 7 16 11 0 11 6.5 4.5 - 8 22 5 0 13.8 3 10.8 - 9 7 20 0 6.3 5 1.3 - 10 26 1 0 23 .5 22.5 - 11 21 6 0 2.1 5.4 3.3 - 12 26 0 1 38 0 38 - 13 27 0 0 48.4 0 48.4 - 14 23 4 0 14.2 2.4 11.8 - - Totals 239 138 1 149.9 29.5 - Grand Total, 378 Net raised, 120.4 - - Average raising of each active touch judgment, .31+ - % of judgments of active touch lowered, 138/378 = 36+ - % of judgments of active touch raised, 239/378 = 63+ - % of judgments of active touch not affected, /378 = .2+ - -Under combination influences, the average is reduced to 4.14+ for -colors, and 3.12 for tones. - -The next Table, V, shows the color-tone results for F. as Table IV -showed them for M. F.'s average for colors (Table I) alone was 4.35, -and was reduced in combination with tones by .26, or to 4.19. So, also, -F.'s average for tones alone (Table III), 4.33, was reduced by .74+ -to 3.59. The averages in both cases show the same general tendency -to a lowering of the appreciation in both series when the series are -combined, but the tones are lowered more than the colors. - -Table VI shows the effect of combining tones and active touches as -reported by M. - -The effect of this combination is clear and unmistakeable. The -appreciation of the tones is raised 1.71+ points; and of the active -touches, .31+ points. This result is the opposite of that shown -in Table IV, where colors and tones were combined. There is this -agreement, however, that the appreciation of the tones is changed more -than that of the other stimuli. Relatively, the appreciation of the -touches changes least. - -Table VII shows the effects on F. of combining tones and active -touches. The same general tendencies appear as in the case of M.; but -the changes in appreciation are not so marked. This is not easy to -explain, for F. estimated both the active touches and the tones higher -when taken alone than did M. - -Table VIII shows the effect on F. of combining tones and passive -touches. The same general tendency to increased appreciation appears, -but the tones are raised more and the touches raised less than in -Table VII. This may be explained, perhaps, on the basis of increasing -appreciation with increased participation. - -Tables IX and X show the effect on M. and F., respectively, of -combining colors and active touches. M. estimates both slightly higher, -while F. estimates both slightly lower. This difference cannot be -explained by the standards for each subject. From Tables I and III we -get: - - _Standards._ - - _Colors._ _Active Touches._ - - M. 4.44 4.24 - F. 4.35 4.55 - - With M. the colors go up to 4.87 - With F. the colors go down to 4.22 - With M. the active touches go up to 4.41 - With F. the active touches go down to 4.17 - - -Table VII. Tone-Active Touch Results. F. - - _No. of times tone was_ - _No. of_ _Not_ _No of points tone was_ _Net results_ - _Tone_ _Raised_ _Lowered_ _affected_ _Raised_+ _Lowered_- + - - 1 11 3 0 9.25 1.75 7.5 - 2 10 4 0 9.5 1 8.5 - 3 7 7 0 5.8 7.2 1.4 - 4 10 4 0 12 3.2 8.8 - 5 9 5 0 9.85 4.25 5.6 - 6 9 5 0 15.1 4.5 10.6 - 7 10 4 0 8 6.6 1.4 - 8 7 7 0 5.2 6.8 1.6 - 9 10 4 0 8 9 1 - 10 12 2 0 14.2 2.8 11.4 - 11 12 2 0 16 2.5 13.5 - 12 13 1 0 9.6 .8 8.8 - 13 13 1 0 12.2 .6 11.2 - 14 10 4 0 7 2.2 4.8 - 15 6 8 0 3 4 1 - 16 9 1 4 11 2 9 - 17 9 0 5 14 0 14 - 18 12 2 0 16.4 2.6 13.8 - 19 12 2 0 27.6 2.4 25.2 - 20 12 2 0 2.4 2.6 .2 - 21 14 0 0 4.2 0 4.2 - 22 14 0 0 17.2 0 17.2 - 23 4 5 5 6 5 1 - 24 0 14 0 0 9.6 9.6 - 25 7 5 2 5.6 6 .4 - 26 6 1 7 8 1 7 - 27 11 0 3 14 0 14 - - Totals, 259 93 26 197.5 15.2 - Grand Total, 378 Net raised, 182.3 - - Averaging raising of each tone judgment, .48+ - % of judgments of tones lowered, 93/378 = 24+ - % of judgments of tones raised, 259/378 = 68+ - % of judgments of tones not affected, 26/378 = 7- - - - _No of times touch was_ - _No. of_ _Not_ _No. of points tone was_ _Net result_ - _Touch_ _Raised_ _Lowered_ _affected_ _Raised_+ _Lowered_- + - - 1 22 5 0 2.2 6.5 4.3 - 2 16 11 0 8.8 8.7 .1 - 3 20 7 0 7 5.6 1.4 - 4 19 8 0 5.8 11.4 5.6 - 5 18 9 0 14 7.5 6.5 - 6 16 11 0 6.8 9.7 2.9 - 7 13 5 9 13 5 8 - 8 13 14 0 13.1 12.2 .9 - 9 19 8 0 14.5 5 9.5 - 10 9 18 0 8.2 7.6 .6 - 11 22 5 0 8.6 3.5 5.1 - 12 15 12 0 15 4.8 10.2 - 13 22 1 4 35 1 34 - 14 20 7 0 26 1.4 24.6 - - Totals, 244 121 13 100.9 12.8 - Grand Total, 378 Net raised, 88.1 - - Average raising of each active touch judgment, .23+ - % of judgments of active touch lowered, 121/378 = 32+ - % of judgments of active touch raised, 244/378 = 64+ - % of judgments of active touch not affected, 13/378 = 3+ - - -TABLE VIII. TONE-PASSIVE TOUCH RESULTS. F. - - _No. of times tone was_ - _No. of_ _Not_ _No. of points tone was_ _Net result_ - Tone_ _Raised_ _Lowered_ _affected_ _Raised_ + _Lowered_ - + - - 1 13 1 0 17.75 .25 17.5 - 2 12 2 0 18 0 18 - 3 13 1 0 11.2 .6 10.6 - 4 14 0 0 14.8 0 14.8 - 5 11 3 0 6.65 1.95 4.7 - 6 9 5 0 12.1 1.50 10.6 - 7 13 1 0 6.3 .9 5.4 - 8 14 0 0 17.4 0 17.4 - 9 6 8 0 5 4 1 - 10 14 0 0 20.4 0 20.4 - 11 14 0 0 12.5 0 12.5 - 12 10 4 0 7 5.2 1.8 - 13 14 0 0 10.6 0 10.6 - 14 12 2 0 8.4 .6 7.8 - 15 8 6 0 4 3 1 - 16 1 2 11 1 2 1 - 17 4 0 10 4 0 4 - 18 5 9 0 7 8.2 1.2 - 19 9 5 0 2.7 4.5 1.8 - 20 13 1 0 2.6 .8 1.8 - 21 13 1 0 3.9 .7 3.2 - 22 13 1 0 8.9 .7 8.2 - 23 6 2 6 10 2 8 - 24 12 2 0 15.2 .8 14.4 - 25 11 3 0 15.8 .6 15.2 - 26 0 6 8 0 8 8 - 27 10 0 4 13 0 13 - - Totals, 274 65 39 221.9 12.0 - Grand Total, 378 Net raised, 209.9 - - Average raising of each tone judgment, .55+ - % of judgments of tones lowered, 65/378 = 17+ - % of judgments of tones raised, 274/378 = 72+ - % of judgments of tones not affected, 39/378 = 10+ - - - _No. of times touch was_ - _No. of _Not_ _No. of points touch was_ _Net result_ - Touch_ _Raised_ _Lowered_ _affected_ _Raised_ + _Lowered_ - + - - 1 0 10 17 0 10 10 - 2 4 13 10 4 16 12 - 3 11 16 0 6.5 12 5.5 - 4 13 14 0 12.8 9.6 3.2 - 5 12 5 10 17 8 9 - 6 12 15 0 7.2 12 4.8 - 7 3 12 12 3 14 11 - 8 14 2 11 17 2 15 - 9 11 16 0 12.8 20.2 7.4 - 10 19 1 7 19 1 18 - 11 5 2 20 5 2 3 - 12 27 0 0 34.5 0 34.5 - 13 14 13 0 8.2 9.1 .9 - 14 17 10 0 25.6 2 23.6 - - Totals, 162 129 87 106.3 51.6 - Grand Total, 378 Net raised, 54.7 - - Average raising of each passive touch judgment, .14+ - % of judgments of passive touch lowered, 129/378 = 34 - % of judgments of passive touch raised, 162/378 = 42 - % of judgments of passive touch not affected, 87/378 = 23 - - -TABLE IX. COLOR-ACTIVE TOUCH RESULTS. M. - - _No. of times color was_ - _No. of_ _Not_ _No. of points color was_ _Net result_ - _Color_ _Raised_ _Lowered_ _affected_ _Raised_ + _Lowered_ - + - - - 1 5 1 8 5 1 4 - 2 0 7 7 0 7 7 - 3 3 11 0 1.8 4.4 2.6 - 4 3 11 0 2.4 4.2 1.8 - 5 3 11 0 2.4 2.2 .2 - 6 12 2 0 6 1 5 - 7 2 12 0 1.6 2.4 .8 - 8 12 0 2 12 0 12 - 9 13 1 0 14.2 .6 13.6 - 10 7 7 0 5.6 2.4 3.2 - 11 11 3 0 6.6 1.2 5.4 - 12 7 1 6 7 1 6 - 13 9 5 0 5.5 2.5 3 - 14 11 3 0 13.9 .3 13.6 - 15 11 0 3 12 0 12 - 16 10 4 0 8 1.2 6.8 - 17 12 2 0 16 1 15 - 18 14 0 0 24.8 0 24.8 - 19 0 0 14 0 0 - 20 9 5 0 7.2 1 6.2 - 21 1 0 13 1 0 1 - 22 14 0 0 5.2 0 5.2 - 23 14 0 0 10.2 0 10.2 - 24 8 0 6 14 0 14 - 25 9 5 0 6.3 1.5 4.8 - 26 4 1 9 4 1 3 - 27 11 3 0 4.3 .9 3.4 - 28 13 1 0 10.5 .5 10 - - Totals, 228 96 68 182.4 12.2 - Grand Total, 392 Net raised, 170.2 - - Average raising of each color judgment, .43+ - % of judgments of colors lowered, 96/392 = 24+ - % of judgments of colors raised, 228/392 = 58+ - % of judgments of colors not affected, 68/392 = 17+ - - - _No. of times touch was_ - _No. of _Not_ _No. of points touch was_ _Net Result_ - Touch_ _Raised_ _Lowered_ _affected_ _Raised_ + _Lowered_ - + - - - 1 8 20 0 3.2 15 11.8 - 2 4 24 0 3.4 11.6 8.2 - 3 18 10 0 10 5 5 - 4 8 20 0 3.4 23 19.6 - 5 8 20 0 5 13 8 - 6 2 26 0 1.8 8.6 6.8 - 7 25 3 0 26.5 4.5 22 - 8 21 7 0 10.4 4.2 6.2 - 9 3 25 0 2.7 8.5 5.8 - 10 27 1 0 33.5 .5 33 - 11 23 5 0 3.3 4.5 1.2 - 12 22 0 6 41 0 41 - 13 26 2 0 42.6 .8 41.8 - 14 19 9 0 9.6 8.4 1.2 - - Totals 214 172 6 150.2 61.4 - Grand Total, 392 raised, 88.8 - - Average raising of each active touch judgment, .22+ - % of judgment of active touch, lowered, 172/392 = 43+ - % of judgments of active touch raised, 214/392 = 54+ - % of judgments of active touch not affected, 6/392 = 1.8+ - - -TABLE X. COLOR-ACTIVE TOUCH RESULTS. F. - - _No. of times color was_ - _No. of_ _Not_ _No. of points color was_ _Net result_ - _Color_ _Raised_ _Lowered_ _affected_ _Raised_ + _Lowered_ - + - - 1 13 1 0 8.3 .9 2.4 - 2 5 4 5 5 6 1 - 3 2 5 7 2 5 3 - 4 9 5 0 7.6 3 4.6 - 5 9 5 0 16.2 7 9.2 - 6 0 14 0 0 20.4 20.4 - 7 3 11 0 2.1 5.3 3.2 - 8 1 3 10 1 3 2.0 - 9 5 9 0 3 8.2 5.2 - 10 9 5 0 10.95 8.25 2.7 - 11 12 2 0 8.6 1.4 7.2 - 12 8 6 0 9.8 2.4 7.4 - 13 4 1 9 6 1 5 - 14 10 4 0 11 1.6 9.4 - 15 2 12 0 2.8 3.2 .4 - 16 2 12 0 1.6 7.4 5.8 - 17 8 6 0 5 4 1 - 18 11 3 0 9.85 3.95 5.9 - 19 0 0 14 0 0 - 20 1 13 0 .8 14.4 13.6 - 21 2 7 5 2 7 5 - 22 8 6 0 11.4 9.2 2.2 - 23 0 14 0 0 11.4 11.4 - 24 0 10 4 0 10 10 - 25 2 12 0 3.8 10.2 6.4 - 26 0 14 0 0 11 11 - 27 0 14 0 0 8.6 8.6 - 28 2 12 0 1.8 6.2 4.4 - - Totals, 129 209 54 57 111.4 - Grand total, 392 Net lowered, 54.4 - - Averaging lowering of each color judgment, .13+ - % of judgments of colors lowered, 209/392 = 53+ - % of judgments of colors raised, 129/392 = 32+ - % of judgments of colors not affected, 54/392 = 13+ - - - _No. of times touch was_ - _No. of_ _Not_ _No. of points touch was_ _Net result_ - _Touch_ _Raised_ _Lowered_ _affected_ _Raised_ + _Lowered_ - + - - 1 11 17 0 1.1 28.3 27.2 - 2 14 14 0 11.2 13.8 2.6 - 3 19 9 0 9.8 7.2 2.6 - 4 11 17 0 2.2 25.6 23.4 - 5 13 15 0 12.5 16.5 4 - 6 12 16 0 4.6 12.2 7.6 - 7 15 0 13 23 0 23 - 8 2 26 0 .6 26.8 26.2 - 9 6 22 0 4 25 21 - 10 0 28 0 0 17.6 17.6 - 11 19 9 0 6.7 6.3 .4 - 12 3 25 0 3.8 10 6.2 - 13 2 26 0 2 32 30 - 14 8 20 0 6.4 19 12.6 - - Totals, 135 244 13 26.0 178.4 - Grand Total, 392 Net lowered, 152.4 - - Average lowering of each active touch, .38+ - % of judgments of active touch lowered, 244/392 = 62+ - % of judgments of active touch raised, 135/392 = 34+ - % of judgments of active touch not affected, 13/392 = 3+ - - -TABLE XI. COLOR-PASSIVE TOUCH RESULTS. M. - - _No. of times color was_ - _No. of_ _Not_ _No. of points color was_ _Net Result_ - _Color_ _Raised_ _Lowered_ _affected_ _Raised_ + _Lowered_ - + - - 1 9 1 4 10 1 9 - 2 7 2 5 7 2 5 - 3 7 7 0 4.2 2.8 1.4 - 4 6 8 0 4.8 1.6 3.2 - 5 9 5 0 11.2 1 10.2 - 6 14 0 0 21 0 21 - 7 13 1 0 14.4 .2 14.2 - 8 11 0 3 14 0 14 - 9 14 0 0 18.6 0 18.6 - 10 7 7 0 5.6 1.4 4.2 - 11 10 4 0 7 2.6 4.4 - 12 3 3 8 3 3 - 13 13 1 0 12.5 .5 12 - 14 14 0 0 25.6 25.6 - 15 2 0 12 2 0 2 - 16 10 4 0 11 1.2 9.8 - 17 13 1 0 16.5 .5 16 - 18 13 1 0 13.9 .7 13.2 - 19 0 0 14 0 0 - 20 13 0 1 12.4 0 12.4 - 21 7 0 7 7 0 7 - 22 13 1 0 11.9 .7 11.2 - 23 14 0 0 18.2 0 18.2 - 24 12 0 2 22 0 22 - 25 14 0 0 15.8 0 15.8 - 26 9 0 5 9 0 9 - 27 12 2 0 9.4 .6 8.8 - 28 10 4 0 6 2 4 - - Totals, 279 52 61 292.2 - Grand total, 392 Net raised, 292.2 - - Average raising of each color judgment, .75- - % of judgments of colors lowered, 52/392 = 13+ - % of judgments of colors raised, 279/392 = 71+ - % of judgments of colors not affected, 61/392 = 15+ - - - _No. of times touch was_ - _No. of_ _Not_ _No. of points touch was_ _Net Result_ - _Touch_ _Raised_ _Lowered_ _affected_ _Raised_ + _Lowered_ - + - - 1 0 3 25 0 3 3 - 2 5 13 10 5 16 11 - 3 5 10 13 5 12 7 - 4 8 3 17 9 3 6 - 5 6 2 20 6 3 3 - 6 5 11 12 5 12 7 - 7 1 19 8 1 27 26 - 8 12 0 16 12 0 12 - 9 22 0 6 23 0 23 - 10 21 0 7 22 0 22 - 11 28 0 0 24 0 24 - 12 16 0 12 19 0 19 - 13 22 6 0 32 3 29 - 14 20 0 8 22 0 22 - - Totals, 171 67 154 160 54 - Grand total, 392 Net raised, 106 - - Average raising of each passive touch judgment, .27+ - % of judgments of passive touch lowered, 67/392 = 17+ - % of judgments of passive touch raised, 171/392 = 43+ - % of judgments of passive touch not affected, 154/392 = 39+ - - -TABLE XII. COLOR-PASSIVE TOUCH RESULTS. F. - - _No. of times color was_ - _No. of_ _Not_ _No. of points color was_ _Net Result_ - _Color_ _Raised_ _Lowered_ _affected_ _Raised_ + _Lowered_ - + - - 1 14 0 0 12.4 0 12.4 - 2 7 2 5 7 2 5 - 3 1 1 12 1 1 - 4 9 5 0 3.6 3 .6 - 5 14 0 0 15.2 0 15.2 - 6 0 14 0 0 2.4 2.4 - 7 13 1 0 9.1 .3 8.8 - 8 7 0 7 9 0 9 - 9 11 3 0 5.2 2.4 2.8 - 10 11 3 0 12.05 4.35 7.7 - 11 13 1 0 14.9 .7 14.2 - 12 4 10 0 2.4 6 3.6 - 13 1 1 12 1 1 - 14 11 3 0 6.6 1.2 5.4 - 15 9 5 0 4.5 .5 4 - 16 5 9 0 4 3.8 .2 - 17 12 2 0 6 2 4 - 18 13 1 0 12.55 .65 11.9 - 19 0 0 14 0 0 - 20 11 3 0 8.8 .6 8.2 - 21 10 0 4 11 0 11 - 22 10 4 0 14 1.2 12.8 - 23 3 11 0 4.7 1.1 3.6 - 24 2 0 12 2 0 2 - 25 4 10 0 5.8 1 4.8 - 26 7 7 0 4.5 3.5 1 - 27 11 3 0 7.6 1.2 6.4 - 28 12 2 0 10.8 .2 10.6 - - Totals, 226 100 66 161.6 6 - Grand total, 392 Net raised, 155.6 - - Average raising of each color judgment, .40- - % of judgments of colors lowered, 100/392 = 25+ - % of judgments of colors raised, 226/392 = 57+ - % of judgments of colors not affected, 66/392 = 16+ - - - _No. of times touch was_ - _No. of_ _Not_ _No. of points touch was_ _Net Result_ - _Touch_ _Raised_ _Lowered_ _affected_ _Raised_ + _Lowered_ - + - - 1 0 8 20 0 8 8 - 2 3 14 11 3 15 12 - 3 23 5 0 14.5 2.5 12 - 4 17 11 0 11.2 4.4 6.8 - 5 21 1 6 27 1 26 - 6 16 12 0 9.6 5.8 3.8 - 7 4 10 14 4 10 6 - 8 13 7 8 14 7 7 - 9 17 11 0 18.6 3.2 15.4 - 10 15 1 12 15 1 14 - 11 0 1 27 0 1 1 - 12 28 0 0 21 0 21 - 13 21 7 0 18.3 7.9 10.4 - 14 24 4 0 31.2 1.8 29.4 - - Totals, 202 92 98 145.8 27 - Grand total, 392 Net raised, 118.8 - - Average raising of each passive touch judgment, .30+ - % of judgments of passive touch lowered, 92/392 = 23+ - % of judgments of passive touch raised, 202/392 = 51+ - % of judgments of passive touch not affected, 98/392 = 25+ - -Evidently no dynamic explanation of this difference is possible. It -has been impossible to reveal the cause of this particular difference; -in all other respects, however, the subjects agree in the general -tendencies revealed. - -There remain the combinations of colors and passive touches. These -combinations are shown in Tables XI and XII. - -In these tables the same general tendency to estimate both higher when -colors and passive touches are combined appears. M. raises the colors -more than F., and F. raises the touches more than M. This is perfectly -regular, as the following table shows: - - _Standards._ _Raised in Combination to_ - _Colors._ _Passive Touches._ _Colors._ _Passive Touches._ - M. 4.44 5.14 5.16 5.40 - F. 4.53 4.56 4.75 4.85 - -The whole results are recapitulated for both M. and F. in Table XIII. - - -TABLE XIII. RECAPITULATION - - _Average_ _% of judgments of_ (----) _Av. + or - influ._ - F. _Standard_ _Raised_ _Lowered_ _Not affected_ _on each_ (----) - 1 Colors 4.35 28 59.6 11.9 (Color) - .26+ - Tones 4.33 16 77 6 (Tone) - .74+ - - 2 Colors 4.35 32 53 13 (Colors) - .13+ - A. Touches 4.55 34 62 3 (A. T.) - .38+ - - 3 Colors 4.35 57 25 16 (Colors) + .40+ - P. Touches 4.56 51 23 25 (P. T.) + .30+ - - 4 Tones 4.33 68 24 7 (Tones) + .45+ - A. Touches 4.55 64 32 3 (A. T.) + .23+ - - 5 Tones 4.33 72 17 10 (Tones) + .52+ - P. Touches 4.56 42 34 23 (P. T.) + .14+ - - M. - 1 Colors 4.44 23 59 17 (Color) - .29+ - Tones 4.20 12 81 6 (Tones) - 1.08 - - 2 Colors 4.44 58 24 17 (Colors) + .43+ - A. Touches 4.24 54 43 1.8+ (A. T.) + .17+ - - 3 Colors 4.44 71 13 15 (Colors) + .72+ - P. Touches 5.14 43 17 39 (P.T.) + .26 - - 4 Tones 4.20 99 .2 .5 (Tones) + 1.71+ - A. Touches 4.24 63 36 .2 (A. T.) + .31+ - -From this last table certain conclusions may be drawn. - -(1) When Colors and Tones were combined, both were lowered in the -appreciation of both subjects. The percentages show: (_a_) That about -the same number of colors was lowered, 59.6% for F. and 59% for M. -(_b_) That about the same average displacement of colors occurred, .26+ -for F. and .29+ for M. (_c_) That about the same number of tones was -lowered, 77% for F. and 81% for M. (_d_) That the tones were lowered -more for M., -.74+ for F., and 1.08+ for M. - -(2) When Colors and Active Touches were combined, for F. both are -lowered; for M. both are raised. The colors are lowered only very -slightly, .13 for F, while for M they are raised .43+; and conversely, -the active touches are lowered .38+ for F, and raised only .17+ for M. -Still, it appears clear that with F. there was an interference,--and -both colors and active touches are lowered while the same combinations -with M. are mutually reënforcing. - -(3) When Colors and Passive Touches were combined, the appreciation of -both was raised for both F. and M. The result shows: (_a_) That the -percentages of colors and passive touches raised are practically the -same for both F. and M. (_b_) That the color displacement is greater -for M. than for F., being +.72+ for M. and only .40+ for F. (_c_) That -there is only a slight difference in the displacement of the passive -touches. - -(4) When Tones and Active Touches were combined, the appreciation -of both was raised for both F. and M. It appears (_a_) that the -displacement for F. is very slight, .45+ and .23+, when compared -with the displacement for M., 1.71+ and .31+. But, (_b_) that the -displacement of tones is greater than that of the active touches for -both F. and M. (_c_) That this same relatively great displacement of -tones occurred in the opposite direction when colors and tones were -combined. - -(5) When Tones and Passive Touches were combined, the appreciation of -both was raised for F,--the tones being raised more than the passive -touches. This combination was not tried with M. for lack of time. - -From time to time some special tests of these general tendencies were -applied. From the results already set forth, one could predict that -there was a strong probability that when the tone-series was combined -with a constant touch-series, active or passive, the appreciation of -the tones would be raised. This was tried by allowing the subject M. to -rub his hand over the somewhat rough pillow of a tilting board. The -results showed that the appreciation of twenty-five out of twenty-seven -tones was raised. Other predictions were similarly verified. - -Of course, any experiment of this nature is exposed to a great many -chances of error. The subjects may be fatigued, or depressed generally. -But the wide range of different readings taken is a reasonable -assurance that the chances of error are minimized. And it is to be -noted, also, that individual differences of appreciation do not vitiate -the results. In getting the "standards" no less than 2000 judgments -were given by each subject, while for the tables each subject gave -no less than 4000 judgments. The curves made from these data show -the effect of each separate combination by their variation from the -standard. The tables and analyses and conclusions already introduced -show, in general, that _our appreciation of each of several stimuli -in combination is different from our appreciation of the same stimuli -when taken separately_. The results show that this appreciation may be -either raised or lowered; that is to say, our feeling of values is not -constant for a given stimulus under all conditions. - -From Table XIII I have found the average displacement of each series to -be as follows: - - Tones, .90. - Colors, .37. - A. Touches, .28. - P. Touches, .23. - -This shows that passive touches are subject to the least displacement, -while active touches, colors, and tones are respectively subject to -a greater variation. The sight-touch world is more stable than the -auditory world. With M. the tones go over a full point both below and -above the standard. - -This report does not treat of the particular effects of a qualitative -nature that follow from the possible combinations of series of stimuli -of different feeling values,--such as the effect of an agreeable touch -upon a slightly disagreeable tone, or upon an indifferent color, and -so on. All such effects can be traced by rearranging the data already -collected, and this may be done in a subsequent paper which may enter -also into the theoretical discussion of the whole problem. - -FOOTNOTE: - -[Footnote 83: Attention may be called to the fact that this paper -arranges the conventional seven degrees of feelings in an order -opposite to that of the other papers of this volume; it follows still -the earlier traditions of our laboratory, while the more recent -investigations call very disagreeable 7 and very agreeable 1; the -indifference point remains the same.--EDITOR.] - - - - -THE COMBINATION OF FEELINGS - -BY C. H. JOHNSTON - - -The problem at issue in the present investigation concerns the -combination of feelings. On the basis of theories as different in -many respects as those of Wundt, of Titchener, of Lipps, etc., the -feeling-state is always a unity. The affective process for Wundt -must be always "coextensive with consciousness." When he chooses to -speak of a "mixed feeling," it never for him signifies a "mosaic in -consciousness," but is always a new _Totalgefühl_, which "swamps -consciousness as a whole." - -Titchener also believes that with every affective experience an -inevitable and pervasive "tilting" of the whole organism occurs. W. -McDougall, in his recent Physiological Psychology, makes the general -statement that always a "massive state of feeling results" when many -sensations are simultaneously excited, and that in such case we cannot -"introspectively distinguish the feeling-tone of each sensation." - -We started to examine by experiment and by introspection which -feeling-effect really results from a combination of various impressions -with affective tone, and whether it is really impossible that various -feelings coexist and remain distinguishable. In case they can coexist, -the question arises: What mutual influences can be discovered? - -For the main part of our study the simplest possible feelings were -chosen, because here presumably the subjects will not be forced to -grapple with complex personal psychoses, necessarily confusing from -their very richness. It was thought that here they could be more nearly -normal, naïve, less artificial, and able to a maximum to rid themselves -of preconceived personal opinions and unaccountable associations. -Here, with simplest stimulations, unsophisticated necessarily, the -hope at any rate is that work with a good number of subjects of -distinct emotional temperaments may bring to light certain fresh -simple introspective facts, which may in their turn offer valuable -considerations concerning the psychology of feeling. - -Throughout the course of the experiment, except in the advanced stage -when more complex states were under consideration, sounds, colors, -odors, simple figures, and tactual surfaces were used. In the late -stage of the investigation sentences and pictures more or less morally -and æsthetically suggestive served to furnish for study the complex -feeling-states. - -The progress of the investigation divides itself naturally into the -following four distinct parts. - -I. From every experience of each individual the investigator sought to -obtain from the subject's own introspection at the time as adequate -a description as possible of the particular feeling provoked by the -chosen stimulus. The feelings studied in this first period of the -investigation are entirely those which heretofore have not been at -all classified except in terms of the objects which call them forth. -Part I is concerned with single stimuli affecting only one kind of -sense-organ, visual, tactual, auditory, or olfactory as the case may be. - -Two requests were made of each subject, viz: - -(_a_) To describe as clearly as possible how the particular experience -_felt_. - -(_b_) To report always all the accompanying physiological or physical -processes which seemed to _mean_, to result from, or apparently -only accidentally to accompany the stimulus judged by him to have a -feeling-tone. - -The work of the experiment covers a period of two years, and -fortunately several of the subjects were available for the whole -period. No subject was used for more than two hours each week. In the -preparatory training with sensations from only one sense-organ, the -range of colors, odors, etc., was chosen as follows: Twenty colors, -and as many tactual surfaces, etc., were presented in turn, and -each subject was requested to make his judgment as to the relative -degree of agreeableness or disagreeableness of the feelings arising -in the several cases. The scale of numbers from 1 to 7 served in -the traditional way to indicate approximately the hedonic value of -the feeling-tones, 1 signifying highest degree of pleasure, 2 very -pleasant, 3 slightly pleasant, 4 indifferent, 5 slightly unpleasant, 6 -very unpleasant, and 7 the highest degree of unpleasantness. Though the -personal differences were in some cases rather striking, the individual -subject from day to day showed a relatively constant standard. This was -done in order simply to be able to choose approximately the stimulus -in the individual case likely to call up the _kind_ of feeling one -wished to study more in detail, and thus facilitate the progress of -the investigation. In this preliminary stage pleasant or unpleasant -seemed to the subjects more or less an exhaustive account of these -faint feelings. This was a means of eliminating practically indifferent -shades, as there is here no special interest in the psychology of color -as such. - - * * * * * - -II. Following upon this preparatory training, the second part of the -experiment consisted in a similar study of the _mutual influences_ -of _simultaneous feelings_ accompanying sensations from different -sense-organs. How does the feeling of pleasure obtained from contact -with a smooth surface influence the feeling occasioned by the _sight_ -of a pleasant or unpleasant object? Here, for example, colors were -exposed in a large black frame manipulated by means of shutters easily -opened or closed, at the same time that a tactual surface was being -applied, or a tone from a tuning-fork was being sounded. - -The introspection method was essentially the same here as in Part I. - -(_a_) First, the subject was requested, without the necessary -distraction of directing his attention at all to the bodily processes, -to give himself up to the situation and to report as accurately as he -could the kind of affective state experienced. - -(_b_) Next, as in Part I again, in a repetition of the same experience, -he was requested to be on the lookout for any and all accompanying -bodily changes. The problem here was to discover to what extent the -more complex state now in question would correspond to the specific -and noticeable bodily reactions such as were noted in Part I, where -single experiences presumably resulted. If different feeling-elements -are in experience at once, can one fix upon correspondingly different -suggested actions? Does the organism react to more than one situation, -or to two sources of stimulation at once? Is affection present only -when the whole organism is, to use Titchener's expression, "tilted" -one way? Is the Totalgefühl the single undifferentiated result -always, or can we here also detect such phenomena as summation, -fusion, inhibition, and partial or total mutual reënforcement of the -different feeling-components? Do the new reactions which seem to mean -the feelings always refer to actions so inclusive as to result in the -inhibition of any other tendencies to response, or is there sometimes a -clear strife between two simultaneously conflicting feelings, two kinds -of relatively self-dependent reactions both going on at once? Or again, -when the hedonic or algedonic characters of two given simultaneous -stimuli, such as a soft, soothing, pleasant touch with an irritating, -exhilarating, invigorating but also pleasant yellow color, do not -differ as to their pleasant-unpleasant character, must one be pale and -empty "intellectual perception" when the other is being enjoyed? These -are some of the questions that suggest themselves at once. - -Not at this point, however, considering the dimensionality of feeling, -the four simple combinations were first studied; such, for example, as -(1) a pleasant color with a pleasant touch, (2) pleasant color with -unpleasant touch, (3) unpleasant color with pleasant touch, and (4) -unpleasant color with unpleasant touch. - - * * * * * - -III. This part of the work was an attempt to estimate the average -time-interval in which feeling-tones develop, and what influences other -feelings given simultaneously or immediately beforehand have upon the -time-development of the feeling-tone in question. Will certain feelings -hasten and others retard a third feeling whose character remains -unchanged when it crosses the limen of awareness? Does the feeling, for -example, aroused by contact with a soft, soothing, yielding tactual -surface, put one in such a state that he will more or less quickly -obtain pleasure from the visual impression coming from a soft rich -red color? What effect will a feeling already aroused by a low tone -have upon the time development of the feeling one gets from looking -at a deep green color? Are there, again, pleasant feelings of certain -dimensions which will be hastened by other feelings, and still others -which, by the same means, will be retarded? If so, under what general -principle do they seem to fall? - -Here the time-development of a certain feeling-tone is taken when -there are no other influencing factors. Then the comparison of this -rate is made with the later reported time-interval when that feeling, -again aroused, has been immediately preceded or accompanied by a -feeling-tone from another source of stimulation. Here also feelings -for colors presented in a frame, without any special suggestion of -form in connection with them, were in like manner compared as to -their time-development with the affective states arising from those -same colors presented again enclosed in cardboard frames of special -character. Some of these forms were very pleasing, such as upright -ovals, small circles, etc., while others, frames cut purposely into -irregular shapes, were to most observers decidedly unpleasant. - - * * * * * - -IV. Here complex feeling-states were in question, and evidence was -sought as to how much could be detected here that would tend to -substantiate or to call in question what seemed to be the fundamental -principles of feeling-relations where the states are very simple. -Further complications, such as three and even more stimulations at -once, were tested. After this, feelings aroused by looking at pictures -of statues were studied and described as accurately as possible. "Perry -Pictures" were used. _Dying Alexander_, _Venus of Milo_, the _Dying -Gladiator_, the _Laocoön_ group, and _Apollo Belvedere_, served to -introduce sufficient variety. Then copies of these same statues were -cut out from the card and presented to the subject with the same colors -before studied used as background. These were allowed to play their -part in the feeling aroused therefrom. - -After this, pictures more or less morally as well as æsthetically -suggestive were used. Millet's _Angelus_ and his _Shepherdess Knitting_ -and Rosa Bonheur's _Horse Fair_ afforded suggestion hints as to the -contrasted motor significance of the complex states called forth. Here -the attempt was made to find out in how far the feeling when once -aroused is dependent upon the retained after-images or memory-images -of the original visual stimulation, and what sort of feelings tend the -longer to persist. Or again when both are taken in in quick succession, -what sort of imagery and associations result. Are the resulting -associations or images colored by both feeling-tones in any definite -way? And if the feeling itself persists despite the loss of imagery, -can it be referred merely to more internal sensations, or does there -seem to be a necessity to consider it of purely central origin? - -Such, in brief outline, has been the proposed method of study. In an -experiment of this delicate nature there are clearly many things to -guard against. There is danger that the investigator will unwittingly -make suggestions to the subjects by his questions. There is a great -danger of auto-suggestion on the part of the subject. The likelihood -is also considerable that the subjects will fall into stereotyped -forms of expression and general listlessness in introspection, where -from week to week these simple experiences are being repeated for -closer and closer examination. Again the special mood of the day will -necessarily tend to affect all such feeling-attitudes toward slight -stimulations supposed to have a feeling-tone. These and other dangers -were recognized at the outset, and avoided as much as possible by -such legitimate variations as could be introduced without changing -the general purpose of the work. No subject was used when he felt, -for whatever reason, unable to adapt himself to the conditions of the -experiment. No subject knew anything of the recorded results of the -others, and it was constantly urged that each person should wholly -regard the present feeling in question, ignoring any remembered tone -which that special stimulation had before afforded him. - -It very soon became evident that the variations among individuals, -especially as to the amount of feeling and the consequent ability to -fix upon the special physical processes involved, were considerable. -The subjects represent types. Hence, it seems necessary at once to -mention briefly some characteristics of the persons themselves who have -reported these various experiences. This was kept in mind throughout, -and seems of decided significance in the interpretation of the recorded -results. After an examination of the results of each individual, -whatever remains that is common to all will be briefly summarized. - -All the subjects were graduate students in Harvard University or in -Radcliffe College. Seven of the twelve had had from one to five or more -years' training in laboratory investigations. Two subjects were ladies, -the rest were gentlemen. - -Subject A was a man of bright cheerful pleasant even temperament, -responsive, very musical, alert, physically vigorous, very careful in -statement, and decided as to the distinctness of his emotional states. -He uses his facial muscles a good deal while conversing. - -Subject B is musical, sings a good deal, is not especially -demonstrative, nor always able to become adapted to the necessarily -oft-repeated stimulations from the same colors and tones. This subject -is especially discriminating as to shades, and has decided preferences -for certain colors. - -Subject C usually found it difficult to find any decided feeling-tone -for many of the stimuli used. This subject is rather reserved and -undemonstrative as a rule. He is not at all musical, nor does he care -for art. He is a rather cool but extremely careful observer, and is -always guarded in his introspection. - -Subject D is impulsive habitually, flashy, responsive, especially to -any suggestion of an æsthetic nature, such as forms, and very decided -as to his experiences. He walks with a quick nervous step, is sprightly -always, vivacious in conversation and outspoken. - -Subject E is rather non-emotional as he often says. He is very -energetic, full of life, quick but not precise in all his movements, -always on a tension, does not enjoy without effort anything so mild as -the stimulations here used, and finds introspection of this affective -nature difficult. - -Subject F is careful, experienced in introspective work, musical, talks -a great deal, enjoys this kind of work, has decided preferences, is -athletic and energetic. This subject makes use of facial, arm, and -shoulder gestures quite freely in general conversation. - -Subject G has a penchant for talking a great deal, is decided in his -likes and dislikes, musical, of an uneven temperament, sometimes -cheerful, often cross, but always animated. - -Subject H confesses he does not ever especially enjoy colors, nor -respond with any sign of demonstration to any situations. He is steady, -calm, apparently unruffled, and not an especially acute observer of his -own states, proving in this experiment unusually undiscriminative as to -simple experiences. - -Subject I is rather morose, claiming to be habitually unmoved by even -display of great passion or excitement. He finds it generally much -easier to call up unpleasant than pleasant experiences, this being -exceptional among the subjects. He is much slower than the average, and -his feelings are not easily aroused. He is deliberative and confident -as to his state of mind. He is nervous and often becomes fatigued -before the hour's introspective work is over. - -Subject J is nervous, of an uneven temperament, emotional, and quick -to react to a situation of any kind, and, rather more than the others, -subject to suggestion. - -Subject K responds very quickly always, is habitually prompt and clear -in statement, of an even temperament, and unusually interested in the -experiment. - -Subject L is unexperienced in this particular kind of work, but slow -and careful. Though athletic, his movements are rather heavy. He is -deliberate in speech and of an even, though rather undemonstrative -temperament. He also is musical. - -In order to verify my somewhat personal descriptions here recorded a -questionnaire was given each subject to fill out according to his own -personal judgment of his emotional disposition. This was done toward -the close of the investigation, and the answers agree in the main with -the descriptions offered above. - -For the first month's preliminary practice, and with the purpose of -stimulating curiosity and interest, and of testing the comparative -richness of even slight feeling-experiences, a great variety of -stimulations was used. Twenty different tactual surfaces from softest -plush to very rough sandpaper served for the tactual impressions. -Twelve different odors, as many colors differing in saturation and -intensity, and tones from high and low tuning-forks, and noises -variously produced, were employed as stimulations for the other senses. -Besides these, circles, upright and horizontal ovals of various sizes, -imperfect circles and ovals, and other irregular shapes were all -presented in the same large black frame. When studied alone indifferent -gray fillings were used. When complex states were in question colors -served as fillings. When the subjects thus became accustomed to these -very simple but very definitely _felt_ experiences, in these for the -most part habitually ignored affective elements of ordinary sensations, -the investigation at once became narrowed to more careful and minute -attention to a few of these feeling-tones. It was soon found also that -odors could not easily be used in combination, since they effectively -effaced all feeling-tones for the simultaneously given colors or -touches. Five colors, fairly representative for all subjects of -different kinds of feeling-tones, were chosen, and were used throughout -the whole investigation. These were the following: a soft deep red, -light brilliant yellow, deep pure green, saturated blue, and a dingy -greenish-yellow. The dimensions of the exposed surfaces were six by six -inches. - -For tactual impressions of approximately equal value soft plush, -velvet, and two kinds of sandpaper were used, and for tones high and -low tuning-forks. All the above-named forms were used in connection -with the chosen colors. The subjects differed considerably as to the -_amount_ of feeling that could be obtained from such material. The -variation of kinds and of intensity in the same subject was sometimes -noticeable from day to day, but not great. It is hardly necessary to -give detailed quotations from each subject. The following summary of -the results of the experimental work, however, contains nothing that -was not frequently reported by a majority of the subjects. This, then, -does not represent at all what was once or occasionally reported by -individual subjects, but what after training seemed to be reliable and -definite and constant feeling-states. - - -PART I - -_Section A._ The following are the collected expressions which many -subjects used to describe the feeling for this _particular shade of -red_. It feels as if it would be soft. It suggests warmth. The feeling -is one of seriousness, pleasantness, quietness, of free repose,--a -full feeling of the sense of safety. It is soothing, rich, full of -strength, and inviting. One feels restful, grave, calm, appeased. There -is an agreeable longing and a tendency to lose one's self in the color. -The feeling is one of comfort, luxury, satisfaction, expansiveness, -tranquillity, and quiescence, with no accompanying feeling of weakness -by exertion of effort or energy. There is neither marked tension on the -one hand, nor collapse on the other. There is a sense rather of easy -self-control and command of one's body, but with no aggressive sorrow -nor joy element,--a feeling of being attracted, with nothing to suggest -any obstacle to the adaptation. - -Occasionally to all subjects this color, and, indeed, all colors, -seemed "dead," arousing no feeling whatever. Here the color "ought -to be pleasant," but is only "for the time potentially not actually -actively pleasant." Still more rarely did this red appear to be -unpleasant. Some subjects thought that this afforded the greatest -_amount of sensual pleasure_. More than any of the other colors they -think it appears to "give you something." It does not so much stimulate -as furnish a content itself. It has a direct effect rather than a -tendency to make one wish to do something and thus give pleasure -from the activity itself. Only one subject failed to find this color -pleasant. His early association of it with blood and ghastly scenes -could not be overcome. Some others, when a glare or glaze appeared on -the red, found in it slight suggestions of stimulation and excitement, -but the general decision in the great majority of cases was that the -feeling was a sort of emotional massiveness compared with the effects -from other colors. - -In marked contrast, for the most part, appears the characteristic -feeling-tone for our chosen shade of _yellow_. Almost universally -subjects find such words as these descriptive of the feeling here -in question. It is cheerful, brisk, pleasant[84] also, bright, gay, -light, sprightly, merry, jovial, easy to get, pleasantly irritating, -stimulating, stirring, spurring, thrilling, invigorating, and produces -agreeable discontent. It is jolly, nice, trim, neat, awakening, full of -the sense of motion, soaring, and arouses a feeling of welcome strain, -of pleasure in action, of alertness and self-assertion. Here, in -contrast for the most part to the red, there is no feeling of sinking -into the color. The impulse rather is to be free, to enjoy motor -expression, even if of some vague sort. There is a _felt_ necessity to -do something, a "joy of overflowing or of exuberance," it is called. -There is little present here of what we mean by a suggestion of sensual -richness found above in the feeling for red. Here there is less of -amount of pleasure, but much more of the general activity element. Some -subjects feel the demand for greater saturation, and occasionally it is -unpleasant for just this reason apparently. Subjects C and B frequently -reported this. They think the feeling would be more "stable" and -"grave" and "secure" and "soothing" and one would not feel "unruffled," -if it could be "toned down." Most of the subjects, however, think that -it belongs to the ultimate elemental feeling for yellow that it should -have just this distinguishing characteristic. - -It is more difficult to describe the feeling for _green_. It is almost -always agreeable. Two subjects, however, never like it. Sometimes it -is somewhat soothing in character, but more often it is exciting. -The feeling seems to be between that for red and that for yellow, -partaking on the whole of the characters of feeling for the latter -rather than the former. For all subjects associations tend to color -the feeling-tone for green especially, and hence introspection for -the feeling of pure color is doubly difficult. The most prominent -partial feeling-tone for it is "irritating."[85] The agreeableness -or disagreeableness of this stimulating character is particularly -inconstant, varying greatly for the same subject, as well as for -different subjects. - -The feeling for the _blue_ seems still more to be dependent upon -the person. Many like it. Many others dislike it decidedly. When it -affords a pleasant feeling, it is described in some such terms as -these: The feeling is spiritual, lofty, beautiful, serene. The subject -himself feels immoveable. To other subjects it is too rich and intense -and painful. To one subject who heartily dislikes it always, it is -offensive or revolting, calling up a feeling akin to the emotion one -has toward insincerity in general. To none does this feeling seem -to have any great amount of sensual significance. Even when it is -called "too rich," the incongruity between the richness itself and the -ultimate qualitative significance of the blue is spoken of. Even when -pleasant, the feeling is of an "airy pleasure," volatile, unstable, and -not reliable, nor safe and secure as is the feeling for red. One feels -that it is always apt to vanish, vague, intangible, and with little -immediate definiteness of meaning. Subjects often desire to call it an -intellectual, æsthetic, or ideal sort of feeling. - -No color was universally unpleasant. Two subjects found this -_greenish-yellow_ almost always mildly pleasant. For most of the -subjects, however, it was unpleasant. Here were reported feelings of -contraction, of withdrawal, of disgust, of doubt, of hesitation, of -stimulation without definiteness, dissatisfaction, slight feeling -of nausea, of sea-sickness, of opposition, and the general feeling -of offensiveness. The necessary, unpleasant aggressiveness, unrest, -or discontent characterizes this feeling. This unpleasant critical -attitude where a decision is wanted but not easily gotten, is called -often the feeling of uncertainty. - -In no sense is this investigation a study of the psychology of color; -the only purpose here is to find certain clearly defined feelings -for slight stimulations, in order to find in what way they relate -themselves to other similarly simple feelings from a different source -of stimulation. - -In a similar manner, then, the investigation was conducted in the -analysis and description of feeling-tones for _tactual impressions_. - -For _plush_ there was a feeling of pleasure, ease, safety, and content. -The mood was one of a general enjoyment of sinking one's self into -the situation, an agreeable self-surrender. Here also is a feeling -of unbending one's self, of general expansiveness, of relaxation. -One is soothed, enjoys a suggestion of freedom from disturbance, of -a "regularity" of the experience, feels at the same time strength in -the suggested repose, responds to pleasant reverberating thrills by -the falling off from the accustomed muscular tonicity, and hence has a -decided feeling of satisfaction. To some subjects the feeling aroused -by the hard, polished, glazed tin surface, possessing no "yielding" -character, corresponded more nearly to the feeling for the yellow -color than for the red. To all red "went best" with the plush. No -tactual feelings offered such distinguishable elements for analysis, -nor were they as definitely described as the visual or olfactory or -auditory impressions. The sensational elements were in many cases more -pronounced. The feeling for the plush, however, much like that for -the red color, suggests a "settling down to," or a "dropping forward -toward," rather than an aggressive "taking in" of the feeling-material. - -The feeling-tone with sensations from sandpaper is grating, irritating, -stirring, stimulating. The feeling is one of contraction, of -withdrawal, of uneasiness. One is full of "collapsing chills," of -minute little pains, and there is a decided call for an opposite kind -of behavior. The sense of weakness, of waste of power and energy, of -being penetrated, of strained expectation, of unwelcome tension, and of -slight "wasteful excitement" results. To some subjects, notably subject -E, at times the whole feeling of stimulation as such predominated, -and the total effect produced was agreeable, as it "satisfied a felt -need of waking up." Here again one subject, subject B, throughout the -whole period of two years, failed to find any element of pleasure in -any tactual sensation that was pronounced or prolonged sufficiently to -furnish material for introspection. - -As regards simple _tones_ from tuning-forks the subjects find little -to say. All are pleasant, as a rule, and almost universally, _low -tones_ are most pleasant, richer in content, greater in amount of -"general appeal," more soothing, and pleasantly stimulating. The -feeling of the easy attitude called for contributes to the whole -feeling. _High tones_, calling for more activity on the part of the -subject, more strain, and greater stimulation, coupled with some rather -unprepared-for irritating elements, are less pleasant, and also more -limited in their general appeal to the whole organism. The noises -variously produced were at first unpleasant, and the only assignable -reason seemed to be that their suddenness came as a shock. If expected -or continued they too became pleasant very often. - -Feelings for _forms_ seem to relate even more definitely to the -activity element. The pleasure for the most part is described as -being far less sensual, if indeed, so at all. Small _upright ovals_, -1-1/2 × 1 in., are most pleasant, because somehow they are "more -suggestive of definiteness." _Circles_ one inch in diameter are next -in order of value as to their feeling-tones. _Horizontal ovals_ are -less pleasant still, though for most subjects not unpleasant. Upright -ovals are best, as the kind of action apparently called for by the -aroused feeling is most agreeable and suitable to the subject's -natural upright position of body. An explanation of this general -result of introspection, as well as the preference for the particular -size chosen almost without exception, is attempted in another part -of this report, where are given in more detail the various kinds of -bodily accompaniments. The feelings for those ovals have also the -characters of stimulation, mild excitement, and a feeling of easy -freedom in a pleasing kind of activity. Tension is always present as -an agreeable element when reported at all. This element is coupled -with the "feeling of assurance of certainty" which the whole situation -calls for. It often seems clearly to suggest that one do something. -Circles tend more to suggest inner stability and completeness. They -stand on their own axes. Here there is a sense of satisfaction, -complacency, and sufficiency. The feeling here of a call for immediate -activity on the part of the subject is weak and indefinite, when not -altogether absent. The subjects do not use for this experience such -expressions as excitement, tension, irritation, quick contraction, or -the impulse to self-assertion. Horizontal ovals are least pleasant, it -seems to me, for obvious reasons. Here such noted elements as "felt -unnaturalness," "difficulty of adapting one's self," "wrong direction -of activity," which alone and in themselves would be unpleasant, are -nevertheless more than counterbalanced by other and pleasing elements, -such as symmetry, definiteness, partial stability, and other agreeable -features. Often these latter features are not pronounced, and then the -judgment is, that the total feeling is unpleasant. - -Likewise as regards so-called bad forms, no single statement is -unqualifiedly true of any considerable number of subjects. The -decided feeling of irregularity, the "bulging-out" or the undesirable -"pushing-in" of the figure, the feeling of weakness in one's own body -corresponding, the feeling of instability which one tends himself to -imitate in various ways, the total effect of lack of poise, all tend -to make these figures on the whole unpleasant. But one cannot even -here count upon the constancy of the subjects' feelings. At times, due -perhaps to undercurrents of association processes of which even the -subject himself is not clearly aware, the figure suddenly looms up as -quite definitely pleasing, and full of vague suggestiveness and hidden -richness of content. These varying characters of the feelings for -forms come out interestingly later in the study of them when they are -presented as frames for the above described colors. - - * * * * * - -_Section B._ The bodily processes noted by the subjects are numerous, -and here also, just as with the amount of feeling above, the personal -differences are striking. Some subjects detect a great many forms of -organic commotion, others rarely find anything that can be said to be -descriptive or explanatory of the feeling-state. To all of them at -first this looking for bodily accompaniments destroyed the feeling -itself. Only after considerable training was it possible for them to -find any physiological processes that seemed at all significant. As a -general statement the evidence would all tend to suggest that feelings -for color are most readily and directly referred to the head, face, -throat, and particularly to the forehead and to the eye-muscles. When, -however, the feelings are particularly strong, they tend to pervade the -whole organism. Red thus often brings about the suggestion of general -bodily comfort, and yellow, when very strong, arouses the impulses -calling for "spreading-out, aggressive movements," referred to arms, -shoulders, and chest. Tones have in general the same reference to -the head. Odors are always more organic, affecting more directly the -respiration, muscles of the abdomen, and the more internal apparatus -generally. Tactual impressions refer to the trunk rather than to -the face, hand, arms, or legs. Forms seem to call forth imitative -movements, and the actual or incipient motor impulses refer to the -action of the eyes in motion, the position of the head, of the whole -body, of the shoulders particularly, of the shaping of the cheeks, -lips, etc., and of the similarly imitative actions in the hands and -arms. The following is a list collected from the reported bodily -references given for the feelings described in Part I, Section A. - -(1) Free full respiration and free activity of all voluntary muscles; -or, for other feelings, the checking of respiration and often the lack -of impulse to move at all, with no suggestion, however, in most cases, -of lassitude. - -(2) Chest expansion and general relief pervading the whole body. -The expansion or contraction is further modified by the _degree_ of -_regularity_ and by the _rate_ of the movements involved, as also by -the ease or _difficulty_ in the performance. So also, in the cases of -feeling whose tone exists but is doubtful in character, the bodily -situation seems to mean "lack of movement or change in any definite -direction." The feeling-tone and its vividness are interdependent and -reported as closely connected. - -(3) A cringing all over and a "holding up of all activities." - -(4) Abdomen contraction, chest and shoulders drawn in, hands clenched, -and jaws set. - -(5) A feeling at once in different parts of the body of both process of -contraction and expansion. - -(6) An incipient feeling of nausea in the digestive tract. - -(7) A tendency to incline the head forward or backward, or to keep it -rigid, or to turn it aside. - -(8) For touch, waves, reverberations, pleasant penetrating thrills -in the chest and abdomen especially, less frequently in the limbs, -occur. Sometimes these suggest expansion of the whole frame; sometimes, -even when also pleasant, the tendency to contraction and tension is -noticeable, but in these latter cases the contraction seems to be -rather definitely the calling into action of those general innervated -muscles which refer to the bodily situation of one when he intends to -go toward the pleasantly stimulating object. - -(9) For unpleasant touch the reference or localization of the bodily -response is, when reported definitely at all, generally in the back, -described as chills not thrills, contractions always, contractions also -which often suggest shivers of withdrawal. These feelings also are -referred to the situation of the trunk of the body, and are felt to -originate in the small of the back, and in the back of the shoulders. -For two subjects there occur twitchings in the tendons of the hips and -thighs, and movements of the knee-cap. - -(10) The pervasive bodily collapse, which seems to accompany feelings -characterized as depressing, altogether unlike the soothing feeling of -unwearied repose given by certain soft rich colors or by low deep full -tones or smooth yielding surfaces, is another form of organic response -which is often spoken of. - -(11) The direction of the stimulus with respect to the normal position -of the body also seems to have something to do with the regularity -of the response, and with the general forward or backward tendency. -Tactual surfaces applied or tones sounded behind the subject do seem -to make the bodily adjustment more confused, and less pleasant. All -that subjects could say was that the position was felt as abnormal and -correspondingly less pleasing. - -(12) In many unpleasant feelings, where there was no specific -localization possible, the "stiffening tendency of hardening one's self -to a necessary experience" was frequently reported. In the case of -other states of undifferentiated pleasure a "consenting bending forward -of the whole body" was often detected. - -(13) Many stimulations seem to demand that one draw one's self erect, -square the shoulders, and "assume the attitude of alertness." - -(14) Certain colors for almost every subject independently hint at -sea-sickness. Others, as noted above, report the incipient suggestion -of nausea in the digestive tract. Indeed, abdominal references are -frequently reported by most of the subjects. The abdominal muscles -become "eased up," or again there is a "sucking-in of the belly." - -(15) The feeling of "being natural," of regularity, a universally -popular feeling, is described as a pleasant relief from all tensions -and habitual inhibitions, or a dropping of one's characteristic -muscular tonicity. - -(16) Other stimulations still, particularly certain delicate odors, for -men, subjects C and E for example, seem to suggest what they call the -"childish play impulse." They are called "simple, foolish, childish -pleasures," ignored in ordinary life. They are slightly pleasantly -irritating, and merely make one wish to do something. It is pure -bodily restlessness, a general kinæsthetic enjoyment. Three subjects, -especially, find here the frequent twitchings in the calves of the -legs, in the knee-cap, and the more decided innervations which contract -the tendons of the thighs and hips. - -(17) Subject I frequently detected sensations of contraction in the -tensor tympani connected with the pleasure derived from high tones. -Others referred feelings for tones partly to the regions of the ears. - -(18) The kinds of facial references are numerous. General contraction -or expansion around the eyes, forehead, temples, sometimes to the whole -head, and quite frequently it seemed as if the feeling referred to the -very inside of the eyeball, to the iris and accommodation movements. - -(19) Subjects A, D, F, and K noted specific incipient tendencies to -smile, to smooth the brow, and to "unbend the face" as characteristic -descriptions of certain oft-repeated experiences. - -(20) Introspections from subjects F and G quite constantly revealed -articulatory impulses vividly accompanying the feelings for many colors -and forms. - -(21) A scowl and puckering of the lips was descriptive of the attitude -taken toward some unpleasant situations. - -(22) A contraction or relaxation of the throat-muscles and of the vocal -chords generally was not infrequently noticed. The tendency to swallow -is spoken of. The throat is felt often to be "concave" when certain -bad feelings are sufficiently pronounced. A contraction in the mucous -membrane, with teeth on edge, such as one would experience in eating -something sour, is frequent. A twitching of the ears, squinting of the -eyebrows, and a "heavy feeling" through the neck and chest occur often, -or again a pressing hard of the tongue against the roof of the mouth. - -(23) Forms suggested a shrinking in the volume of the face, sometimes -of the crown of the head, and even of the whole head. - -(24) Upright or horizontal ovals especially provoked the impulse to -imitate the figure itself, either with the lips or with the hands and -arms. When the feeling was particularly strong, all these impulses -often occurred together and appeared mutually to reënforce, or to -intensify each other. - -(25) Horizontal ovals gave one the feeling of being "flattened out," -coupled with an impulse to adjustment altogether unlike the sprightly, -alert, airy feeling aroused by the "trim," upright figures. - -(26) Occasionally when the irregular shapes were presented directly -after a subject had been enjoying one of the perfect figures, that -side of his face or body corresponding to the distorted portion of -the figure was felt to be in an abnormal and unpleasant position. -This "caving-in" or "bulging-out" sensation, which accompanies the -unpleasant feeling, happens when the whole muscular system at the time -for the subject seems inert or externally controlled. - -All these sensations of bodily processes, taken from the introspective -descriptions given by the subjects, are distinctly reported by them -as very faint. They by no means detect them in every experience, nor -do they always seem to the subject himself to _mean_ the whole of -the feeling as experienced. Neither did any one subject find all the -concomitant processes recorded above. Subject H failed throughout the -whole period to detect anything whatsoever, except slight tendencies -to frown, smooth the brow, or to open wide the eyes. This subject was -unable to detect any special differences in his feelings, either in -variety or in amount. For him neither soft red nor brilliant yellow -was either exciting or soothing. They were and always remained for him -more or less vaguely pleasant, and this description for him was both -ultimate and exhaustive. - -Subject B could get no kind of pleasant feeling from any tactual -surface, while to Subject E even the coarsest sandpaper usually -afforded pleasant stimulation. As spoken of above, articulatory -impulses were characteristic of the motor tendencies of Subjects D -and G. To Subject A the experiences seemed richest and fullest, and -the corresponding bodily processes were likewise more pronounced and -varied. In the great majority of the experiments, especially during -the period of training, the feeling itself vanished when the subjects -attempted to analyze the bodily processes. It was chiefly, however, a -matter of training, and this more and more ceased to be a disturbing -element. - -Some subjects preferred often to speak of circulatory, or at least, -decidedly internal and usually involuntary changes in addition to, and -sometimes without, the controlled muscular actions. The mood of the -time affects the amount of feeling, and occasionally, but far less -frequently, the quality. The moral significance of the feelings was -most prominent when the subject felt most interested in the experiment, -as may be noted above in their descriptions of the feelings for red -and yellow. What may be termed the "_regularity element_" would seem -generally to serve as the test especially for the pleasant-unpleasant -character of the feeling-tone. The feeling of expansiveness never -accompanied unpleasant feelings. Feelings of contraction, on the -other hand, very often occurred when the feelings were not at all -disagreeable. In such cases there was a significance attached to the -direction or meaning of the adjustment. - - -PART II - -_Section A._ Here simultaneous stimulations of different sense-organs -were given, and the situation became at once more complex. For some -time only colors and tactual surfaces were employed. Later tones from -tuning-forks and noises were added. Forms with different colors as -fillings still further complicated the experience. Odors as a rule were -unsatisfactory, being so strong as entirely to inhibit all noticeable -effects from the other senses. - -For all subjects at first the feeling-tone related only to the one -object directly attended to. Some effort is required to detect the -feeling-tone for these slight stimulations, and while this is being -done, the feeling for the other sensation tends to vanish. If, while -enjoying the soothing contact with the plush, a chosen color is -disclosed in the frame and attended to sufficiently to obtain from it -a decided feeling, there is a distinct awareness of the dropping of -the feeling for the touch. To some subjects, whatever the combinations -used, this almost constantly occurred for perhaps a month. Often again -there seemed to result a total "feeling of the situation," when the -attention was on neither stimulating object. - -Frequently, too, the attempted introspection at this point failed to -fix upon any feeling-tone at all definite. The condition was one of -confusion and bewilderment. The state of mind when one cannot feel at -all definitely seems to correspond closely to that state of mental -confusion when thought processes are in a jumble, with no path for -the moment leading anywhere. All these difficulties were overcome, -partially at any rate, by continued training. It was not as if -introspection revealed the fact that there was nothing to be found, and -this was frequently reported by the subjects. After some time the touch -character could be retained, and its peculiar value for feeling did -not disappear when other things came in and contributed an affective -element of their own. The old law of the opposition, or mutual -exclusiveness, of feelings would thus seem to mean little more than -that we, generally speaking, experience one thing at a time. Without -a special analytical purpose in view, we do not find many distinct -elemental feelings, as we do not, until we psychologize, find elements -of cognitive character separable. It has been, and is now, commonly -supposed that myriads of ideational elements, partially analyzable at -any rate, go to make up what we choose to call a single perception. -This experience as a whole is of some affective nature; but, as -generally stated, of one unanalyzable sort always. It is true just in -the same sense as in the cognitive state, perception. In the sense -that every perception is unique, in this sense every affective state -is likewise a unit. The evidence I submit, however, is that one may be -the subject of analysis into elemental parts just as much as the other. -Affection, as Titchener defines it at the beginning of his treatment -of feelings, is merely a "tilt of the whole organism." If this is the -ultimate statement, then there are no combinations, and no relations of -feelings except that of mutual exclusion from the field of awareness. -He has taken only one of the above possible attitudes toward affective -states. Geiger, in his study of very complex emotions, however, has -taken the other attitude, and bases his whole position upon it. This -present experimental test furnishes evidence that the latter position -is also a legitimate, and perhaps more desirable position, if feeling -shall have scientific analytical treatment. - -In this investigation, after considerable training, the subjects, -with a single exception, _were all convinced that both feeling-tones, -for tactual and visual impressions, could be present at once_. When -three or more were given at once, confusion as to the state of feeling -was usually so great that valuable introspection was always rendered -exceedingly difficult. Impressions from the same field, as, for -example, colors presented in chosen forms as enclosures, were most -often taken as one object with one feeling-tone. This even was by no -means always the case. When it was thus taken, the experience was still -reported as more complex than either element alone had produced. - -When the feeling-tones for simultaneous stimulations from two -different sources came out sufficiently clearly, the kind of feeling -was described in some such terms as indicated in Part I, Section A, -except that almost invariably the introspection was more difficult. -The relations of these various feeling-components of an affective -experience are numerous. There is a frequent tendency to read one -into the other. The soft soothing feeling coming from plush, if in -the particular experience the color be the more prominent partial -element, tends often to make the subject enjoy more the color, because -there seems to be added to it a soft yielding surface texture. -Frequently also, as in the case of red above, the warmth it suggests is -intensified. - -In cases of feelings of opposite nature occurring together, the -stronger generally prevails, finally in most cases effacing all -specific tone for the weaker element. An odor, for example, even when -always unpleasant, becomes less so when one looks at a pleasant color, -when a feeling-tone can, or often even when it cannot, be detected for -the color at the time. Again, when a very unpleasant form or tactual -impression is being felt, a slightly unpleasant color tends to arouse -often in this situation, as if by contrast, a simultaneously pleasant -element in the total experience. - -For many subjects frequently there results what I shall call a "Total -Mood." This, as to its feeling-character, can be merely different -from, more than, less than, or the same as either component or of -both together. To some the feeling is proportionate to the degree of -concentration of attention, and in all such cases rarely does the -whole complex situation afford a feeling equal to that given by either -component alone, the extra stimulation for the time being simply a -disturbing factor. To others the shifting of the focus of attention -from one to another of the external objects of interest, or from one -feeling-element to the other, is not at all disturbing, "any more -than is any general state of satisfied self-contemplation." This kind -of experience is often and distinctly reported, not as the enjoyment -of two where the discernible elements persist wholly unrelated, but -rather an enjoyment (or disagreeable experience as the case may be), -simply from two sources of stimulation, a total mood with similar or -harmonious constituents. The red color and the tactual feeling for -plush afford this. Similarly the unpleasant color above combines with -certain odors or with the sandpaper. Yellow, however, does not as a -rule produce a feeling that peaceably "falls in with" the tactual -impression brought about by the plush. Low tones tend to combine thus -with the red color or with the softest plush in the same kind of Total -Mood. The feeling-tones usually for pleasant high tones are described -as "falling in with" the feeling for yellow when the feeling exists as -described above, and as nearer to that of the feeling for the green -color than for the particular deep shade of red. What may be termed -the "_Congruity_ or _Incongruity of Feeling-Tones_" is perhaps a good -name to designate feeling-tone relations. It implies neither mutual -exclusiveness nor total fusion, and some such term is necessary. - -The various phenomena of fusion, summation, partial reënforcement, -merely simultaneous, independent coexistence, partial and total -inhibition, of one by the other occur. The feeling-tone for yellow -tends most readily to fuse with the feeling-tone for high tones and -upright ovals. This is not so marked for the green, but more so for all -other colors than for the red. Red harmonizes and tends to fuse, for -most subjects, with the feeling-tones for soft plush, low tones, and -circular forms. This harmonizing, however, is not all that contributes -to the amount of feeling in these complex cases. Subjects often prefer -the low tones with yellow, even though there is less harmony. So -also upright ovals are in themselves generally so much more pleasant -than the circles that red is preferred thus presented, though its -feeling-character is more akin to that suggested by the circles. These -are cases where the intensity itself of the feeling-tone is preferred, -even though what is felt to be an harmonious combination is lessened. - -When the situation admits of a complete fusion, the one resulting -feeling is almost always greater. When summation of unpleasant stimuli -occurs, the singleness of the attention process is not a prominent -feature of the experience. Rather each unpleasant element exists -throughout, each in turn intensifying the whole undertone of feeling, -but also remaining a feeling-tone of a particular kind. Partial -reënforcement is descriptive of that state when both feeling-tones -contribute to a feeling of the same kind, yet do retain some individual -characteristics which stand out for themselves. The general state of -pleasantness, for example, is increased by both elements contributed -by a low tone and the yellow color, yet one retains its soothing and -the other its exciting character. Again, the feeling-tone for green -may occur when its relation, on the other hand, to a pleasantly -sounding tuning-fork is not at all noticed. Subjects find in such -cases always more effort required to note both the feeling-tones, and -there is probably some diminution in quantity of feeling for each of -the simultaneous elements. Other subjects have preferred to call this -partial inhibition. Cases of total inhibition have been noted above, -and are by far the most frequent, as would naturally be expected. When -sandpaper is being applied, and no repose is felt in the body, a color, -suddenly presented, for a moment pleases the eye, but quickly loses all -feeling-character, and can only be "intellectually perceived." - -Again, the way in which subjects will take certain combinations seems -to depend entirely upon the person. Beautiful colors, presented in -disagreeable forms, bring about for some a feeling altogether worse -than does an unpleasant color in the same form. To others there is -always the tendency to enjoy the color and to "reconstruct" the form, -or stress in it those elements only which do suggest symmetry and -definiteness. All feel, when two or more elements contribute to the -feeling-experience, that a total mood generally serves as the undertone -for them. When there is a clear strife between the two, they both can -exist as equal partial tones with an undertone of unpleasantness in the -failure to coördinate them. There are still other cases where the total -result cannot well be called a fusion or summation. For example, when -an unpleasant color in an unpleasant form, or for Subject D, a pleasant -color in an unpleasant form, is presented, the feeling for the whole -is often out of all proportion to the value of each alone, or of what -might be expected from the simple summation. The uncommon revulsion -here was frequently so striking that the subjects would afterwards -laugh heartily over the strength with which it first appeared. - - * * * * * - -_Section B._ Introspection here as to the physiological accompaniments -referring exclusively to one of the two or more existing feeling-tones -is still more meagre, but at times very definite. When the elements of -a total feeling fuse there is of course no reference to the particular -processes which bring this about. It is then simply a general response -to a situation. _When, however, distinct, or opposing feeling-tones -are present and detected, they do often mean opposing inclinations -to action._ The yellow color can retain its exciting tone, and refer -clearly to such activities as opening wide the eyes, incipient -smiling tendencies, and general alertness of facial expression, when -a soothing touch is also felt as suggesting a toning-down of the body -and a general relaxation of the muscles of the abdomen. This is the -most frequently noticed effect. Tactual impressions are accompanied -by pervading organic feelings in the trunk, while visual and auditory -stimulations, in their incipient stages, at least, have the more -pronounced effect upon facial muscles of expression, and general -sensations in the head. When any of these feelings are particularly -strong, however, the sensations, whose feeling-tones seem to constitute -the feeling in question, tend to pervade the entire system and to usurp -the whole bodily activity. The motor tendencies noticed above for -the irregular forms are also reported when the color itself remains -pleasant. Yellow, possessing more of this activity itself, is least -pleasant when exposed in these forms. The opposition of tendencies is -noticed, yellow meaning its own peculiar kind of aggressive movement, -and the bad form at the same time calling for that irregular kind -of unpleasant adjustment. Red does not "intrude itself" nor demand -action, and is always less strikingly in opposition to the form than is -the case with yellow or green or blue. Forms, almost perfect, relate -themselves to feelings of tension. One feels that he cannot quite take -them as perfect figures, and this strain and inability to take them -for what they suggest provokes a decidedly unpleasant feeling. Very -irregular forms become "grotesque" or ludicrous, and the bodily change -is indicated as a "jumble of partially carried out reactions." - -In many cases sensations or motor tendencies are noted all over the -body during the existence of these complex states. At such times -they are not recognized as referring to either feeling-tone in -particular. When also a favorite color is presented to a subject who -is experiencing a disagreeable feeling from sandpaper, the touch is so -pervasive usually that he feels that this "controls the whole response" -and inhibits any reaction, or even any suggested reaction to the -color. When there does fail to be even any possible incipient motor -suggestion, as a rule the feeling-tone for the object is extremely -vague if it exists at all, and the object appears for the time "dead" -or "valueless." Subjects speak of their own inability to respond -in such cases. It is not at all as if the color is definitely bad, -but rather as if one cannot do two different things with the same -muscular apparatus at once. As often, as has before been noted, does -the opposite occur. Colors in definitely characterized forms illustrate -the relations of similar activities when feeling-tones occur together. -Yellow is preferred in upright ovals, for both accentuate the same -demand for activity, and calling for the same kind of response, tend to -fuse into a single object. Yellow and plush do not harmonize, and in -many cases where both retain their feeling-tones, distinct activities -in different parts of the body are aroused simultaneously. With the -circles the feeling-tone for yellow does not agree with that for form. -The yellow becomes almost unpleasant at times. Circles are "heavy," -"stable," "on their own axes." A yellow thus enclosed seems "too fat," -too "unnaturally heavy," not free and light, and the effect is less -pleasing. Circles suit the red better than they do the yellow or the -green or the blue, and tend to be seen as one object, or to fuse, more -readily than red in an upright oval form. The feeling-tones for red and -for upright ovals are both very pleasant, but not as much in harmony, -and consequently usually taken as two different feelings. - -As a general result of introspective analysis at this point, when -different feeling-tones did occur together, they were described in -terms similar to those used when each alone was experienced. The -bodily references, when found, were of the same character, the only -difference being that there was much difficulty in determining to which -feeling-tone the response referred. In many instances, however, again -it seemed quite certain that different kinds of adaptation in different -parts of the body were suggested which seemed to correspond to distinct -affective qualities. Also distinct feeling-tones, each of which alone -could call forth a similar kind of action, when given together tended -to accentuate the total unified response. The upright ovals mean -alertness and soaring motions with a general suggestion of drawing the -shoulders up. The yellow color accentuated this. The circle with the -soothing red, or the fusion of feelings for red and plush, pleases in -quite another fashion. - - -PART III - -In attempting to measure the rate at which feeling-tones for -those slight stimulations develop when no disturbing factors are -consciously present, an interval of from one and one half to two and -one half seconds seemed to be required. At such a time the feeling -was experienced as having reached its maximum. There was no marked -difference for different subjects, nor any constantly noticeable -difference among the kind of stimulations used. A possible exception -was found for Subject I, but this was probably due, as he himself -thought, to his inability to adapt himself easily to the requirement of -the experiment. - -After this was sufficiently tested, the interval which was required -for one feeling-tone to arise when another was already present, was in -the same manner tested. The interval in all cases was too long to be -measured by means of a chronometer. A stop-watch was used. - -While the subject was consciously enjoying a sound from a tuning-fork -or a tactual impression from some chosen texture surface, one of the -colors was presented to him. The time-interval thus ascertained as -necessary for the new feeling-tone to reach its maximum was compared in -each case with the time-interval when the color alone was presented. -Various combinations were here employed also. Colors in forms in -addition were studied in comparison with the same colors presented -without regard to the enclosing forms. No definite results could be -obtained in most cases. It was thought that the repose one feels -for plush might appreciably hasten the feeling-tone for the red and -probably retard that for the more exciting yellow. The evidence is not -directly conclusive. This was not found to be the case in much more -than half of the tests. It did, however, in the great majority of the -cases with all subjects, retard the time-interval for the development -of the unpleasant character of ordinarily disagreeable colors. Given -at such times also the normally unpleasant colors not infrequently -appeared themselves as slightly agreeable. In these cases the interval -was also appreciably longer, suggesting evidence that new processes of -some sort were set up. A pleasant low tone hastened the arousal of a -pleasant feeling-tone for red quite perceptibly for three subjects, and -had no influence upon the other subjects. The feeling-tone for yellow -under the same circumstances was for two subjects retarded regularly, -with no marked effect either way for the others. The same low tone -retarded all the unpleasant colors, as did the plush, in many cases -causing them to appear as pleasant. - -The effect of forms, as enclosures for colors, upon the time-rate was -more marked and constant. Subject I again was always disturbed when -colors were presented to him in definite forms. For him feeling-tones -never arose so quickly when the form-element entered. For the other -six subjects, available for this part of the work, upright ovals -considerably increased the whole state of pleasure whether or not -fusion of the different elements resulted. For them the feeling-tone -for every pleasing color was hastened from two fifths to four fifths -of a second. These same forms retarded the unpleasant colors whenever -one element of the experience seemed to be opposed to the other. -Occasionally here also the color appeared as itself directly and -unaccountably pleasant, the prepared situation of the subject being -such, apparently, that the ordinary character of the color did not -appear at all. This was very frequently the case for all subjects. - -The irregular unpleasant forms generally retarded the feeling-tone -for the enclosed color when that color appeared to have lost some -of its accustomed agreeableness. When, however, the contrast in -feeling-character between the form-element and the color-element as -such was noted as marked, the feeling-character of the color was more -often hastened than retarded. These same forms in almost every case (of -nearly two months' work for seven subjects) hastened the feeling-tone -for the corresponding disagreeable color. Often again pleasant colors -changed the feeling-tones for these irregular forms. In such cases the -influence could not be attributed to the effect of unpleasant forms -upon feeling-tones. - -Statistics alone seem insignificant here. Each variety of affective -experience in itself presents its own peculiar difficulties. In a -great number of tests the affective phases of the experiences were -all described in such terms as to suggest that too general a grouping -of them would not mean much. Often when one thought, after a careful -choice of the stimuli to be used, that the experiment would show that -feelings whose prominent characteristics were those of excitement or -tension, for example, were exerting an influence upon some other kind -of feeling, introspection would reveal the fact that altogether other -phases of the experience were the pronounced elements. Examples of what -at first appeared to be capricious results illustrate the baffling -nature of the problem here dealt with. Red is very pleasant. The oval -with the bulging side is repulsive. This combination caused no marked -retardation in the time required for a feeling-tone to develop. The -blue, not so markedly pleasant alone, with the same bulging oval as -its frame, had its feeling-tone changed, and the time-development -quite perceptibly hastened. This same blue color with an upright oval -as its frame produced a feeling-tone much more pleasant, also with -marked hastening of the speed-development of its feeling-character. -The pleasant-unpleasant dimension of the feeling clearly cannot alone -furnish one with an explanation of these different phenomena. The red -under normal conditions, _i. e._, if not influenced by either favorable -or unfavorable coexisting feeling-tones, aroused its peculiar and not -necessarily pervasive kind of physiological process. Likewise all our -evidence goes to show that the feeling for blue is correlated with a -peculiar physiological process, not so deeply seated in the organism, -and not so satisfactorily coördinated, or "definite." Now the specific -feeling-tone for forms arises when the imitative adjustment called -for is successfully accomplished. In the first combination cited -above the feeling-tone for red, being mild, soothing, more pervasive -than blue, but lacking in the exciting character, is correlated with -processes not so easily influenced by the reactions occasioned by -the presented forms. Subjects say that it does not call for "surface -reactions." It is less "intrusive." It does not "fall in with," nor -does it strikingly oppose, the necessary reaction to the forms. Its -influence upon the time-development of feeling-tones for accompanying -stimuli is consequently small. This is not the case with the blue. -The explanation, however, does not here differ in principle. This -"volatile, unstable, indecisive, thin, or shallow" feeling, can be more -easily influenced by the definite and decisive processes characteristic -of the forms. It, indeed, needs something to determine its character, -or coördinate its general reaction. Hence in both the above -combinations the development period of the new feeling-tone for blue -is shortened. The feeling reaches its maximum in either combination -more quickly than when it occurs alone. As one should expect, fusion -or mutual reënforcement quickens coördinated reaction; and partially -independent coexistence, except where the contrast is sharp, serves as -a condition for the lengthening of the latent period of feelings. - - -PART IV - -It is beyond the province of this paper to report the accounts the -subjects have attempted to give of the complex feelings aroused by the -pictures of statues. The primary and limited purpose is to try to trace -out the influences of the feelings before dealt with for colors when -these are also present in some way related to the now complex æsthetic -states. The _Einfühlung_, often reported for the simple forms, is here -much more easily detected, if the statues arouse agreeable feelings. -They "work themselves into the statue," or assume the position, or -the facial expression if this is prominent, or feel very strongly in -their own body what seems to be the most prominent element in the -feeling portrayed by the figure. Few subjects liked all the statues. -Incipient if not actual tendencies to motion of some sort, with the -sensory counterparts to these situations called for when the subject -feels that he is in the "proper attitude" to get most feeling from the -presentations, chiefly constitute what was in different ways reported. - -These statues presented on colors as backgrounds are variously and -interestingly modified. The feeling-tones for colors distinctly affect -the meaning of the statues. Of the above colors our shade of red is -preferred with Venus by all subjects. Here the feeling-tones more -nearly fuse. Always the feeling-character of the statue predominates, -and the other feeling-elements of the situation are accepted or -rejected in proportion as they harmonize or fail to harmonize with the -predominant partial tone. Red, for example, here adds to the "richness -and luxuriousness." It accentuates the strength, poise, grace, balance, -ease, rest, wisdom, composure, endurance, and dignity. It is more -soothing, and calls for no unnecessary action. One subject never liked -any color as a background. In this case colors were good in proportion -as "they kept out of the way." This is the reason for red being always -preferred to yellow or green. With these latter colors there is an -interplay of reactions not coöperating. The color-exciting element is -more immediate, tension is brought about, the color asserts itself, is -pleasant, and tends directly to inhibit the feelings for the statue. -The pleasure in the color is called "thin" in comparison, and the power -of sympathetic appreciation of Venus is lessened. There is suggestion -now in the statue still of its strength, but with no "enduring" -quality. It has become commonplace, merely a "pretty woman," jaunty, -self-sufficient, cynical, and with little dignity. The motion element, -now prominent, is not pertinent. The statue looks "cheap," and as a -figure is volatile and unsteady. - -In a similar way one finds these feeling-tones for colors variously -playing their part. The statue of Apollo is not pleasing to some -subjects. They want it "toned down." The red effects this. To some it -is most pleasing by its suggestion of easy grace and springy, elastic -step. The yellow harmonizes and accentuates this chosen feeling. The -blue often destroys its moral meaning. The red hampers the feeling -for the _Laocoön_ group. They become listless, dead, and have still -strength, but no struggle. Yellow increases the amount of activity, -but often lessens the "serious despair." Fierceness is added, but -the liveliness thus furnished is at the expense of the necessary -balancing solemnity. The color again becomes intrusive. "The snakes -fairly dance," and the "flashing action behind" the statue is now too -prominent. - -For the _Dying Gladiator_ or _Dying Alexander_ red is preferred. It, -however, as do all the other colors, often produces an overbalance -in the whole situation. Here it suggests no conflicting feelings. It -adds--often too much--to the hopelessness of the situation, and gives -to them an exaggerated solemnity and resignation, which emphasizes -a melancholy cast, not altogether called for. Green and yellow are -always incongruous. They tend to distract the attention to certain -particular muscles, thereby lessening the whole general effect. The -little "prettiness" they still retain is not called for, and is not "of -the right sort." They do not allow one to be sufficiently contemplative -or thoughtful. They have little depth, and cause inharmonious bodily -commotions, and too much intensify the life-struggle and anguish. - -The general effect of the statues here is much like that of the simple -forms above. Both not only call for something to be done by the -subject, but some action more or less already definitely outlined. -The Einfühlung for little wooden figures, such as cones, columns, -pyramids, etc., was clear and decided. The tipping character or the -straight erectness caused a feeling which seemed describable in terms -of the way in which the bodily position, as one naturally adapted -himself to the object, took place. Statues afford richer experiences, -but the principle is not different. They seem full of suggestions of -abstractions, such as strength, wisdom, grace, beauty, power, and, in -general, what are often called spiritual feelings. These are not so -easily imitated in detail. Subjects have their own ways of adapting -themselves. They want to carry out the suggestion or impulse in their -own way. These impulses are projected into the figure, and all of the -vigor inhibited in one's own body becomes a living part of the figure. -The impulses thus from the colors may or may not be of such a character -as to bring about the same proportionate adjustment as a desirable -intensification equally of all the feeling-elements. Whether desirable -or not, however, these feeling-combinations furnish additional -illustrations of the various mutual relations of coexisting feelings. - -The _Angelus_ or the _Shepherdess Knitting_ bring about feelings in -striking contrast to the feeling for the _Horse Fair_ picture. The -latter arouses suggestions of a tumultuous bodily condition, increased -muscular tonicity, muscles twitching everywhere, breathing heavier, -shoulders strained, and in comparison, great general innervation. -When the characteristic feeling had been aroused, the subjects were -requested to close their eyes and observe if possible to what extent -the feeling already aroused was dependent upon the retained images. -The results were clear. If the feeling is slight, as it is for some -subjects, the feeling tended to vanish and return with the recurring -images. If it is fairly strong, the feeling persists for some time -after visual imagery is lost. If very strong, the feeling is constant -for a still longer period and still less dependent upon the original -peripheral excitation. The feeling is always more constant than -any imagery. Not often for example is the whole picture retained. -Sometimes one prominent part only remains. Often again various kinds -of imagery aid in preserving the feeling. Besides visual, auditory, -the sounds of the horses' hoofs, of the tones of the Angelus bell, are -chiefly prominent in preserving the situation and the condition for -the feeling. Articulatory impulses again, in the tendency to repeat to -one's self such words as are descriptive of the moral meaning of the -pictures, offer sufficient clues to keep the desired feeling aroused. -When the feeling has "struck deep," subjects report motor imagery -pervading the whole system. In such cases the recurring visual imagery -has little effect upon the feeling. On the whole, the feelings for the -more quiet pictures last longer and are more easily retained than is -the case with the more exciting ones, if the original feelings are, as -to mere intensity, approximately equal. - -The character and strength of these feeling-tones determine also to -a large extent the lines of association followed. Here the mutual -influences of feelings are clearly recognized. The character of the -new associated images and situations is colored by the feelings which -were connected with the original stimulations. The pictures, such, for -example, as the _Angelus_ and the _Horse Fair_, were presented to the -subjects in quick succession. These were to be merely starting-points -for association. For all the subjects who were able to report anything -definite, the feeling-tone for one was read into the associations which -were aroused by the other. The second of the two starting-points as -a rule controls the imagery. A few examples will illustrate how both -feeling-tones are retained. The _Angelus_ was presented first in these -cases, and the _Horse Fair_ second. - -For subject K, the parts of the picture of the _Horse Fair_ remained. -The feeling of seriousness and quietness, foreign to it itself, was -projected into it. Solemnity and the feeling of strength and power was -accentuated. The gaiety originally present was very much lessened, and -finally not noticed at all. - -For subject C, a sacred feeling was aroused. Wars of the Bible were -recalled. There was a fusion of the imagery. He saw the church on a -battlefield near a cavalry fight. The feeling of active earnestness and -the sacred moral character was reported as due to the retained feeling -first brought about by the _Angelus_. The influence of the other -starting-point is clear. - -Subject B found the incongruity between the two feelings very strong. -The _Angelus_ was the stronger in influence. The other caused one to -stress the lighter, more trivial character of the former. Meadows, -streams, pools, and enchanted regions typified the fanciful mood thus -brought about. - -It is not a question as to whether such trains of thought would have -occurred if only one starting-point had been used. It is rather that, -in such cases as the above, two distinct feeling-tones were actually -detected as playing their part in the resulting complex experiences. -It is with some effort that both feeling-tones can be thus at first -retained. The resulting undertone or general mood, however brought -about, colors and determines to a certain extent the associations which -follow. The feeling is more deeply seated than the image, and here also -it is retained longer. - -The above recorded account of the behavior of simple feelings fairly -represents the accumulated data at our disposal. How they can be -adjusted to modern theories of the relation of consciousness to -movement may be briefly suggested. Yet the rudimentary state both of -the psychology and of the physiology of feeling makes the present -task a hazardous one. Psychologists are not agreed as to the best way -to conceive of the relation of feelings to sensations. Feeling-tone -is in some ways dependent upon sensations; and at the same time, -in comparison with other sensation attributes, it is relatively -independent. Physiologists are still farther from agreement with regard -to the nervous processes involved. - -But the _deeply organic seat_ of feelings is unquestioned. However the -concept of feeling itself may differ, all are looking for corresponding -bodily processes by means of which to classify these affective states. -Clearly, to say that feeling is of such a nature that one need never -hope to be able to predict it from psycho-physical conditions, is -no more justified than to say that we can never predict exactly the -intensity nor the vividness of any stimulation. Feeling-tone is here -simply on a par with other attributes ascribed to sensation. - -According to Münsterberg's Action Theory the intensity of the sensation -depends upon the strength of the incoming current. Its quality depends -upon the position or location of this current in its particular -neurone. The vividness depends upon the "openness" or "closedness" of -the neurone conditioning the _outgoing current_. And finally to the -feeling-tone shall correspond the local difference of this discharge in -outgoing currents. For instance, the pleasant feelings have, related to -them, central outgoing paths which lead to approach, and thus to the -continuation of the stimulus, and the unpleasant feelings have related -to them in turn central neurones which lead to withdrawal or escape, -and thus to the breaking-up of the stimulus. - -Our empirical data gathered from the experiments above reported demand -not so much a modification as an elaboration of this theory. The -_tridimensionality_ of the feeling-tone itself must be physiologically -described. We must conceive the feeling-tone itself as possessed of its -own vividness, intensity, and quality. - -It seems clear indeed that any explanation of the affective or -feeling-character of experience must be sought somewhere in the -outgoing currents from the motor region. This alone will serve to -account for the inevitable volitional or "intent" aspect which -invariably accompanies feeling, and I think may serve to account also -for the organic or necessarily coördinating or functioning aspect -required by some writers who so stoutly object to "barren atomistic or -structural" psychological explanations. - -The Action Theory might then be specialized in the following way: - -The _intensity_ of the feeling will depend upon the force or amount -of the outgoing currents from the motor cells. This would enable one -to explain that state of mind when a sensation only is experienced -from a stimulus which ordinarily has a characteristic feeling-tone, -but which feeling-tone in the special instance is lacking. Many cases -have been cited above where one feeling seemed to efface another. The -nerve-energy called for in arousing the unpleasant feeling-tone for -the sandpaper inhibited the process of the discharge from the cells -conditioning any response to the ordinarily pleasing red color. Others -again can reënforce or at least not seriously interfere with each -other. All cases already cited where two feeling-tones were detected -as existing simultaneously are examples in point. It is quite clear of -course that the intensity of feeling is not at all commensurate with -the intensity of sensation. Commotion is not the only condition for -emotion. Yet where there is no tendency to _do_ anything, as is so -noticeable in the reported introspections above, there is no feeling. -A mere shock, even though intense as a sensation, simply benumbs one. -In thus describing any feeling for a particular stimulation, one -should include, besides the original results of the chosen peripheral -excitation, all the reënforcing factors that accumulate by reason of -the sensory counterparts to this originally called-for movement. When -one is, for example, feeling sandpaper, the feeling for the soft red, -when it exists at all, is less intense. Subjects say, "It ought to be -more pleasant than it is. The trouble is in me, not in the color." -The suggested movement which conditions the intensity is lessened in -amount, or partially inhibited. One could scarcely say, so far as the -sensation is concerned, that it has lost some of its brightness, or -that it is not strong enough to arouse its customary feeling-tone. This -is distinctly reported as not the case. It is of course almost always -recognized as the same shade of color. The recorded examples, showing -that intensity of feeling is itself one dimension of a feeling-tone -in no way necessarily related to the intensity of the sensation, are -numerous. - -The _vividness_ of the feeling-tone is likewise a relatively -independent phenomenon, and it, too, is not commensurate with the -vividness of the sensation as such, and hence demands a different -explanation. It can then be dependent upon the _actual stage in the -process of completing the movements suggested_ by the color or tone -or form in question. All feelings dealt with in this investigation -one can describe by relating them to the actual stage in the process -of completing the _coördinated adjustments_. Without some progress -in such a process no feeling would cross the threshold of awareness. -In Part III above are recorded many illustrations, where _degrees of -vividness_ for feelings are noted by the subjects. When they were -attempting to report the actual time when a feeling became definite -enough to be called such at all, there was much difficulty in knowing -just when to give the signal. Feelings develop much more slowly than -do perceptions. Subjects often give the signal too soon, at once -correcting themselves by saying that it was too vague at that moment. -It grows in definiteness, and has degrees of vividness. A movement -in the first stages of the process, before the feeling-tone has -sufficiently developed, is a state of vague feeling. Again, many states -of so-called indifferent feeling meant, according to the subjects, -not lack of feeling, but rather vagueness, lack of vividness. Three -or more stimulations from different sources resulted in confusion -where no feelings were vivid. When the color again, for example, is -pronounced "dead" so far as feeling is concerned, other feelings and -other movements are too prominent. The sensations are in such cases -unchanged. The intensity and vividness of the feeling-tone for the -color are at a minimum. - -And thirdly the _quality_ of the feeling-tone must be dependent upon, -and must be described in terms of the particular kind of coördinated -movements suggested or actually carried out. Thus the characters of the -feeling-tones for the yellow color above described, for the upright -ovals, for the very high tones, for the _Laocoön_ group, and for the -_Horse Fair_, are in some respects alike. They have the same general -_Gefühlsgrundlage_. The qualities of the feelings for soft deep red, -for tactual plush, for low tones, and for the _Angelus_, and, for most -subjects, for Venus, would represent another class having the same -_Gefühlsgrundlage_. This admits of all the uniqueness specific feelings -may have, and at the same time permits of a general classification -and description. Some subjects, D and F, for example, may have a -feeling whose quality is disgust at some color-form combination. The -accompanying sensations may be localized, as they frequently are, -in the arms, with impulses to "ward off" the displeasing influence. -Subject B often for the same feeling finds sensations of contraction -in the throat most prominent, and subject A a stiffening of the -features and incipient scowl. The most prominent localization depends -upon the habits of the person and the habitual kind of reaction he -has acquired and developed during his lifetime. The localization of -muscular activity may differ, but _the kind of coördination does not, -so far as our introspection shows_. The _regularity_, the _rate_, the -_smooth light ease_, or the _heavy, ponderous, deep-seated character_ -of the suggested responses indicate some of the terms which would serve -as aids in classifying kinds of processes which are physiological -conditions for feelings of definite character. Again, feelings of -pleasant repose, of depression, or of sudden collapse are still changes -also in innervation tonus. These are adaptations for situations just as -are the more positive or aggressive kinds illustrated above. Feelings -where quick collapse occurs differ in _quality_ from feelings of calm -repose. All can be conceived as kinds of adaptations or responses, and -clearly correspond to the characters of feeling-tones rather than to -any other dimension of feelings or sensations. - -Certainly the central preparedness for discharge largely determines the -feelings. The external excitations are merely the clues. The internal -apparatus is set vibrating in a constant manner if no other external or -central stimulus is present to demand other adjustments or to intensify -the same kind. When such synergetic or antagonistic stimuli are also -present the mutual influences of feelings do seem to be, indeed, of -great significance. - -FOOTNOTES: - -[Footnote 84: As Mach long ago pointed out, _pleasant_ is a vague term -and in itself does not serve as a true descriptive term. _Pleasant_ -here applies to both feeling for red and for yellow, but something more -is needed to distinguish these very different feelings.] - -[Footnote 85: "Irritating" as I shall use the word has no hedonic or -algedonic significance.] - - - - -THE ÆSTHETICS OF REPEATED SPACE FORMS - -BY ELEANOR HARRIS ROWLAND - - -Part I - -The object of this paper is to discover some of the sources of our -pleasure in repeated space forms, and the laws which govern this -repetition. The repetition of an object, and its regular recurrence -subject to certain possible variations, is one of the basal principles -of art, and of architecture in particular. - -It is necessary at the outset to define our use of the word -_repetition_ more exactly, for there are obviously different meanings -of the word, which may lead to confusion. - -1. The term repetition may be applied to the existence of any two -objects similar to each other, whether they are near together or widely -sundered. Our pleasure in such a repetition would be merely that of -re-seeing and recognizing the two as counterparts of each other. This -kind of repetition I call _conceptual_, for it requires only that the -memory-picture of the object be held in mind and the two recognized -as similar when met again. This is not the kind of repetition which I -have in mind, and I shall never use the word in this sense during the -discussion. - -2. In any one work of art there may be some feature repeated, some -motif which is taken up and carried out in different ways throughout -the whole, and these features we recognize as having an orderly -relation to one another in the unity. This might be termed repetition -of _content_, and be applied to the recurrence of some type of -decoration over a window or a peculiar arch taken up in various ways -throughout a cathedral. I do not use the word in this sense, but limit -it still further. - -3. By _repetition_ is meant during this discussion the regular -recurrence of an object, and an equally regular recurrence of -intervals. The repeated object must come at uniform intervals, and -this restricts us to the consideration of that repetition alone which -consists of recurrence at regular intervals of some object more or -less beautiful in itself, and the description of the nature of our -æsthetic feeling in experiencing such a series. - -Although this discussion is divided into the two divisions of -_experiments_ and _analysis_ of architectural examples, and the -experiments are described first, the investigation was not carried out -separately in this order. The two went along together, the art-analysis -suggesting experiments, and the experiments in turn throwing light on -the analysis. The two parts of the discussion are kept separate merely -for the convenience of the reader, and in the experimental discussion -all allusions to the art-illustrations are excluded in order to avoid -confusion. In reality the two went hand in hand, but the connection -between the experiments and art-analysis will be reserved for the -latter half of the paper. - -The experiments were begun in the following manner: In a velvet screen -about a foot high was cut a window 460 mm. by 35 mm. in size. Behind -the window was a metre measure and a rod from which hung small strips -of cardboard 10 mm. wide. First two, three, and four strips were -hung behind the window, and the subjects were required to arrange -them at the intervals where they preferred to see them repeated. The -results were uniform in certain particulars and very suggestive. In -their arrangements of two, three and four strips, the subjects were -guided by considerations of symmetry or proportion. They insisted that -although they knew that the strips were repeated, they did not feel the -repetition, but the strips seemed like parts of some larger unity to be -arranged with reference to the unity of the whole. With the addition -of the fifth strip came a difference in their apperception. Instead of -the strips seeming parts of a whole including figure they seemed like -repeated units. - - -FAVORITE ARRANGEMENTS - - 2 _strips_ 3 _strips_ 4 _strips_ 5 _strips_ - - J. 30 mms. 4 mms. { mid. sp. = 25 any symmetrical - { ends = 10 arrangement - better than - equality - - S. 170 12 { mid. sp. = 15 {mid. sp. = 40 - { ends = 12 {ends = 30 - - U. 40 20 30 35 - - R. 30 130 { mid. sp. = 30 - { ends = 10 10 - - L. 23 40 70 70 - - W. 40 10 30 30 - - V. 20 10 { mid. sp. = 100 - { ends = 60 15 - -It will be seen, from the table, that with two exceptions they -preferred five strips equally distant from one another, while with four -strips, four subjects had preferred a symmetrical arrangement. These -gave as their reason that with five strips the latter appeared more -definitely to be repetitions of one another, while the four strips -seemed more like parts of a whole which required symmetry in its -arrangement. Moreover the two subjects who preferred five strips in -symmetrical arrangement instead of at equal distances affirmed that a -distinct feeling of repetition came with five strips that had not been -felt before, only they did not enjoy this feeling of repetition as well -as one of symmetry. After having seen the five strips, some subjects -could feel the repetition with four strips, but none with three. The -question naturally arose, what is this _feeling_ of repetition which -makes one say that four or five repeated objects deserve the name, -while three or less are regarded in a different light? The analogy -between the apperception of this visual repetition and auditory rhythm -seemed so strong as to deserve attention. - -In auditory rhythm it is necessary that there be recurrence of more -than two elements; they must come at a certain rate and within a -certain temporal space to seem connected with each other, and they may -be subjectively grouped in different ways. The apperception of both -kinds of repetition had so many analogies as to suggest that some of -the factors in both experiences were identical. - -To focus the problem I took a definite thesis in regard to it. Our -apperception of repeated space forms is due to the rhythm of our own -motor adjustments which are excited in face of repetition, harmoniously -if they accord with certain rhythmic laws in us, inharmoniously if they -do not. It was then necessary to find what facts would support such a -thesis, to see if in reality such facts could be marshalled, and if the -explanation and support they offered was conclusive enough to make it -needless to look farther. - -It would seem, if our pleasure in repetition depended on temporal -motor responses in us, that if the amount of time normally taken to -traverse a repeated series were shortened, or if the eyes were fixed -and not allowed to move over the field at all, our enjoyment would -cease altogether, or at least be seriously diminished. If we found it -impossible to enjoy the series except when seen for a certain time, -long enough for the eyes to go over it in the rhythm peculiar to each -subject, we should then conclude that our enjoyment did depend, to some -extent, on such temporal rhythm. - -I experimented on this question with nine subjects, and the results -brought out different ways of apperceiving repetition, which divided -the observers into two rather well-marked types. - -The apparatus was of the simplest, consisting of white silk strings -hung on a wire against a black background across one side of the room. -The strings were attached to the wire by little hooks, which enabled -one to change their position easily, while a cloth hid the weights on -the ends of the strings, so that nothing but the vertical white lines -were visible. - -Fifty strings (50 mm. apart) were hung before the subjects, and they -were asked to survey the field and give a signal as soon as the -experience became pleasant. Then having found the average length of -time for each subject to enjoy these simple repetitions, a shorter -period was given when they were to shut their eyes at a given signal, -and see if in that shortened time they were still able to enjoy the -series. Next they fixated the eyes and kept the whole body rigid, to -see if pleasure was still possible when all outward motor response was -checked, so far as possible. - -The results of this experiment were very suggestive. Of nine subjects, -all felt pleasure when allowed to move the eyes over the series at -random; with eyes fixed, five felt their pleasure much altered in -its quality as well as lessened, while with one it was altogether -destroyed. With four, however, although there was considerable -alteration in the quality of the pleasure, its amount was increased -rather than lessened. - - B. (1) Average time necessary to enjoy the series: 4.7 seconds. - (2) Three-second exposure. No pleasure, needs more time during - the movement. - (3) Eyes fixed: 4 secs. = Av. time necessary to enjoy it. Lines - bunch toward centre and fade away at sides, giving a kind of - unity, but he feels constraint. - - R. (1) Av. time: 4.3. Sees them in pairs. - (2) Two-sec. exposure. Very faint pleasure; feels that only a part - is perceived. - (3) Eyes fixed: 4.3. One pair fixated, the others fade away, making - a kind of figure. Pleasure faint and constrained. - - L. (1) Av. time: 2.1. - (2) 1-sec. exposure. Pleasure faint and incomplete. He feels the - pleasure comes from memory of the previous experience. - (3) Eyes fixed: 2.2. Great effort to find any pleasure. It consists - mainly in seeing a few strings, and feeling there are others, - even though they are not distinguished. - - V. (1) Av. time: 2.2. Sees them in pairs. - (2) 1.5-sec. exposure. Enjoys the experience in memory after the - eyes are shut again. - (3) Eyes fixed: 1.9. Still sees them in pairs, but cannot see enough - of them, hence they are less pleasant. - - W. (1) Av. time: 4.3. - (2) 2-sec. exposure. Not enough time to feel any relation between - the strings, most of the pleasure supplied by the memory. - (3) Eyes fixed: 5.3. Pleasure is very faint, and consists in having - the strings appear to converge to a central point, and fade at - the sides. - - J. (1) Av. time: 2.3. Sees them in pairs. - (2) 1.5 exposure. Less pleasant. - (3) Eyes fixed: 2.7. Series seems more like a unity and he enjoys - it more, since no time is spent in exploring the field, but it - is one unified experience. - - U. (1) Av. time: 28. Only enjoys it by ignoring all except those in - the centre--does not want so many. - (3) Eyes fixed: 18 secs. Enjoys it when eye lights on one string, - so that the others can fade away equally at the sides, in one - figure. - - S. (1) Av. time: 5. - (2) 3-sec. exposure. Less pleasant. - (3) Eyes fixed: 8.8. Pleasure consists in converging of lines toward - central point. It appears like one figure and is more intense - than (1). - - H. (1) Av. time: 9. Sees them in pairs. - (2) 1 sec. Just as pleasant as before. - (3) Eyes fixed: 4.6. Pleasure in unity of whole series with centre - of fixation emphasized. Only felt pleasure anyhow when the eyes - had stopped moving, so now it comes all the sooner. - -From these introspections it is obvious that there are two distinct -ways of apperceiving repetition: One in which the rhythmic element -is pronounced, so that when the time necessary for such a rhythm is -shortened, or by fixating the eyes the motor response is hindered, the -pleasure in the repetition is either altered or destroyed altogether. -The other type takes a repeated series in the sense of a unified -presentation and wants it all at once in a symmetrical whole. The -rhythmic factor is present in both, as is shown by the fact that the -quality of the pleasure was changed in every case when the time of -exposure was shortened. But in the latter type of subject the pleasure -felt in the presentation of the whole at once, and the feeling of -symmetry around a middle point, are more intense than a rhythmic -apperception. These two kinds of apperception remain fairly constant -throughout the experiments, and for convenience' sake we shall call -them spatial and temporal types. With the former, the value of the -experience consists especially in having a central fixation-point from -which the repeated elements fade away equally on the sides, making a -symmetrical whole. With the temporal type, the pleasure is felt by -means of the rhythmical passage from one element of the series to the -other. In passing from point to point the rest of the field still -remains in indirect vision, so to the distinctly temporal a distinctly -spatial factor is also present. For this reason the temporal type of -apperception is the richer of the two, and a description of it comes -more nearly to the essence of repetition as such. - -Up to this time, the repeated element had always been a single string. -This was varied and the strings hung in pairs (50 mm. wide, 100 mm. -between pairs). When the strings had hung at equal distances from -each other, six out of the nine subjects had seen them in pairs while -enjoying them, and had found such grouping more or less essential to -enjoyment. In seven cases the pleasure was increased by this grouping. -They expressed their preference in various ways: "Easier to keep track -of where we are going." "Can go quicker over field, for repetitions -are more well-marked." "Single line is too thin to rest on, this gives -broader space for repose." All these introspections instanced the -necessity of the rhythm being marked and made plain, so that there -should be no confusion of point with point. The two who disliked this -grouping were of the spatial type, who found no pleasure in traversing -the field, hence too little content in it, in this arrangement, at -any one time. Grouping of some kind would seem to faciliate the -apperception to a certain class of subjects, while with others the -amount and quality of the content of the field is of more consequence. - -Since accents are such an important factor of auditory rhythm, the -next experiment was to see if the apperception of a series of repeated -elements would be facilitated by accenting every other one. - -[Illustration: Fig. 1] - -Another string was hung in every other pair thus making it more -striking, but here came a difference between the feeling of accent in -auditory and visual rhythms. The subjects declared the pairs in which -a third line was hung were not intensified alone, as when a greater -stress is put on a tone in auditory rhythm, but the pairs were changed -qualitatively. The group of three became the repeated element, while -the pair was only an alternating figure different from the principal -unit. This unanimous testimony brought up a variety of questions. -1. Is any purely _intensive_ accent, without involving qualitative -changes, possible in visual repetition? 2. What factor makes us choose -one object rather than another as the repeated element? 3. What is -the value of the alternating figure in such a series? 4. What is the -value of the empty space between repeated figures, and does it have as -distinct a value as an alternating figure? 5. Are all the recurring -objects and spaces felt as separate repetitions; if so, how many can be -carried on at once? - -These questions were put to the subjects in regard to the series just -described with considerable uniformity of answer. - -(1) No such thing as purely stress accent seemed possible. The word, -signifying greater intensity without change of quality, did not apply. -If one attempted to _intensify_ the repeated object in any way, either -hanging another string, thickening the strings, or any similar device, -it ceased to be the old unit but became a new one, whose repetition -was followed for its own sake, while the weaker one retired into the -background, and was not _felt_ as the element repeated in the series. - -(2) Any regular change of the element which made it more interesting or -caught the attention, fixed it as the chosen unit of the series, whose -repetition was followed. - -(3) Concerning the exact _value_ of the alternating figure in the -series, there was great difficulty in introspection. They all "_knew_ -the alternate figure was just as truly repeated as the principal -one, but could not feel it so." The three-group formed the unit of -the repeated series, and although the pair was clearly part of the -experience and distinctly perceived, for some reason it was not -felt as repeated in the same way as the other. It was merely an -alternate, a filling, which was essential to the other, but which had -no significance in itself as a repeated thing. Two subjects were able -(if they tried) to carry both repetitions along together, _i. e._, not -only feel the three-groups as coming at regular distances from each -other, but the pairs as forming another interlacing series. This kind -of apperception was very fatiguing, however, and they could not enjoy -it. For any pleasure to be derived, the pairs must retire into the -background, and attention be fastened on the three-group. - -(4) If the alternating figure was to be so subordinate, was there any -difference between its significance, and that of an empty space? This -was everywhere answered in the same way. The alternating, or minor -figure, had a very distinct value, and any irregularity in it was even -more irritating than in the principal unit itself. When the space was -empty they thought nothing of it, the equality of the interspacing -was taken for granted; while if they felt an irregularity in it, it -destroyed their pleasure in the whole series. But there was no feeling -for the empty space until its regularity had been violated, while there -was a distinctly pleasant factor in the minor figure, even though -different in quality from the principal element. - -In the foregoing experiment the differences between the spatial and -temporal type of observer were still strongly marked. The former type -invariably grouped the elements (usually with the three-group in the -centre and a pair on each side) and they took their pleasure in the -symmetry of each figure so made, moving from the centre of one to the -centre of the next adjacent. In this method of apperception there -was no empty space between repetitions, for the whole group of three -figures was taken as the repeated unit. The empty or rest-phase was -gotten in moving from the centre of one to the next, in which passage -the limiting pair was ignored. One spatial subject, finding the -proportions of this artificial grouping poor, got no enjoyment at all. - -With the temporal type, the experience was quite different. They moved -across the field with the three-group as their stopping-points. These -principal elements were what they looked for, and their pleasure seemed -to consist in expecting and meeting it. What part the _pair_ played, -they had difficulty in analyzing. Some said that while the three-groups -occupied most of their attention, they gave a lesser degree to the -pair, so that the rhythm of the passage across was marked by heavier -and lighter beats. Another found the figure in the alternate space -only an obstacle, and felt he was hindered in the passage from unit to -unit, the only compensation being, that the "hindrance" came at regular -distances. Others felt that two repetitions were actually being carried -on at once. By this they meant that the two sets of elements were kept -distinct, although objectively combined, but the repetition of the pair -was subordinate in interest to that of the three-groups. - -I tested the same thing (accents or major elements, and the value of -the alternating minor elements) by simply doubling every other string -of the series 50 mm. apart. In every case the effect was found poor. -It was "confusing," "too much work." They all felt adjusted to the -repetition of the double string and then encountered the single one, -which hindered them, and by trying to keep both elements going at once -they were fatigued. Most of them had a distinct feeling that they -wanted to swing from one element to the next, and were baffled by the -alternate. In this arrangement, even members of the spatial type who -had not been able to get any rhythmic feeling before, felt the movement -in the series as if they were going across, although they went (in -two cases) in groups instead of single elements. They all, however, -felt the single string as an obstacle which hindered their enjoyment, -whether the double string or a group was taken as element. This -suggested the question: What makes the difference between the minor -figure being an enrichment to the experience and being a hindrance? -They insisted some rest-period was necessary; some really empty space -between the repeated units, and when in place of rest they had more to -do, it spoilt the pleasure. - -[Illustration: Fig. 2] - -Next, two strings were hung at equal distances between the double -strings, and the latter put 100 mm. instead of 50 mm. apart. This was -liked better in every case, and the reasons given were much alike. -The double string was still the repeated unit, while the two strings -between did not _feel_ repeated. In spite of the obvious inconsistency -of the statement that they did not _feel_ the alternates to be repeated -even when they knew that they were so, just as much as the double -string, several subjects made the same remark. V. felt the series as -a rhythm, where the double strings were all he was interested in, -although he knew he should notice if the others were changed. B. could -not detect that they were of any importance, except as he imagined them -absent. B. could feel either the double strings or the two strings -between them as the major unit, only, whichever one he took, the -other retired into obscurity. He felt the minor units in a different -way as being repeated together with the majors, but very weakly, and -not at all unless he previously considered that he ought to do so. -L. said his attention was fastened on the double strings, but it was -the "effort or ease with which he passed over the alternates which -formed the pleasure." Another temporal subject felt the rhythm as the -others did, with more emphasis on the double strings. But the major -units seemed the _rest-phase_ in his rhythm, _i. e._, he paused here -in observation of the series, although his attention was most active; -_vice versa_, the minor units required little attention, but were the -active or moving parts of the rhythm. Since they all considered the -strings in the alternate space merely as steps or lesser beats on the -way to the major element which they sought, and as obstacles rather -than otherwise, why did they prefer the space with two strings rather -than one? This suggested that some factor in the alternate spaces was -important other than simply the amount of resistance to overcome in -getting past the two lines. In answer to this they could only say that -the two strings in the alternate space formed a pleasanter unity by -itself, although, as they went across, they did not think of it in -terms of unity. - -What, then, is the real rest-phase of the rhythm of alternating -repeated objects? - -In the beginning of the discussion, when the analogy between visual and -auditory rhythm was felt so strongly in a certain type of subject, they -had expressed themselves as if the object which they called the unit of -the repeated series were the active stimulated part of the experience, -while the alternate space was the rest-phase, valuable only as a period -of repose or blankness before the object was again encountered. But -in this case, although they felt they were putting no attention or -emphasis on this space, in reality they were keenly alive to what was -hung in it, even preferring more "hindrance" in the way of strings -than less, which suggested that the alternate space was of more value -than they were conscious of. (Some of this increase in pleasure was of -course due to the increased actual distance between the double strings, -but some also to the extra string.) The introspection on this question -as to which part of the rhythm was actually the rest-phase (if there -were any such) was difficult for them all. They felt they spent more -_time_ on the major element; that was what they looked for and found -pleasure in meeting again. - -One said, "The unit is what I look for; as soon as I have it the -pleasure ends and I want to move on again. The pleasure does not -consist in resting on it after it is found, but in knowing I am going -to meet it again, and in doing so." As to the alternate spaces, he -could only say he was not consciously interested in them, he took -them for granted, but knew he should feel it, if they were changed. -His feeling for them was wholly negative. The other temporal subjects -agreed essentially with this. The alternate figures had to be passed, -but passing them was only of importance as it helped or hindered the -perceiving of the major elements. All agreed that any change was -noticed and felt irritating at once, although they could not understand -how it should, since so little attention was paid them normally. -One subject felt the alternating strings only as obstacles between -the doubles, and demanded an actual, empty rest-period between any -repeated units. When asked if it were really the rest-period _between_ -elements or _on_ them, he said he felt there was a complete discharge -of attention on the major units, and an attempted one on the minor or -alternate units, and the attempted ones became confused. - -These introspections would point to the fact that alternate minor -spaces while affording rest for the attention were periods of activity -of some other kind. The fact that no one could say _what_ kind, and yet -insisted on the feeling of its being important and distinctive, and -moreover repudiated the idea of change in a minor space even more than -in a major--this seemed to show that there was a value in the alternate -spaces quite aside from attention, but fully as distinct in its own way. - -As might be expected, those of my subjects to whom rhythm was not a -conscious factor of the experience of repetition could not understand -exactly what was meant by the distinction between _rest-phase_ and -_emphasis_ of rhythm. In all the preceding cases where the temporal -type gave the introspection I have described, the spatial subjects -grouped the single lines, in Fig. 2, about the heavier pair as centre, -and moved from the centre of one such group to the next. The experience -then consisted of a succession of adjacent symmetrical groups, -connected by movement from centre to centre. When asked if there was no -pleasure in finding equal distances between their centres, _i. e._, any -temporal element whatever, they all denied feeling any. They could not -detect that they _felt_ the distances between their centres as equal, -although they _knew_ them to be. They spent so much attention on the -group that all feeling of the distance between its centre and the last -was lost before going on to the next. - -These two marked types of apperception of an alternating series seem -varieties of _emphasis_, rather than of actual experience. It was -evident that those in the spatial type must have some recollection of -the amount of distance passed over between the various groups to feel -the whole series as connected in any way; while those of the temporal -type could not be wholly absorbed with the separate lines of the series -as they traversed it, but were distinctly conscious of the space -relations of those in the side of the field that they had just passed -or were coming to. - -[Illustration: Fig. 3] - -Next, I tried to see what were the different factors which made up the -value of the minor spaces. By varying both their size and filling, and -doing the same to the major element, I could judge the relative value -of these changes on the two, and their effect on the whole series. - -The test was made in the following manner. The series as it stood -consisted of a double line alternating with a single one. - -With every temporal subject the double line was conceived to be the -repeated thing, and the space between considered as an alternate, -with a repeated line of its own, to be sure, but not felt in the -same way as the other. With the spatial type, the single line was -merely the limiting edge of the symmetrical figure, with a double -line in the centre. One subject varied back and forth in his method -of apperception, and considered the richness and variety of these -different apperceptions as one of the chief sources of the pleasure -therein. - -_Variation of alternating spaces:_ The minor spaces were varied by -hanging two strings in one, and one in the other, and subject asked how -such a change affected his feeling for them. The change was marked. - -The spaces which had before been minor were so no longer. The alternate -space in which two strings were hung with the boundary-line of the two -double strings became the new element, and the alternate in which only -_one_ string was hung continued to be the alternate in the new series. -The whole series shifted itself, and settled into a new equilibrium. -Some of the subjects were able to feel all the former minor spaces -still as such, but only by a definite effort, and not while taking any -pleasure in it. The change in the alternates spoilt the whole scheme of -the repetition as it already stood, and made a regrouping necessary. I -next tried varying alternates by removing a string at intervals. - -[Illustration: Fig. 4] - -[Illustration: Fig. 5] - -Since the strings were not removed in any regular fashion, and because -the subject could not find any possible consecutive way to group them -with the double strings, this variation was partially overlooked, -and although confusing the series somewhat, repetition of the double -strings could still be felt. Thus a mere _gap_ where the scheme -remained the same was not so disturbing as an extra feature inserted, -or one noticeably changed. Something could be supplied by the subject, -but not altered so easily. In these cases, however, the change was only -tolerated because it was ignored. They felt it as a mistake and so -overlooked it, but, accepted as a component part of the series, it was -impossible to feel it as a repetition or get pleasure from it. - -[Illustration: Fig. 6] - -The next variation was in the position of alternate figures. With -a three-group as the major element of the repetition and a pair of -strings in the alternate space, the size of the two minor spaces -was altered, thus making the distance between the three-group and -adjacent pair shorter than between that and the next three-group. This -immediately threw out the feeling for the old series and made a new -one. The new series thus formed varied with the different subjects, -although no particular difference was noticed between spatial and -temporal types. They all disliked the new arrangement, in whichever -of a variety of ways it was apperceived. (It will be noted the actual -distance between the three-groups was not varied, but the size of the -spaces each side of the minor figure, _i. e._, the minor figure was -shifted from its central position.) One typical spatial subject took -it in either of three ways: (1) He grouped the three-group and pair -nearest together, into the repeated element of the new series; (2) -he ignored the pair and regarded it as a repetition of three-groups; -or (3) ignored the difference in the division of the alternates, and -regarded them as alike. The artificiality of the latter methods of -taking the series is evident. What pleasure survived after such a -strain was very slight, and was moreover not of the series as given, -but as imagined differently, which was not a valid judgment. Most of -the subjects grouped both figures into one, and, finding the unity thus -made ugly and unsymmetrical, derived no pleasure from it. One tried to -keep both elements in separate series and have them go along together, -equally distant from those of their own kind, although not from each -other. This was, however, very fatiguing and unsatisfactory. Those -who grouped the different figures said they did so because they could -not help it, not because they liked it, and said it was impossible -to regard the alternate figure as such, if varied from its central -position. If they were all varied together, they were grouped, with -the major unit, into a new one. If varied irregularly the series was -spoiled--no rhythm whatever remained. It became a heap. - -Next, I tried varying the size of the alternate spaces, keeping the -filling in its central position. - -[Illustration: Fig. 7] - -Here also it was universally regrouped. They found it more difficult -to feel the rhythm of the three-groups as separate elements than when -the minor spaces had remained uniform in size, but different in the -position of the filling. The alternate space, then, which had at first -seemed the unimportant part of the rhythm and for which no subject -could assign any conscious value whatever, was evidently a potent -factor of the experience, and when varied either in size or filling -(especially the former) it not only changed the feeling-tone, but -shifted the entire scheme of the rhythm, or broke it up altogether. - -_Variation of major units:_ Was variation more allowable in the major -than in the minor unit of a series? This was tested first in the same -manner as for accents. In a series of which a double string was the -major element, a third string was hung with every such double, thus -changing the unit in both size and content. - -[Illustration: Fig. 8] - -The series immediately readjusted itself with the three-group as -element for most of the subjects, although one was still able to feel -them all as one unit, varied by the added string. Varying only the -_size_ of the major unit gave the same result. - -[Illustration: Fig. 9] - -The pairs, instead of remaining the same size, were made alternately -larger and smaller, and a new repetition was made, _i. e._, with the -larger pair as major element and the smaller one as minor. They all -agreed, however, that less change was made in these cases than when the -_minor_ spaces had been changed in size. In the latter case either a -regrouping was made, changing the whole character of the series, or it -was spoiled altogether. With change of _major_ units alone, however, -although a new element was made, it was still possible to take it in -the old way without much difficulty or change in feeling-tone. - -It was then necessary to see how change of content would affect the -major unit, the size remaining constant. A group of two sets of double -strings 10 ccm. apart was taken as the repeated element, and these -groups placed at 10 ccm. from each other. - -[Illustration: Fig. 10] - -Within one element was hung one string, and within the next two, thus -varying the content while the size remained constant. In every case the -answer was the same. It was not so pleasant as when the filling was the -same, but the group still remained the unit of the repetition, and the -series essentially the same. - -Several variations were made in this element. Instead of hanging -strings regularly (1 in one, and 2 in the next) they were hung -irregularly, _i. e._, an extra one here and there at intervals in no -special order. As long as the boundary-lines of each group remained -at the same distance from each other, and from the next group, thus -keeping the unit at uniform size, although the pleasure-tone varied, -the balance of the series was not changed. No regrouping or shifting of -the equilibrium resulted. - -It would seem from the preceding experiments that in any series -variation of the _major unit_ was tolerated more than of the -_alternate;_ while in _either case_ variation in _content_ had less -influence than variation in _size_. - -_Symmetry:_ In the previous experiment, three subjects had insisted on -symmetry as a necessary attribute both of the unit and its alternate. -U. (spatial type) described his experience as "a succession of -symmetrical experiences or states of equilibrium; when they are not so, -they must be regrouped, or pleasure is impossible." R. (temporal type) -insisted especially on the necessity of the alternate figure being -symmetrical as regards the major units, _i. e._, halfway between them; -and also on symmetry as regards itself. One temporal subject said -there was some pleasure in merely going from one unit to the next, even -though no repose was possible on each because of its asymmetry. This -suggested experiments on the importance of symmetry in repeated series. -Is it necessary that the separate elements of a series be symmetrical? -Must both major and minor element be symmetrical? Does this necessity -vary according to the temporal or spatial type of the subject, _i. e._, -is it more necessary to the spatial type, whose pleasure depends more -on repose in the unit, than to the temporal type, whose enjoyment rests -mainly in the rhythm of movement from one unit to the next? Or is it a -common demand? This experiment was begun in the following simple way. -The strings were hung in two group-forms; one with three and the other -with four. - -[Illustration: Fig. 11] - -This was a symmetrical grouping and uniformly pleasant. The series was -then changed by removing the second string in the four-group, thereby -making it unsymmetrical. - -[Illustration: Fig. 12] - -This change made the repetition less pleasant in every case, but did -not spoil it. Instead of the four-groups becoming more prominent they -seemed less so, and the three-group on account of its "compactness" -became in most cases the major element, thereby shifting the balance -of the repetition, but not detracting very much from the pleasure. -Next the three-group was changed by moving the middle string to the -left. By this means the group which had been minor in Fig. 11, became -unsymmetrical, while the four-group was regular. - -[Illustration: Fig. 13] - -This change was preferred to that in Fig. 12, although different -reasons were given. One said it was because this change in arrangement -made the elements more distinct, hence easier to keep apart, while in -Fig. 12 they were made more alike. Moreover, one element seemed as -important as the other. He did not class them as major or minor, so -he could not compare the relative values of symmetry in principal and -alternate units, for in this series he did not feel the distinction. -The other answers to this question were rather incoherent, but the -series did not seem to suffer much change, either pleasantly or -otherwise. Since lack of symmetry in _the element_ was at least -tolerated in the examples already given, would it be allowable so -to place the units that the two adjacent to any one unit should -lie unsymmetrically on either side, that is, may the elements lie -unsymmetrically with regard to one another? Suppose a four-group to be -repeated at regular intervals, and a three-group likewise; if the two -series were combined, must they occur halfway between each other? That -is, must they be symmetrically placed as regards the intervening space, -or could they be put to one side? - -[Illustration: Fig. 14] - -The subject was asked not to group them (as in previous similar -arrangements), but to keep them as separate repetitions if possible, -and to see if this equal distance was necessary to keep them apart. -The result was the same in all cases. The subjects could not help -grouping them, and found it impossible to keep them distinct unless -so much effort was put into it that no pleasure was left. They said -they "_knew_ each unit was as equally distant from the next unit in -its _own_ series, as if it did not come at unequal distances from the -units in the other, but they could not feel it so, and were obliged -to group the two together." For this reason the experiments did not -satisfactorily illustrate the point in question. It was necessary -to have a series of elements whose unity was more strongly marked, -and whose different parts would still remain one _whole_ even after -variations, instead of shifting into each other. It was suggested -by these imperfect experiments that symmetry was _not_ so important -a factor in the different units of a series as the subjects had -previously supposed; but that, on the other hand, the different units -must be placed at equal distances from each other, if they are to be -kept distinct either as two series or as one. Moreover, that _two_ -series could not be kept distinctly in mind as separate, _anyway_, -without fatigue, the tendency being always to group them into one -series with a new repeated element, composed of a combination of the -other two. It was necessary, however, to test this more completely. By -a simple device the former series was changed radically, so that the -difficulties mentioned were overcome. The strings of both the three -and four groups were twisted together at the bottom, thus binding them -closely into separate unities. By remaining attached at the bottom, -whatever variations might occur elsewhere in the figures, they could -not lose their individuality and become merged in each other as before. -They remained distinct groups without effort on the part of the subject. - -[Illustration: Fig. 15] - -With this I began as in the previous experiment. The subject was asked -to look at the series of repetitions, enjoy them as much as possible, -telling what was the pleasant factor in the experience, and how he -apperceived the series. The subjects separated into types as before; -the spatial type immediately grouping the elements into a larger -unity and enjoying the groups more for their own sake than for their -repetition, while the temporal type went from one to the next in the -series, enjoying the _rhythm_ more than the elements as such. (It may -be remarked here that the subjects were perfectly naïve as to their -apperception. They did not know they were separated into types, nor -were they urged to be consistent. Even the experimenter did not know -of the distinctness with which these types separated themselves, and -consistently held to their own method of apperception, until looking -over the records afterwards.) - -With the temporal type the four-group was the major group. Some -expressed its prominence in terms of _time_, _i. e._, they spent more -time on it, and less on the three-group. One felt it as emphasized, -because he moved from one four-group to the next like it, and at each -step moved back and forth from left to right, to see the alternate -three-groups on each side, always _resting_ on the four-groups. - -It is noticeable with these subjects, in whom the rhythmic element -was more strongly developed, that although they admitted that the -language of "temporal rhythm" did not adequately cover their experience -(because the element did not disappear after perception as in auditory -rhythm, but remained in the visual field), still they could not express -themselves in other terms. L., the most extreme of this type, insisted -that the experience of repetition would be exactly as pleasant if he -saw the elements pass one by one behind a moving window, with never -more than one in the field at once. In other words, their temporal -relations were all he felt. - -The others did not go so far as this, and agreed to the significance of -the whole field, even while especially interested in passing from one -to the next. B. partook of the characteristics of both types, and by -combining the apperceptions of both bridged the chasm between them. - -With the four spatial subjects, the apperception showed its usual -divergence. Three grouped the elements, either with the three-group -in the centre on account of its being more compact and graceful, or -the four-group because it was heavier. One of them could group it -either way, distinguishing between the prominence in an element due -to _interest_ and due to _beauty_, _i. e._, he found the four-group -more noticeable and interesting on account of its size, while the -three-group was more beautiful as a unity, on account of its proportion -and grace. Therefore according as one factor or the other predominated, -one or the other figure was taken as the more prominent element, and -placed in the centre of the group. Sometimes they separated into two -series running along together, but this was not usual. - -Having got these varied introspections, with yet a certain likeness -running through them, the balance of the four-group and of the -three-group were varied in turns, to see how the change in symmetry of -elements would affect the series; and the relative value of symmetry -for the major and minor units of a series. - -First, the four-group was altered, by moving the second string further -to the left, while the three-group remained symmetrical. - -[Illustration: Fig. 16] - -In three cases this arrangement was preferred to the regular one -previous, and each time for the same reason. The four-group was -made more noticeable by being unsymmetrical, and hence more easily -distinguished from the other. The two were easier kept apart, and the -alternation between the two was made more clear-cut and obvious. With -others the change was unpleasant for the reason that it affected them -in an exactly opposite manner. The four-group _lost_ its individuality, -and, by separation into two unsymmetrical parts, could not be -distinguished so well from the three-groups as formerly, hence the -effect was spoiled. - -A distinction was made between the relative _importance_ and _interest_ -attached to the units, when symmetrical and when unsymmetrical. -Every one agreed that making the four-group unsymmetrical gave it -more prominence of a certain kind. With the first three subjects -mentioned, this prominence was enough to accent the rhythm still more -than before, and differentiate the two units more strongly. But with -the other there was a feeling that while it gained prominence and was -more _noticeable_, it lost coherence and interest, thence it could not -be kept as the principal unit, but the attention passed over to the -three-group which maintained its unity. - -It would seem, then, that the mere fact of one unit in a series -alternating with another, and being more noticeable, taking up a larger -space, being more complicated, etc., did not insure its being the chief -unit in the series. One subject voiced essentially the feeling of all, -in his comment on the series: "There is a constant struggle between -the prominence which the four-group gains from size and eccentricity, -and the insignificance which it deserves on account of its looseness -and lack of unity; it cannot hold its own as one individual thing, -and because the three-group still does, it becomes in one way more -prominent, while the four-group remains so in another." Another subject -felt he gave more _time_ to the four-group than before, because being -separated it would not bind together again without effort. At the same -time the three-group gained in interest because it was easy to find -and did not vary. Another subject felt that the _time_ spent on a unit -had nothing to do with its rhythm; it was all a matter of interest and -attention. Often he looked a longer time at one unit, choosing another -for the chief element in his series, because it interested him more. - -All this introspection brought out two things clearly: - -(1) The apperception of a series of alternating units, whether of the -spatial or temporal type, is not fixed, but any variation of its unit -is liable to shift the emphasis. Thus, as in the present case, when a -symmetrical major unit is made unsymmetrical, it may not remain the -principal unit, but becomes the minor one, because the attention shifts -to the other which was before relatively unimportant. - -(2) Whether either element shall be the principal one or not, does not -depend wholly on its objective prominence, but on the amount of beauty -or interest which it holds for the observer. Neither size, complexity, -nor eccentricity can force a certain unit to be taken as the major in a -series, unless it thereby presents an interest which makes the observer -choose it. - -The next change was to vary the three-group in a similar way, by -pushing the middle string to the left, thereby making it unsymmetrical. - -[Illustration: Fig. 17] - -The responses were as follows: Five said it did more violence to the -series to have the alternate varied than the major unit; it was more -confusing. Three preferred it, giving as their reason that it made -the elements more different from each other than before, hence more -easily distinguished. The preponderance of evidence was, therefore, -that, although any variation from symmetry in a unit was likely to -be detrimental to the repetition, it was more likely to be tolerable -in the major unit than in the alternate space. In either case it was -demanded that the two units be distinctly different, and it depended -on the individual subject, whether in this experiment the variation -of one unit or the other brought out this distinction more obviously. -Aside from this consideration, however, it appeared that the alternate -spaces as such required equilibrium more than the principal unit. -Also, variation of symmetry in the major unit, while it made it more -prominent in the way of _eccentricity_, also made the symmetrical minor -unit more prominent in the way of _interest_. As one subject expressed -it, "Since the others vary, the attention requires something which does -_not_ vary, and forces prominence on the minor unit, because it remains -symmetrical"; and "The minor unit is too small to merit such prominence -as it gets by lack of symmetry. It is distorted, and has not enough -content to bear it." - -These introspections from temporal and spatial subject alike, all point -to the fact of a certain _value_ attached to the alternating units in -a series. (1) The units must not be too much alike in _interest_, or -they rival each other. (2) They must not have more prominence given -them as regards the whole than they have interest to sustain. (3) There -must be a congruity between the two elements so that one shall not be -noticeable in one way, and one in another, thus carrying the attention -in two different directions. - -One more thing was suggested by this experiment: (4) The subjects who -had invariably _grouped_ their different elements in other series found -it very difficult to do so in this, or wholly impossible. None of them -did so when taking the series naturally, but moved on from one to the -next just as the rhythmic type did. They felt "forced to move on," "no -place to rest," while one in whom the rhythmic feeling was weakest was -much fatigued by this movement, and insisted on having something stable -to rest upon if he was to gain any pleasure at all. - -Next the series was varied by making both units unsymmetrical; first -with the balance tipping the same, and second in opposite ways. - -Those who preferred this gave essentially the same reason. They agreed -that the unity of both elements was broken up by this change, and they -did not stand out distinctly from each other; but all felt a certain -_congruity_ in having both major and minor units follow the same scheme -in composition. They were not distinctly an alternating series, but -harmonized better as lines. The two spatial subjects, who disliked this -arrangement more than the other, gave the same reason: the unity of the -elements was spoiled, they did not "hang together." Their dislike was -similar in kind to that of the others, only the congruity which made -up for it with the former failed to satisfy these. With the symmetry -broken and the balance tipping in different ways, the feeling was not -strong in either direction. They still criticised it in the same terms -of congruity and distinctness, with no especial change on account of -this modification. - -[Illustration: Fig. 18 A] - -[Illustration: Fig. 18 B] - -These experiments all pointed to the fact that (1) a certain amount -of congruity and equality was necessary between elements of a series -(although it did not establish what were the essential features of such -a harmony). (2) It is more pleasant, as a rule, to have the elements -symmetrical, although symmetry was not a necessity for an agreeable -series. (3) Provided the change in the symmetry of the units was not -enough to shift the whole order of the series, changing the major to -minor units (and _vice versa_), any varying of the symmetry of a minor -unit was more disturbing to the repetition than of the major, while -varying their symmetrical position, as regards the unit on either side, -was absolutely destructive to the order. - -The next experiment dealt with a different side of the question. Since -the unit of a repeated series may be a group with repetitions inside -itself, does the repetition of lines or figures _inside_ the group -differ from the repetition of the groups as a whole? If so, how? That -is, in the enjoyment of a series of groups with repeated lines in the -group, in what respect does our apperception of the repetition differ -in the two cases? Or does it in reality differ at all? - -To test this, the strings were arranged in the following way. 10 groups -of five strings were hung 100 mm. wide and 100 mm. apart. Each unit -had, then, five repetitions within it. - -[Illustration: Fig. 19] - -The arrangement was pleasant to all the subjects, and they described -the effect of the experience, falling at once into the spatial and -temporal types as before (this was wholly naïve, for the same questions -were asked of each, and they had no idea of being grouped in types). -The introspection of both types must be taken in some detail, to fully -analyze the experience. - -_Spatial:_ J. felt he took in all groups at once. Each unit seemed like -a rich experience in itself, but he could not detect any rhythm in it, -nor in the whole series. The pleasure consisted in getting a number of -similar objects in the field at once, and enjoying the combination of -them all, feeling that they stretched away in each direction. H. and U. -grouped several unit-groups into a larger unity and enjoyed the cluster -as a whole. They did not group them in any particular system, nor could -they detect the slightest pleasure in moving from one such group to the -next. One found his enjoyment solely in the contrast effects in each, -while the other laid it to the space relations of each independently. -The pleasure only came when each group of groups was spread before -him. Those outside the immediate field meant nothing to him, and the -movement between them had absolutely no conscious interest for him. -S. said that enjoyment stopped altogether during motion of any kind, -and the experience was pleasant only during total repose, on whatever -happened to be in his field at once. - -With the temporal type came a marked difference in apperception. - -B. affirmed the pleasure to _consist_ in going from one cluster to -another, and to _begin_ just at the point where he meets the next -stimulation and feels it is _going to be_ the same as the one previous. -It is the _expectation_, rather than the _verification_ recurring at -intervals, which makes up the pleasure; not the actual movement, or -subsequent contemplation of a group. The pleasure came in pulses; in -knowing by seeing from the side of the eyes that the experience _is to -be_ repeated, and on reaching the edge of a new group, in the feeling -that the experience is just about to begin. - -R. felt that she "wriggled around" in each group of lines, and that a -certain _feeling_ came from "wriggling" among the lines in a particular -fashion. - -The pleasure consisted in having this feeling recur at regular -intervals. The repetitions inside the group and of the group as a whole -differed in this respect: For the separate unit-group, it apparently -consisted in repeated short irregular movements, back and forth, enough -to bring about a certain feeling which seemed pleasant and sufficient -unto itself. Repetition of the groups as a whole meant movement across -the field in one direction, for the purpose of meeting another group, -and getting the required feeling from it again. The pleasure was not in -the movement or in any repose (she could detect no repose at all), but -in experiencing the group again, feeling that it had been so before, -and would be again. - -L. (the most extreme of the temporal type) agreed with R. that the -lines inside the group were perceived and enjoyed _temporally_, as well -as the groups as a whole. There was no experiencing the groups _at -once_. He felt that he moved regularly across the field encountering -five lines, one after the other, then an empty space, then five lines -more. The only meaning which the group as such had for him was the -five accents which came near one another in time. He could feel no -unity whatever apart from this. He was even certain that his pleasure -would be identical if in some mechanical way the same figure could be -pushed forward, so that the same amount of time and movement would be -necessary to reach it that was required to move from one figure to -the next on the field. The experience was in every way analogous to -auditory rhythm with him, and he was unable to express himself in other -than temporal terms. Immediate perception, repose on the object, or -groupings, had no significance for him. - -The other two subjects were links between the extremes already -described. They could feel each group, and sometimes even the whole -series _at once_ apparently, and yet were all the time conscious of -a certain rhythm in going from one to the next. The whole experience -seemed immediate at first, but on reflection a certain alternate -rhythm was felt to be present, which was too rapid to take any -considerable time, but yet had to be included as a factor in the -experience. These introspections I believe to throw light on the nature -of the whole experience of repetition. Since there are two methods -of apperception so extreme, but moreover certain subjects partake of -the characteristics of both, it might seem that both types represent -but _one_ side of the experience. Since both are enjoying the same -objective series, but in their description of their feeling in face of -it emphasize such different sides (leaving at the same time the other -side unaccounted for), and since certain subjects share the experience -of both, it might be that the sum of both methods of apperception was -necessary to the fullest appreciation of the repetition in question, -only in certain subjects one aspect of it was so much stronger that the -other possible factors in the experience were overlooked. - -It would tend to bear out this view, that when it was suggested to -those of the temporal type (always excepting L.) that according to -their description the other groups remaining in the field, after -having performed their part in a temporal series, _ought_ to have no -further influence in the repetition, whereas they did in reality, they -admitted the fact, but could not account for it. Moreover, those of -the spatial type admitted that their enjoyment in having spaces equal, -and in having repeated objects exactly like one another, had a certain -character which no other experience possessed. This did not seem -accounted for by any description they could give of its effect on them, -although they could not detect what this other elusive factor might be. - -These introspections, therefore, and the confessions on the part of -both that there was a feeling of something _more_ which they could -not hold long enough to describe, suggested that both types were but -opposite ends of a series of possible apperceptive types, and that in -both cases certain essential features were emphasized at the expense of -the others. - -After these experiments, the next step was to find how a series of -groups was apperceived when the lines in each group were arranged -symmetrically about a centre, as distinguished from their arrangement -at invariable distances apart. The same number and size of groups were -taken, but the arrangement of lines in each varied as stated above. - -[Illustration: Fig. 20] - -_Spatial subjects:_ J. felt a different kind of pleasure from that -felt with Fig. 19. Here the enjoyment was in each unit for itself, a -certain repose in its symmetry. Although he fixated on the centre of -the groups, and in going across the field moved from centre to centre, -there was no feeling of rhythm whatever, merely enjoyment of the unit -itself. Moreover, although he had _detected_ no rhythm in the previous -experience, this one seemed distinctly different in having lost a -feature that the other had. He felt by comparison that the other had -had a temporal character, some movement in the groups, which was wholly -lacking in this. This was more beautiful and restful, the other more -exciting and rich. - -H. and S. both enjoyed this series better on account of possibility -of greater repose in the unit-groups. The pleasure was solely in each -unit for itself, not in their repetition, so the group which offered -most balance and equilibrium in itself was pleasantest. S. also found -enjoyment in slight variations in the groups (trifling difference in -distance, different light effect, etc.). It is noticeable that when -repetition alone was the main feature of the series, any variation was -either ignored or found unpleasant. But when the unit for itself is the -object of enjoyment, variation if slight is another element of pleasure. - -There is also pleasure in the mere _repeating_ of symmetrical groups, -although, when the attention is turned to this feature, the feeling of -_symmetry_ is less felt. Even when attending chiefly to the repetition -of the groups, the symmetry of each is felt somewhat, which makes the -whole experience better than Fig. 19, but the two attitudes seem to -hinder, rather than help each other. - -This introspection was suggestive, giving rise to two more questions: -(1) When is variation allowable, and when not? Is it adapted only to -objects when taken, as ends-in-themselves, and not when considered as -means to something else, _i. e._, as means to make a series or border, -or anything which takes attention from themselves as unities with -individual meaning? (2) Is a distinctly symmetrical group as adapted -to repetition, as such, as one with merely equal divisions? Does it -not tend more to repose in itself, instead of to the motion necessary -for the apperception of a repeated series? These questions will be -considered later. - -_Temporal type:_ R. felt a difference in the movement across, in that -in Fig. 20 it was from the centre of one unit to the next, while in -Fig. 19 there was no regularity in the movement. - -L. felt the difference between the two apperceptions very strongly. In -Fig. 20 the movements seemed organized. He felt as if his attention -(if not his eyes) went back and forth from edge to edge of the unit, -finally settling in the centre; while in Fig. 19 the very essence -of the apperception was that every line was compared with every -other, meaning a great number of movements in both directions, _not_ -stopping in the centre. If he did rest finally in the centre, in the -unit of Fig. 19, instead of seeming evenly repeated, it too became -symmetrically perceived, but the usual way to get from one such unit to -the next was to move _from_ and _to_ any point in the next adjacent, -other than the central one. In either case the pleasure came in -identification of the second figure with the first, and the feeling, "I -have seen it before." The pleasure lay in the process of recurrence of -sameness. - -V. also, who had not felt much motion in Fig. 19 at first, felt it -strongly now in comparison with Fig. 20. He said in the former, -although he did not make actual movements across (in fact his eyes -were plainly at rest), he was sure he felt "dispositions to do so" -which were lacking in Fig. 20. The pleasure came in the first moment of -repose after finding the new unit was the same as the old. - -After we had investigated the different methods of apperceiving groups -of repeated lines, and compared the effects of different groupings, -and studied the feeling of one unit alternating with another, another -question arose. - -These questions had all referred to the alternation of _two_ units; -either a unit with an empty space, or with a space of different -filling. How did the apperception differ when _three_ repeated units -alternated with each other? To test this, three spaces were taken -equally wide (110 mm.) and equally distant from each other (150 mm.), -but with three different designs within them. These designs were of -the same general character and importance although different, and -repeated themselves regularly. - -[Illustration: Fig. 21] - -The subjects were asked as before to describe their reaction on the -series. Not one of all the number was able to _feel_ the repetition -of the three units; what pleasure they got from the series (if indeed -they got any) was from other sources. The general type of answer was -formulated more fully by L. He saw 1, then looked for 2 and found it -different, but could have included it in the series if it were not for -3. That being still different sent 1 and 2 out of mind, so that he -could not _feel_ any repetition of 1 when he met it again. He felt a -certain sense of repetition in that the spacing and general motifs were -the same, but there was no pleasure in that. What pleasure he got was -wholly intellectual, not immediate, except for a slight pleasure in -their uniformity of position. In him the rhythmic feeling had always -been of the strongest, but he found in this experience none whatever. -It was simply impossible to keep the three units going at once. Another -temporal subject tried to group 2 and 3 as one element, with one as -an alternate, thus reducing it to a rhythm of twos. This process was -labored, but otherwise no enjoyment was possible. The spatial subjects -derived what pleasure they could, either from the units separately, -with no regard to their repetition, or from some method of grouping, by -which their difference could be overlooked. One expressed his pleasure -solely in terms of contrast of the white strings against a black -ground. Any immediate feeling for the repetition was impossible for -either type. It will be noticed that the _feeling_ of the repetition is -quite different from the _knowing_ it is there. They were all perfectly -conscious that 1 was repeated again after 3, but could not _feel_ it, -while repeated simply after 2, they _could_ feel it. - -Next, the series was varied again. The size of the blocks, instead of -being alike, was varied three ways, while the designs remained similar. - -[Illustration: Fig. 22] - -The interspaces were 150 mm. in every case, but 1 was 150 mm. wide; 2 = -110 mm.; 3 = 70 mm. All the spatial subjects found Fig. 22 worse than -Fig. 21. The irregularity and general disorder was more pronounced. -Although the rhythm had never consciously given them pleasure, and, -when not violated, was never noticed, still the threefold difference -in size violates some feeling which they can only express in rhythmic -terms. Some tried to group the three units into a larger group, but -this being unsymmetrical displeased them. Others picked out the most -satisfactorily proportioned unit and ignored the others, but any -possible apperception was irritating. The temporal subjects found it -equally poor. They felt the continual dissatisfaction of having their -expectation, that the adjacent unit should be the same, disappointed. -They all said that they could carry the feeling of repetition over -_one_ dissimilar unit (_i. e._, in an alternating series of two -different units), but that the third difference completely upset -the scheme. When only the filling varied as in Fig. 21, it could be -partially ignored, but difference in size could not be ignored, and -only the equal distances apart kept them from being a heap. They could -not _feel_ the evenness of the empty interspaces, however. They were -not consciously present in the experience at all, they merely _knew_ -they must be even. There was no feeling-tone whatever to the empty -alternates. - -Only one subject preferred Fig. 22 to Fig. 21, and the reason was -obvious. 1, 2, and 3 appeared as the same unit where variation in size -was apperceived as due to perspective. Thus, instead of appearing as -three units repeated, they were one set which progressed by means of -"pulsations" or regular intervals of perspective. This gave an added -richness to the rhythm, and was very pleasant. As three separate units -of different size, there was no meaning in the series whatever. - -It is evident from these introspections that, although the likes and -dislikes may vary, the principles on which they are based have much in -common. - -The points on which they agreed unanimously were the following: - -(1) There is no feeling of repetition for three separate units. The -series may be enjoyed by means of subjective grouping of one kind or -another, but as separate elements, the feeling of repetition is broken -by adding the third. - -(2) There is a distinction between perceiving or _knowing_ a -repetition, and _feeling_ it. Even though a subject is equally -conscious that elements are repeated according to some scheme in two -different cases, he may feel it in one case and not in the other. - -(3) The empty spaces between the elements have no conscious part to -play in the experience. Even when there is a figure in the alternate -space, it comes very little into consciousness as part of the -repetition, yet it is alterations in these alternates which make or mar -the feeling of repetition. A series may not be beautiful in itself, but -if the alternates are regular, it _feels_ repeated. _Vice versa_, the -units may be enjoyable in themselves, but they do not feel repeated -unless the alternates are regular and conform to certain requirements. -In the units lies the _meaning_ of the repetition, in the regular -alternates the possibility of its expression. - -(4) The rhythmic character of repetition is not felt by a certain type -of subject, when it goes smoothly. When a variation is made which would -destroy any possible rhythm, its lack is felt, and its violation finds -expression only in rhythmic terms. - -(5) More violation is done to a series to have the _size_ of units -varied than the filling. (This corroborates previous experiments.) - -(6) A certain amount of ignoring and regrouping can be done by the -subject. The series is not taken exactly as given, but with selective -attention. - -(7) In a series of different elements alternating, the most prominent -one is chosen for the major unit, and the others for alternates. This -prominence is more influenced by _size_ than any other factor, but may -be due to intrinsic interest of any kind. - -(8) The major and minor elements must have a certain difference from -each other, both in _appearance_ and _interest_, and they must be -different enough for the difference to be easily perceived, but not -enough to be incongruous. They must differ in interest enough, so that -one is easily more prominent than the other, or may be made subservient -to the other, in the apperception. - -(9) Variations are pleasant in the principal unit repeated, but not in -the alternating figure unless very slight indeed, or affecting only -secondary parts of the figure, not the main lines. - -(10) Not the time actually spent on a unit makes it more or less -prominent, but the feeling of more or less "energy" expended on it. - -_Ends:_ In an alternating repetition, must the series end on a light or -heavy beat? That is, must the major or minor unit be on the end? - -To test this a series of strings was hung in which a group of three -alternated with a single string. - -[Illustration: Fig. 23] - -The subjects were asked to look at it with the three-groups on the -end, and with the single string. In every case the three-group ending -was emphatically declared the best. What reasons were given were much -the same, although most of them could give no explanation at all. S. -said the minor space on the end left him "hanging in mid-air, it needs -the heavy beat to land me again." Others said it was "ragged" unless -the three-group ended the series. R. said anything _interesting_ would -do on the end, as well as the larger-sized unit, it simply needed -something of sufficient interest to stop the rhythmic process and keep -one from going on. - -It was impossible to describe the experience except in rhythmic terms, -and those in whom this sense was not strong could give no account -whatever for the difference in their feeling for _end_. - -It will be remembered that some experiments were previously described -relating to the difference in apperception of a group of lines equally -distant from one another, and a group averaged at equal distances each -side of a middle point, but unequally from each, to emphasize the -bilateral symmetry. Two such series were now taken to find if there -were any difference necessary in appropriate endings. Since the two -types of groups differed so much in apperception, did that difference -so extend to the whole series that a different space was needed at the -end to finish them off? - -The method of experiment was the following: Two series of repeated -groups were hung (100 mm. wide and 100 mm. between) with the design -of the groups varied as described. At the end of each a strip of -cardboard was hung, which the subject was asked to move so that it -bounded the amount of space at the end, necessary to finish the series -adequately. - -[Illustration: Fig. 24 I] - -[Illustration: Fig. 24 II] - -Thus _b_ is the cardboard strip, and _a_ the space which was to be -varied according to his taste. The same experiment was tried with each -series, with the following results: - - I II - U. _a_ = 96 mm. _a_ = 90 - J. 33 50 - S. 97 90 - H. 109 104 - R. 160 150 - V. 170 135 - T. 145 125 - W. 80 68 - -In the case of every one but J. the subjects preferred a longer end -space with I than with II. J. was, however, of the extreme spatial type -who gave as his explanation that with II, when the central line was -prominent, the end (_a_) must equal just the distance to another middle -line, while with I it must harmonize with the shorter distances in the -group, but not exactly equal them, for that would make it too narrow. - -It would mean, then, that the apperception of the repeated group in -I (if it accords with the subject's own introspection) consists in -repeated fluctuations of attention over the five strings, with no -repose on any one more than another. The movement is back and forth -from edge to edge, and hence needs more of an end to finish it than in -a series of symmetrical units where the movement is not back and forth, -but balanced and resting on the central point. In other words, in -Group I there is a rhythm of movement within the group itself, as well -as of the whole, while in II it is balanced and coördinated from the -centre of each group, out and back, so that a longer, or at least more -important end of some description is necessary to break the rhythm, and -stop the series in I than in II. - -It is noticeable also that H. and S. thought in both cases they were -making the end spaces equal to the interspaces; but after Series I, -_a_ was made 102 and 109; and after Series II 95 and 104 respectively. -This naturally raised another question: Does a series of groups, with -repetitions within each, tend to make one overestimate distances -between or at the end, or at least does one overestimate these -distances in comparison with a series of symmetrical units? - -The subjects were so unanimous in preferring a larger "embankment" -after Series I than II, that it was useless to test them further on -that point, and the experiment was changed to the other question -according to the suggestion above. - -A series of eight cards was prepared (125 mm. wide) on four of which -five heavy black strips were drawn equally distant from each other, and -on the others a much wider strip in the centre with another on each -side near the edges. Of the two series just made, one was composed of -what we have called "rhythmic units" and the other of "symmetrical -units." - -[Illustration: Fig. 25] - -The subjects were asked to arrange the two separate series so that -the interspaces should be exactly equal to the units. It will be -observed that the rhythmic unit had a black strip on each edge, thereby -apparently decreasing its size, while the edge of the symmetrical unit -was white. In this respect the comparison was hardly fair, but the -result was the following. The figures represent an average of two -trials, and stand for the size estimate of the interspaces for each -subjects respectively, in the two series. - - I II - J. 132.5 130 - S. 125 122 - U. 133 129 - H. 128 124 - R. 126 122 - W. 136 133 - V. 129 131 - -Average difference of estimate of both series = 2.64. Mean variation = -1.37. - -It might be contended, however, that Series I is an example of optical -illusion, that the card was overestimated for that reason, and the -interspaces necessarily made wider. To avoid this difficulty another -series was made. Two sets of cards (125 mm. wide) were prepared; one -with five black strips at equal distances apart as before (excepting -that the strips were made heavier), the other with six strips. The card -with an odd number of strips had thereby a strip in the middle upon -which the attention could centre,--possessed a kind of balance. The -card with an even number of strips had, moreover, no such central line -but only a space, thus preventing repose of attention, and making the -unit more pronouncedly rhythmic. (It will be noticed in the foregoing -table that one subject, V, made narrower interspaces in I than in II. -He said he felt the units as centring around the group of three lines -in the centre, not as proceeding equally to the edge. The unit became -thus for him symmetrical instead of rhythmic, which could easily -account for the difference in estimation.) - -The results in the present case are an average of three trials: - - I, 5 strips II, 6 strips - J. 129 137 - S. 125 129 - U. 132 133 - H. 125 131 - R. 127 138 - W. 126 133 - V. 123 129 - -Average difference in estimate of both series = 6.1. Mean variation = -2.1. - -Since both these figures represent an effect usually explained by -optical illusion, that factor may be counted out, and the difference -in the estimate be accounted for by the difference in the rhythm of -the units. The difference in estimation between the two rhythmic -units, differing only in odd and even number of strips, is greater -than between the rhythmic and more strictly symmetrical, and yet the -two were more comparable in construction. It would seem, then, that -the greater overestimation of II is due to the rhythmic movement which -is not limited or driven back to a central line as in I, but, by -continuing over the limits, produces a greater feeling of breadth. - -The same question was experimented on in another way. Smaller strips -of cardboard all 50 mm. wide, but with different designs, were hung -behind the narrow window previously used. Four of each set were hung -at a time behind the window, and subjects arranged them so that the -interspaces appeared to equal the strips. These designs were to -illustrate different points in question. The difference in estimation -for an empty card, and a filled one; the difference according to the -strongly centred, or rhythmic, or slant lines of the filling. These -experiments were not so complete as the former ones, since the subjects -were scattered; hence they represent only one trial or an average of -two. But the results conform with what we have been led to expect. - -[Illustration: Fig. 26] - - I II III IV V - J. 49 57 52.5 52 53 - S. 51 56 50 49 51 - U. 53 54 49 50 48 - H. 53 52 49 51 - R. 52 52 51.5 48 51 - W. 50 55 50 50 52 - V. 51 53 49 48 51 - - Average = 51 54 50.6 49.4 51 - Mean Variation = 1.5 1.4 1.2 1.06 .9 - -These results point to the fact that there is a tendency to -overestimate the strips unless there is a strong central accent, which -draws the attention back to the middle of the strip, in which case it -is slightly underestimated. This would seem to be contradicted in I, -where the centre is strongly marked by slant lines coming toward it. -But the subjects, instead of taking the lines as pointing _towards_ -the centre, in almost every case felt them as leading _away_ from it, -and the oblique lines gave an appearance of greater breadth, which -result was carried out by the greater overestimation of II. In this -case, in addition to slant lines, there was no central accent, and the -overestimation was proportionately large. III and IV were intended -to illustrate the difference in estimate of rhythmic and symmetrical -units, but although a slight difference is apparent, the subjects did -not feel III as strongly rhythmic, because the black lines on the -ends of the strip were ignored against the black background, and only -the two central lines were taken. This made it more a balanced than a -rhythmic unit, so it is not a fair type of the point in question. - -We may say, in conclusion, that oblique lines (which involve a more -complex muscular adjustment to perceive them) give an impression of -greater distance traversed, hence are overestimated; of two rhythmic -groups, the one containing an even number is more overestimated than -the odd, since the movement across is unchecked, and not balanced -around a central line; a series of strongly centred groups is more -correctly estimated as to its interspacing, and even slightly -underestimated, because of the check imposed by the centre of fixation -in each group. Although these results are very uniform, a more complete -series of experiments should be done on this subject, to make the -conclusions thoroughly valid. - -[Illustration: Fig. 27] - -Another question was suggested by these results: Is it more agreeable -to have a series of repeated space forms nearer or farther apart -when a design is within? Does the design, by drawing attention to -itself (especially if it be markedly central), make the objects -demand narrower or wider interspacing? To test this question, four -blank strips of cardboard were hung behind the narrow window, and the -subjects arranged them at the distance apart which suited them best. -Then two other sets of cards, of the same size, but of different -designs, were hung successively the same way, and these arranged also -at the most agreeable distances. One decorated card had a circle within -a rectangle, the other a triangle of gilt stars. The judgments were -made in pairs, _i. e._ the blank cards and the one with the circular -design were arranged twice in succession; then the blank cards and the -star design. This gives three judgments for the blank cards, two for -the circular, and one for the star design, and the judgments are given -in full, since an average would disguise the point in question. - - I II III - J. 50 50 - 55 52 - 55 50 - S. 35 70 - 45 20 - 55 35 - H. 85 75 - 90 65 - U. 50 45 - 50 48 - 57 50 - R. 45 25 - 15 10 - 45 23 - L. 90 35 - 65 65 - W. 20 10 - 25 10 - 25 0 - V. 45 60 - 30 35 - 30 25 - -Although the favorite arrangements varied somewhat on the different -days, the _filled_ cards were with only four exceptions preferred -nearer together than the _empty_ ones at any one trial, and two of -these put them equal. (The choice of V. was affected by the fact -that the circular designs produced such strong after-images that he -was obliged to put them farther apart, to avoid confusion with the -real design.) The reason suggested by the subjects for a narrower -interspacing with decorated cards was that, when they attended to the -design, they paid no attention to the actual edge of the card, but -the card ended so far as its interest was concerned with the design. -Therefore they had to be nearer together to bring the _designs_, not -the whole field of the cards, into a series. If, then, the design -extended over all the card, and its interest was no more in the centre -than the ends, would this difference in interspacing cease to be -demanded? - -Another series of cards was hung with a design of oblique lines over -the whole field, and these arranged as the others were, at the most -agreeable distances. - - I IV - J. 53 mm. J. 53 mm. - S. 45 S. 47 - U. 52 U. 50 - R. 35 R. 37 - W. 23 W. 43 - V. 35 V. 34 - -[Illustration: Fig. 28] - -If, for the sake of comparison, the average be taken of the favorite -arrangements of the four blank cards, and they compared with the -interspacing of the oblique line design, it will be seen they approach -each other closely, except in the case of W. - -These experiments would seem to show that an empty space, or one -completely covered with decoration, is taken in its entirety when -repeated in the series. But when decorated, especially toward the -centre, the _design_, instead of the whole including space, is taken -as the repeated unit, and for this reason the different units must -approach each other to make a satisfactory series. - -To what extent does change in _level_ and _plane_ affect the units of -a series? To test this, a series of diamond shapes was hung on the -same level and at equal distances, and the subjects enjoyed them as a -repeated series. - -[Illustration: Fig. 29] - -Then another row was hung above them, and halfway between. - -[Illustration: Fig. 30] - -The subjects grouped them either in twos or threes, thus transforming -them into one series of similar group-units of triplets and pairs. They -were asked if they could take them up and down, one after the other -without grouping, as they would have done when on the same level. With -a little practice two of them succeeded, but they found the series -tiresome when taken in this way, and deprived of much of its pleasure. - -The series was then changed by hanging a smaller diamond between the -others, at the same level. - -[Illustration: Fig. 31 A] - -[Illustration: Fig. 31 B] - -This was enjoyed even more than the other, as an alternating series, -but when the smaller diamond was hung between but on a higher level -although it could still be included if _grouped_ in some way with one -or two of the larger diamonds, it baffled all attempts to include it as -an alternate minor unit in the other series. The two series separated, -and one ran along above the other, or else a definite grouping took -place, so that the large and small diamonds made one group-unit which -was repeated. But to combine two different elements as major and minor -units of one series, when the two were on different _levels_, was -generally declared impossible. - -Provided units stay on the same level, however, a difference in _plane_ -does not prevent their being in one series, provided the plane varies -regularly, and the variation is not too great. The variation in plane -of a few inches, used with these shapes, did not prevent their being -taken as one series, although it much facilitated their being taken as -two, if desired. - -These experiments have all pointed to the fact that our pleasure -in repeated space forms is an immediate experience. We do not look -over the series and merely recognize that regular repetitions occur, -but there is an immediate _feeling_ of repetition, analogous to our -feeling of auditory rhythm. This feeling does not always accompany -a recognition that certain repetitions occur, but is a distinct -experience in itself dependent upon certain conditions in the series. -The series excites a certain response in the observer, which, if it -corresponds with his rhythmic organization, is pleasant, and if not, is -otherwise. - -With a certain class of subjects this rhythmic response is very -noticeable, and they feel it as a conscious part of the experience. -With others, the symmetrical properties of the series are the more -prominent, and they detect no rhythmic response until the necessary -objective conditions for such a rhythm are violated. Then they feel it -as keenly as the other type. - -In a series of units, there is a rhythmic discharge of energy on each, -the fixed temporal intervals being regulated by the alternating space. -When the units are too near together, or when the alternating spaces -vary irregularly in size, this rhythm is disturbed. If the alternating -spaces vary regularly in size, a richer rhythm is introduced, which -increases the pleasure up to a certain point when more variation makes -it too complicated, and confusion results. When one element alternates -with another, the one on which more energy is expended for any reason -becomes the principal unit. The other has less significance as to -its content than as to its size, for on this depends the regularity -of the rhythm. Variations in the content of alternating figures must -be cautious not to disturb, by the extra attention necessary to take -them in, the rhythm of the whole. Variation in the principal unit may -take place almost without limit, provided there is an equal amount -of interest in each, thus making a rhythm of equal discharges. There -must be an alternation of _two_, _i. e._ of discharge of attention and -rest. However rich the rhythm is made by greater and lesser accents -or groupings, the rhythm must fall eventually into a discharge of -attention, and a rest-period. In the temporal type of subject, to whom -the actual _motion_ across the series is a necessary factor of the -pleasure, this discharge and rest-period of _attention_ is exactly -inverse to the _motion_ across the alternate and rest upon the unit. -That is, on the principal unit is the discharge of the attention, but -the rest-period of the motion across; while the alternate unit supplies -the field which is travelled over, but requires but little attention. - -The rhythm of the series may be not only of the units, but inside the -units as well, in groups of elements. The rhythm inside such a group -may be of two kinds: (1) a rhythm, which is at the same time restrained -and coördinated about a central point or line, and (2) a rhythm which -goes back and forth from edge to edge, and has a tendency to overstep -its limits, thereby carrying on the series with more activity. The -former is more connected with odd-number groups, and the latter with -even, although modifications in their arrangement may reverse the -effect. Since the eye moves more slowly and intricately over a curve -than over a straight line,[86] it may be that that is the reason why -an arched series is taken as the unit of a series, rather than the -vertical supports (as it invariably is in some unfinished experiments -not recorded here), whereas in a series of lintels the horizontal line -of the lintels requires less muscular adjustment to perceive it than -the vertical support, therefore the latter are taken as the units. - -In any case, the unit of the series which attracts the most attention -and interest, for whatever reason, is taken as the principal unit, and -may vary in details, while the alternate must be invariable, except in -certain cases where it meets other demands. There may be rhythm in a -series, and at the same time symmetry with respect to a middle point. -In such a case a balance must be obtained between the two different -motor responses. - -A series of analogies between the rhythm of sounds and of visual -objects, will illustrate more forcibly the similar demands of both. - -(1) Auditory Rhythm: Periodicity is necessary. Accentuation may be -supplied by the subject, but there must be fixed temporal intervals, -and if the temporal conditions are not fulfilled, no impression of -rhythm is possible.[87] - -Visual Repetition: Alternate spaces must be of invariable size, or -the series is broken up. Different degrees of interest may attach to -the principal unit, or the subject may group them in different ways, -but the alternate spaces must be uniform, or there is no feeling of -rhythmic repetition. - -(2) Auditory Rhythm: Sounds must recur within a certain rate. When -succession falls below, or rises above a certain rate, no impression -of rhythm results.[88] A certain voluminousness is necessary for very -slow measures, to make the separate elements connect themselves in a -series.[89] - -Visual Repetition: Objects must recur at certain proportionate -distances from each other, to connect themselves into a series. Larger -objects may be at a greater distance from each other than smaller ones, -and still form a series. - -(3) Auditory Rhythm: "Perception of rhythm is an impression, an -immediate affection of consciousness, depending on a particular kind of -sensory experience. It is never a construction or reflective perception -that certain relations of intensity, duration, etc., do obtain."[90] - -Visual Repetition: The feeling of rhythm in a visual series is -immediate, and wholly distinct from the knowledge that certain -objects do recur. This is especially illustrated in repetitions of -three distinct units, when subjects saw and understood the scheme of -repetition, but could not feel it. - -(4) The number of units in an auditory group depends on the rate of -succession, but any higher number of elements in a group than _six_ -or _eight_ falls back into smaller groups.[91] _Eight_ is about the -highest number that can be held in a rhythmic group.[92] - -Visual Repetition: _Eight_ is the highest number that can be held in a -rhythmic group, and some subjects can only hold seven. Many more units -can be felt in a group, when the size of the including space is taken -as the measure and compared; but no more than eight can be felt and -recognized as the number of units it is. (There may be exceptions to -this rule in either auditory or visual rhythm, but this is the norm in -both cases.) - -(5) Auditory Rhythm: In all long series, there is a subordination -of the higher rhythmic quantities, so that opposition of simple -alternate phases tends more and more to predominate over triplicated -structures.[93] - -Visual Repetition: However complicated the repetition becomes, with -regular variations of the size of major or alternate units, the units -tend to re-group themselves, and so resolve ultimately into a simple -alternate repetition of two group-elements. - -(6) Auditory Rhythm: "The introduction of variations in the figure of a -group does not in any way affect the sense of equivalence between the -unlike units."[94] - -Visual Repetition: Changes in the content of the major unit do not -affect the repetition provided the alternate space remains invariable. - -(7) "Feeling of rhythm is more definite as we proceed in a verse, or -in a series of simple sound sensations. At first the cycle is not -perfectly adjusted, and complete automatism established."[95] - -Visual Repetition: Observers often had to look over a series several -times "to learn it" as they said, before the rhythm was felt. - -To these may be added several other analogies, which, owing to the fact -that visually repeated objects remain in the field, while auditory -rhythm is purely successive, have other features which somewhat confuse -the resemblance. The principle, however, is the same in both. - -(8) Auditory Rhythm: "At the close of a period, we have a pause, during -which the tension between the two opposing muscle-sets dies out, and we -have a feeling of finality."[96] - -Visual Repetition: An alternating series must end on the heavy unit, -but since one does not look at series from left to right any more than -from right to left, a heavy unit must be at both ends, not on one -alone. In auditory rhythm, this final pause is not a function of any of -the intervals of the period, for it comes at the end, when the sounds -are no more present. But in visual repetition, after feeling the series -rhythmically, it is still in the field, either as an unending series, -or as a whole, in which each part is equally related to all the others. -The final pause of a series that ends must be at _each_ end, and the -series perfect from either point of view. It therefore fulfils the -demands of symmetry as well as rhythm, but since symmetry in its strict -sense has no meaning for sound-series, this double finality of visual -repetition cannot be analogued in auditory rhythm. - -(9) I have found no recorded experiments of rhythms of sounds of -different timbre and pitch, _i. e._, a regular rhythm of a bell with a -violin, a piano with a whistle, etc. It would seem, however, that such -a succession would produce the same irritation as a visual repetition -of incongruous elements; as a circle introduced into the Greek fret, -or a series of Renaissance columns and Egyptian monoliths. In both -cases, the whole set of adjustments for each element would be thrown -into confusion by encountering the next one, which would require a -different attitude. Such a readjustment would be impossible in the -space necessary for the perception of any rhythm, hence there must be -congruity in elements, either auditory or visual, to be in a series at -all. - -(10) Auditory Rhythm: "If every alternate element of a temporally -uniform sound-series receive increased stress, the interval which -succeeds the unaccented sound will appear of greater duration."[97] - -Visual Repetition: The distance between unit groups with a strongly -accented centre appeared shorter than between rhythmic groups where the -movement was not restrained at the centre, but went from edge to edge. -The principles which explain these similarities are, however, different. - -In the auditory rhythm, the stronger accented beat excites a greater -response than the unaccented. This lasts over longer in consciousness, -and for that reason the interval after the accent seems shorter. - -In visual rhythm, however, the symmetrically rhythmic group drives -the attention in toward the centre, and whatever excursion it makes -to either side, it returns finally to the centre. In the even-number -rhythmic group, there is no such central line to restrain it, and -as one goes across it one has less check at the edge, the rhythm -does not wholly finish, and the space is thereby overestimated. The -_overestimation_ is due to the rhythmic activity in the group which -oversteps its limit. - -The essentially rhythmic character of the experience is, however, the -same in both. The experience of visual repetition is only one-sided -when the symmetry or proportion of a finished series is regarded as the -explanation of its essential character, and when the temporal rhythmic -factor is neglected. - - -PART II - -The purpose of the latter half of this discussion of repetition is to -consider a certain number of examples of its use in typical buildings -of all the European styles of architecture from Greece down, and to -show that the principles laid down in the earlier half have been -expressed almost without exception in those of recognized merit. In -other words it is to show that the laws of repetition, which have been -brought out in the experiments of the first part, and which would of -necessity be true if that explanation were correct, have indeed been -exemplified in types of architecture universally accepted as beautiful. - - -The illustrations have all been drawn from architecture beginning with -Greece, and not from the older Eastern styles. Egyptian architecture, -although it recognized the importance of repetition to some extent, in -its colonnades, avenues of sphinxes, and hieroglyphic decoration, never -reduced it to any principle, nor adhered to any one scheme throughout -a piece of work. Supports of the same kind and diameter have no fixed -relation to each other, they may be of the same or different lengths, -and may vary in diameter as well.[98] Spaces between columns of one -size and design may vary considerably, and the entablatures be of -different proportions. The art of Egypt was not rhythmic. - -The architecture of Assyria and Chaldea had even less of repeated -forms in its style. They made but little use of columns or piers, and -had few arches.[99] The bare Assyrian edifice was like a great box, -perpendicular to its foundations, and the long walls pierced by hardly -an opening in the way of windows or doors. - -Persian architecture was noted for extreme nicety of execution, but -a monotony in all its forms, and conventionality about its use of -the column, which makes it little more fruitful for our study of -repetition as an artistic value. In its decorations of bas-relief, the -pose and gesture of each figure is so exactly similar that they appear -almost machine-made.[100] When a little variety is introduced, it is -evidently done with misgivings, and shows none of the spontaneity or -first-hand pleasure in either repetition or variation which would make -it profitable for illustration. - -Such a lack of feeling for repetition is, indeed, according to the -peculiar genius of these styles of architecture, what might have -been expected. The ruling idea, especially in Egyptian and Assyrian -architecture, was ponderous strength. Everything was built with the -idea of remaining immoveable through centuries to come. The enormous -temples and tombs, the long palaces with their heavy walls without an -opening to relieve them, the pyramids themselves like mountains of -rock--all these meant strength and immutability, to which the motion -and rhythm involved in repetition was totally foreign in spirit. In -Persia indeed (as well as India and China, which will not be considered -here) there was a change in tone. The column was used, not the massive -one of Egypt, but a lighter shaft, which showed a tendency toward -other effects than immensity and strength. - -With this change of ideal, repetition in some kind of system made its -appearance, but its variations were tentative. It had not become used -to its new sense, and it was left for Greece to develop the rhythm and -movement of repetition, and to combine it with proportion and symmetry -into its perfection. - -The method of analysis employed has been to go through a certain -number of architectural photographs, picking out all the examples of -repeated forms of any description, and classifying them according -to the principles which they exemplified or seemed to violate. For -this purpose a collection of about five thousand photographs from -the library of Robinson Hall, Harvard University, was analyzed. The -photographs were taken in order of styles: Greek, Roman, Romanesque, -Gothic, Italian and French Renaissance, and modern. The examples of the -different points in question were taken as they came in the cataloguing -of the library stacks, without respect to whether they appeared to bear -out the previous conclusions or not. - - -VARIATION OF ALTERNATING UNITS - -The first principle which we shall consider is the variation allowable -in the units of an alternating series. It will be remembered that -the principle was as follows: (1) In any series of two alternating -units, the one on which the most energy is expended is regarded as the -principal unit, the less important one as an alternate. Variation of -the principal unit is allowable, often desirable and even necessary; -variation of the alternate never allowable, unless other circumstances -change the situation. If the minor unit is changed, so that in interest -it equals the major unit, the rest-phase of the rhythm is destroyed, -the effect is of two rival repetitions going along together, and -fatigue results. If variation in the alternates exceeded that of the -principal units, the balance of the rhythm would change, the alternate -become the major unit, and a new series begin. - -From the very nature of the case, then, it will be impossible to look -for variations in alternates, which make it exceed the principal units -in interest. We must investigate alternating series, in order to see if -_one of the elements remains the same_, while the other may or may not -vary. If this were true, a rest-phase for the rhythm would be assured -in the series, while the principal unit might vary, provided the same -amount of attention were required in each case. (2) It will also be -remembered that _size_ and _limiting shape_ were the factors that could -not vary without doing violence to the rhythm, while content might vary -almost without restriction. (3) The position of alternating units as -regards each other cannot vary; the two units are so dependent on each -other that the position of one must remain halfway between two of the -opposite kind. In other words, if the two series of units run between -each other, they form _one_ series or rhythm. Two rhythms cannot be -kept up alongside; so if one unit, however regularly placed with -regard to another of its own kind, recurs at unequal distances from -the _other_ units, the feeling of the repetition is lost, the rhythm -broken, unless the two units can be grouped into one, and so make a -single rhythm again. - -We shall, then, look for alternating series, of which the two units are -at _equal_ and _invariable_ distances from each other; the variations -of content (if such there are) occur only in the major unit; and are of -the filling, not of the including shape or size. - -It may be readily seen that there are difficulties in finding -alternating series which exactly illustrate this particular point, or -in reducing them to any system. It was necessary to look through many -photographs to find one that presented the required conditions (_i. -e._, two repeated series of units, alternating with each other), and -when found, they were of so many different varieties, from windows in -an apse to reliefs on a fountain, that each has had to be described -by itself, and any rigid classification was impossible. Moreover, it -was difficult to find a scale of judgment by which to decide whether -a series was really alternating or plain repetition. From one point -of view, _every_ repetition is alternating, that is, the repeated -unit always alternates with an empty space. Although such repetitions -bear out the theory still further, and emphasize yet more strongly -the invariability of alternates, and the possibility of variations in -the principal units, I have used the term in a stricter sense, and -only given illustrations of repeated objects, when one unit actually -alternated with another definite unit. - -Had the other sense of the term been used, examples might have -been multiplied without limit, of slightly varying repeated units, -and unvarying alternate blank spaces. But it was felt that such -accumulation of illustration was unnecessary, and that what was true in -a stricter sense of the term would be recognized as true for the larger -number of cases that might be cited with a wider meaning. If the minor -units had a definite enclosing outline, they were counted even though -they were blank within, but without an enclosing outline, that is, if -they were mere spaces, they were not considered, although the fact that -there is such universal use of this type of decoration shows only more -conclusively how the necessity of the invariability of alternates is -taken for granted as an axiom of design. - -Another type of alternate repetition was not included in the -illustrations, _i. e._, when two sets of units alternated, _without -variation in either one_. To this class belong all the conventionalized -designs used so much in all kinds of decoration, and of which a very -full account is given in Owen Jones's Grammar of Ornament. - -These, to be sure, illustrate the negative points, viz., that size and -shape are unalterable for rhythmic repetition; that distances must -be equal and invariable; and that alternate units must not vary. But -since the principal units do not vary either, it seemed needless to -give them as examples of the point in question. A mention of this class -of alternating repetitions, of which there is such a great number, is -enough to show that they fall within the theory. But one example is as -good as a thousand, and their inclusion among the illustrations for -rhythmic alternates will be taken for granted without further mention. - -We are left, then, to the consideration of those alternating -repetitions alone, where both have a definite outline, and one or -both varies to a greater or lesser extent. The effort will be to show -that the unit which for some reason is of principal importance in the -rhythm, is the one chosen to vary, and if not that the repetition -suffers thereby. - - -125 EXAMPLES - - A. Variations in Principal Unit alone: 87. - - I. Content alone: - - a. Metopes and Tryglyphs in Friezes: 9. - b. Arches and Columns: 2. - c. Statues in niches alternating with supports: 37. - d. Windows alternating with supports or decorations: 12. - e. Paintings or mosaics: 7. - f. Carved designs in screens or ceilings: 17. - - II. Size and Content. - - a. Doors, paintings and reliefs on façades. - Vary in size to emphasize symmetry: 4. - b. Statues or shields over arcades. - Vary in size to complicate rhythm: 1. - - B. Variations in Principal Unit AND Alternate: 37. - - I. Content alone: - - a. Windows and decorations on façades. - Alternates vary in design to emphasize symmetry: 4. - b. Windows and turrets. Vary alternately in design to complicate - rhythm: 2. - c. Reliefs alternating with tablets; reliefs or statues and - pillars: Alternates vary in design to give richer effect: 11. - d. Alternate unit is human figure: 9. - e. Alternate unit varies in design, but is on a different level: 3. - f. Irregular variation in alternates (windows, shields, and - railings): 3. - - II. Of Size of Alternate Unit. - - a. Windows and supports. Vary in size to emphasize symmetry: 1. - b. Statues and pillars; windows and pilasters. - Alternates vary in size to complicate rhythm: 3. - c. Vary in size irregularly. Disorder: 1. - - C. Variation of Distance. - - Row of windows--Distance between first two is wider: 1. - -The 125 illustrations of alternating repetition which were taken at -random among 5000 photographs show a decided compliance with the -principles already laid down. But there are many divergences as well, -which it is necessary to consider, to see whether they are really -contrary in principle or fall under its wider application. Eighty-two -accord exactly with the principles with which we started. The distances -between each set of units are equal and invariable; one unit varies in -content but not in size or including shape; the alternating unit is -invariable. - -There is an interesting modification of this principle in the case of -the metopes and triglyphs of the Greek friezes. Here the triglyphs are -unquestionably the principal units structurally, and to many observers -the principal beat of the rhythm when taken rhythmically. But the -triglyphs never vary and the metopes do, which would seem at first to -violate the rule that principal units alone, and not alternates, should -vary. This difficulty is obviated in two ways. With the spatial type of -observer, the triglyph is indeed the principal beat of the rhythm when -the series is at such a distance that the difference in the metopes (if -there is such) cannot be detected. When, however, the series is nearer -at hand, there ceases to be any rhythm, but each carved relief is -taken for itself without regard to the others. With the rhythmic type -of observer, if the triglyph has been the principal unit before, the -principal beat changes on nearer approach to the metope and the whole -series shifts its accent. It is impossible for any observer to keep -the triglyph as the principal unit of the rhythm, when so near that -differences in the metope are easily perceived. - -There are still thirty-eight cases which vary from these rules, and -many of them vary in more than one respect. These exceptions fall into -several classes, quite distinctly marked off from one another, and will -be taken up in turn. - -In five cases, the _size_ of the principal unit varies as well as the -content, but in four cases the variation of size is either at each end, -or in the centre unit, to emphasize bilateral symmetry of the series as -a whole. The series in this case is taken as a larger unity of which -the separate units are parts; and hence they are not only repeated with -respect to themselves, but are symmetrical with respect to the whole. -In the other case where the size of the principal unit varies, it -varies on _every other one_, thereby complicating but not confusing the -rhythm, _i. e._, a stronger accent comes on every other principal unit. - -There are also five cases in which the alternate spaces vary in size. -Three vary regularly, thereby enriching the rhythm by introducing -alternate heavy beats, and one varies at each end of the series to -emphasize bilateral symmetry of the whole, with regard to the central -unit. In the other case the alternates vary in both shape and size, -with no regularity and from the point of view of repetition alone, -disorder is all that results. This is on the Palazzo Pretoria in -Pistoia, where carved shields occur at equal distances between windows. -These shields are not component parts of the building, but were added -with some other kind of significance; hence they express nothing so far -as repetition for its own sake is concerned. - -The other variations are all in the _content_ of the alternate, minor -space. Four vary _symmetrically_ in the designs on each side of the -central point, so as to accent the bilateral symmetry of the whole -taken as a unity. Two vary rhythmically in design, _i. e._, there are -two sets of designs which alternate with each other in the unaccented -spaces. When they vary regularly in design, the rhythm of the whole -is _enriched_ not confused, provided there are only _two_ sets, not -three or more. The alternate spaces are passed over on the way to -the principal unit, but by having an alternating design between them -(varying only in detail, but of the same general character) a more -complex rhythm is introduced which is good, since in both cases the -alternates and principal units are so different they could not possibly -be confused with each other, even though both varied. (In one case, -turrets and statues vary with windows of the same shape but different -decorations; in the other, arched windows and arched spaces alternate -with statues.) - -Eleven more cases of variation in the minor as well as major spaces -fall under another head. These do not vary with regularity, but are -different in each case--the detail of the design varying, while the -shape, size, and distance remain unchanging. It is interesting to -notice that these examples of variations of alternates were almost all -taken from examples of Renaissance architecture, where a richness of -effect was desired, even at the expense of regular rhythm. This could, -indeed, be attained in no other way so well as this. In all these -eleven cases, the conditions are alike: both of the repeated units -are enclosed by limiting lines of unchanging outline. The principal -units are more prominent than the others on account of greater size or -interest, but the alternates, instead of retiring entirely into the -background, have slight variations in decoration. This variation is -always only in detail: the tracery on the pillars of the tomb of Louis -XII, of the Loggia dei Novoli, in the Chiesi di Frari, Venice, etc. So -unimportant in fact is the variation that it is not observed until one -attends closely to it, and yet the rhythm is just enough disturbed by -its presence to give a feeling of _extra sensation_ or _luxuriance_ -which cannot be attained through variation of the major units alone. -It is in the alternate spaces that the _feeling_ of repetition lies. -Any material change in them destroys the series, but a slight variation -in the lines of decoration, a little rearrangement of the conventional -curves in each alternate, gives, even though unattended to, in fact -partly _because_ unattended to, a vague feeling of variety, of some -superfluous sensation being brought into consciousness, although the -regular shape, size, and distance of the objects remains unchanged. It -is this feeling of superfluity and slight disturbance which constitutes -the peculiar richness of certain styles. These examples, then, far -from falling outside of the laws of repetition, owe their opulence of -sensations to the very principles of regular rhythm which they violate. - -Another set of exceptions will involve more searching analysis. Nine -of the examples described have the human form for the alternate unit, -and in every case where this happens, the alternate varies. In the -majority of cases where statues of the human form alternate with any -other object, the statue is taken as the principal unit on account of -its superior interest, but this is not always the case. In the Padua -Basilica, and in the Church of St. Guistiana, cherubs alternate with -conventional decorations, but the latter are so much larger and more -elaborate that they would naturally be taken as the principal units. In -the other seven cases, statues alternate with bas-reliefs which also -have human figures in them; hence, since the bas-reliefs equal the -statues in interest and exceed them in size and importance, they are -taken as principal units. - -It might at first be expected from the previous discussion that, in -order not to shatter the repetition, the alternate statues must be -alike, must be conventionalized into identity; but this is not the -case. Another principle now comes into play. We demand variation in -the human form whatever its place in art, even in the unimportant -position of alternate in a repetition, and although they are kept as -much alike in pose, size, level of head and feet, general character -(_i. e._, cherubs do not alternate with old men, nor draped figures -with undraped), yet there is some variation of pose or direction of -glance, to keep them from being duplicates. We should expect this -variety of repetition to be in danger of becoming fatiguing because of -its lack of an unchanging rest-phase, but this difficulty was evidently -felt in building them, for in every case _some unchanging element_ -has been supplied to the series to bind it together and to keep the -constant changes of attention from upsetting the series. The cherubs -of the Padua Basilica are in high relief against a uniform rectangular -background which does not vary, and which furnishes an alternate -just in character with the principal unit, the bas-relief. In the -Cantoria of Donatello, although the dancing children move across the -whole space, uniform double columns occur at intervals, and supply an -unchanging alternate, while the children vary in position behind them. -Around the pulpit of Lincoln Cathedral, although both units, reliefs, -and statues vary, the pilasters behind the statues are invariable and -supply a constant, unchanging factor in the series. In the alternating -reliefs and statues of the Milan Cathedral or in the paintings of -different sizes in All Souls Church, Oxford, an unchanging element -is supplied in the frame, which is of like design in every case, -so that in passing from one to the other an unvarying alternate is -always present. In the Sienna font, and in the statue to Leonardo da -Vinci, which are types of a vast quantity of repeated forms, there is -uniformity in the minor pedestals and in the frames of the alternating -bas-reliefs, which supplies the unchanging factor. - -Moreover, another factor is noticeable in this kind of repeated -series,--it is never long. The fatigue which would certainly result -from a too long continuance of varied alternates, even with unvarying -factors in the way of supports, pillars, and frames, is obviated in -various ways. The series is either short and the whole has a definite -bilateral symmetry, as in the Padua Basilica, and in the Oxford church; -or, as in a great number of cases, the series goes around a fixed -central point so that only three units are seen at a time. It is thus -especially that this method is used in fonts, pulpits, and monuments, -where from the circular arrangement enough can never be brought into -the field at once to fatigue the attention. - -This consideration of alternates which vary widely, as do human -figures, even when they are alike in size, general shape, and -character, and, moreover, the discovery that there is almost without -exception an invariable element _between_ the other alternating units, -_i. e._, a third alternate; or _behind_ them, as in the case of the -pilaster behind the statue, may well bring up two questions: - -(1) When the unchanging factor comes _between_ the other two units, -is not _it_ in reality the alternate, and the two other units either -variations of shape and size of one principal unit or two sets of -principal units? In other words, do we not actually apperceive the two -principal objects as the units of importance, and take the unvarying -factor which comes between, no matter how slight it may be, as the -alternate? Do we not demand the unvarying as our alternate, no matter -how many variations may be in the other figures? - -(2) When the unchanging factor comes _behind_ the alternating statue, -in the same plane with the bas-relief, do we not inevitably take _it_ -as the alternate in the series, and regard the statues more as episodes -or attendants on the series but with real values of their own? Is not -the fact that the unvarying factor and principal units are in the same -plane an indication that they constitute a real series, while the -statues or paintings which are in a plane by themselves make a series, -harmonizing with the other, it is true, and in part coinciding with -it, but felt in a different way? Therefore the actual repeated series -conforms to the given conditions and is made to do so in every case by -its unchanging alternate in the same plane; while human figures with -values of their own never can be considered quite as alternates, but -are really felt to be a series by themselves. - -This introduces another question. In two more cases of varying -alternates, there was variation in decoration above the level of the -rest of the series. In the Borghese Casino, there is variation in the -busts placed _over_ the alternate windows. In the Venice rood-screens, -there is variation in the carving of the alternating supports, which -rise _above_ the rest of the series. Is that part of the series above -the level of the principal units really included in its perception? It -would seem rather that when the series as a whole is being taken, those -variations above the level of the main units (if they are not very -marked, and they were not in either of these two cases) are ignored -or only felt in a vague way as added richness. When, however, the -attention is turned toward them especially, they form a series of their -own, in which they become the principal units, and alternate with empty -spaces. There is no limit to the changes possible in apperception, -according to the _level_ and _plane_ of the alternating units. - -There are three cases left; two where alternates vary in content -with no system, and one with variation in distance. The first two -are differently carved sections of railing on the side of Freiburg -Cathedral, and a differently decorated frieze of squares and circles in -the S. Lorenzo Cloisters, Rome. The effect is only of disconnected and -fragmentary series in both cases, and especially in the latter case it -is impossible to feel it as a repetition at all unless the variations -are ignored, and the attention fixed on the unvarying factor of size. - -The variation of distance is in the Beauvais Palais de Justice, where -the first window is at an unequal distance from the others in the -series. The effect is only of disorder and accident. - -We have, then, surveyed all our examples of alternate repetition, and -found that in the exceptions to the general principles laid down some -other effect than repetition as such was sought. Either (1) symmetry -for the series as a unity was required, which demanded variation of the -end or central units. In so far, then, as it fulfilled the requirements -of symmetry, those of repetition were disregarded. - -(2) Richness of effect was accomplished by those slight variations -in decoration of alternates as well as the principal units. These by -their vague suggestions of different combinations of similar elements, -and minor differences felt but not attended to, gave a superfluity of -experience which made up its peculiar richness. - -(3) When the human form (or any other form of especial meaning in -itself) makes the alternate unit, some variation is demanded as in -keeping with its own significance, since in proportion as a thing -has meaning in itself, it must not be exactly duplicated. But an -invariable alternate is always supplied in the way of a frame, or -background, which is felt as the real rest-phase of the rhythm, while -the varying alternate forms have a place in a series of their own. -Also, since such a complex attitude would be fatiguing, such series are -always short, or circular, so that few units are in the field at once. - -(4) Regular variations in size or content, in either major or minor -which recur at fixed intervals, give a heightened rhythmical effect by -making certain beats heavier than the rest. As has been stated before, -the major unit holds within it the real significance of the _content_ -of the experience; the minor unit holds the secret of the _rhythmic_ -effect. - -(5) Only 4 examples of the 125 were found to repeat themselves -alternately with irregular variation of alternates and violation of the -other principles laid down at the start. These can only be regarded as -accidents, as faulty examples of art, whose virtue lies in some other -part of the work as a whole, and not by any beauty they possess in -themselves as repeated series. - - -SUMMARY - - 125 _Illustrations._ - - I. Variations in Principal Unit alone, 87 - - 82 Content - 5 Size 4 Symmetry - 1 Rhythm - - II. Variations in Alternate Unit (and Principal Unit) - 32 Content 11 Richness - 9 Human figure - 2 Rhythm - 4 Symmetry - 3 Different level - 3 Disorder - 5 Size 1 Symmetry - 3 Rhythm - 1 Disorder - - III. Variation in Distance - 1 Disorder - -Several questions have been raised in this discussion of variations, -but one which seems directly leading from it will be considered next. - -When is variation _necessary_ in a repeated series? We have considered -the numerous cases where variation is _possible_, and the different -ways in which a series may vary according to the idea to be expressed. -Moreover, what appeared to be exceptions to the rule were shown to be -guided by a desire for some other effect than repetitions as such. - -But when do we demand variation in a series? Is there any case where -variation of the unit is not only allowable, but positively necessary -to its æsthetic value? - -There were no experiments on this question, for it will be seen from -what follows that they would have been impracticable. But observation -of several thousand photographs has made the following clear: When the -series consists of objects having an æsthetic significance of their -own, not depending on something else for their value, then variation -is demanded. In other words, when a thing is an end in itself, we do -not tolerate an _exact_ duplicate. It may have a place in a series -of others similar to it, but its own meaning loses force if another -is beside it precisely alike. When, however, an object has no great -significance by itself, or when however great its value, it be regarded -as means to something greater, hence not an end in itself, it may be -repeated without variation. - -This principle may be stated from another point of view: Any work -of art, of the _highest_ significance in itself alone, must not be -repeated at all. There must not be even the suggestion of repetition. -The highest values are individual, and to have a copy or a series -defeats its whole reason for being. Thus, a second Sistine Madonna, or -a series of Venuses, would shock our whole æsthetic feeling. Moreover, -we do not want a _suggestion_ of repetition; even a series of different -Madonnas in similar frames would take away from the significance of -each, in so far as they were regarded as a series, and not as a mere -collection of detached units. - -But grading down from these works of the highest value in art, there -comes a point where an object, although possessing considerable value -in itself, is not so intensely individual but that it can gain somewhat -by a place in a series of others like it _in some respects_, but -differing enough so that each still keeps its own meaning distinct from -the rest. - -The balance between these two artistic aims, _i. e._, the significance -of the unit, and the rhythm of the series, must be adjusted with -great nicety, and certain principles obtain wherever such series are -found. It would be useless to cite the numberless cases where such -series occur. Many have already been given in the examples of statues -of saints, paintings on altar-pieces, and reliefs alternating with -statues. One such series is a type of all. The human form represents -that which has the most significance in itself, so when it is used -in a rhythmic series, its individuality must be toned down and -conventionalized; it must have no marked feature in one unit that does -not appear in another; the head and feet must be on the same level, or -vary with regularity; the general character and spirit of all must be -similar, but never identical. - -The reducing to a common type is the demand of the rhythmic series; the -difference in attitude and arrangement of detail is the demand of the -unit. - -Thus, the subjects chosen for repetition of this kind are in the -majority of cases apostles and saints, whose spirit and general -conception are the same; typical representations of abstract qualities, -such as Virtue, Courage, etc.; or conventionalized cherubs, and even -animals. As has been stated before, a long series of this kind is -impossible without fatigue. In proportion as the object is repeated -the individual units lose their own meaning, and they must have their -individuality definitely toned down and conventionalized to avoid the -clash between the two artistic values. Yet their essential peculiarity -must always be maintained, for we refuse to admit or allow the total -identity of any expression of living values, especially as expressed in -the human form. - -It may be urged that statues are often arranged at regular intervals -around a building, where the effect of repetition is distinct, and -yet each statue is distinctly valuable for itself. But a distinction -must be insisted upon. The statues form a repeated series as regards -uniformity in position, height, pedestal, and color, so that the direct -sensuous effect may be called rhythmic. But as the attention fastens on -each for itself and takes it for its own meaning, it ceases to be part -of a series at all, but becomes a unit in a world of its own. - -But what of the cases where the human form is repeated in a series, -and does not vary? Examples of this are rare, but they do occur, and -are interesting, since they throw light on what has been already said. -In the whole collection of photographs only two were found where a -series of identical statues of the human form occurred,--_The Porch -of the Maidens_ in the Erectheum of Athens, and the _Baths of the -Forum_ in Pompeii. In the former case the left knee of the caryatids -on the right of the centre, and the right knee of those on the left -of it, are raised a little; but aside from this slight variation the -six statues are exactly alike. In the latter case a row of titans all -around the interior bear the ceiling on their uplifted forearms and are -all alike. These two examples are very perfect of their kind, and, far -from offending us, are very satisfactory. The reason is obvious. In -both cases the statues are not the æsthetic end in themselves, but are -there for a purpose, namely, that of a support. They are not ends but -means to something else, and as soon as we feel _that_ in regard to any -work which would otherwise be of individual significance, it ceases to -be individual, or to demand a peculiar expression different from all -others, but may be duplicated without offence. Therefore, since the -support of the superstructure obviously is dependent on the maidens -in the one case and on the giants in the other, and since instead of -existing simply for their own value they are there to hold up the roof, -their artistic significance changes at once from _ends_ to _means_, -and variation is not required. Moreover, it will be found in the -majority of cases that we demand this invariability in actual supports. -Although we find but these two cases where caryatids are actually -identical, we find also that in most cases the caryatids do not really -uphold the weight, but a pillar or pier behind them supplies the real -architectural support, and, that although they have a place in front of -the pillar and give an apparent assistance in bearing the weight of the -roof, yet the eye is not deceived. We see that the work is really done -by the pillar behind them, so they that resume their place as artistic -ends demanding variation, and not as means to something else. The -following examples were found: - -_Milan. Arca di S. Pietro Martire._ Pillars uphold the arch while four -statues of women stand just in front. The pillars bear the weight -although the statues add strength to the whole. The statues are varied. - -_Dijon. House of Caryatids._ Piers behind the caryatids give real -supports to the roof, while the figures added for decoration are all -varied. - -_Dresden. Zwinger._ Conventionalized figures ending at the waist are -put on the outside of unvarying piers which bear the actual weight of -the superstructure. The figures are all varied, but they cannot be -conceived as really bearing the strain, since they have no foundation, -but are merely added to the pier as a decoration. - -_Rouen. Tomb of Duc de Brezé._ Four caryatids, all different, under -four jutting projections of the arch. These projections are built -securely into the rest of the structure and do not depend in the -slightest on the figures for support. The figures are not integral -parts of the whole architecturally, for the arch would stand exactly as -well if they walked away, which indeed they are apparently in the act -of doing. - -_Toulouse. Hotel de la Borde._ Two caryatids under jutting projections -of a window. The projections are securely built into the lintel and -no weight rests on the caryatids nor even appears to. They are there -solely as decorations and are different. - -_Paris. Hotel de Ville._ Two caryatids under jutting projection of -a window, again. Here is a very slight variation of the two female -figures. The position of each is reversed to accent the symmetry of -the whole. Very little weight is actually borne by them, but more than -in the former cases, and we find proportionately less variation in the -figures. They approach identity, but there is variation in detail. - -These were the main instances found of the point in question, and are a -type of the other minor ones found in support of pulpits, choir-stalls, -and windows. It will be seen that in no case but the two classic ones -given at the beginning are the human figures architecturally necessary -to the structures, and in these cases they do not vary. In the other -cases they are more or less playful, and the effect of the whole would -be very unsteady did the superstructure actually depend upon them for -support; but since piers rise invariably behind them and bear the -weight, they fall into the sphere of decoration and from that point of -view they must and do vary. - -We have, then, considered variation of units in a repeated series, -where they may vary and where they must, and we find the real value -of repetition to appear in inverse proportion to the individual -significance of the separate units; the more interesting or expressive -the unit is in itself with individual significance, the less do -we want it repeated; and so repetition of the human form must be -conventionalized to the type (or to the same unvarying features), with -enough individual differences still remaining to meet the demands both -of the series and the individual. What apparent exceptions we have -found to this rule have been shown to be meeting, in reality, another -artistic demand. - - -ENDS OF SERIES AND ARRANGEMENT OF REPETITIONS WITHIN THE UNIT - -The next question to consider is the _ends_ necessary for a repeated -series. Do they end with a heavier or with a lighter unit than the rest -of the series, or with a unit of the same size? It will be remembered -in the experiments touching this point that the subjects, without -exception, preferred the series ending with heavier units. We should -then expect, in examples of repeated groups of posts, pillars, etc., -alternating with wider or more prominent ones of the same kinds, that -the series would end with the heavier or more prominent one. Examples -of railings or balustrades alternating with heavier supports are so -common, and the supports come so invariably on the end, that repeated -examples seem almost unnecessary. But another question arose in -connection with this: Does not the apperception of a group of lines -equidistant from each other consist in going back and forth over them -from edge to edge, with no rest on one point more than on another; -while in a group of lines arranged at equal distances each side of the -centre but not from each other, to emphasize bilateral symmetry, does -not the attention rest on the centre, and move from the centre of one -group to the next? - -Moreover, we found that a wider space or embankment of some sort was -necessary, to finish off a series of groups in which the separate lines -were equidistant from each other, than to finish the groups whose lines -were symmetrically arranged. This suggests that the activity which -goes back and forth in the former case, being less coördinated and -not bound to a middle point, needs more at the end to stop it than is -needed in the latter case, when the attention is more upon the centre -of each figure. It would seem, then, that the former arrangement would -be appropriate for railings and balustrades, where the effect is of -continuity either running wholly around the structure and into itself -again or where a continuity of parts is desired and a connected series. -The other arrangement divides the series into discrete parts. If the -attention is stopped at every central point, the effect is less of -continuity and more of separate unities bound together externally by -their equal distances. We should, then, expect such series of units -much less in continuous balustrades, but if they occurred at all, that -they would be in connection with separate unities that did not want -continuity or place in a series emphasized at the expense of their -individuality. All this we might expect from the experiments alone, -although whether such a refinement would have got into architecture -seems questionable. Moreover, the question whether a symmetrical -group of units needs a less heavy end to finish it than a group of -the equidistant type is even more difficult to illustrate. Although -the two types may be given under some conditions in experiments, in -actual architecture they never appear so, for the two types never -appear in the same buildings allowing them to be compared. Besides, few -photographs are taken exactly in front, and no two at just the same -angle. Any accurate measurement of such end piers and any comparison -of them is out of the question in the present methods of research. - -One other question may be considered here. Does a series ever occur in -which three units are repeated regularly, instead of one or two? In -experiments we discovered that the subject found it impossible to feel -repetitions of three in a series, and the only way that such a series -was tolerable was when the three could be grouped somehow into one or -two units. Therefore we should not expect to find such repetitions -frequently, if at all. - -To sum up: Do series always end with a heavier unit? Are units equally -distant from each other more adapted to continuous or run-on railings, -while units with symmetrical arrangements within themselves are found -more often where separateness of objects enclosed is more aimed at than -their connection? Is a less heavy end found after symmetrical series -than after the other kind? Are repetitions of three units used at all, -and if so in what way? - -Obviously the only illustrations of these questions will be found -in the arrangement of posts and pillars in balustrades of whatever -description. In these cases alone do we find repeated series, with -repetitions within the unit, as well as of the unit as a whole. The -following examples have been taken by looking over about one thousand -photographs and by recording every instance that occurred. - - 100 _Examples_ - - A. 73 Continuous Railings: Balustrades across façades; around roofs; up - flights of stairs; around towers and baptisteries. - - I. 57 Rhythmic Units: - a. 31 Even numbers of units in group. Support arches 5. - b. 26 Odd number of units in group. - 11 Support even number of arches. - 6 More than eight units in group. - 1 Two sections of railing. Odd number in ends, decoration - in centre section to emphasize symmetry. - 4 No grouping. Too many to count. - 4 Other reasons not assignable. - - II. 16 Symmetrical units: Slabs with carved reliefs or plain; Carved - scroll or diamond designs alternating with posts; Heraldic - designs on shields; - Conventional decorations in stone or wrought iron. - - B. 27 Detached enclosures: Separate windows and doors. - I. 4 Symmetrical units: - II. 23 Rhythmic unit-groups. - a. 10 Odd number of units in group. - b. 11 Even number of units in group. - 4 Support odd number of arches. - 4 Although before separate windows make a continuous row - across the side of the building. - 2 Three sections of railing. Odd number in ends, even in - centre section to emphasize symmetry. - 1 No reason assignable. - c. Indefinite number in group. Iron bars in railings, and slender - pillars on façade. - - C. 8 Do not end on the heaviest unit. - - D. No cases of regular repetition of three units. - -Having 100 illustrations of repetitions of groups, with units repeated -equidistantly between them, and of elements distinctly symmetrical, -several new factors came to light. In all the one thousand photographs -looked over, not a single instance was found of unit-groups with the -units within, arranged at other than equal distances. There were many -variations in the number of units in the groups; but the number being -given, the units were arranged at equal distances from each other -wherever the effect desired was of detached sections or of continued -series. There are obvious structural reasons for this. Any repetition -of groups for a balustrade or protective railing, which is the almost -exclusive use of this variety of repetition, would be weakened by wider -apertures on either side of the centre. A reasonably enclosed space -is necessary to make the railing of value, therefore the specifically -symmetrical unit as opposed to the rhythmic unit was found always -in carvings, scrolls, bas-reliefs, etc., alternating with vertical -supports. We should expect, then, in general, that in railings where -an aspect of continuity of progress along some border or a tendency -to go around an enclosure was sought, the units would be rhythmic -in character, impelling one to motion and to carrying the eye and -general organism out of repose into movement. We should expect, on -the contrary, that symmetrical units would be found where repose or -partial distinctness of the separate elements enclosed was desired, and -where the attention was not to be carried away in so marked a degree. -Seventy-three of the one hundred illustrations were of balustrades -where the rhythmic factor was presumably aimed at. - -The Rathaus at Braunschweig had a symmetrical design alternately -occurring, but with four in a section, so that the section as a whole -was not symmetrical and the attention was driven on, and in the other -cases some other effect than rhythm was obviously aimed at. The genius -of the structures was heavy and massive and the balustrade made in -keeping with them, since an effect of motion or rhythm would have -clashed with the spirit of the whole. - -These examples have all been of the balustrades around enclosures, -balconies, etc. Since the rhythmic unit has been found more fitting for -them, we should expect, conversely, that in front of separate unities, -such as windows, doors, etc., the symmetrical unit would be more in -evidence. At first sight, the facts do not seem to bear us out in -this. Of twenty-seven examples of separate windows, doors, and gates -enclosed by railings, only four had distinctly symmetrical designs. -(Casa Palladio, Bergamo Chapel, Petit Trianon.) These are wrought-iron -designs in the centre with repeated rods on each side, or a row of six -pillars with the central two larger and more decorated. Twenty-three, -however, remain to be accounted for, and the solution of the difficulty -is observed at once in the distinction between _odd and even_ numbers. -As was previously suggested there are obvious difficulties in having -posts in a balustrade at any but equal distances, since the gaps -left by unequal distances from the centre would destroy their reason -for being. This difficulty can easily be overcome in wrought iron by -extra central decoration, although it is not always done by any means; -but in stone balustrades, unless there is carved open-work, or solid -reliefs, there is no other choice than repeated posts, either divided -into sections or continuous, and no variation is possible except to -have an even or odd number of them. We should then expect that there -would be an odd number in separate detached enclosures, bringing a post -in the centre to emphasize the balance, while in a continuous series -each group would have an even number, thus giving no centre to fixate -upon, but driving the attention on without repose at any one point more -than another. It might seem doubtful that any such refinement should -have been actually expressed in architecture, but examination of these -examples shows this treatment to be very general. Of the twenty-three -examples of separate enclosed details, eleven have an odd number of -posts. Of the ten that remain, _four_ are examples of windows along the -side of a building, with separate detachments of balustrade in front -of each. By having an even number of group-units the continuity of -the row is maintained in spite of a separation of the sections. _Two_ -of the ten are sections of balustrade over the central doorway of a -building. These balustrades are divided into three sections, of which -the centre is widest and the ends only half as wide. Thus, although -there are six posts in the central section, the balustrade as a whole -is distinctly divided into a bilateral symmetrical arrangement. _Three_ -of the others have an even number of pillars, but they support an odd -number of arches; and the arch, not the pillar, is taken as the unit -of the repeated series. (Arches will be discussed later.) The _one_ -example unaccounted for represents a number of possible cases, where -for some reason, following out a general scheme of building, or what -not, the odd number is not insisted upon for separate clusters. But the -fact that only one out of twenty-three is thus unexplained shows an -unmistakeable tendency in the other direction. - -A distinction between odd and even numbers cannot be felt above eight -repetitions without actual counting, and often not even then. - -The two final exceptions are of a gate and a decoration over a door -(Fontainebleau, Piacenza) where there are nine or more units in the -group. It is impossible to feel the system of this arrangement, and -the result is proportionately confusing. A reservation must be made -here concerning iron railings. There is no discrimination between odd -and even in the number of iron rods in a section of railing and no -tendency to symmetrical designs rather than rhythmic before detached -enclosures. This is because from the nature of the case, there is no -distinction possible between odd and even in the number of slender iron -rods necessary to enclose a space with any security. There must of -necessity be so many of them that the difference cannot be perceived, -and so slight is the importance of each rod that the effect is more -of a variegated surface than of actual beats of a rhythm. As soon as -iron is wrought into large enough shapes, each repeated detail is of -the same importance as in stone, but the slender rods commonly used -in iron railings, although their repetition is rhythmic like all the -others, give too slight a motor impulse to carry the attention past the -heavy limits of whatever they enclose. They are found in front of many -windows, but on account of the lightness of their rhythm compared with -the solidity of limiting piers, no confusion results. - -Having thus concluded that the odd numbers of units in groups is -more adapted for separate enclosures, is the opposite true? In the -continuous balustrade, previously discussed, are the units of groups -made up of an even number of elements? Of the fifty-seven examples -cited of continuous railings, thirty-one have an even number of posts -in their groups. These conform to the rule: but what will explain the -twenty-six remaining? It will be noticed that _six_ of these have too -many in a group for the eye to perceive any difference between odd -and even, since they range from nine to thirteen. When so many units -are in a group, the effect is always of the run-on type, whether the -actual number turns out to be odd or even on subsequent count. _One_ -has a balustrade with only two sections on a side, each side of the -centre door. Seven are in each section, and since the appearance of -a symmetrical whole is the desired effect, an odd number is more in -keeping than an even; in fact, this example, Monte Berico, might -better come under the other head of separate enclosures, although it -partakes of the character of both. Another balustrade with three in a -section (Blois Château) is so heavy and massive in all its parts that -fixity and solidity is more in keeping with it than rhythm. _Eleven_ of -them, that is, the larger proportion of all those with an odd number -of pillars in a section, support arches, and the arch is taken as the -unit instead of the separate pillar; and we find an even number of -arch-units in each section, which is what we should have expected. It -is a noticeable fact, which was previously suggested in connection -with separate enclosures, that when a row of pillars supports a plain -lintel, the _pillar_ is taken as the unit of repetition. (When the -row is on the front of a building, temple, etc., the _opening_ may be -the unit, if the _purpose_ of the central door or the fact of _going -through_ is in the mind: but when the series stands for itself, the -_pillar_ is the unit.) When pillars support arches, the _arch_ is the -unit, unless it is very narrow as in the Moorish style, when the pillar -is often so high and the arch so narrow in comparison that its value is -weakened. - -Of the thirty-one balustrades with an even number of parts in a -section, four sets of pillars bear arches, and make an odd number of -them. This would seem to make an exception to the rule were they not -so narrow in two cases that the pillar was still the unit, and in the -other two the motif of the arch was built around the intervening piers, -so that they did not seem divided into sections at all, but continuous. - -We have thus surveyed the whole field of repetitions of rhythmic and -symmetrical units, and their difference in treatment according to -the end they serve, and the results bear out our expectations. The -symmetrical unit, as exemplified chiefly by an odd number of units in -groups, is more used for detached enclosures; and the rhythmic type, -with even numbers, is used more especially for continuous ones. In -the former case the motor tendency is toward the central balance, -while in the latter it is driven on out of itself through the series. -When pillars support arches, the arch is the unit; when they support -lintels, the pillars themselves remain the unit. Any number of units -over eight loses its value of odd or even, since the difference can no -longer be perceived and becomes rhythmic whether odd or even. - -It must not be supposed that these rules are inevitably carried out or -that the effect is necessarily poor if they are not. It shows a general -æsthetic demand, however, which in individual cases may be modified by -other demands, or altered in parts to make a more unified whole. When, -however, the series is taken for itself, and judged entirely on its own -merits, these conclusions will be found generally valid. - -We have still to consider whether series always end with a heavy unit. -All the series examined _do_ end in this way; in fact we feel the -necessity of this so clearly that one illustration would be as good as -a hundred. But there is a difference in the use of the end unit, which -is noticeable in any two series of symmetrical and rhythmic units. Of -the sixteen examples of continuous series whose units were distinctly -symmetrical instead of rhythmic, eight of them, although ending on -supports, do not end on the principal unit of the series. This can be -best shown by one or two examples. The Orvieto Cathedral has on the -façade a balustrade of rectangular reliefs alternating with supports. -The reliefs are undoubtedly the more interesting and important element -of the series, yet the series ends with the less important element, the -support or post, and we feel that it must do so. The Palazzo Contarini -has a balustrade on its façade in which carved wheel-like designs -alternate with supports which come at the ends. Why, in these cases, -do we feel it as inevitable that the heavier and more important unit -should _not_ come at the end, as with rhythmic units we feel that they -should? The answer to this is partly structural and partly æsthetic. -We must feel, first of all, that the series is properly supported, -that it will not fall away at the ends or down in the middle, and for -this reason support of some kind must come at the end to hold it up -and give a feeling of solidity and stability. But why are not these -supports made the more interesting and important unit so that they -might still bear up the superstructure and end the series as well? Here -the æsthetic demand appears. As soon as the object is regarded as an -æsthetic unity and care put upon it to make it beautiful for its own -sake, it must not be thought of as the _end_ of any series. It must -be cut off from the rest of the world by supports or framed in some -way, and while it still may have a place in a series, provided it is -sufficiently conventionalized and not too important in itself, it must -not be thought of as either ending or beginning, as depending on a -series to give it importance, or lending support to anything else. It -simply exists, cut off from the world, even though in the balustrade -not an integral part of it, and one ought to be able to remove it -without affecting the stability of the structure. - -The question whether series of symmetrical units have less heavy ends -to finish them than series of rhythmic units cannot be settled by -these methods of analysis. While it seems certain that the rhythmic -series drives the attention on by its greater motor activity, and hence -would need more of an end to stop it, so many other factors enter in -of more importance, such exact measurements would be necessary (quite -impossible with the photographs of the scale here used), the refinement -would be so great, since the stone of which most of the examples are -made, by its own weight supplies a check to rhythmic activity, all -these considerations make it impossible to illustrate this conclusion -and it must remain an experimental result alone. - -There remains one question: Is regular repetition of three units ever -found? They may be in combination of some kind so that they fall into a -rhythm of twos, but are they ever found repeated as three separate and -distinct units? The answer to this is without exception. Of the five -thousand photographs analyzed, not one instance of this kind of series -was found. In many cloisters the pillars are of different design, and -often one design is repeated through an otherwise varying series, but -their repetition is either without scheme of any kind, or in some -combination that falls into a rhythm of twos. No three-rhythm has been -used in art, any more than it has been found possible in experiments. - - -ARCHES - -It has been noticed in the preceding discussion that when a series -of pillars supports arches, the arch, not the pillar, is taken as -the unit. If this is so, it would seem that the arch by binding two -pillars together with a curve awakens a more vigorous response than the -vertical line of the pillars, and this greater expenditure of activity -makes it to be taken as the element of repetition. It suggested that -the arch (like the rhythmic unit) tends to drive attention on out of -one unit to the next in the series. The outward thrust of the arch -arouses an outward-tending activity, and for this reason a row of -_arches_ would need, to give a finished, stable effect, a wider and -heavier embankment at the end than a series of lintels. The experiments -on this point were inconclusive owing to the difficulty of obtaining a -series of arches and of lintels which should be comparable in size. -For this reason the validity of this suggestion must depend upon the -actual treatment of arches in architecture. It would seem that the -arch would, like the rhythmic unit, be more appropriate for continuous -series than for detached short rows; or if the series were short, the -ends should be treated in some way, by reduction in size, change in -width of pillar, pier, or decoration, so that the outward-activity -might be counteracted by some inward thrust or some accentuation of -the centre. Thus the unity or balance of the series as a whole would -prevent the arches from seeming to "run away" which they might appear -to do without such treatment. We shall, then, look through photographs -of buildings where arches are used, to find if their treatment carries -out the supposition. - -It may be seen at once that such a treatment of arches differs from -the arrangement necessary to make plain lintels effective. The pillars -on the front of Greek temples were indeed slightly farther apart at -the middle entrance, and the centre was moreover further accented by -the point of the pediment. But on the sides the rows of from thirteen -to sixteen columns had equal interspace and no noticeably heavier -columns or embankment of any kind at the ends, for none was necessary. -The series appeared ended whenever it stopped, and did not carry the -attention over, nor demand some finish to "hold it down," as does the -arch. The pillars, to be sure, completely surrounded the temple, and so -were, in name, continuous. But on a building with square corners, the -other sides do not carry the series on to the eye (with variations in -foreshortening of the ends) as in a circular structure, and the effect -of continuity is not immediate. - -Many examples might be given of buildings with pillars and lintels -on the façade, which have no visible modifications of central or end -columns to give balance or symmetry to the whole, and yet which are -perfectly satisfactory as repeated series and do not demand either -such treatment or further continuation, but are complete and finished: -London, Trafalgar Square; Rome, Pantheon; Vienna, St. Karl, Barrome -Kirche; Berlin, Schillerplatz, etc. These have the centre accented by -the superstructure, but there is no discernible modification of the -series itself. - -Examples might be multiplied, but there are sufficient to illustrate -the essential stability of repeated vertical units and to contract them -with the outward-tending, run-on effect of arches which need various -kinds of treatments to finish a series. - - 165 _Arch Series._ - - A. 45 Go completely around exteriors: Colosseum, arenas, baptisteries, - towers, cloisters, courts, basilicas, tombs. - - 59 _Series that end:_ - - B. I. 30 Central arch largest: triumphal arches, doors and windows on - façades of churches. - II. 1 Central arch smallest: doors on Peterborough Cathedral. - III. 4 End arches larger: windows or decorative arches on the walls - of buildings. - IV. 6 End arches smaller: windows, decorative arches, or arches - halfway around a court. - V. 6 Arches go obliquely into higher central point and back: - decorative arches running into the pointed roof on - Romanesque façades. - VI. 6 Central arch accented by decoration: windows and gates. - VII. 6 End arches in different planes: doors on façades of - buildings or in gates. - - C. 20 Arches go around interiors: up naves and across the apse of - churches, halls, and loggias. - - D. 27 Around the outside of porches, apses, etc.; diminish in size - at ends; are carried on in the transepts; motif is carried on, - although whole arch is not; end arches are closed, or centres - decorated. - - 7 _Good_ - - E. 14 Other arrangements: Roman aqueducts (endless); interlacing - arches; filled with statues; finished by gables or turrets; - bridges (land on each side a sufficient embankment); arches - included in large ones. - - 7 _Poor_ - - Series not sufficiently finished at the ends; only two arches - in series; three arches, with first arch different from the - others. - -Of one hundred and sixty-five examples of such series examined, only -seven do not conform to the principles we have considered, and these -are proportionately unsatisfactory. Forty-five illustrate buildings -where the arches go completely around the outside of a structure, -so that the series instead of requiring an end simply runs into -itself again. It will be noticed further, that unlike series of -columns around rectangular Greek temples, these are around circular -structures where the series does not change its direction suddenly -but by degrees. With the exception of courts and cloisters where the -observer stands within and sees the whole series, these are all around -domes, baptisteries, etc., where the end arches in the field at any -one point of view are seen in perspective gradually fading off and -yet leading attention on around the building. There may indeed be -arches which go across square-cornered buildings or even around them, -but in these cases some other device is necessary to make each side -a finished series in itself. The mere fact of its continuance around -a corner where it cannot be seen from the same point of view is not -enough. (These various arrangements of arches on a flat façade will be -taken up later.) Rows of arches are often used around towers square -as well as round, but towers from their very shape and size allow the -observer to see different sides from nearly the same point of view, -so the series is not broken up into sections on different sides of -the tower as it is in a larger building. Twenty more examples are of -arches in interiors and are all of arches down a nave, with either a -regular arch or an arch motif carried across the apse. It might be -supposed that an arrangement of arches in an interior would be more -difficult than on an exterior surface, since the genius of an arch -is its outward thrust and its tendency to run on. Without careful -treatment it would spoil the interior by trying to overstep its bounds; -by making certain walls look wider than others; the arched sections -utterly discrete in general character from the plain or otherwise -decorated section. In point of fact, the use of the arch-series in -interiors is quite conventionalized, and all the illustrations are of -loggias, or of churches where the arch goes down the nave and in a -more or less modified form across the apse. In the Sistine Chapel the -arched windows go down the side walls and across the end in a vaulted -double-arch. In some cases a series of Roman arches down the nave has -a more or less pointed arch across the apse, but in every case the -continuity has been kept in some way so that the series is unbroken. -Moreover the columns in the cathedral naves are often so high and the -arches so proportionally narrow that the pillar instead of the arch is -taken as the unit. This is somewhat true in St. Mark, Venice, also in -St. Sophia, Constantinople, where the large arches are divided into -sections of seven smaller ones, each one of which is so narrow that the -pillar is felt as the repeated unit instead of the arch; or if the arch -be taken, the narrow span prevents it from too great outward thrust. - -Thirty of the arch-series are on façades of buildings or in structures -by themselves, as gates and triumphal arches, where the central arch -is larger than the other, thereby emphasizing the middle point and -drawing attention to it away from the ends. This centralizing a series -or balancing it as a whole may be accomplished in various ways. Two -examples make the central arch larger instead of smaller. Six make the -end arches smaller while four make them larger. It will be readily -seen that just which one of these variations is chosen for the series -depends on the function of the series. The central arch is wider, with -only one exception, when the series is of arched doors and the central -door is the main entrance; while the end arches are more apt to be -varied when the series is purely decorative and serves no function. -The central balance may be further gained by differences of level. -In the decorations of many façades, especially the early Romanesque, -rows of arches go obliquely into the point of the roof and by this -strong pointing toward the centre create an inward tendency. Six of -the illustrations have the central arch accented by decoration; seven -have heavier piers around the central and end arches; six have the end -arches brought out into a nearer plane which effectually finishes the -series. All these examples illustrate the necessary disposition of -arches on a flat wall or façade where the series in the field of vision -must end suddenly, that is, cannot gradually fade away around a corner. -The variety and yet invariability of these devices shows the need felt -for some finish at the end, some balance of the whole with the central -accent, which need, apparently, is not felt for pillars and lintels. - -When the arch-series is on a circular structure, such as apses, -porches, and the like, even when it does not entirely surround it, as -an arena or spire, the regular diminishing of the series on either -side, owing to the curve, supplies the finish necessary, and the size -and arrangement of the arches need not vary otherwise. Twelve of the -examples illustrate such a use of the arch, and although in some cases, -Morano Cathedral, Nomantala Church, the arches are continued into the -transepts gradually tapering in size, or are modified in size growing -narrower from the centre, as in the Bergamo Church, such a treatment -is not necessary for finished effect. The difference in proportion -resulting from a curved series, or even on arches carried around a -square corner (as in porches on Goslar and Braunschweig Rathäuser), -where the series is open enough to clearly see its continuity as it -runs into the main building, will suffice to make a series finished -without modifications of the arch-units. - -There are many instances of long rows of very narrow arches on -cathedral façades which are too narrow to give outward tendency, or -else they have statues within them which really take the attention -and form a series of vertical units in place of the arches. There -is also the common device of interlacing arches, where a supporting -pillar of another arch stands in the centre of every arch, thereby -always driving the attention backward and restraining it. Perhaps the -natural outward tendency of the arch-series and the necessity for its -limitation can be seen by violations of the principle. Seven of the -examples do not conform to any application of this rule and the results -are not satisfactory so far as the mere series itself is concerned. -Over the right and left doors of the Piacenza Cathedral are sections -of nine arches which end abruptly and do not even meet each other. -The Fredericksborg Schloss at Copenhagen has a row of fifteen arches -enclosing a court. These run into wings on each side, to be sure, but -all seen at once as they are and without central or end modification -they are too sharply cut off and inclined to overstep their limits. The -Loggia dei Lanzi at Florence, with its three wide arches and narrow -pillars, the William Tell Chapel in Switzerland, with only two arches, -illustrate forcibly the tendency of an arch to move outward, to appear -too wide for the superstructure and too "active" unless bound down in -some way. Four arches on the right and left of the façade of Marmonte -Church, but not across the centre, have the same unfinished effect. The -roman arch on one side of the St. Lo Cathedral façade with two gothic -arches on the other defy every principle of repetition and symmetry as -well. - -From this survey of one hundred and sixty-five of arch-series we find -through a variety of means a uniformity of purpose in their treatment; -that all point to a common demand, however differently expressed, -according to the function of the series. The series must be prevented -from "running away." It must either run completely around a structure -into itself, or be balanced as a whole so that the attention which -naturally runs off the ends is driven towards the centre. This may be -accomplished by enlarging, decreasing, decorating, or pointing toward -centre of the arch by means of the obliquity of both halves of the -series. It may also be brought by enlarging, decreasing, changing the -plane of the end arches or altering the size of the limiting piers. The -essential value of the arch may be altered by narrowing it, by filling -it with something more important than itself, thereby making it only an -attendant series upon its content, by interlacing it, or by any device -that transforms or revises its outward tendency. - - 165 _Examples of Arch-Series._ - - 45 Go around outside a circular structure. - 32 Go around interior and apses. - 30 Central arch largest. - 2 Central arch smallest. - 4 Ends largest. - 6 Ends smallest. - 6 Central arch accented by decoration. - 6 Central arch accented by upward incline of two halves. - 6 Ends in different planes. - 7 Different width of piers around centre and ends. - 5 Very narrow arches. - 9 Other reasons. - 7 Unaccounted for. - -The question discussed in the experiments, as to whether narrower -interspacing was required between units decorated toward the centre, -and units blank, or covered entirely with non-centrally accented -decoration, could not be taken up in the latter analysis. To settle -such a point, illustrations would have to be found of blank and -decorated units of the same shape and size, in the same structure, and -their relative interspacing compared. But no such examples were found, -where the spacing was not regulated by some obvious structural reason -other than pure pleasure in the repetition. This must stand, therefore, -solely as an experimental result. - -The use made of difference in plane or end, to facilitate two series -being taken along together, whereas they would be fatiguing if the -same in those respects, has been touched upon in the discussion of -statues and bas-reliefs, and other series of more complicated units. -Where the unit and alternate are both rich and significant, and would -tire the observer by following each other at the distances they are -obliged to be in a series, a slight difference in plane relieves the -situation, and is used largely in monuments, fountains, pulpits, and -such structures. - -Many other questions have come up in the investigation which might be -discussed in the same manner as the preceding, but can only be hinted -at in conclusion: - -Just what factors make an element and its alternate congruous? What -is the exact relation of lines, which makes the scroll decoration in -a balustrade alternate satisfactorily with an upright support, while -the alternation of the arches in the Colosseum with the Greek pillars -between them is incongruous? - -In what does the pleasure in repeated series differ, when the observer -is not certain just what is the repeated element? May there be a bare -rhythmic pleasure, when the series is too far away to distinguish -what the elements are, or when they run together, so that no definite -demarcation is felt between them? Do such series excite a pleasure of -repetition without content as to elements, and does it differ from mere -variation and contrast? - -The series of unsymmetrical units was found in the experiments to have -a peculiarly unstable run-on effect similar to that of rhythmic units -and of arches. Are they used in the same kind of cases as the others -were, when a particularly active effect is desired? - -Must a space be wholly enclosed, to be taken as a unit? - -In a series of projections along a wall, the _projections_ are taken as -the unit, even when they almost meet at the top of the alternate space. -When they actually do meet at the top, the enclosed space becomes the -unit instead. - -These questions and others similar might be experimented upon, and -examples of their treatment analyzed, as in the previous questions -discussed. - -[Illustration: PLATE V.] - -FOOTNOTES: - -[Footnote 86: Stratton: Eye-Movements and Æsthetics of Visual Forms, -Philosophische Studien, vol. 20, p. 350, 1902.] - -[Footnote 87: MacDougall: Structure of Simple Rhythm Forms, Harvard -Psych. Studies, vol. 1, p. 321, 1903.] - -[Footnote 88: MacDougall: Structure of Simple Rhythm Forms, _ibid._ p. -322.] - -[Footnote 89: MacDougall: Structure of Simple Rhythm Forms, _ibid._ p. -322.] - -[Footnote 90: MacDougall: Structure of Simple Rhythm Forms, p. 325.] - -[Footnote 91: Bolton: American Journal of Psychology, p. 223, 1894.] - -[Footnote 92: Külpe: Outlines of Psychology, p. 395.] - -[Footnote 93: MacDougall: Structure of Simple Rhythm Forms, p. 348.] - -[Footnote 94: MacDougall: Structure of Simple Rhythm Forms, p. 349.] - -[Footnote 95: Stetson: Rhythm and Rhyme, Harvard Psychological Studies, -vol. 1, p. 455, 1903.] - -[Footnote 96: Stetson: Rhythm and Rhyme, Harvard Psychological Studies, -vol. 1, p. 455, 1903.] - -[Footnote 97: MacDougall: Structure of Simple Rhythm Forms, p. 377.] - -[Footnote 98: Perrot and Chipiez: Art in Ancient Egypt, p. 100.] - -[Footnote 99: Perrot and Chipiez: Art in Assyria and Chaldea, p. 126.] - -[Footnote 100: Perrot and Chipiez: Art in Persia.] - - - - -THE FEELING-VALUE OF UNMUSICAL TONE-INTERVALS - -BY L. E. EMERSON - - -Modern theories of melody start always with the presupposition that the -scale must be composed of tones having the simple mathematical relation -to one another of 2, 3, 4, 5, 6 (and by Meyer 7) and their multiples -in order to give pleasant combinations of successive tones. But the -question arises whether other tone-combinations which given together -appear disharmonious may not, by their mere acoustical difference, -similarity, and contrast, awake definite feelings of pleasure. And -if such feeling-tones exist independently from harmony it is evident -that they would enter into every melody in addition to the strictly -musical feelings of harmony and that they deserve consideration as a -factor of music. It would not even appear impossible that if every -successive tone-distance has its particular natural feeling-character, -the distances of successive harmonious tones might be only through -secondary factors as habit and training preëminent among the various -possibilities of combinations. A tone-consciousness, which under the -guidance of experiences of harmony has been trained in our musical -tone-relations, must give instinctive preference to such successions -as our melodies offer. But if we artificially inhibit the conscious -relation to our musical system by introducing a continuous tone-series, -or at least one of steps much smaller than musical intervals, do -we destroy the possibility of pleasure, and if not, do we find the -pleasure in the musical interval stronger than that in other instances? -That even the musical subject introduced into the realm of smallest -tone-steps can easily forget and inhibit his normal standards is well -known; the whole acoustical perspective seems changed by the new -intervals, and the subject begins at once to build up a new temporary -system of relations. The experiments in Wundt's laboratory have shown -that in such cases the theoretical judgment of distances is indeed -quite different from the standardized one; the octave may appear -equal to the higher fifth. I wanted to study in a similar way the -feeling-value in such a state of musical disorientation, when all -imaginative representations of our musical intervals are inhibited. - -The instrument I used was an Appun Tonmesser giving reed-tones from 128 -to 512 vibrations in intervals of 4 vibrations between adjacent tones. -The intervals with which I experimented varied from 4 to 88 vibrations -in steps of 4. The observers were all experimental psychologists, and -varied in musical discrimination from a very low to a very high degree -of natural ability and skill. - -The observer reported his pleasure in the progression given, in the -traditional grades of 1 to 7, where 1 represents the greatest degree -of pleasure, 2 means very pleasant, 3 pleasant, 4 indifferent, 5 -unpleasant, 6 very unpleasant, and 7 most unpleasant of all. - -The immediate problem was: What is the relation between the width of -interval used and the pleasure got by hearing the motive _a-b-a_ and -_b-a-b_, where _a_ is always the lower tone. The method of procedure -was to take a fixed tone (460 vibrations in the first case) and get -a series of observations on successive progressions _b-a-b_ where -_a_ differed from _b_ by 4, 8, 12 ... 56 vibrations. The greatest -difference thus is approximately a musical whole tone. Then a series of -observations was taken on _a-b-a_ where _a_ similarly differed from _b_ -by 4, 8, 12 ... 52 vibrations. The progressions were given in irregular -order, that there might be no chance of the observer getting into a -fixed habit of replying. The intimate relation between the pleasure -in successive musical tones and the pleasure in musical harmonies -suggested naturally the question whether the feeling-value of these -unmusical progressions was not somehow dependent upon the affective -character of the simultaneous presentation of the same tones. Therefore -after a progression had been given once and judgment recorded, the -two tones used were given as a "harmony," that is simultaneously, -and a judgment taken as to its agreeableness. This was immediately -followed by the same progression, thus giving opportunity to observe -the relation between the feeling-tone of the interval as it appeared in -successive and in simultaneous presentation. - -The results of this part of the investigation are graphically -represented in the following plates. Tables I and II indicate the -feeling-value of _a-b-a_ where _a_, the lower tone, is 460 vibrations, -and _b_ is from 4 to 56 vibrations in addition, and the feeling-value -of _b-a-b_ where _b_, the higher tone, is 460 vibrations and _a_ is -from 4 to 56 vibrations less. - -[Illustration: PLATE VI.] - -The base-lines from which the vertical lines to the curves are drawn -represent the feeling-tone 4, the indifference-point. Above comes 3, -2, 1 and below 5, 6, 7; each square represents a unit. The horizontal -abscissæ represent the width of the interval; the arrows indicate the -musical intervals. The observers are given by initials. The first -evident fact for both average curves of Plate V is that the maximum -pleasure does not coincide with a musical interval, but comes with an -interval four or eight vibrations less than either the half or the full -tone of the musical scale. While in both cases the first elevation -of the curve comes before the semi-tone, _b-a-b_ shows a decrease of -pleasure as the whole step is approached while _a-b-a_ rises again. The -order _a-b-a_ is liked better than _b-a-b_. - -Plate VI gives the "harmony" curve for the same tone-combinations, and -it is clear at the first glance that the curves for the simultaneous -tones do not correspond to those for the successive ones; in many -respects they are directly the opposite. The hypothesis that the -pleasure in such an amusical "melody" results from the resolution -of the corresponding "harmony" is thus untenable; both are highly -independent of each other. Yet, here too we notice the insignificance -of the musical interval, while the strong pleasure in the tones -different by 4 vibrations only refers probably to the complete fusion -of the tones; there arises a direct enjoyment from the four waves of -sound in every second, given by the beats. The pleasure-curve of these -simultaneous tones indicates of course that the inhibition of the -musical dispositions and expressions holds over from the successive to -the simultaneous series. The pleasure is thus clearly different from -that in real harmony. - -Plate VII finally gives the "melody" curve for _aba_ and _bab_ with -changes from four to four vibrations when the interval started with is -larger than a full musical step. In _aba_ the _a_ is 384 vibrations -and _b_ varies from 436 to 516, the variations lying thus between the -musical Second and the musical Fourth. It is evident that here again no -feeling-preference is given to the musical intervals. - -The question arises whether such small tone-intervals of amusical -character allow the construction of more complex combinations of -æsthetic value. Can we have amusical micromelodies with their own -completeness and feeling of end? The following experiments represent a -first step into this field. We used three tones only, _a, b, c_ in 26 -different combinations, and each of the 26 variations with intervals of -4, 8 and 12 vibrations between _a-b_ and _b-c_. Each of the resulting -78 "melodies" was given repeatedly to six subjects in a time-order -which allowed one second for each tone. The subject had to judge on -the pleasantness of the whole progression and had further to judge -whether it produced a feeling of end or not. - -The combinations followed in the experiments in this order: _abc_, -_cbabc_, _abcb_, _cba_, _abcba_, _cbab_, _bcba_, _cbabcb_, _ababc_, -_babc_, _abcbab_, _babcba_, _cbcba_, _bcbabc_, _abca_, _acba_, _acb_, -_cbac_, _abcab_, _cabc_, _cbacb_, _acbab_, _cab_, _bca_, _cabcb_, -_bac_. The lowest tone was varied between 200 and 444 vibrations; _b_ -and _c_ were thus always still less distant than the next musical -tone. The chief results may be shortly characterized as follows. -There are hardly any judgments of indifference, the combinations are -always decidedly pleasing or unpleasing. Of course a certain training -in the apperception of such small-interval melodies preceded the -real experiments and produced an attitude of adjustment to amusical -relation. If we are in the midst of musical tone-relations and go -over directly to such miniature intervals, we are seeking for the -fulfilment of the habitual expectation and feel dissatisfied, or in -the best case the procession is an indifferent chance combination. -But as soon as a certain training with small intervals has inhibited -the strictly musical expectations, a new setting of judgments with -new standards comes in and a new source of pleasantness is opened. -Of course even then no extreme feelings are to be expected; while -the indifference-judgment 4 is lacking, the strong pleasure and -displeasure, the judgments 1 and 7 are completely lacking too; three -fourths of the judgments are 3 and 5. The pleasantness is decidedly -more frequent than the unpleasantness, and this relation increases -with the interval. The differences of four vibrations were especially -with the higher tones hardly distinct for some of the subjects. Among -288 judgments in each group there were 150 pleasant and 138 unpleasant -when the distances between _a-b_ and _b-c_ were four vibrations, 208 -pleasant and 80 unpleasant when the distances were 8 vibrations, and -226 pleasant and 64 unpleasant when the distances were 12 vibrations. - -The order of pleasantness expressed by the fraction of judgments of -pleasantness and unpleasantness is the following: the largest number of -pleasant feelings belonged to the figures _cbab_ and _bac_, immediately -followed by _abcb;_ the further order downwards in affective value was: -_cab_, _cbac_, _babc_, _abca_, _cbcba_, _ababc_, _abc_, _cabc_, _acba_, -_cbabcb_, _bcba_, _acb_, _abcba_, _cba_, _cbabc_, _abcab_, _babcba_, -_cbacb_, _acbab_, _bcbabc_, _abcbab_, and _cabcb_ as least pleasant. - -[Illustration: PLATE VII.] - -As to the feeling of end or æsthetic completeness the results are -similar and yet independent. In a few cases the answer was "doubtful," -but in the overwhelming majority a definite reply was given; and -while the judgment of completeness was by far more frequent in the -pleasant combinations than in the unpleasant ones, yet often the -unpleasant processions appeared as complete and the pleasant ones -as incomplete. Here again the feeling of completeness grows with -the interval, being smallest for the figures with distances of four -vibrations. But most characteristic seems the fact that the feeling -of end is in no way as in music dependent upon the return to the -starting-point. The combinations which involved such return to the -"tonica" show in no way a preponderance of judgments of completeness. -If we order the results according to the number of this æsthetic factor -the figures _acba_, _cbac_, and _cabc_ stand very low, giving in the -majority of cases the suggestion of not-completeness in spite of their -return to the beginning, while the figures of the type _abcb_, _cbab_, -or _cba_, or even the complex _babcba_, suggest in a majority of -judgments the feeling of an end. The feeling of an end comes, according -to the subjective reports of the observers, with an "internal unity of -meaning" of the phrase given. This unity of meaning is here evidently -quite independent from any simple mathematical relation. - -The music-like quality of the figures was emphasized frequently in -the subjective records. "I just enjoyed the progressions as music." -"The elements are the same as in music." A melody of 384, 392, 400 -was called a "very mournful strain"; 444, 452, 460 "Wagnerian motive; -Tristan and Isolde"; and the same tones in another order "Very -pleasant; expressed a pathetic resignation," or "Sounds like a little -piece of music"; and so in most varied forms. - -The basis of these experiments is of course by far too slender to -build on them a theory, yet our results suggest at least a greater -interest in the æsthetics of those tone-combinations which are -excluded from our regular music. This interest is reënforced by the -self-observations of all participants. They felt strongly that after -all our musical pleasure in melody does not belong intrinsically to -the tone-perception, but is learned and acquired like the grammar of -our mother tongue. Such grammar too controls completely our internal -demands for expression, and yet the learning of a different language -can bring a new adjustment and a new set of psychophysical dispositions -for linguistic demands. That whole apparently natural demand for the -tone-combinations which give fusion and consonance can be inhibited -during the listening to amusical combinations as soon as a short -training in miniature intervals changes the acoustical perspective. - -The development of instrumental music demanded evidently the selection -of distinctly separated tones and of intervals which give harmonious -combinations. The external conditions of resonant chambers may have -reënforced this selective process of historical music. It is certainly -different with oriental nations, which produce music not in resounding -chambers but in the free air and who are singers and not players, using -instruments mostly for producing a mere body of tone as a background -against which the melodies move; their intervals appear to our musical -ear at first bizarre, and yet there too we are readjusted to the -new dispositions for satisfaction with unsuspected quickness. We -have no right to identify æsthetic pleasure in successive tones with -the pleasure in our conventional music with the simple mathematical -relations which alone give the pleasure of fusion; but being accustomed -to this system of harmonies and being trained to expect it also in the -resolved form of the melody, we need indeed an inhibition of habits and -a certain new training till the more modest pleasure in amusical tone -progressions comes to its natural right. - - - - -ASSOCIATION, APPERCEPTION ATTENTION - - - - -CERTAINTY AND ATTENTION - -BY FRANCES H. ROUSMANIERE - - -The results of the experiments on the feeling of certainty which I -have conducted fall into two divisions--those on the nature of the -feeling itself, and those on the effect of voluntarily attending to -certain aspects of a total experience upon certainty in the judgments -as to the constitution of that experience. The problems of the first -division are: Are there different kinds of certainty? In any one kind -of certainty are there degrees, and if so, are these of a limited or an -unlimited number? Can certainty be analyzed into elements? The problems -of the second division are: Can it be said that in the report of any -experience the judgments made with the highest degree of certainty will -be confined to an attended-to group, and if not, will there be more -there than elsewhere? In such a report will the direction of voluntary -attention toward certain aspects materially alter the distribution -of the judgments of the highest order of certainty over the various -aspects of any given field? - -These two divisions are so distinct in problem and result as to make -it seem best to describe them as independent experiments. As some -interesting results on the relation of error to the different grades of -certainty and to the effect of attention developed in connection with -this second division of the experiment, those results are given also. - -In general the same subjects took part throughout the experiments. -One, an instructor in Harvard University, whom I shall call K, was -not subject for the second division of the experiment. Two others, E -and H, both graduate students in Harvard University, could not serve -as subjects in an important part of the first division. Of those -remaining, B was a student in Radcliffe College, F an instructor in -Harvard University, and A, C, and D graduate students in Harvard -University. These last five were my subjects for all parts of the -experiment. - - -I. THE NATURE OF THE FEELING OF CERTAINTY - -The general method here was, of course, the method of introspection. -Situations were created about which the subject might be expected -to make judgments with different sorts or different degrees of -certainty, if such should be possible. He was then questioned as to -his experience. The method has the fault of all introspective methods, -viz., its results can in no case be verified. The results here are none -the less suggestive, and, for the second problem, at any rate, definite -enough to be convincing. - -Most of the experiments were conducted in connection with visual -fields. In working at the first problem which we have now to consider, -however, the certainty connected with the dermal sensations and that -connected with the simple reasoning process of addition were also -examined. The apparatus used consisted of three sets of cards. On -one set were pasted geometrical shapes cut from colored paper, and -black and white letters or figures. Each of these cards was shown to -a subject for a second and a half, or two seconds. After the exposure -he told what he judged to be on the card, giving all that he could -about the nature of his feeling of confidence (or certainty) for each -judgment. On the second set of cards square pieces of tin, smooth -rubber, rough rubber, cotton, felt, undressed kid, leather, eiderdown, -flannel, coarse and fine sandpaper, and pricked paper were stuck, six -on each card. The experimenter passed these cards so that these bits -of material rubbed against the forefinger of the subject, while a -curtain kept the card and the hand hidden from the subject's sight. -Here, again, the subject judged of what had been on the card, just as -he had done after seeing each of the first set of cards. Small sample -cards, each having pasted upon it a piece of one of the substances -used, were also behind the curtain, and the subject was allowed to feel -of these as much as he wished while giving his report. Such sample -cards were required because of the underdevelopment of the association -of names of any kind with the dermal sensations. A single card with -three groups of figures for addition upon it made up the third part -of the apparatus. Here the subject was asked first to add the columns -rapidly and to introspect as to his certainty of the correctness of the -different results; then to go over the addition again, and yet a third -time, and to compare his feelings of certainty in the different cases. -The introspection was developed partly through the help of questions -put by the experimenter, but in asking these questions great care was -taken to prevent their influencing the judgment of the subject. Some -observations made by the subjects during the second division of the -experiment (also conducted in connection with visual fields) are, also, -introduced here. Apart from this, the experiments on the feeling of -certainty connected with this sense of sight were greater in number -than the other experiments; and it is those that have given us most of -the data for answering the second and third problems. - -The subjects did not agree in their answers to the first problem. Some -found not only that the certainty connected with their belief in the -results of their addition seemed to be of a distinct type from that -connected immediately with the sense of sight, but also that there -were different sorts of certainty connected immediately with the sense -of sight itself. Others found but one kind of a feeling of certainty. -All agreed, however, that so far as the kind or kinds of certainty -associated with them was concerned there was no difference between -the sense of sight and the dermal senses, so that it would seem to be -true that any distinctions which are to be found within the feeling -of certainty will not be distinctions springing from the difference -in the sense-organs. Within the sense of sight, however, subjects B, -E, and F divided their feelings of certainty into two classes,--an -absolute feeling of certainty which they felt could not be shaken, -and a feeling of confidence which they would act upon but which they -felt might be shaken by questioning, and which seemed different by -more than degree from the feeling of certainty proper. Subjects A, -C, K and H found no such marked distinction between their feeling of -greatest certainty and all lesser feelings of conviction. Subject D -at one time felt that the distinction into two such distinct classes, -the definitely certain and the more wavering, fitted his experience, -and at another time said that it seemed to him that each degree of -conviction stood for an unique feeling of certainty and that any two -of them were as different from each other as any other two. A second -division of the feelings of certainty into two classes is to be found -with subjects A, F and H. This developed in connection with the -visual experiments again. The distinction here may be called one into -psychological and logical certainty. The latter rests on reasoning -either from the probable character of the field, or from a feeling -as to its general character, to the nature of some detail. We shall -notice the characteristics of these two classes later. One subject, A, -further distinguished as different the feelings of certainty connected -with the two methods of logical certainty just given. The others made -no such distinctions. In the experiment with the columns for addition -only six subjects, A, B, C, D, F, and K took part. Of these the two -who had made the distinction into psychological and logical certainty -with the visual experiments (subjects A and F) again made the same -distinction. Subject F, however, who had had occasion to do a good deal -of important work with statistics, found practically no element of -logical certainty in connection with his addition, though it seemed to -him that what confidence he felt in his result should be distinguished -from the psychological certainty he had had as to the character of -the visual fields. Subject B felt no certainty in her results except -as she could so hold the process together as to have what seemed to -her a simultaneous experience. When she had to judge of the results -of a set of successive experiences that could not be so unified, she -characterized her state of consciousness not as holding a feeling -of certainty or of uncertainty, but as simply lacking any feeling -of certainty. The other three subjects found no difference between -the feelings of certainty and uncertainty associated with visual -experiences and those associated with the process of addition. As a -whole, it seems then that we must answer our first problem by saying -that the case seems to be different with different individuals. With -some the highest grade of certainty associated with a sense-experience -is sharply distinct from the other grades, and with some again there -appear at least the two general classes of psychological and logical -certainty. On the other hand, there seem to be people for whom the -feeling of certainty has no such sharp distinctions of kind within it. - -The results as to the second problem may be more briefly and more -distinctly given. No subject found any evidence that the number of the -grades of certainty which he could distinguish would be limited by -anything except his keenness in introspection, although in the simple -tests given for the experiment, four was the greatest number of grades -distinguished at any one time. Two of the subjects (B and F), who set -the highest grade of certainty apart from the judgments made with -lesser confidence, said that there might be degrees within that higher -grade as well as among the "uncertainties." There was no evidence that -logical certainty differed from psychological in respect of the grades -to be found within it, and some evidence that they were alike in that -respect, although logical certainty was less carefully examined. It -would seem, then, that our second problem is to be answered thus: There -are degrees present in some if not in all kinds of certainty, and there -is no evidence that the number of these degrees is limited. - -It was not generally found possible to analyze the feeling of certainty -into a sum of elements, although certain characteristics seemed to be -persistent in it. Here again there is marked individual variation. The -general test used for the difference in degrees of confidence was the -question "On which judgment would you risk more?" This satisfied every -one as a true criterion for such distinctions, but subjects H and C -said that for them the feeling of certainty had a much more distinct -relation with the past than with the future. Perhaps for that reason, -subject H proposed the test "Which judgment could I be converted from -most easily and simply?" The distinctness of an image had something to -do with the feeling of certainty for subject C. Beyond this, he could -not characterize his feeling. Neither was he sure that the degree of -certainty varied exactly with the degree of distinctness. Subject D -found that all objects about which he made judgments of which he was -certain were present to his mind in the form of distinct images; but -did not feel that that covered all that was to be said of the feeling -of certainty. The number of images present, as visual and auditory, -seemed to increase the degree of certainty for him. Subject F could -give no characterization of his feeling of psychological certainty. His -feeling of logical certainty seemed to spring largely from a feeling of -consistency between the present experience and his past experiences. -With subjects A, B, and K the vividness of an image was a strong -determining factor in the degree of certainty felt in any judgment, but -again was not the whole story. Something they could not characterize -was also present for A and B, and, as well, a feeling of more or less -perfect congruence between an image and the general character of a -field. (This introspection developed in connection with the visual -experiments.) Among these eight subjects we have but one (K) who is -satisfied with reducing certainty to a set of elements. - -To my mind the most valuable thing to be gained from this division -of the experiment is the suggestion that there are definite types -of certainty, and that people may be classified by these. There are -obviously marked individual variations as to the characteristics of -this feeling. I should expect from my work this year that two pretty -distinct types could be discovered. For one of these, certainty in a -judgment as to an experience would rest very largely upon the vividness -of an image; for the other, upon the congruence of an image with other -previously accepted images, that is, the absence of conflicting images -when the experience judged about is imagined part of a wide setting -of past experiences. I should not expect either element of certainty -to appear absolutely, without the other form. For many people one -element would predominate in certain fields, as in judgments regarding -sense-experiences, the other in the more logical fields. For some, -again, perhaps, the two would be nearly coördinate in every experience -of certainty. But for some subjects, as, I think, for subject K here, -the vividness of the image would always be the determining factor, -while for others, as for subject H, congruence with wider experience -would be much more important. This classification of subjects according -to their types of certainty might develop into a much more complicated -affair. The experiments described here have gone no farther than -to suggest lines along which it may perhaps run. There may be other -elements equally important with these two. A set of experiments -consisting of attempts to raise uncertainty to certainty would bring -out the essentials of certainty from a new point of view, and would, -perhaps, test this theory that individuals may be classified according -to the types of their certainty, in the most satisfactory manner. - - - II. THE EFFECT OF VOLUNTARILY ATTENDING TO CERTAIN ASPECTS OF A TOTAL - EXPERIENCE UPON CERTAINTY IN THE JUDGMENTS AS TO THE CONSTITUTION - OF THAT TOTAL EXPERIENCE. - -As has been said, judgments as to the elements of visual fields were -tested for this part of the experiment. The apparatus used was the -following: The subject was seated before a low table which was shut -from his view by curtains and boards. He looked down upon the table -through an opening into which a camera-shutter had been fitted. This -shutter was set for a two seconds' exposure and opened by means of a -bulb which the subject held in his hand. Just before each exposure, -the experimenter placed a card on the table below the camera-shutter. -The set of twenty cards so used were alike in that the background for -all was gray and the objects pasted upon the cards black letters and -numerals and simple geometrical figures of chosen shapes and colors. -No color was repeated on any one card. The cards were different in the -choice and arrangement and in the number of objects used. The number of -letters and numerals on any one card varied from two to five, the total -number of objects from eight to twelve. A white card on which were -pasted dark gray samples of each of the eleven shapes used, together -with a card of the background of those shown in the experiment on which -were pasted torn scraps of the eleven colored papers used, was always -in sight at the subject's side. A camera-shutter, experiment cards and -sample cards thus made up the apparatus. - -The presence of the sample cards needs explanation. They stood for -the attempt to place the colors and shapes on the same footing as the -letters and numerals. Their presence, in the first place, and, as well, -the limitation of the number of letters and numerals used, did away -somewhat with the advantage that letters and numerals naturally have -for ease of naming. In the second place, the use of a new color for the -sample shapes and the absence of definite shape in the sample colors -helped to keep the colors and shapes more distinct. With the help of -these cards it seemed that we could properly hold we had a a visual -field of three very nearly coördinate sets of elements. - -The experiment as a whole, as conducted, had four phases which, except -for one particular, were exactly alike. The subject's attention was -directed toward a certain aspect of the field by (1) asking him before -each exposure (or less often if that appeared unnecessary) to attend -to that aspect, as, for instance, to the colors present, and (2) -taking care that any questions asked should tend to strengthen rather -than counteract the effect of that voluntary attention. At a given -signal the subject pressed the bulb which opened the shutter. On the -closing of the shutter he reported what he had seen. This report the -experimenter recorded almost in the subject's own words, and later -tabulated in the manner described presently. So far as giving the -objects present was concerned, the report was given almost invariably -without any suggestion by the experimenter as to the possibilities of -the field. To help the subject distinguish the amount of confidence -which he had in the judgments that such or such objects were present, -however, the experimenter frequently asked such questions as, "Would -you risk more on the fact that there was a square in the field than -on the fact there was something blue there?" In giving his report the -subject pointed to the sample cards or spoke, as he might wish. He was -also allowed to be as leisurely or as rapid in giving it as he chose. -A half-minute interval elapsed between the end of each report and -the signal that the shutter be opened again. No persistent effort to -distract the subject's attention was made then, though conversation on -other topics was frequently carried on. The point in which the phases -of the experiment differed was in the aspect of the field to which -attention was called. In the first, this was the shapes, in the second, -the colors, in the third, the letters and numerals, and in the fourth, -the number of objects in the field. Fixing the attention upon the -number of objects in the field served to distribute it equally over all -the groups represented there. The general method of calling attention -to the different aspects and of learning the effect of such attention -was, as has just been said, the same for all phases. - -As a preliminary to making up the tables here given, from which we are -to answer our problems, the experimenter first tabulated the reports -of the subjects in such a way as to show how many judgments (correct -and incorrect) of each of the four grades of certainty adopted for -this division of the experiment were made by each subject on each card -for each group on the card (shape, color, or letter or numeral). From -these tabulations the tables that follow were in turn compiled. - -The number of grades of certainty adopted for this division of the -experiment is obviously decidedly arbitrary. Grades of certainty there -surely are. The introspection of the subjects develops that clearly, -as has been stated. But there is no reason in the conditions of the -case for holding to the number four, as is done here. In giving the -results for which the experiment was undertaken, I shall, indeed, -confine myself to studying the range of the judgments made with as high -a grade of confidence as the subject believed he should ever have. This -is called certainty (1) or certainty proper. But for the tributary -discussion on the relation of certainty and error, the consideration -of three other grades used in the report and early tabulation, is also -introduced. This lowest grade (4) might better be named "as complete -uncertainty as will admit of one's making any judgment." The other two -are intermediate. It was at first intended to give the results with -regard to the effect of voluntary attention upon the place of these -grades of certainty, also, but such a discussion has been omitted -because it promised to add very little more than complexity to the -report. Besides this, the classification into these lower grades is -too purely approximate to make the distinction there of great value. -For judgments of the order certainty (1) we have the test, "Are you -as certain of this as you can imagine being in an experiment of this -sort?" but no such test for the other grades could be found. Yet, -though he tended to omit judgments of the lower grades of certainty, -each subject seemed to find four grades a convenient number to use in -giving his report. - -The number of experiment cards used varied with the subjects. E had so -clear a memory of the cards that after as many as ten had been shown, -he found difficulty in distinguishing his memory of the one which he -had just seen from that of others seen earlier. Ten cards only were -used in his case. A, B, D, and F showed signs of fatigue after fifteen -cards which made the value of any later results questionable. C and K -showed no such signs of fatigue. The same set of cards was, of course, -shown any one subject for all four phases of the experiment. Those -omitted were the last ten or the last five of the complete set as the -case might be. - - -TABLE I - - % of cards where % of cards where % of cards where % of cards where - certainty (1) certainty (1) certainty (1) certainty (1) is - appears in the appears elsewhere in attended-to stronger outside - attended-to than in the group only. than within the - group. attended-to attended-to - group. group. - - A 91% 49% 49% 13.3% - B 97 91 83 28 - C 95 67 30 16.6 - D 93.3 69 24.5 11.2 - E 96.6 83.3 13.3 26.6 - F 88.8 30 53.3 8.3 - H 91.6 70 26.6 10 - -Table I answers the first part of our first problem promptly. Every -subject gave judgments of the order certainty (1) about groups other -than that attended to, in the case of a very considerable percentage of -the cards. True, again in the case of a considerable (though generally -smaller) percentage of those cards, each subject confined his judgments -to the group attended to. The fact of individual variation stands out -again here; and, moreover, the conclusions drawn should be qualified -slightly because of the fact that it was often possible for the -subjects to give all the letters and numerals on the cards, and still -have, as it were, some attention left over for the other, supposedly -non-attended-to groups. Such reaching beyond the properly attended-to -group never seemed to be possible with either shapes or colors. Aside -from this, however, it is clear that judgments of the highest grade of -certainty were by no means limited to the group attended to. - -This same table answers, also, the second part of the problem. Each -subject found certainty of the highest grade sometimes stronger outside -than within the group which held his attention. It is, of course, -practically impossible to make absolutely certain that each subject's -attention was invariably held to the group toward which it was turned, -yet the percentage where certainty was stronger outside than within -such groups seems large enough, in some cases, at least, as with -subjects A, B, and H, to warrant our answering this second part of the -problem in the negative. I should feel, however, that this was answered -less definitely than was the first part of the problem. We may say, -then, that the judgments made with the highest degree of certainty -about a visual field will not be confined to the group attended to, and -that we have strong evidence pointing toward the belief that we cannot -expect there will invariably be more of such judgments within the group -attended to than outside it. - - -TABLE II - - # 1: % of judgments of certainty - (1) given to each group in phase - I (or when shapes were attended to). - - # 2: % of judgments of certainty - (1) given to each group in phase - II (or when colors were attended to). - - # 3: % of judgments of certainty - (1) given to each group in phase - III (or when letters and numerals - were attended to). - - # 4: % of judgments of certainty - (1) given to each group in phase - IV (or when the attention was - equally distributed over all the - groups). - - 1 2 3 4 - - Subject Shapes (a) 94% 38% 18% 31% - A Colors (b) 5 61 20 59 - Letters and (c) - Numerals 0 0 61 9 - - Subject (a) 48 39 21 33 - B (b) 43 60 29 38 - (c) 8 0 51 28 - - Subject (a) 88 15 26 34 - C (b) 8 77 28 8 - (c) 5 7 47 58 - - Subject (a) 60 13 11 40 - D (b) 19 67 2 37 - (c) 19 19 86 23 - - Subject (a) 51 15 0 37 - E (b) 22 56 8 29 - (c) 26 28 91 34 - - Subject (a) 66 12 0 50 - F (b) 14 77 0 27 - (c) 19 10 100 23 - - Subject (a) 43 21 7 24 - H (b) 29 52 4 19 - (c) 27 26 88 57 - -The most interesting part of this division of the experiment is brought -out in Table II in answer to the problem, "Will the place of voluntary -attention materially alter the distribution of judgments of the -highest order of certainty among the given groups?" In every case the -percentage is affected, in most cases, greatly affected. Take the case -of subject A, for instance. Although, when his attention is equally -distributed over the field 59% of the judgments we consider were of -colors, yet when his attention was fixed on shapes and on letters and -numerals this fell to 5% and 20% respectively. When it was fixed on -colors, it rose, indeed, only to 61%. When, however, subject A fixed -his attention upon the letters and numerals, 61% of the judgments -were confined to the group attended to,--the same percentage as when -colors were the attended-to group,--although, when his attention was -distributed over the whole field, the percentage of these judgments -about the group of letters and numerals was 9% only. When shapes were -attended to, the 31% of the fourth phase of the experiment rose to -94%,--almost all of the judgments of the highest grade of certainty -that were given were judgments about shapes. A similar study of the -results given in the table can be made for the other subjects. The -degree of change varies with the subject and with the group, but -always there is some change, and often a very marked one. In this -experiment the place of voluntary attention clearly did alter, and -alter materially, the proportion of judgments of the highest order of -certainty made about any given group. - -That, indeed, would seem to me to be the answer of this experiment to -the question as to the effect of voluntary attention upon certainty -in one's judgments. Every subject showed a tendency to have more -certainty in those judgments which were made about that aspect of the -field toward which his attention was directed. Yet, on the other hand, -this was a tendency only, one not strong enough to make it possible to -predict beforehand exactly how great a proportion of the judgments in -which he had the highest degree of confidence would be limited to that -field, or even to be sure in every case that the greater proportion of -those judgments would be so limited. The place of voluntary attention -has an influence upon the subject-matter of the judgments made with -certainty about a visual field just seen, but an influence of varying -and uncertain strength. - - -TABLE III - - 1 = % of mistakes in judgments of certainty (1). - 2 = % of mistakes in judgments of certainty (2). - 3 = % of mistakes in judgments of certainty (3). - 4 = % of mistakes in judgments of certainty (4). - x = no judgments of that kind given. - 1 2 3 4 - - Subject A (in giving shapes) (a) 7% 10% 0% 100% - (in giving colors) (b) 2 14 23 0 - (in giving letters - and numerals) (c) 0 0 x x - - Subject B (a) 2 10 10 0 - (b) 3 6 20 25 - (c) 4 50 0 x - - Subject C (a) 1 8 10 0 - (b) 4 14 14 0 - (c) 1 0 16 0 - - Subject D (a) 3 4 0 16 - (b) 1 6 0 0 - (c) 5 0 0 0 - - Subject E (a) 2 10 25 50 - (b) 1 33 40 0 - (c) 0 0 0 0 - - Subject F (a) 1 25 7 25 - (b) 4 15 29 26 - (c) 3 0 0 x - - Subject H (a) 3 6 5 0 - (b) 6 2 15 15 - (c) 4 0 0 20 - - -TABLE IV - - Label 1: General % of mistakes - in judgments - of certainty (1). - - Label 2: % of mistakes in judgments - of certainty (1) about - attended-to groups. - - Label 3: General % of mistakes - in judgments - not of certainty (1). - - Label 4: % of mistakes in - judgments not of - certainty (1) about - attended-to groups. - - 1 2 3 4 - - Subject A 4% 1% 17% 27% - - Subject B 3 2 10 7 - - Subject C 2 3 9 24 - - Subject D 3 4 4 0 - - Subject E 1 2 22 34 - - Subject F 3 1 21 23 - - Subject H 4 6 6 10 - -The results given in Tables III and IV were compiled from the same -records as those of the two Tables just discussed. They give the -relation of error to certainty and to attention, as that relation was -developed in this experiment. No experiments were conducted with these -relations of error primarily in view, but the results developed in -connection with the problem of the effect of attention upon certainty -in one's judgments. - -Both Tables show again marked individual variation. They suggest to me, -in the first place, a further line of investigation in the same field -and for the same purpose as those investigations which L. William Stern -outlines in an article[101] entitled _Aussagestudium_. This further -line is the testing subjects to learn the probable relative correctness -of the judgments made with different degrees of confidence. Although a -comparison of the first and third columns in Table IV makes it clear -that the proportion of mistakes for the highest grade of confidence is -lower than for the other grades taken together, there is a very marked -difference among the subjects to be noticed. The difference in the two -percentages is, for instance, very slight in the cases of D and H, and -very great in the case of E. It is interesting to notice with regard -to E that while he has the lowest percentage of mistakes for certainty -(1), he has the highest percentage for the group of certainties (2), -(3), and (4). In the more detailed percentages given in Table III we -see further that in certain fields and sometimes in all fields (as -with subject C) judgments made with the lowest grade of confidence -were invariably correct. Such Tables might be of help in a case where -the evidence of eye-witnesses conflicted. We might perhaps learn that -witness N made a large proportion of mistakes where he was absolutely -certain, whereas witness M was seldom wrong in judgments in which he -had a low degree of confidence. Even when the probity of both was -unquestioned, we should not then assume that N was more probably right -because he had so much more confidence in his judgments than M had in -his. A much longer and more comprehensive set of experiments would be -necessary before we could feel that we had at hand a table from which -to work in this way. - -The question of the effect of voluntary attention upon error, for -answering which Table IV was compiled, brings out again the marked -individual variation among these seven subjects which has shown itself -in practically all parts of the experiment. Some effect seems to -have been produced always, but this was sometimes to give a larger -percentage of mistakes in the attended-to groups and sometimes a -smaller. With A, B, and F the percentage of mistakes in certainty (1) -was lower for the groups attended to than for the total number of -judgments of that order. Only with subject B, however, is this true -of the group of lower grades of certainties also. On the other hand, -with subjects C, D, E, and H the percentage is greater for certainty -(1) in the groups attended to than for certainty (1) in the collection -of all the judgments of certainty (1) taken together. Here, too, in -the case of subject D, the results with regard to the lower grades of -certainty reverse those for certainty (1). Thus all four possibilities -as to the kind of influence of voluntary attention upon certainty -appear. We cannot say that the place of voluntary attention will tend -to affect the percentage of error in any given way. We can only say -that apparently it made some difference with each subject. It might be -found by further experimenting that the character of this difference -is associated with some other characteristic of either attention or -the feeling of certainty, as, for instance, with the ease with which -attention is held to the chosen field or with the type of the subject's -certainty. - -Like all experiments, these open up further questions quite as much -as they answer those toward which they are aimed. To repeat something -of what has already been said, I feel that what it has established is -(1) that introspection develops distinct grades of certainty in the -case of every individual, (2) that the particular characteristics of -the feeling of certainty vary markedly among individuals; (3) that the -feelings of certainty associated with the different senses are not, as -feelings of certainty, to be distinguished from each other; (4) that -the judgments of the highest degree of certainty which are made about -the constitution of any visual field just seen will not be confined to -the group in that field toward which the attention is directed; and -(5) that such fixing of the attention will, nevertheless, materially -alter the subject-matter of such judgments of greatest certainty. The -rather vague statement that the percentage of error is not surely less -with the judgments of a group because attention is fixed on that group -may perhaps be added as a sixth conclusion. The most interesting and -promising of the problems which the experiments seem to me to raise -are: (1) the problem, are there such definite types of the feeling -of certainty that people may be classified according to their types, -and, if so, what are the types and what their relation to other -psychological characteristics of the individual? (2) the problem, what -will be the result of careful and trained introspection as to the -relation of so-called logical and psychological certainty and in what -fields do these appear for different individuals? (3) the problem, -how can a test for grading the probable percentage of error in the -judgments of different grades of certainty made by any one person be -constructed? and (4) the problem, how are such facts as those given -in Table IV to be connected with the effort required for attention, -the type of certainty of each subject, etc.? Other problems could, of -course, be suggested, but these, I feel, mark the steps that naturally -follow the experiments described here. - -[Illustration: PLATE VIII.] - -FOOTNOTE: - -[Footnote 101: Stern: Beiträge zur Psychologie der Aussage, vol. 1, p. -46, 1904.] - - - - -INHIBITION AND REËNFORCEMENT - -BY LOUIS A. TURLEY - - -Experiments made by Ranschburg[102] on the significance of similars -in the process of learning and remembering determined that when -duplicates occur within a series of stimuli, one either totally or -very greatly inhibits the perception of the other according as they -are contiguous or are separated by other stimuli. Dr. Yerkes,[103] -in testing the effect of auditory on visual and tactual stimuli in -frogs, found that if the auditory stimulus preceded another stimulus -by various time-intervals, it had an alternating reënforcing and -inhibitory effect. A similar result was obtained by Hofbauer[104] in -a similar experiment on human subjects. The question now arises,--if -the time-interval were increased between a stimulus and its duplicate -in a series would the inhibitory effect gradually approach zero where -all effect of the preceding stimulus ceased, to which Ranschburg's -experiments point, or would the inhibitory effect be alternated with -one of reënforcement as the experiments of Dr. Yerkes and Hofbauer -would indicate? This problem--the effect of a stimulus on its duplicate -in a succeeding series of stimuli--is the problem I undertook to solve. -For this purpose, it was necessary to introduce exactly determinable -time-intervals between the stimulus and its duplicate. Therefore I -used--as Miss Kleinknecht[105] did for other purposes--a stroboscopic -arrangement instead of simultaneous presentation which Ranschburg used. - -My apparatus was Professor Münsterberg's Stereoscope without Prisms or -Lenses, a description and photograph of which was published in the -article by that title in Psychological Review, vol. 1; or rather, I -used Professor Münsterberg's attachment to Kohl's centrifugal machine, -since my apparatus was not identical, except in principle, with the -"Stereoscope." The "attachment" consists of two black discs about -thirty inches in diameter, mounted about eight inches apart on the -disc-shaft of the centrifugal machine. The back disc is of wood. The -outer three inches of its face is furnished with thirty-six equidistant -strips of black tin, one end of each of which is bent so as to grip a -groove in the rim of the disc, and the other end of each is gripped -by tiny thumb-screws so that the strips lie along radii of the face -of the disc. The front disc, slightly smaller than the back disc, is -of pasteboard. Between the two discs a stationary black screen with -a short narrow slit was placed so that the slit revealed only the -strip on the horizontal radius of the back disc. Behind this screen an -eight-candle-power electric light was placed to illuminate the back -disc,--as the experiment was carried on in a darkened room. By moving -this light I was enabled to vary the intensity of illumination to -offset the skill of the observer. - -For my purpose, a small white figure--one of the ten characters of -the Arabic notation--was stuck on about the middle of each of the tin -strips on the back disc; and radial slits, one millimetre wide and an -inch long, were cut from one sixth of the circumference of the front -disc so as to come opposite six of the strips on the back disc. Similar -radial slits were cut at various intervals from the remaining five -sixths of the circumference of the front disc. These were covered by -small pieces of cardboard fastened to niagara clips, thus making them -readily removeable. By this means any desired figure could be exposed -in the same revolution with the series exposed by the six slits above -mentioned. - -The thirty-six strips were divided into six series of six each, -indicated by chalk-marks on the disc. Each of the series was often -changed in whole or in part by shifting and interchanging the strips. - -The figure on which the effect of a preceding stimulus was tested -occupied the fourth place in the series, since this is the place where -the greatest number of errors occur, as is shown by the experiments -of Ranschburg and previous investigators in the Harvard Laboratory. -In my experiment, 4, 5, 6, 7, 8, and 9 occupied the fourth place -in the 1st, 2d, 3d, 4th, 5th, and 6th series respectively, and the -effect of a preceding stimulus was tried on each of these figures -for each time-interval. The preceding stimulus in each case was a -duplicate of the fourth member of a series, and was a member of some -other series. Thus the fourth member of each series was at all times -fixed and constant while the preceding stimulus occupied successive -progressive positions round the disc. The other members of each series -were chosen at random, care being taken that the fourth figure was not -duplicated within its series, since it would then have taken part in -inhibition within the series. - -[Illustration: PLATE IX.] - -By adjusting the front disc, I exposed any one of the series desired, -and by removing the cardboard blind from one of the suggestion slits, I -gave a stimulus at the desired time-interval in advance of the fourth -member of the series. The first interval I used was 1.11 sec. as Miss -Kleinknecht had tried intervals up to 1 sec. My second interval was -1.39 sec., the third 1.8 sec., and then every .277 sec. up to 4.3 sec. -In performing the experiment I exposed alternately a series without -and a series with a preceding stimulus--taking from the observer three -reports of each--until the six series had been seen. I then repeated -this, exposing with a preceding stimulus those series that had been -exposed without preceding stimulus, and without preceding stimulus -those series that had been exposed with a preceding stimulus in the -first instance. In this way I equalized and minimized the effects of -novelty and memory. - -At 1.11 sec. there was considerable inhibition in five out of six -cases. In the sixth case there was slight reënforcement at this -interval. With an interval of 1.39 sec., with one exception,--not the -exception above mentioned,--there was a stronger inhibition than at -1.11 sec. Inhibition in all cases began to decrease from 1.39 sec. -until it ceased at about 1.8 sec. The preceding stimulus then had a -reënforcing effect which reached a maximum in four cases at 2.08 sec., -one at 2.36 sec., and one at 2.64 sec. Then, in all cases, there was -a decrease of the reënforcing effect which in three cases amounted to -inhibition. In the other three cases, the preceding stimulus had no -inhibitory effect for an interval greater than 1.8 sec. For one of -these, Fig. 5, the preceding stimulus had a reënforcing effect for -all the intervals beyond 1.8 sec. The second trough in the wave or -interval of maximum inhibition was at either 2.64 sec. or 2.92 sec., -except for the person for whom there was constant reënforcement beyond -1.8 sec., in which case the first interval of least reënforcement or -second trough was at 3.19 sec. This was the second interval of greatest -enhancement, or second crest, for four of the others. Then followed a -third point of no effect or inhibition, which was 3.75 sec. or 4.03 -sec. For the person for whom the preceding stimulus had least enhancing -effect at 3.19 sec., the second interval of greatest reënforcement -coincided with the interval of greatest inhibition for the majority -of the other observers. For four of the six observers, the third -interval of greatest reënforcement was 4.3 sec. In this, the observer -agreed for whom the last interval of greatest reënforcement was 3.75 -sec. Thus while, for this observer, the first two points of greatest -reënforcement were separated by an interval of 1.11 sec., the second -and third points were separated by an interval of only .55 sec. This -same thing occurred in the records of two other observers, for one at -this point, and for the other at another point. Of the two dissenters -from the opinion of the majority that the third crest was at 4.3 sec., -one was an erratic observer; and for the other, there was a slight -reënforcement at 4.03 sec. and no effect at all at 4.3 sec. - -Fig. 1 represents the average of the records of the six observers. -The curve is based on the difference between the number of times the -fourth members of the series were seen with and without preceding -stimulus. The base-line represents the number of times the figure was -seen without preceding stimulus, taken each day as the normal for that -day. Figures above the base-line represent the greater, and those below -the line, the less number of times the figure was seen with preceding -stimulus, or reënforcement and inhibition, respectively. The first two -points are the average of fifty-four observations; each point beyond -the second is the average of 108 observations. Figs. 2, 3, 4, and 5 -represent individual records constructed as Fig. 1, each point being -the average of eighteen observations. - -The curve in Fig. 1 is somewhat misleading in showing points of maximum -reënforcement at 3.19 sec., 3.75 sec., and 4.3 sec. In no individual -case was this true. The reason for the crest at 3.75 sec., or at least -for its height, is that in two cases reënforcement was considerable -at this interval, and there was little inhibition to offset this in -the general average. At 3.19 sec., which was the second interval of -greatest reënforcement, for four out of the six observers, owing to -practice, the reënforcement was not great (Fig. 4), but in no case was -there inhibition at this point. Thus for the lack of strong positive -effect at 3.19 sec. and the lack of strong negative effect at 3.75 -sec., the two crests are the same height, while the first represents -the maximum effect for four and the second for two observers. - -From these results, taking everything into consideration, my -conclusions are: - -(1) If a stimulus precedes at various time-intervals its duplicate -in a series of stimuli, it will alternately inhibit and reënforce the -perceiving of the duplicate stimulus. - -(2) Within 4.5 sec. there are at least three points each of maximum -inhibition and maximum reënforcement. - -(3) The points of maximum inhibition and likewise those of maximum -reënforcement are separated by intervals of from .55 sec. to 1.2 -sec.--more often by one of the two extremes than by any mean. - -(4) Up to 4.5 sec., as the time-interval increases, the maximum -inhibition generally decreases, while the maximum enhancement -correspondingly increases. - -What the limit of this periodic effect is, I cannot as yet say, as up -to the present I have not used time-intervals beyond 4.3 sec. But from -the intensity of the effect at this interval, I do not expect the limit -to be within several seconds. - -FOOTNOTES: - -[Footnote 102: Ranschburg: Ueber die Bedeutung der Ähnlichkeit beim -Erlernen, Behalten und bei der Reproduction, Journal der Psychologie -und Neurologie, Bd. 5, p. 94.] - -[Footnote 103: Dr. R. M. Yerkes: The Sense of Hearing in Frogs, Journal -of Comparative Neurology and Psychology, vol. 15, no. 4, 1905; also -this vol. Harvard Psychological Studies.] - -[Footnote 104: L. Hofbauer: Interferenz zwischen verschiedenen Impulsen -im Central-nervensystem, Pflügers Archives, Bd. 68, p. 564, 1897.] - -[Footnote 105: Kleinknecht: This volume.] - - - - -THE INTERFERENCE OF OPTICAL STIMULI - -BY H. KLEINKNECHT - - -The purpose of this investigation is the determination of the location, -extent, nature, and cause of the interference of optical stimuli. -Ranschburg[106] studied the phenomena carefully in using optical -stimuli which were spread over the retinal field, for instance, a -series of letters or figures one beside the other. But if we are -to experiment on the inhibitory influence of a certain qualitative -impression, we must try to eliminate the local difference; the letters -or figures ought to be seen at the same spot. - -This became possible by a stroboscopic arrangement, consisting of two -parallel circular discs one foot apart on the same axis, whose motion -was controlled by an electric current. - -The discs were 60 cm. in diameter. Thirty-six radii were drawn -equidistant on the farther disc, and on these were clasped black tin -strips bearing letters or numbers or colors. The nearer disc was -similarly divided and an opening, 3 mm. in width, was cut at each -radius. This exposed the number. A cardboard placed between the discs -limited the range of vision, its opening being 4 × 5 cm. - -The figures were 10 mm. high, white, and placed on a dark background. - -Preparatory stimuli were given to enable the subject to adjust his -eye to the farther disc. They were so placed as to fall on different -retinal points, thus avoiding fatigue. - -Many of the tests employed by Ranschburg were used again to ascertain -the influence of the change in method and with the hope that such -differences might throw some light on the nature of the interference. -At first there were six subjects, afterwards eight--all graduate -students and trained in laboratory work. The experiment was carried -on in the morning. Numbers consisting of six digits were exposed on a -dark background. The time of exposure varied with the subject, but was -constant throughout the experiment. The subject was asked to record -the number immediately after perceiving it, but in almost every case -it was read verbally (its retention being thus facilitated) and then -recorded. - -For the first few weeks letters were used. But since subjects found -it very difficult to distinguish these, a change was made to figures. -For a month and a half numbers were given for the purpose of training -the subjects and of ascertaining the speed best adapted to each. This -varied from 5-1/2" to 8" a revolution, each figure being exposed from -115 to 166 sigma. - -Three series of numbers were given: (1) Homogeneous, containing a -repeated figure, as, 495851. (2) Heterogeneous; as, 708654. (3) -Similar, that is, in construction; as, 813470 (8 and 3 being easily -substituted for each other). Other similars given by Ranschburg are 9 -and 0, 9 and 6, 9 and 2, and 5 and 3. - -In order to determine the place of greatest interference, the repeated -figures were located in all possible positions, while the preceding -and succeeding figures were left unaltered, so as to obviate any -new influences which might result from a change of relations. There -are fifteen possible variations of the series: _mabcdm_, _ambcdm_, -_abmcdm_, _abcmdm_, _abcdmm_, etc. - -The following table, illustrative of the scheme _ambmcd_, will show the -character of the results obtained. Only the numbers in which errors -occur are here recorded, those figures which were incorrectly perceived -being printed in heavy type. The dash is used when the location of the -figure omitted is known, and the interrogation mark when the reply is -doubtful. - - 8" 8" 5-1/2" 5-1/2" 5-1/2" 8" - V. R. S. M. H. E. - 708025 70625 76082 ..... 70825 7082-5 70285 - 958564 95584 ..... ..... 95864 985 ? 4 958-54 - 281845 281485 ..... 20861 28185 281-54 - 436392 43632 43636 436932 436924 43632 43632 - 526273 526723 5257 572673 52763 ..... 52623 - 940469 94069 940465 ..... 94069 94640 940-69 - -The interference may result in permutation, substitution, or -inhibition. The latter two may take several forms; as, inhibition of -identicals, of similars, of dissimilars, the location of the omitted -figure being known or unknown; also, substitution of an identical, -similar, or dissimilar figure which precedes or follows. - -The homogeneous series (540 tests) gives results as follows: - - -HOMOGENEOUS SERIES - - Inhibition of Inhibition of Inhibition - Identicals. Similars. due to Location. - Location - of the Spot Spot Spot Spot Spot Spot - Identicals. Known Unknown Known Unknown Known Unknown - - _mabcdm_ - 1 1=6 1 1 4 5 - _ambcdm_ - 2 2=6 5 2 1 3 - 3 3=6 2 3 5 - 4 4=6 3 3 4 2 - 5 5=6 6 15(?) 4 5 - 6 1=5 1 2 1 2 1 3 - 7 2=5 5 3 3 - 8 3=5 3 7 2 1 - 9 4=5 2 21(?) 2 5 3 - 10 1=4 9 4 3 - 11 2=4 3 9 4 1 7 - 12 3=4 3 19(?) 1 2 4 - 13 1=3 [107]5+3(?) 2 1 10 - 14 2=3 1 11(?) 3 8 - 15 1=2 6(?) 1 4 9 - - Total 19 48+75(?) 6 38 17 71 - - -I. _Inhibition_ - -(1) There is considerable inhibition only when identicals are next to -each other. - -(2) There is but little difference in the amount of inhibition when -identicals are removed two and when removed three places. - -(3) The interference is greatest when 3d = 4th, 4th = 5th, and 5th = -6th figures, in which schemes it is almost equal in amount. - -(4) When identicals are adjacent, it is impossible to decide whether -there be inhibition or fusion, _i. e._, whether one be inhibited and -the other appear, or whether the figure seen be a fusion of the two -(unless there is an omitted figure whose location is known to the -subject). Its intensity does not serve as a clue, for the perception of -the number demands the full concentration of the attention. - - -II. _Substitution_ - -When the interference is not sufficiently great to cause inhibition, -substitution may result. - -(1) In the majority of cases the substituted figure is a dissimilar not -occurring in the number. - -(2) A preceding figure is frequently substituted. - -(3) Occasionally a figure is replaced by its similar, but this is not -true of the homogeneous element. (Cf. with Ranschburg.) - -(4) Sometimes the next figure in the natural number series is -substituted; as, 9 for 8, 6 for 5. - -(5) The figures containing straight lines (4, 7, and especially 1) are -less subject to illusion; likewise the smaller numbers (1, 2, 3, 4). - - -III. _Permutation_ - -The permutation represents the least interference. - -(1) The 4th and 5th figures are most often exchanged. - -(2) The figure is seldom permuted more than two places, and generally -but one. - -The recording of the number was most interesting. Generally the -first few figures and the last were written without comment, but the -4th and 5th often called forth an expression of doubt, which was -immediately followed by an exclamation at the coming of the figure into -consciousness as if by "inspiration." The experience was extremely -peculiar. The figure, fully as distinct as those already perceived, -was always from 5″ to 10″ late, and seemed to "pop in unannounced"--to -"come from nowhere." A substitution or permutation occurred without -this lapse of time. - - -HETEROGENEOUS SERIES - -(1) There are less than half as many inhibitions as in the homogeneous -series, the largest number being in the 4th and 5th places. - -(2) The number of substitutions is decreased by a fourth, the -identicals and similars remaining the same. - -(3) There are no fusions. - -(4) Fewer permutations are found in this series. The 4th and 5th -figures are most often permuted. In a very few cases the figure is -permuted four and five places. - -(5) There are an equal number of doubtful perceptions in both series. - - -SIMILAR SERIES - -(1) There are few cases of inhibition, and even more surprising is the -small number of cases in which a figure is inhibited by its similar. - -(2) There are more substitutions, 6 being very often substituted for -5, generally in the 6th place and when preceded by 0 or 9, often by -both. Similars are never replaced by identicals (69 by 66 or 99) as -Ranschburg found in his experiments. - -(3) The fusion of similars equals that of identicals in the homogeneous -series. - -(4) The number of permutations is the same as in the homogeneous series -and less than in the heterogeneous. - -(5) The doubtful perceptions have decreased by half. - -That there are fewer errors in this series than in the homogeneous -or heterogeneous, may be due to the fact that it was given last, -especially since one subject showed marked improvement in the entire -series and another during the last half. These subjects suddenly began -to see six figures, while previously they had seen but five and those -contained errors. - -In the above 1620 tests, 9 and 0, and 8 and 3, are sometimes inhibited -by and substituted for each other, but the remaining similars mentioned -by Ranschburg seldom have any such effect. - -It is impossible to determine definitely the nature of the -interference, the greatest uncertainty existing in the homogeneous -series when two identicals are adjacent. But the interference is -dependent not only upon the identity or similarity of the figures of -which the number is composed but also upon their location. - - -INHIBITIONS - - 1 2 3 4 5 6 Total - Place Place - known unknown K. U. K. U. K. U. K. U. K. U. K. U. - - Homogeneous 1 13 2 28 9 41 15 31 15 44 42 157 - 6(?) 14(?) 19(?) 21(?) 15(?) 75(?) - - Heterogeneous 2 5 1 8 2 15 4 36 5 34 2 25 16 123 - - Similar 4 4 5 3 6 2 13 5 32 - - Total - excluding(?) 2 5 2 25 4 47 13 82 23 71 19 82 63 312 - - Total of Known - + Unknown 7 27 51 95 94 101 375 - - (?) Inhibition or fusion. - - -SUBSTITUTIONS - - 1 2 3 4 5 6 Total - - Homogeneous 8 12 26 27 38 14 125 - Heterogeneous 4 4 14 21 30 20 93 - Similar 1 5 9 25 33 27 100 - - Total 13 21 49 73 101 61 318 - - -FUSIONS [See (?) under Inhibitions] - - 1 2 3 4 5 6 Total - - Homogeneous 1 2 1 3 10 17 - Heterogeneous 0 0 0 0 - Similar 3 3 6 6 18 - - Total 1 5 4 9 16 35 - -Note. There were no clear cases of fusion, but the evidence favored -fusion rather than inhibition. - - -PERMUTATIONS - - 1 2 3 4 5 6 Total - - Homogeneous (a) 6 29 46 56 30 167 - (b) 5 21 45 68 35 174 - Heterogeneous (a) 15 25 60 62 28 190 - (b) 14 23 51 82 44 214 - Similar (a) 13 20 37 78 16 164 - (b) 12 17 26 75 28 158 - - Total (a) 34 74 143 196 74 521 - (b) 31 61 122 225 107 546 - - (a) forward, (b) backward - -Note. The permutation of an inhibited figure was not noted unless its -location was known: hence the difference in the number of forward and -backward permutations. - - 1 2 3 4 5 6 Total - - Total Interferences 54 160 323 509 524 300 1870 - % 3% 9% 17% 27% 28% 16% - Absolute Errors - (excluding 20 55 119 191 225 103 713 - Permutations) 3% 8% 17% 27% 31% 14% - - -ABSOLUTE ERRORS (excluding Permutations) - - Homogeneous Heterogeneous Similar - Inhibitions 199 139 37 - Substitutions 129 93 101 - Fusions 17 18 - (?) 75 - - Total 420 232 156 - 52% 29% 19% - -Over 50% of the errors were found in the 4th and 5th places. - -[Ranschburg: 90% of errors in right half--60% in 5th place, 30% in 4th, -few in 6th.] - -In 1620 tests, the homogeneous series contained 52% of the absolute -errors, the heterogeneous 29%, and the similar 19%. - - -COLORS - -In the hope that some light might be thrown upon the main question at -issue, the writer changed the stimuli, using colors instead of numbers. - -It was important that the colors should be of the same or only slightly -varying intensity and that they should be easily distinguishable. In a -series of preliminary experiments in which red, blue, yellow, green, -brown, gray, pink, and violet were used, red was lost in 8% of the -tests, and gray in 25%. - -Colors 1×4 cm. in size "ran into each other," while those which were -1×1 cm. remained distinct. - -Here it was found necessary to distinguish between the various -factors which might cause inhibition. Three factors entered into each -test--perceiving, naming, remembering. - -Four subjects found difficulty in naming, especially at first. The -various methods of naming are given below in detail. M. says: "The name -of the color is localized in my mouth. Generally there is no movement -of the tongue--an impulse only; and the name is felt in that part of -the mouth where the sound would be reflected, as, red in the upper -part, blue near the front, etc." - -S.: "Usually there is no apparent tendency to pronounce. Occasionally, -naming them over inaudibly before recording is found advantageous." - -E., V., and H.: "The naming is mental, but is accompanied by a slight -movement of the tongue and throat." - -684 heterogeneous and 200 homogeneous tests showed that greatest -inhibition occurred in the following order: 4th place (27%), 3d -(26%), 5th (24%), 2d (11%), 6th (8%), 1st (4%). There was but little -difference in the 3d, 4th, and 5th places. - -During first tests subjects were allowed only one exposure, but later -it was thought best to eliminate all omissions resulting from inability -to name colors perceived, and hence they were asked to record only when -able to name all colors perceived during that exposure. However several -required but one exposure. - -Preliminary drill was given for two weeks. Since no clear cases of -fusion had been obtained in the entire number-series, the one aim -of the experimenter was to ascertain whether fusion of colors, even -though of heterogeneous, be possible. Eight hundred heterogeneous -tests gave 927 cases of inhibition, 7 of fusion, and 18 which, though -somewhat doubtful, yet gave more evidence of fusion than of inhibition. -Yellow (3d place) and brown (6th place) were seen as yellowish-brown, -brown and pink as pinkish-brown, etc. Gray was seen several times -instead of a color and its complementary when these were in immediate -succession. This was true of both red and blue. Half of the total -number of substitutions was due to the displacement of yellow by brown. -And a color not in the series was as likely to be substituted as one -preceding or following the displaced color. - -Two hundred and fifty-two homogeneous tests showed that there is -greatest interference when identicals are in immediate succession, and -least, when removed two places. The doubtful (fusion?) cases number -_one third_ of the inhibited. The 4th and 5th colors are permuted most -often, as was found to be the case in the heterogeneous series also. -The element is generally permuted but one place. - -The heterogeneous color-tests show three times as much interference as -the corresponding number-tests, and the homogeneous twice as much. The -discrepancy in the amount of variation may be due to the experiments -with the heterogeneous colors being earlier, when naturally more errors -would be made. - -However, a comparison of 252 homogeneous with the same number of -heterogeneous tests, taken at the same time, shows that there is -a much larger difference in the number of absolute errors between -the heterogeneous and the homogeneous number-series than there is, -proportionately, between the two series of color-tests. - -Lest the want of correspondence in the results might have been due to -the comparatively small number of immediately successive identicals in -the color-tests, 90 homogeneous tests, equally distributed among all -possible variations in the location of the identical elements, were -compared with 90 heterogeneous, and it was unexpectedly found that the -absolute errors as well as the permutations were almost equal in the -two series. Nevertheless, the validity of a conclusion based on so few -tests may well be questioned. - -Ranschburg found that simultaneous homogeneous stimuli interfere with -one another; while simultaneous heterogeneous stimuli clear the way for -one another. On the basis of the experiments with numbers, the writer -would amend the conclusion reached in the earlier research to read -thus: Homogeneous optical stimuli, whether occurring simultaneously in -different positions, or in immediate succession in the same positions, -interfere with one another; while heterogeneous stimuli clear the way -for one another. - -FOOTNOTES: - -[Footnote 106: Ranschburg: Zeitschrift für Psychologie, vol. 30, 1902.] - -[Footnote 107: Fusion or inhibition?] - - - - -SUBJECTIVE AND OBJECTIVE SIMULTANEITY - -BY THOMAS H. HAINES - - -This investigation finds its starting-points in two widely separated -lines of experimentation in the problems of attention. These two lines -are the "scope-of-attention" experiment with the tachistoscope, and the -"time-displacement" experiment with the pendulum apparatus. It seems -to me these two can be brought into relation to each other to the help -of each of them individually, and that an investigation taking these -wide relations within its scope may reasonably be expected to throw -new light upon the manner in which mental processes are related to -each other when they are together in consciousness at the same time. -The first of these experiments (tachistoscopic) is concerned with the -number and relative clearness of the processes which go on at the same -time. The second (displacement) is concerned with the conditions of -the subjective displacement of one of two objectively simultaneous -stimuli with reference to the other. Its problem is the essential -psychological problem involved in the astronomer's error in transit -observations by the eye-and-ear method, for the personal equation -arising in these observations is more a matter of the reciprocal -relations among the processes which are together in consciousness at -the moment of observation than it is of mere reaction time. It is -primarily more a matter of relative clearness, as controlled probably -through interference of one with another, than it is of the more or -less temperamental facility of converting ideas into action. - -The psychological question at the heart of the observation-error, -called the personal equation, is this,--What are the conditions which -hinder such a division of attention among the parts of the complex -operation of coördinating sense-stimulations, that the processes -which start simultaneously may proceed to equal clearness at the -same time, and so be perceived as simultaneous? The facts sought in -order to answer this question are the very same as some of those, -at least, demanded by the "scope-of-attention" investigation when -it really opens up to its true problem. W. Wirth[108] has recently -shown, in an exhaustive criticism of the tachistoscopic method, that -"scope of attention" is primarily concerned with the _relations_ of -the processes present together, and that this demands a previous -exhaustive study of their _relative clearnesses_. Earlier studies by -the tachistoscopic method, as, for example those of Cattell[109] on -the relatively short time for the perception of letters in words, -as compared with that for separate letters, and the overlapping of -processes in continuous reading, showed that the important question is, -_what_ are the processes which may go on at the same time. Leaving out -a statement of the nature of the processes is equivalent to leaving -out one of the dimensions when endeavoring to state the contents of -a solid. The scope of attention can be defined adequately only when -one knows fully _what_ the separate processes are as well as _how -many_ there are. This analysis, which the scope-of-attention problem -demands, cannot fail to be directly fruitful for the solution of the -time-displacement problem. The analysis of this larger problem directly -involves the former. Any attempt to investigate the time-displacement -of sense-impressions from simultaneous stimuli must inevitably place -the highest value upon the whole detailed analysis of any moment of -attentive effort. - -The present investigation, starting with the facts of -time-displacement, and taking the hint offered by Gonnessiat,[110] -attempts to show, by a more complete analysis, the effects of the -various relations within each series,--the visual within which the -sounds are to be placed, and the auditory series itself, and also -relations existing between the two series. In other words, the -attempt is made to strip the "displacement" experiment until nothing -more remains to be coördinated than a single pair of simultaneous -stimuli. This was the experiment of Exner.[111] He investigated -the shortest discriminable interval marked off by various pairs of -stimuli, addressed to the same sense and to different senses. From this -coördination of a visual and an auditory stimulus, where the limits -of the "specious present" are obtained, I make a turn into the realm -of the scope of attention. By a new method, whereby impairment of -accuracy of processes is made the test as to whether the processes have -proceeded together, it is shown that two such perceptual processes can -go on just about as well at the same time as separately. Since this -test is subject to the objection that the visual and auditory processes -may really be successive, though seemingly at the same time, owing to -retinal inertia, the same question is removed to an entirely different -plane in a further and more detailed set of experiments where the -processes combined are _judgments of comparison_ based upon one and the -same visual sensation. - - -EXPERIMENTS IN TIME-DISPLACEMENT - -The Leipsic Complication Experiment with the pendulum apparatus (for -description of this see Wundt's Physiol. Psy., 5th ed., vol. 3, p. 82) -was an early adaptation of the astronomers' eye-and-ear method to the -purposes of psychological experimentation. Instead of localizing a -visual stimulus (star on meridian) in an auditory series (clicks of a -chronoscope) as in the eye-and-ear method, this adaptation localized -an auditory stimulus (bell-stroke) in a visual series (successive -positions of a pointer on a graduated circle). This pointer passed -around to the right and to the left from the position of rest, in -which it pointed vertically upward, as the pendulum, to which it was -connected by clockwork, swung back and forth. By a simple adjustment -the bell-stroke could be made to come at any point in the complete -double swing of the pendulum, and so anywhere in the arc over which -the pointer moved. This machine makes an additional problem as to the -effects upon displacement of the increasing and decreasing speed. My -aim being to simplify as much as possible the displacement-error and -so reduce it to its elements, this feature was not only not of direct -interest, but it was very desirable to dispense with it altogether. -This was done by arranging the visual series so that the members were -shown in perfectly regular order, _i. e._ with equal time-intervals, -throughout the series. These equal intervals were secured by the -rotation of a disc at a uniform rate. - -My method also gave a more distinctly serial character to the visual -stimuli, in that they were separated by blank periods. The series -consisted of letters in alphabetical order. Denison's smallest white -letters, about six millimetres in height, were pasted upon a disc of -black cardboard, near the circumference and perpendicular to radii, so -that they would appear in succession and right side up, to an observer -looking through a slit at the peripheral region of the disc, as it -rotated. The letters were placed in three concentric rows, so that as -the disc rotated they appeared in three different places. The disc was -56.5 cm. in diameter. As a further aid in securing separate exhibitions -of letters, another black disc of the same size as the one bearing -the letters, with radial slits 2 mm. wide and cut in from the edge 4 -cm., opposite each letter on the other disc, was mounted on the same -shaft, six inches from the first, and between it and the observer. A -short observation-tube was placed at the same height as the axis of the -discs parallel to this axis, and opposite the slits when they were at -this elevation. Looking through this, as the discs were rotated, one -would see the letters right side up and in serial succession. Uniform -illumination was secured by working in a dark room with artificial -light. An electric lamp was hung between the discs. Uniform motion was -secured by an automatic control gravity motor, connected by belt with a -pulley on the disc-shaft. - -The auditory stimulus, a click, adjustable to any part of the series, -was made as follows: A wooden shaft, mounted on the same axle as the -discs, and beyond the discs from the observer, could be rotated freely -around the axle when the nut securing it was loosened. This shaft -extended beyond the edge of the disc. It carried a copper wire which -was in contact with the axle. A mercury cup was placed on the table, -upon which the machine rested, in such position that the copper tip -passed through the mercury when the discs rotated. It was thus a very -simple matter to connect an electric sounder so that it would click -every time the circuit was made by the copper passing through the -mercury. And, by the adjustment of the wooden shaft, the click was -readily placed anywhere in the visual series. - -As already suggested above, the length of interval between members -of the visual series, and also the time between clicks, seem to be -important factors in determining the amount, and perhaps also the -direction of the displacement. Bessel found his personal equation was -considerably diminished when he used a clock marking half-seconds -instead of one marking seconds. Wolf also diminished his error by using -a clock beating one hundred times a minute instead of one beating -seconds, which he was accustomed to use. Wundt found his customary -negative displacement on the pendulum apparatus (coördinating the -sound with a position of the index earlier than that with which it -was actually simultaneous) disappeared when he had members of the -visual series one thirty-sixth second apart and the auditory stimuli -one second apart. It seemed important at the outset, therefore, to -determine, if possible, the effects of each of these factors. - - -BOTH INTERVALS PROGRESSIVELY VARIED - -In each experiment the observer was allowed to observe as many -complications (coincidences of click and letter) as he desired, in -order to assure himself of his judgment. The experimenter counted and -recorded the number observed in each experiment. Experiments were made -in series of ten. Six different combinations of intervals were used in -this first group of experiments. The auditory intervals (time between -successive clicks) and visual intervals (time between successive -members of the visual series) are given at the tops of the columns in -Table I. This table is a summary presentation of the results of this -group. There were three observers. During each hour of experimentation -with a given observer, at least one series with each of the first four -time-interval combinations was tried out. "Aver. num. Trials" means -the average number of complications observed in the whole number of -tests averaged. "Num. Series av." means the number of series of ten -experiments each averaged to give the displacement results below. -"Aver. Error" is the average of all the displacements of the auditory -impression, _irrespective of the direction of the displacement_. "Mean -Displacement" is the _actual mean displacement_ as obtained by dividing -the algebraic sum of all displacements, positive and negative, by the -number of experiments. The plus sign indicates a positive displacement, -and the minus sign, a negative. Negative and positive are here used in -the sense customary in similar experiments,--namely, the click, being -heard as simultaneous with a visual impression which actually came -before it, was said to be displaced negatively, and the click, being -heard as simultaneous with a visual impression coming in fact later -than it did, was said to be displaced positively. Average errors and -mean displacements are given in the table in thousandths of seconds. -Observers were asked to locate the click in the visual series in terms -of one tenth the distance or time between the letters. - - -TABLE I - - Aud. Interval (sec.) 1.28 2.56 4.04 8.40 1.28 2.02 - Vis. Interval (sec.) .040 .080 .120 .260 .080 .120 - - Obs. - B Av. num. Trials 13.9 5.8 3.8 2.1 9.8 13.9 - Num. Series av. 8 13 13 8 2 2 - Aver. Error (sec.) .056 .064 .077 .164´ .045 .067 - Mean Displac'mt (sec.) +.045 -.040 -.067 -.152 +.045 +.067 - - Bo Av. num. Trials 9.4 4.1 3.0 2.0 5.5 3.5 - Num Series av. 6 10 11 8 3 2 - Aver. Error. (sec.) .114 .060 .054 .049 .05 .082 - Mean Displac'mt (sec.) +.114 +.045 +.033 .000 +.045 +.082 - - M Av. num. Trials 6.3 3.1 2.5 2.2 5.3 4.4 - Num. Series av. 9 12 12 10 3 2 - Aver. Error (sec.) .09 .07 .076 .110 .067 .172 - Mean Displac'mt (sec.) +.089 -.058´ -.058 -.104 +.062 +.168 - -The first four combinations of intervals above, with which the major -part of the results was obtained, it will be noticed, are approximately -proportionate increases in each interval, column by column. These -conditions were planned with a view to revealing the conditions, most -favorable for coördinating the auditory and visual impressions, for -each observer, so that his displacement would disappear, or show a -tendency to disappear. So far as is shown by these results, there -are here two types of observer. Bo has no mean displacement for the -8.40-.260 sec. combination, and it steadily decreases toward this -point as the two intervals increase. Both B and M, on the other hand, -have a considerable positive mean displacement for the 1.28-.040 sec. -combination, and a considerable negative mean displacement for the -2.56-.080 sec. combination, and there is a further increase in the -negative displacement as the intervals increase from this point. It -seems as though these observers would give a mean displacement of zero -for some combination of intervals between these first two. It will be -noticed that the average number of trials is exceptionally large for -all three of the observers in the first combination. This seemed to -be pretty clearly due to the very short interval separating visual -impressions. - - -THE AUDITORY INTERVAL _alone_ VARYING - -In order more certainly to isolate the influence of the time-interval -between successive auditory impressions, another series of experiments -was performed, in which this interval between clicks, alone, was -varied from series to series. The visual interval was kept at .083 -sec. throughout. This seemed to be about the shortest time-separation -at which the successive impressions were perfectly distinct. The -auditory impressions were at 1, 1-1/2, 2, 3, and 4 sec. intervals. -The additional observer, H, was myself. I obtained these results by -experimenting alone. I adjusted the wooden shaft carelessly to a new -position and started the machine. When speed was attained, I would -make the observation just as an observer for whom the adjustment had -been made. I would have as little idea beforehand as he with regard to -the position of the click in the series of letters. Having made the -observation, however, I measured the actual place of the sound and -recorded it, as well as my judgment. In this way, of course, I had some -idea, all the time, as to what kind of displacements I was making and -how large. I was as careless of this knowledge as possible, and the -records were laid aside absolutely, until I was through with the whole -experiment. Terms used in Table II are the same as in Table I. - - -TABLE II - - Aud. Interval (sec.) 1 1-1/2 2 3 4 - Vis. Interval (sec.) .083 .083 .083 .083 .083 - - Obs. - B Av. num. Trials 8.5 6.8 6.2 4.8 4.8 - Num. Series av. 10 10 10 10 10 - Aver. Error (sec.) .097 .108 .106 .097 .101 - Mean Displacement (sec.) +.097 +.108 +.106 +.097 +.101 - - Bo Av. num. Trials 6.0 5.0 4.2 3.2 3.1 - Num. Series av. 10 10 10 10 10 - Aver. Error (sec.) .103 .080 .081 .092 .082 - Mean Displacement (sec.) +.102 +.073 +.078 +.089 +.075 - - M Av. num. Trials 4.4 3.8 3.4 3.0 2.8 - Num. Series av. 10 10 10 10 10 - Aver. Error (sec.) .088 .084 .081 .068 .052 - Mean Displacement (sec.) +.086 +.079 +.072 +.051 +.048 - - H Av. num. Trials - Num. Series av. 10 10 10 10 10 - Aver. Error (sec.) .043 .036 .047 .040 .037 - Mean Displacement (sec.) -.022 -.012 -.027 -.017 -.013 - -One series of ten of each of these combinations was given during each -hour of experimentation with each observer. These were also given -in a different order each day, so that no combination should have -the advantage, by practice or lack of fatigue, in the average of the -ten series. Here again it was evident, in the records of each of the -observers for whom the count was made, that the largest number of -trials was necessary in the 1-.083 sec. combination. It thus appears -that it was not the short visual interval, .040, in Table I, that was -responsible for the large number of trials necessary in the first -combination. Here, where there is the same visual interval of .083 -sec. throughout, it must be the short auditory interval which makes -particularly difficult conditions for attention. This agreement between -the results in both groups of experiments seems to indicate unfavorable -conditions for accurate coördination at auditory intervals as short -as one second. The large changes in the mean displacement for B and M -between the first two combinations in the first group (Table I) was -kept especially in mind in planning this second series of combined -intervals. It was presumed from the results given by these observers -in Table I that they would each, with the range of auditory interval -presented them in these experiments, show a point of no displacement, -or a very slight one, and an increasing displacement on each side of -this point. They both seemed to indicate a time-interval favorable -for the "ripening of apperception" as Wundt and Von Tschisch call -it, and I planned these experiments especially to bring it out more -clearly. But there is far less indication of a time most favorable for -"ripening" than in the previous group of experiments. B and M both give -all mean displacements as positive, and decidedly small differences in -displacement for the various combinations. Results of Bo are, however, -entirely consistent with those of Table I. H gives a very small -negative mean displacement throughout. This, as well as the smallness -of the average error, may be due to the knowledge of results which I -had. - -An examination of the detailed daily results, which cannot be exhibited -here, shows considerable change in the direction of the displacements -as the work proceeded. This is especially marked in the case of B, -who, during the first two hours of experimentation, gave only negative -displacements. Through the rest of the first group there was a gradual -increase of positive displacements, and in the last two hours about 90% -were positive. In the second group he did not give a single negative -displacement. The same change is manifested in the results of M for -the first group; but he did not change over nearly so completely. -In the five hundred experiments of Table II, for M, there are three -hundred and ninety-two positive, sixty-seven negative, and forty-one -_no_ displacements. Bo gave a number of positive displacements from the -start. These increased considerably in the second over the first group, -showing only thirty-seven negative displacements in the second group. -This change in the direction of the displacement, rather independently -of the intervals, is an interference with the main purpose of the -experiment. It may represent the effect of practice. - -Angell and Pierce[112] found the same progressive change from negative -to positive displacements. They explained it as a change in the focus -of attention. The visual series is focal at first, and the sound -becomes focal in later experiments. Negative displacements result from -fixing the last possible point in the visual series before the sound -is heard, while positive displacements result from getting the first -letter possible after the sound. The method of my observers, with -the large numbers of trials at their disposal, was to "let the sound -_announce_ the letter" on the first trial, and then to "lie in wait for -the letter" so announced, and to "see whether it was too late or too -early." It was found to be too late usually, for this was the second -method of Angell and Pierce, which gave positive displacements. - -So at the next trial the preceding letter would be waited for, and -tested in the same way. The first trial was thus auditory-visual -attention and the second was visual-auditory, and there was a striving -after a balance where neither auditory nor visual impression had the -preference. - -As soon as adjustment to the conditions of a given combination had -been secured, it was a simple matter to anticipate, with a fair degree -of accuracy, both a given letter and the recurrence of the sound. The -attention could thus be pretty accurately divided between the two, and -a very small time-displacement was the result. When I was acting as -observer, a change of the auditory interval _upset_ the whole _plan_ of -procedure for a short time. I had to accustom myself to the new rhythm. -But as soon as this adjustment was made, it was just as easy to make -the judgment at one rate as at another, barring variations which might -be called fortuitous, since they were so small. This experience with -the conditions here under consideration, as well as the introspections -of the other observers, convinces me that the conception of an -apperception-ripening time has been overworked. - -It is true that I find here, just as Pflaum[113] found, displacements -in both directions with every observer. It seems very doubtful to me, -however, whether these are in any sense due to what may be considered -a fixed apperception-time for a given observer, under fixed objective -conditions. The facility with which adaptation is made to the changed -conditions of a new combination of intervals, so that just as small -displacements are made under one as another, indicates to my mind that -one can control the conditions so that the apperception shall ripen -quickly or slowly, depending upon the warmth of the interest, and the -concentration or division of the attention,--that there is a capacity -in the ordinary individual so to adapt himself to the conditions as to -do equally good work in coördinating two sense-impressions anywhere -within a wide range of intervals. The influence of the length of the -interval separating succeeding clicks, in determining displacements, -has been considerably overestimated. I should state here that no -one of the three observers had any specific training to reduce the -displacement. The results were not discussed with them. They had no -means of knowing what displacements they were making. This certainly -adds strength to the inference, from these results, that there are -adaptable apperceptive conditions for coördinating sense-impressions. - - -THE INFLUENCE OF THE LENGTH OF THE SERIES OF VISUAL IMPRESSIONS - -The next step in the analysis of the complication experiment, bringing -it into relation with the simple coördination of two disparate stimuli, -is to show, if possible, the influence of the _series_ of _visual_ -impressions. This naturally divides into two lines, namely, (1) the -_length_ of the series as such, and (2) the relative influence, in -case of a given kind of displacement, of the part of the series coming -_after_ the auditory stimulus, and the part _preceding_ it. For the -first, I used in comparison, a series of twelve letters, a series -of three, and a single letter. For the second, the letter, whose -coördination with the click was set as the task of the observer, was -made successively the first, the last, and the middle member of a -series of five letters. - -During each hour of experimentation, the observer was tested as to -his accuracy of localization of the click, (1) in a series of twelve -letters at intervals of .083 sec., (2) in a series of three at the -same interval, and (3) with reference to a single letter. The method -for the first two was exactly as in the preceding experiments. In the -case of the single letter, he was asked to localize as accurately as -possible in terms of the intervals as he remembered them from the -series. This introduced an element of uncertainty. One observer, St, -would not give any judgments as to time-differences in the case of the -single letter. Another method had to be adopted in order to obtain more -comparable results. These results (Table III) are presented as showing, -by comparison with the following table, the transition from one method -to the other. Clicks were at 2-sec. intervals. Each number in the -table is the average result of fifty or more experiments. They are in -thousandths of seconds, and the plus and minus signs indicate positive -and negative displacements. - - -TABLE III - - _Observer_ _Twelve Letters_ _Three Letters_ _One Letter._ - A +.012 sec. -.029 sec. -.010 sec. - G -.022 sec. +.004 sec. -.004 sec. - Sh +.028 sec. -.079 sec. -.057 sec. - St -.050 sec. -.036 sec. - Bo +.029 sec. -.015 sec. -.022 sec. - -The method of right and wrong cases was used in the next group of -experiments, to secure the same conditions of making the judgment in -each of the three cases used above. Selecting a letter near the middle -of each series, I asked the observer, in each of these cases, just as -in that of the single letter, to say whether the click was before, -on, or after the letter. I worked _out_, in successive experiments by -successive adjustments, from the position of apparent simultaneity -of click and letter, in both directions, to a point where in 75% of -the cases the click seemed to come before; and also to one where it -seemed to come after, in 75% of the cases. So also I worked _in_ both -ways, by successive adjustments, from regions of clear discrimination -of time-difference and direction, to points where the time-relation -was uncertain or wrong in 75% of the trials. By averaging the just -perceptible and the just not perceptible, in each case, the thresholds -were obtained for "click first" and "click last." The time between -these thresholds I call the "range." It is really a measure of James's -"specious present" and of Stern's "Präsenzzeit." (An admirable -presentation of similar results by Wilhelm Peters[114] has appeared -since this work was done.) The best means of comparing these results, -for our present purposes, and also of bringing them into relation with -the complication-results already obtained, is to take the mean point -between these thresholds, and state its position, in time, relative to -the time of the visual stimulus (letter) just before or after which -the click came. This mean point is called the "Threshold Mean" in the -following tables. In Table IV, for example, "After Letter .026 sec." -means that the mean point between the thresholds, "click first" and -"click last" falls twenty-six sigmas after the time of the exposure of -the letter. These results are readily comparable with those of Peters. -By dividing the "range" by two, and adding the "threshold mean" to one -half, and subtracting it from the other, one has the total interval -between "click first" and "click last" and its place with reference to -the time of the visual stimulus. - - -TABLE IV - - _Obs._ _Twelve Letters_ _Three Letters_ _One Letter_ - - A Threshold Mean After After - Letter .026 sec. On Letter .041 sec. Letter .020 sec. - Range .093 sec. .062 sec. - - G Threshold Mean Before Before After - Letter .015 sec. Letter .020 sec. Letter .062 sec. - Range .072 sec. .083 sec. .304 sec. - - Sh Threshold Mean Before After After - Letter .003 sec. Letter .027 sec. Letter .003 sec. - Range .172 sec. .111 sec. .241 sec. - -It must be distinctly understood that these "threshold means" are -not displacements, and that the two cannot be compared as if they -were statements of the same facts. These _means_ indicate the centre -of gravity of the "click first" "click last" interval with respect to -the visual stimulus. Changes in this centre of gravity may reasonably -be expected to approximate a variation _inverse_ to that of the -displacements of the auditory stimulus. For example, any change in the -conditions which would tend to increase a _negative_ displacement would -tend also to put the centre of gravity of the "click first" "click -last" interval _after_ the visual stimulus, or, if it were already -after, to increase its time after. So also the _positive_ displacement -and the position of the threshold mean _before_ the visual stimulus may -be considered similar indications. For a click given at the time of the -threshold mean of a given observer, in connection with the same visual -stimulus, would certainly be judged by that observer as simultaneous -with the visual stimulus. If, then, this mean is before the visual -stimulus, the sound will be displaced positively, _i. e._, coördinated -with a visual stimulus coming later. If the mean is after the visual -stimulus, the sound will be displaced negatively, _i. e._, coördinated -with a visual stimulus coming earlier. The position of the mean of the -thresholds indicates a tendency toward the displacement of the auditory -impression in the opposite direction. - -In Table III, three out of five observers, A, Sh, and Bo, show a change -from a negative displacement in the series of three to a positive -displacement in the series of twelve. If this were the effect of the -series, the same should show in the series of three as compared with -the single letter. Such a change is manifest in the results of Bo. It -is, however, very slight. The others increase the negative displacement -from the single letter to three letters. In Table IV, of the same three -observers represented, Sh changes the threshold mean from _after_ in -the three-letter series to _before_ in the twelve-letter series, and -A changes from _after_ in one letter to _on_ in three letters. These -changes correspond to changes from negative to positive displacements -for increase of series and introduction of series. G shows the same -change from one letter to three, in both tables. These changes, in -55% of the cases offered for comparison in the two tables, indicate -a _decrease_ of _negative displacement_ and an _introduction_ of -_positive displacement_ as the _effect_ of the _visual series_. The -visual element is made more focal in expectant attention as it is -more isolated, and so the tendency toward negative displacement and -increasing negative displacement as the serial character of the visual -impressions is stripped off. But there are strong counteractive -tendencies, which control the 45% of comparisons not mentioned above, -where the increasing series shows increasing negative displacement. - -In the series all the observers adopted the method which has been -outlined above, that of letting the click pick out the letter, or -letting the letter announce itself. One said "the letter hits the -sound." After this sorting-out of the letter, they resorted to the -system of tests and counter-tests, in succeeding trials, to correct -the first impression. One can readily understand, then, that when -they were taken off the series altogether, an entirely different -kind of adjustment had to be made. G did not succeed in making this -new adjustment very well, as is shown by his exceptionally large -range under one letter. He could not get the two impressions to come -together. In attending to either one, he could not get the other in -relation to it. There was something in the visual series which enabled -him to get the visual impression in line with the auditory, and when -this was absent the same kind of work could not be done. - -St had also a peculiar method, which was directly dependent upon the -serial character of the visual stimuli and impressions. He allowed the -series of clicks and the series of visual impressions to establish -themselves as a complex rhythm. Each series was rhythmic independently. -The two got connection by means of the click appearing as an -"after-strike," as on the piano, to a member of the visual series. -The letter "flashes out" for him as that of which the click was the -"after-strike." The click was thus between two letters. But there was -no amount of before or after about it. It was a general quality of the -whole complex which was taken to mean such and such a position of click -in the series. What he thus translated into temporal judgments, were -qualitative aspects of the rhythmic experience, to which he usually -attached no temporal meaning whatever. Learning how so to translate -them into temporal terms was a definite process of training for him. -Under these circumstances, he of course had an entirely new lesson to -learn when the visual series was taken away. In fact, it might be, he -would now find no visual impression to which the click could be an -after-strike, and so he would be entirely without material to translate -into temporal terms. - -Under these circumstances it is not surprising to find G and St -exceptions to the majority of the observers in this experiment. This -makes more probable the effect of the series, inferred above for the -other observers,--namely, series decreases negative displacement. - - -THE INFLUENCE OF THE _Position_ OF THE _Series_ OF _Visual_ -IMPRESSIONS - -It was noticed in the series of the three letters, particularly, that -some observers were much more accurate in their work when the click was -near one end of the series. In this experimental group, the comparison -is between cases where the click is coördinated with (1) the first -member of a visual series of five, (2) the middle member of a series -of five, and (3) the last of such a series. The method was the same as -that used in obtaining the results of Table IV. H was the letter used -in each case for coördination. Results follow in Table V. - - -TABLE V - - _Obs._ _H first_ _H middle_ _H last_ - A Threshold Mean After Letter After Letter After Letter - .010 (sec.) .021 (sec.) .025 (sec.) - Range .072 (sec.) .085 (sec.) .093 (sec.) - G Threshold Mean Before Letter On Letter Before Letter - .007 (sec.) .007 (sec.) - Range .124 (sec.) .083 (sec.) .151 (sec.) - R Threshold Mean After Letter After Letter After Letter - .032 (sec.) .016 (sec.) .042 (sec.) - Range .464 (sec.) .398 (sec.) .369 (sec.) - Sh Threshold Mean After Letter After Letter After Letter - .025 (sec.) .015 (sec.) .030 (sec.) - Range (sec.) .176 .176 .166 - St Threshold Mean After Letter After Letter After Letter - .050 (sec.) .062 (sec.) .078 (sec.) - Range (sec.) .140 (sec.) .108 (sec.) .108 (sec.) - -Under these conditions, whatever the effect of the visual series, if -it has any effect, opposite tendencies in direction of displacement -ought to be shown in the "H last" from those in the "H first," results, -as each is contrasted with "H middle." Contrasted in this way, these -results, for A and St, show a relative approach of the mean to zero -for "H first," and a relative departure from zero for "H last," or a -_decrease of a negative displacement for "H first"_ and an _increase -of the same for "H last."_ In other words, the series draws the -displacement of the click toward itself. A _negative displacement is -increased by a series coming before the visual stimulus_ in question, -and _decreased by such a series coming after_. For R and Sh, the -negative displacement is increased in both H first and H last as -compared with H middle, but relatively the most for H last in both -observers. For G there is the same positive displacement introduced -by both H first and H last, but it is less than in any of the other -cases. The drift of the evidence here, then, is that the _visual series -draws the displacement in its own direction_. Each observer who has a -negative displacement (Threshold mean after) with "H middle" increases -this when the series all comes before (H last) and two decrease it -when the series comes after (H first). - - -THE EFFECT OF RHYTHM (_Repetition of Auditory and of Both Stimuli_) - -It is very evident to any one who has worked at all in the complication -experiment, that rhythm plays an important part in the displacement. -Witness also the astronomers' experience cited above, St's waiting -for the rhythm to establish itself, and my own readjustment to the -new conditions when a new combination of intervals was given in the -experiment with varying auditory intervals. In order to show the part -played by rhythm, I tested each one of five observers on several -different days, to fix for each of them both the "click first" and -the "click last" thresholds, as above, under each of the following -conditions: (1) one visual (single letter) and one auditory stimulus -(one pair), (2) one visual (single letter) and many auditory stimuli, -and (3) many visual (single letter repeated) and many auditory stimuli -(many pairs). For visual fixation, the observer had a very dim light at -the end of the observation-tube. The visual stimulus was a flash of red -in the place thus fixated. It had a total duration of less than .005 -sec. The surface exposed subtended a vertical visual angle of about -seven tenths of a degree. In the case of one visual and many auditory -stimuli, the visual stimulus was given when the observer had heard the -recurring auditory stimuli several times and had himself given the -"ready" signal. The results follow in Table VI. - - -TABLE VI - - _Obs._ _One Visual and_ - _One Pair_ _Many Auditory_ _Many Pairs_ - A Threshold - Mean After - Letter (sec.) .005 After Letter .022 After Letter .042 - Range (sec.) .021 .024 .039 - G Threshold - Mean After - Letter (sec.) .022 After Letter .009 After Letter .005 - Range (sec.) .078 .083 .084 - H Threshold - Mean Before - Letter (sec.) .011 After Letter .006 After Letter .012 - Range (sec.) .035 .035 .039 - Hy Threshold - Mean After - Letter (sec.) .034 After Letter .030 After Letter .046 - Range (sec.) .089 .074 .072 - St Threshold - Mean After - Letter (sec.) .054 After Letter .037 After Letter .041 - Range (sec.) .096 .080 .083 - -In this experiment, the observers A, H, and Hy, show an increasing -distance of the threshold mean after the visual stimulus, with the -successive introductions of the auditory series and the combined -series. In other words, the second column negative displacement is -larger than that of the first, and the third column has a still larger. -G and St are again exceptions, as they would be expected to be from -the above analysis of their methods. Each did his most accurate work -in a case where there was some rhythm present. St said in regard -to this work "the one pair abolishes the sound as a standard." The -rhythmic factor most missed by these observers, in the case of the -single pair, was the sound; for their results are almost the same in -the second and third columns. Introduction of the repetition of the -visual series does not make any decided difference. A, H, and Hy were -able so to adjust their attention as to get the best results in the -case of the single pair. The rhythm seemed to introduce for them a -subjective rhythm which upset the nice adjustment of attention and so -increased the displacement or the time between the threshold mean and -the visual stimulus. The negative displacement was increased under -these circumstances, probably as a result of the facilitation of the -auditory perceptive process. It has an _opened path_. It is a case of -pre-perception. Even when both were repeated (many pairs) the auditory -dominated, and so did the most at opening its path. But it seems more -likely to me that the rhythm, as such, whether auditory or auditory and -visual, claimed the attention and so proved a distraction from the work -of accurately discriminating the times of the impressions. And this -exaggerated the displacement or lack of discrimination in whichever -direction it was tending before. - -In the successive stages of the investigation thus far, the -complication experiment has been stripped down by degrees to the -simple problem of the shortest possible interval between two disparate -stimuli,--in this case shortest auditory-visual and visual-auditory -intervals, as in the one-letter experiment of Table IV and the one-pair -experiment of Table VI. The various factors in the complication -experiment which have been successively analyzed out--the interval -between members of the auditory series, the length of the visual -series, the position of the visual series in relation to the auditory -stimulus, and the auditory series itself--have all been shown to be -factors intimately connected with the way the observer attends to -the stimuli in question. From the present standpoint, it may be said -they are all factors which, being introduced into the simple interval -discrimination experiment, modify the resulting judgment with regard to -the interval, by an interference with the normal attention-processes in -the discrimination of intervals. - - -INTERVAL DISCRIMINATION - -The method of interval discrimination deserves special consideration. -Some of the introspective observations made by observers while engaged -in the work, already reported, are instructive in this connection. In -the case of a single pair, one observer said, "I know which is first -because it gets hit first." This remark is a very apt expression of -my own experience in trying to answer the same question. "Getting -hit first" clearly means, to my mind, some kind of _action_ on the -part of the observer. He was ready, in the moment of preparation for -the experiment, to see a flash of red with his right eye (either eye -could have been used) and to hear a click with his left ear. (The -stimuli were each produced 25 cm. from the respective sense-organs.) -His preparation consisted in securing the "hair-trigger" condition in -the two parts of the cortex and conduction apparatus immediately in -question in the sensing of the two expected stimuli, and other parts -are in a shut-off-from-discharge condition. This is the interpretation -which seems to me an appropriate explanation of the feeling of special -readiness to discharge in these two directions, when the expected -stimuli shall come. The eye- and ear-muscles, in such case, are held -tense on the sides (in the organs) where the stimuli are expected. -The breath is held, and the whole trunk is under a strain. All bodily -processes, in so far as they are controlled, are directed in such wise -as to get whichever of these expected impressions shall come first, in -as short time as possible, in order to know that it is first. - -The reaction which gives the basis for the judgment may be a conscious -"hitting" of the first. Or it may be a reaction, ostensibly as a part -of the whole apperceptive process of which the auditory and visual -processes are parts. This reaction may be any one of many kinds. -Often it is a letting-go of the held breath. The exhalation or other -reaction comes in response to the whole stimulating or "setting-off" -process, and the one or the other of the two stimuli is judged to -be first by certain peculiar relations within the experience of the -moment. Such an explanation is in part suggested by the expression -of St, that the visual impression when it came before the auditory, -appeared as a "grace-note," and when it came after the auditory, as -an "after-strike." St played the piano. He himself thought that this -discrimination was a motor affair, _i. e._, a difference judged on -the basis of a difference in the motor response. The judgment of the -temporal order of the two impressions seemed to be an interpretation -or translation of the different motor responses. - -A, whose method brought the shortest range in Tables IV, V, and VI, -said, "I hold my breath at the moment of expected stimulation, and it -goes at the first impression." At another time he said, "When I say -'click first' I have the feeling that the click is left, and when I say -'click last,' that the click is on the right." He interpreted this to -mean that when the click sounded first, he had moved slightly toward -it, that is, to the left, and that when the visual stimulus had come -first, he had moved slightly toward it (it was sensed by his left eye), -and this was rather away from the sound, which would have come before -the movement could have been more than initiated. - -In my own case, I felt distinctly different motor responses in the -two cases. There was an immediate feeling of release in whichever -organ the stimulus first reached. A little involuntary jerk occurred -in the musculature of this sense-organ, and sometimes the head moved -slightly in the direction of the first stimulus. The condition of -the next moment from which the judgment proceeded seemed to be best -expressed thus, "I had it at a time when the other was not there." The -attention was accurately set for both. Right eye and left ear were both -distinctly innervated. The first stimulus "struck" the appropriate -organ, and the "set" of the organ was released. - -I am persuaded that the difference in sensitivity to intervals between -auditory and visual impressions is due, in part, to a difference in -the power of "cocking the ear" to hear, as one fixates the eye to see. -The observers who got the smallest ranges between upper and lower -thresholds had the most distinct kinæsthetic sensations in the moment -of preparation, in the middle ear and about the external meatus. -All had some sensations from the side of the head in question. The -less accurate had a general feeling in the neck-muscles. Accuracy of -discrimination was in no wise connected with voluntary control of the -musculature moving the pinna. This was subject of careful enquiry with -all observers. - -If this introspective evidence leads me aright, it seems that the -non-discriminable interval between auditory and visual impressions is -due principally to two things, (1) the impossibility of perfect balance -in the preparation of the attention for two expected stimuli, and (2) -the possible difference in time it takes to react to the different -impressions. The various complicating conditions which are added to -the simple interval discrimination in the cases of a complication -experiment, such as we started with in this investigation, are -chiefly interferences with the first-named factor. They disturb the -nice balances of attention. In this simple discrimination experiment, -under favorable conditions, a close approximation to a balance can -be attained. Any difference in the reaction-times to different -stimuli will remain as a constant error of displacement. It is well -known that reaction-times to visual stimuli are longer than those -to auditory. There is a retinal inertia which delays the perception -of the visual impression, in comparison with the auditory, coming -from exactly simultaneous stimuli. Having this physiological basis, -it will be relatively constant, as compared with the ever-varying -attention-differences. - - -THE COEXISTENCE OF MENTAL PROCESSES - -Having given, then, these relatively fixed temperamental conditions of -reactions to different stimuli, which remain after practice (training -in the control of attention) has reduced the reactions to their -lowest terms, and has secured the conditions which are favorable for -the best balancing of the attention, there is yet one other question -very germane to the subject. It will have occurred already to any one -reading the above, that while the response to one stimulus is being -made, the other may be held in abeyance in the fringe region of the -attention-field, and that it is only brought up to clear perception -when the first has been disposed of. In other words, it may well be -that the first of two simultaneous but disparate stimuli, which gets -a start at setting-off its appropriate response in its sense-organ, -will bring out this response and be perceived before the other one -gets started,--that we do only one thing at a time,--that even in -such minute processes as this there is no possibility of division of -attention. It is hardly probable on the basis of the experimentation -already reported, that this is the case. There is some division of -attention. Otherwise there would be an equal certainty of judgment in -every case, no matter how small the separating interval. But still -the question as to how two mental processes, starting at the same -moment of time, do proceed, as compared to the progress of each of -the same processes when it holds the field alone, is very vital to -the understanding of the psychology of interval-discrimination. And -thus the question of objective time-relations is necessarily involved -in that of making judgments of the time-relations of simple mental -processes (subjective time-relations). The question is, Do these -processes, starting simultaneously, proceed just as freely as if they -were the sole occupants of the field of attention and so had the whole -energy of attention concentrated upon the single process, or do they -_interfere_ with each other? - -Distribution of attention, of some sort, is granted. It is generally -conceded that there must be some sort of overlapping of the processes -in any complex mental operation. But there is the greatest lack -of information as to how this overlapping takes place,--as to the -mechanism of the distribution of attention. Fechner held to the notion -of a fixed maximum of available psychophysical energy. If this energy -is being consumed in a single process, that process is very vivid, and -all other processes are below the threshold. If, on the other hand, it -is distributed over several simultaneous processes, they are all of -diminished vividness. Distribution of attention always means diminution -of vividness, and concentration of attention, increase of vividness. -(See Elemente der Psychophysik, vol. 2, p. 451, 1860.) There is no -question of the truth of the last statement, and very likely Fechner's -fundamental concept is a true one; but there is need of more definite -data on the conditions and nature of simple mental processes occurring -at the same time, before it is considered proved. - -Such researches as those of Paulhan,[115] Jastrow,[116] Loeb,[117] -and De Sanctis[118] all dealt with the combination of processes which -were themselves quite complex. It may well be that such processes as -reciting a poem, performing a subtraction or multiplication of long -numbers on paper, or keeping time with a metronome with the hand, seem -to go along together when combined, so that the time taken to do the -two of them together is much less than the sum of the times required -for their separate performance, and, in some cases, no greater than the -time required for either alone, and yet there may be no real proceeding -together. The apparent saving of time may be due, as Paulhan suggested, -to a rapid oscillation from one to the other of the two complex -processes which are largely automatic and can proceed, to such extent -as they are automatic, without any attention. This illustrates how -these investigations have probably missed the real point at issue with -regard to the division and distribution of attention. The attention -might be distributed over several of the minuter part-processes of -these processes so that many were proceeding at the same time, and yet -the method of these experiments would not reveal it. They were not -planned with sufficient precision. There is a problem in the division -of attention which they did not come within sight of, and this is the -real question of division in case of the simplest processes. - -This problem is really that of the mechanism of mental assimilation. -The process it investigates is illustrated by the maturing collective -idea, as a melody or a spoken sentence. There is a gradual enrichment -or growth in meaning, as such a process goes on toward its completion. -At any instant during the process, implicit associative and nascent -perceptive elements are working together to their own mutual -clarification and explication. All focal content is the result of -complicated interworkings of such fringe material. It is impossible, -it seems to me, to question the causal relation of the fringe elements -or processes of one moment to the focal of the next; and it is equally -impossible to deny the complication of these same fringe processes. -They must go on at the same time in order to enter into one and the -same resultant process. The question of direct interest at this point -in the discussion is, To what extent do they proceed at the same time? - -It would seem from the way in which this question, of the relationship -and interference of mental processes which proceed or start to proceed -at the same time, has come up in this investigation, that the natural -method of pursuing it would be that of comparing reaction times for -cognition reactions to the single and combined stimuli. But we are -warned against this by very clear inferences from an investigation of -Professor Münsterberg's in which he used the reaction method.[119] -By an ingenious use of the reaction experiment, the author shows -that two-part processes in a reaction, as, for example, a restricted -judgment of class and a subjective preference, occupy about the same -time when combined in a single reaction as when either is performed -in a separate reaction. In other words, two judgments of distinctly -different kinds can be made in the same time as either can be made when -it has all the attention concentrated upon it. The conclusion that -these elementary processes go on together--that at least there is some -degree of overlapping--seems unavoidable. - -But when the first part of the same report is considered in relation -to the second, it is clearly shown that the reaction experiment is not -adapted to the finer investigation of this problem. For the first part -shows that no matter how much a _motor_ reaction is complicated by -choices or other judgments, it always takes place in just about the -same time as the simple reaction. The complications may be such as -actually to double the reaction time in the case of a sensory reaction, -and yet a motor reaction, under precisely the same conditions as far as -they may be the same for a motor, shows no increase in time. The "set" -of the attention in the motor reaction is, no doubt, such a change -in the order of succession of the parts of the process that some of -those, which come after the stimulus is received in the case of the -sensory reaction, are made to come before the stimulus in the motor. -When, however, it is found that the motor response to the question, -"Is this the name of a scientist, philosopher, poet, statesman, or -musician,--Sappho?" is made by the appropriate finger, as previously -agreed upon, in just as short a time as the observer can make a motor -response with any finger to a simple auditory stimulus, it indicates, -either that the whole of the choice judgment has been made before the -stimulus was received, or that the judgment itself is so automatic -that it is practically a reflex. This latter cannot be true. The -judgment, as conscious choice, cannot be made before the stimulus is -given, _i. e._, until the question is completed. And judgment cannot -be made automatic and yet be a judgment. In fact both alternatives are -untenable, and there is no other course than to hold the situation -which gave rise to them at fault. If the judgment process here required -previous to the reaction does take time apart from the processes of the -simple reaction, the reaction process is shown by these experiments to -be unable to exhibit it. A more microscopic method is demanded before -the matter can be settled. - -The Leipsic method of measuring the scope of attention by means of -the tachistoscope is the standard means of securing data as to the -_number_ of elementary processes which can go on at the same time in -consciousness. The same question, with which we are here concerned, -grows directly out of the investigation of the number of processes -which can go on together. Wundt acknowledges the great difficulty which -inheres in the investigation of this problem.[120] Cattell's early work -with the tachistoscope showing the numbers of letters, syllables, and -words, which could be apperceived under the same objective conditions, -indicated the great importance of what we may best call _meaning_, in -apperception, and its influence on the number of different processes -which may proceed together. In fact the number depends upon the -definition of the unit with which the investigator starts out. Wirth, -the latest emendator of the tachistoscopic method, has shown,[121] in -a very thoroughgoing and genuinely constructive criticism of earlier -work, that the one question of primary importance in investigations -of the content of the moment of consciousness, _i. e._, scope of -attention, is to set forth the relative clearnesses of the elementary -processes there proceeding together. He shows that the different grades -of clearness which may present themselves in the field of consciousness -of a momentary act indicate, on the one hand, the impossibility of -sharply distinguishing the "scope of attention" from the "scope of -consciousness" as Wundt uses these terms, and, on the other, the -serious indefiniteness of any merely numerical statement of the scope -of attention. His main purpose is to set forth a method by which -this field can be enriched by exhaustive statements of the relative -clearnesses of the processes going on at the same time. All the work of -the present study had been performed before the publication of Wirth's -work. Otherwise some of his suggestions would have been used in the -plan of the experiments following. I may say, however, that I believe -the method here used has its own distinctive merits. - - -GENERAL METHOD FOR TESTS IN COEXISTENCE - -Taking the suggestions offered by Professor Münsterberg's study of -apperceptive and associative processes, I selected simple _judgments -of comparison_ as the best means of trying-out this question of -coexistence. The perceptive act itself is made up of judgments, and -these may very properly be the processes studied in combination as in -the tachistoscopic experiment. But the judgment which has a previous -perceptive act as its condition, determining its start, seems to be -better under control. It is itself a central process, not dependent -upon the variations of the objective factors in sensation. My plan -was to have the stimuli so arranged as to give rise to two or more -perceived conditions at the same moment, and so have one or more -judgments of comparison between the perceived features made at the -moment the perceptions were completed and immediately stated. If one -makes two series of single judgments of comparison, and a series -wherein these two judgments are combined in a single act, all three -under precisely the same objective conditions, and the same subjective -conditions, saving only the necessary changes in the _direction_ of -the attention, and the percentage of correct judgments is recorded in -each case, providing always that in no single series of judgments were -the conditions such that all judgments could be correctly given, he -would then have reasonable grounds for making inferences with respect -to the _interference_ of simple mental processes going on at the same -time,--whether there is any, and, if there is, how much there is. -_Interference_ would be indicated by the _falling-off in percentage of -correct judgments as the combinations were increased_. - -Such relative accuracy of judgments, single and combined, was the test -sought after and relied upon in the following experiments. It was very -necessary to have the objective conditions such that the results in -cases of single judgments, later to be combined, should be short of -absolute correctness, in order that interference from the combination -should show itself in impaired accuracy. Otherwise there might be some -_free energy of attention_, which could readily take up the extra work -when the judgments were combined, and so there would be no impairment -of accuracy. It was the aim to have the objective conditions, such as -duration and extent, so regulated that about ninety per cent correct -judgments resulted in the series of single judgments. If, then, when -two were combined, eighty per cent were given correctly, and when three -were combined, seventy per cent, the inference would seem reasonable -that this falling-off in correctness was due to interference. The -failure of the perceptive process, indicated by the ten per cent -incorrect judgments in the series of singles, would remain a _constant_ -source of error throughout. - -There is, however, one other source of increasing error, with the -increasing combination of judgments, supposed above. The judgment -processes might go on at the same time without any impairment of the -accuracy of the single judgment, and yet the results, as expressed, -might show a falling-off in accuracy. This imperfection would then be -due to a partial failure of the retentive and reproductive processes, -and not to the imperfection of the judgment processes. I have found -no sure means of separating this factor and excluding it. As the -experiments were arranged and conducted, though, I believe any -impairment in accuracy resulting from combination is more likely due to -interference of the judgment processes. - -If neither of these factors is efficient, on the other hand, there will -result no falling-off in accuracy of results when single judgments are -combined. To be sure the conditions of the experiment, as outlined -so far, do not preclude the possibility of the combined judgments -occurring in succession, and so giving rise to as large a percentage -of correct results as when occurring singly. That is, while one of the -so-called combined judgments was in process, the latent conditions -of the other would remain for the moment as mere physiological or -possibly psychical dispositions, and to these one would "hark back" in -the next moment. Here the reaction method is suggested as the means of -assurance that this is not the case. But this method, we have already -seen, will not lend itself to work of such precision as this. The -probability of this succession of judgments is reduced to a minimum in -the experimental groups following. - -It can be practically precluded by a prevention of all sensory images. -In these experiments every precaution was used to prevent them. In -all cases where visual stimuli were used, for instance, a brightly -illuminated blue field immediately succeeded the momentary stimulus, -while comparative darkness preceded it. I cannot be so sure that there -were no memory images functioning. But all observers were carefully -questioned on this point at frequent intervals during the experiments, -and no evidence of their existence was found in any case. I feel sure -sensory images were excluded and think memory images very improbable. - - -SINGLE AND COMBINED JUDGMENTS FROM VISUAL AND TACTUAL STIMULI - -In this group of experiments, I used judgments from visual and tactual -stimuli, singly and in combination. Both stimuli were given by means -of a large pendulum in the Harvard laboratory, specially constructed -for Professor Münsterberg. This pendulum is about one and a half metres -in length. It is hung in a heavy steel frame which rests upon a large -table. A curved steel bar, concentric with the swing of the pendulum, -and ninety degrees in extent, is so set to the frame that it serves -as the attachment for an electro-magnet, at any point in the swing of -the pendulum. The pendulum-rod carries an armature which fits this -magnet. By means of this magnet, the pendulum may be held at any point -between the position of rest and forty-five degrees out in either -direction; and it may be released by _breaking_ the circuit through the -magnet. The pendulum also carries a segmental screen of about seventy -degrees extent. An opening about nine by eight centimetres near the -centre of the screen affords means of tachistoscopic observations. A -sliding shutter makes the slit as narrow as may be desired. In these -experiments a black tube was set up, at right angles to the direction -of the motion of the pendulum, and at the height of the slit in the -screen. On the other side of the pendulum screen, and directly opposite -the tube, was placed a support for holding the object to be shown. - -The object for the visual stimulus was one of two light gray lines on a -black background. These lines were 4 mm. wide, and one 44 mm. long, and -the other 40 mm. The work was done in a dark room. The stimulus card -was illuminated by an electric light hanging between it and the screen. -Both cards were shown the observer several times, before experimenting, -till he was sure of their lengths. Upon one being shown, in experiment, -he was asked to say whether it was the longer or shorter. The touch -apparatus was so arranged that the experimenter could at will give -the observer one or two contacts on the back of his right hand. The -contacts were made by means of an electro-magnet. This was actuated by -a current which was _made_ by the closing of a switch which was secured -by a set-screw to the same curved steel bar as bore the pendulum -magnet. This switch was closed by the pendulum in passing. It was -adjustable on the bar. Another similar switch, opened by the falling -pendulum the next instant, removed the tactual stimuli. These switches -were so placed in the course of the pendulum fall that the tactual and -visual stimuli were exactly simultaneous. The tactual judgments were, -_one_ or _two_ points touched. Results are presented in Table VII for -three observers, A, B, and Bo. The number of series which were averaged -in each case is given, in order properly to weight the results. - - -TABLE VII - - _Combined_ - _Single_ _Single_ _Tactual_ - _Obs._ _Tactual_ _Visual_ _and Visual_ - A Number of series - averaged 3 3 3 - Per cent Correct 80 89 79 - Judgments \-------\/-------/ - Average 84 - - B Number of series - averaged 5 5 5 - Per cent Correct 72 78 78 - Judgments \-------\/-------/ - Average 75 - - Bo Number of series - averaged 5 5 5 - Per cent Correct 88 71 78 - Judgments \-------\/-------/ - Average 79 - -In Table VIII are given A's results for further experimentation under -the same conditions, also for a pair of visual judgments, a pair of -tactual, and all four combined. One series of each of the five was -given each hour of experimentation. For the additional visual judgment, -the observer was required to say whether the line was _high_ or _low_. -It was of two heights from the lower edge of the card, 17 mm. and 20 -mm. For the other tactual judgment, he reported the point or points -touched on the hand, as on the _right_ or _left_ side. The middle line -was traced by the experimenter, before tests, as often as the observer -wished to be reassured of its position. - - -TABLE VIII - - _Tact._ _Two Tact._ - _Obs._ _Sing._ _Sing._ _and_ _Two_ _Two_ _and_ - _Tact_ _Vis._ _Vis._ _Tact._ _Vis._ _Two Vis._ - A Number of series - averaged 6 6 6 6 6 6 - Per cent Correct - Judgments 87 88 83 9 81 83 - -The next additional combination was a pair of judgments based upon -auditory stimuli. Four electric clickers were placed on the wall behind -the observer. Two were loud and two faint. Each pair was accurately -adjusted so they were of the same intensity and quality. One of each -pair, _i. e._, one loud and one faint, were hung about four feet to -the left of the observer's median plane. The other two were hung at -an equal distance to the right of this plane. The circuit making the -click was _made_ by a switch closed by the pendulum as it fell. The -experimenter by pressing any one of four buttons gave the one of -the clicks he desired. The observer's two judgments were as to the -_loudness_ and the _position of the click_. - - -TABLE IX - - _Two Vis._ _Two Tact._ _Two Aud._ - _Obs._ _Lgth._ _Pos._ _Num._ _Pos._ _Inten._ _Pos._ - B Number of series - averaged 8 8 8 8 8 8 - Per cent Correct 82 94 89 100 94 92 - Judgments \----------------\ /----------------/ - Average 91.7 - - Bo Number of series - averaged 12 12 12 12 12 12 - Per cent Correct 77 91 87 97 81 82 - Judgments \----------------\ /----------------/ - Average 85.8 - - _Six Judgments Together_ - _Visual_ _Tactual_ _Auditory_ - _Obs._ _Lgth._ _Pos._ _Num._ _Pos._ _Inten._ _Pos._ - B Number of series - averaged 14 14 14 14 14 14 - Per cent Correct 89 97 86 96 70 86 - Judgments \----------------\ /----------------/ - Average 87.3 - - Bo Number of series - averaged 20 20 20 20 20 20 - Per cent Correct 77 93 85 98 81 80 - Judgments \----------------\ /----------------/ - Average 85.7 - -It is evident, on the face of these returns, that there is no positive -assurance of interference. Each of these observers had been in some -part of the complication work. And so the inference from lack of -evidence here can be carried back to that work, and we may rest assured -that the lack of accuracy in interval discrimination work by these -observers was due in minimal measure, if in any, to interference of -the mental processes, auditory and visual, tending to proceed at the -same time. Some parts of the results here presented look like evidence -for interference. But there is, on the whole, just as much evidence -of what one might call facilitation, in combination, as there is of -interference. - -There is one source of possible explanation for the non-appearance -of evidence of interference in these results: that is the fact that -the stimuli are disparate, and so probably take different times for -maturing. Thus the judgment processes, so far as they thus start -from disparate sensations, may start at different times. There was -good reason for using disparate stimuli first for the combination of -two mental processes, as this was the closest related to the simple -interval discrimination experiment to which the complication experiment -had been reduced. But this objection is now easily overridden by making -the conditions of experiment such that all judgments start from one and -the same perceptual process. - - -ONE, TWO, AND THREE JUDGMENTS BASED UPON A SINGLE SENSE-PERCEPTION - -The conditions here were such that the perceptual basis for any one of -the single judgments was at the same time the possible basis for any -other single judgment and also for any or all of them combined. What -judgment or judgments were given depended entirely upon the directions -given, and the consequent preparation of the attention. Under these -conditions, there could no longer be any doubt about the even start -of all judgments, so far as outer conditions were concerned. The only -remaining cause of an uneven finish--lagging of a process, as shown by -its increased inaccuracy when combined--must be interference with its -progress by other processes going on at the same time. - -Visual stimuli were used. The objects to give the perceptual basis -for the judgments were small rectangular openings in cardboard seen, -on exposure, by _transmitted_ light. These rectangular windows in the -cardboard were 2 cm. by 1 cm. and stood in the vertical position 1 cm. -apart. The judgments were all based upon differences existing between -these rectangles as shown. One of these differences was in _length_. -They might be of the same length, or either the right or left might -be 2 mm. longer than the other. Another difference was in _shade_. -This was secured by different thicknesses of paper, pasted over the -openings. Two shades were used. The opening on one side might be shown -as either the same brightness, brighter, or less bright. The third -difference was in the _number of lines_ which crossed the rectangles. -Two or three wires were placed across them horizontally and about 5 mm. -apart. Thus they had the same number of lines, or one had fewer or more -than the other. - -The same large pendulum was used in these experiments. The moveable -magnet on the curved steel bar was kept in one position throughout. -It held the pendulum, ready for release, at twenty degrees from the -position of rest. The adjustable weight on the pendulum was also kept -in one position. The only adjustment which was changed during this -series of experiments was the width of the slit in the window of the -screen. This was varied from one millimetre to five. The whole time -during which any part of the two rectangles was in view (the total -exposure) with a 5 mm. slit was .033 sec.; with a 3 mm. slit .031 sec.; -with a 1 mm. slit .029 sec. These times were measured with a Hipp's -chronoscope. The entire visual field, embracing the two rectangles, was -about 2 cm. by 3 cm., and was about three fourths of a metre from the -observer's eye. It could be accurately fixated beforehand and fully -exploited during the moment of exposure. - -The observer was always instructed to give his judgments in terms of -one of the two rectangles. If, for example, length was in question, he -should say of the left-hand rectangle that it was longer, shorter, or -of the same length as the right-hand one. The process of expressing -the judgments was also facilitated by using the terms plus, minus, and -equal, for all three sorts of judgments. This was a special aid to -expression where two or more judgments were in question at the same -time. In these cases the observer was always given an order beforehand, -in which the judgments were to be given. This order for the three -combined, for example, was always, "length, lines, shade," as in the -following tables. If, then, the judgments were given "plus, minus, -minus," it meant that the left-hand rectangle was longer, had fewer -lines, and was less bright than the right. The process of making these -interpretations, as well as the order, was made automatic with the -observer, by practice, before experimenting. - -Three observers, A, B, and Y, were used in this experiment. The -judgments were made in series of ten. Each hour's work was distributed -over (1) several series of single judgments, (2) two at a time, and -(3) three at a time, the aim being to get an equal number of judgments -of each kind, length, lines, and shade, under each of the three -conditions. The results are given as general percentages of correct -results. To properly weight these averages, the number of series (of -ten judgments each) which are included in making up any average, is -given just above the average. - - -TABLE X - - KEY: Lth = Length - Ln = Lines - Sh = Shade - - _Single Judgment_ _Two Judgments_ _Three Judgments_ - _Obs._ _Lth_ _Ln_ _Sh_ _Lth_ _Ln_ _Sh_ _Lth_ _Ln_ _Sh_ - A Number of - series - averaged 11 12 10 15 17 14 11 11 11 - Per cent - Correct - Judgments 95 93 96 90 91 83 94 91 89 - \----\/----/ \----\/----/ \----\/----/ - Average 95 88 91 - - B Number of - series - averaged 8 8 7 9 10 9 7 7 7 - Per cent - Correct - Judgments 93 80 90 76 77 90 75 70 75 - \----\/----/ \----\/----/ \----\/----/ - Average 88 81 73 - - Y Number of - series - averaged 12 13 13 19 19 16 13 13 13 - Per cent - Correct - Judgments 76 80 58 72 76 61 72 74 58 - \----\/----/ \----\/----/ \----\/----/ - Average 71 70 68 - -Since these general averages for the single judgments are so close -to those in pairs, it seemed possible that the presence of objective -differences, other than the single one asked for, might be a -distracting agent, and really interfere with the judgment process -in question. For example, when judgment on length was in question, -it might be possible to give it correctly a larger number of times, -if there were no differences in shade or lines, than if these were -present. Some careful test experiments were made with a view to -clearing up this situation. The observers in no case knew the nature -of the investigation, nor were they aware that other differences -were absent in some of the cases. The results presented in Table XI -certainly show that the presence of other differences than the one in -question is no cause of interference. - - -TABLE XI - - _Length_ _Lines_ _Shade_ - _With_ _With_ _With_ - _Obs._ _Diffs._ _Alone_ _Diffs._ _Alone_ _Diffs._ _Alone_ - A Number of - series - averaged 5 5 5 5 5 5 - Per cent - Correct - Judgments 98 96 96 96 98 94 - - B Number of - series - averaged 5 5 5 5 5 5 - Per cent - Correct - Judgments 90 92 96 94 78 84 - - Y Number of - series - averaged 7 8 8 8 7 8 - Per cent - Correct - Judgments 73 76 75 64 88 67 - -Notwithstanding the precautions taken to secure the full energy of -attention for the single judgment process, as already indicated in the -discussion preliminary to these experiments,--namely, by making the -stimulation conditions so near the threshold that only a part of the -judgments could be given correctly,--there still appeared a probability -that there was free energy of attention during the single judgment -process. The observers seemed to do more work when more judgments were -asked for. If this is true, the results of Table X are not a true index -of interference. If there is free energy during the moment of making -the single judgment, this may readily be used for another process when -combined with the first, and so there will be no interference. This -is a sufficient proof so far as it has immediate bearing upon the -interval discrimination experiment, but the further question as to what -will take place if we can use this free energy, if it exists, in both -processes alike, is an important one for the question of the relation -of two processes going on together in consciousness. - -To ascertain the fact in this matter, I performed a series of -experiments with the same observers, in which previous occupation -of the mind served as a distraction. The distraction consisted in a -simple arithmetical operation,--addition or subtraction. The moment -before giving the stimulus for the judgment processes,--in the place -of the "ready" signal, I would call out some numbers, as, for example, -"twenty-four from sixty-three" or "fifty-seven and fifteen," the -first indicating subtraction and the second addition. The answer to -the addition or subtraction was always given before the judgment or -judgments, to make sure that it was performed. And in any case where -the observer knew that the addition or subtraction was done before he -attended to the stimulus for the judgment, that particular test was -thrown out. The results are given in the same form as in Table X. - - -TABLE XII - -(_Addition and Subtraction as a Distraction_) - - KEY: Lth = Length - Ln = Lines - Sh = Shade - - _Single Judgment_ _Two Judgments_ _Three Judgments_ - _Obs._ _Lth_ _Ln_ _Sh_ _Lth_ _Ln_ _Sh_ _Lth_ _Ln_ _Sh_ - A Number of - series - averaged 8 8 8 15 15 16 15 15 15 - Per cent - Correct - Judgments 79 84 67 66 68 66 53 69 59 - \----\/----/ \----\/----/ \----\/----/ - Average 77 67 60 - - B Number of - series - averaged 6 4 5 8 7 11 7 7 7 - Per cent - Correct - Judgments 57 70 60 66 44 53 51 50 44 - \----\/----/ \----\/----/ \----\/----/ - Average 62 54 52 - - Y Number of - series - averaged 8 8 7 15 16 15 14 14 14 - Per cent - Correct - Judgments 66 60 51 56 62 56 66 57 55 - \----\/----/ \----\/----/ \----\/----/ - Average 59 58 59 - -These results (general average percentages) show, for observer A, a -more regular and somewhat larger falling-off with combination than in -Table X, for B and for Y, a diminished falling-off, and relatively less -for the three than for the two combined judgments. The percentages are -lower throughout. This is a result to be expected. But there is no -notable change in the relative lowering of two judgments in comparison -with single judgments, or of three in comparison with two, such as -should appear if, as supposed, in the experiment resulting in Table -X, there had been free energy of attention in the case of the single -judgment. - -It was my aim in these experiments, with distraction through another -simultaneous process, to secure a uniform residue of attention for -the judgment processes, whether single, in twos, or in threes. The -arithmetical operations were therefore as uniform as possible. But -it may readily be that very unequal demands were made upon a given -observer by successive operations, one's automatisations in number-work -may be so various. These would no doubt tend to average up in the -course of the whole work running through several weeks. But in order -to make more sure of the point, I tried another means of using the -free energy of attention which may exist in the case of the single -judgment, namely, by suggesting a judgment or series of judgments just -before an exposure. It will be recalled that the order of judgments -was always the same as that of the tables, and that all were expressed -as minus, plus, or equal. So if the experimenter called out before -a three-judgment exposure, "plus, equal, minus," it would be in the -nature of a challenge to the observer to assure himself beyond a -doubt whether or not the exposure showed the left-hand rectangle as -longer than the right, having the same number of lines, and being less -bright. The so-called suggestion was a distinct factor in heightening -attention. This is shown especially in Y's case by the larger -percentage of correct judgments. Results are averaged in Table XIII. - - -TABLE XIII - -(_Attention heightened by Suggested Judgments_) - - KEY: Lth = Length - Ln = Lines - Sh = Shade - - _Single Judgments_ _Two Judgments_ _Three Judgments_ - _Obs._ _Lth_ _Ln_ _Sh_ _Lth_ _Ln_ _Sh_ _Lth_ _Ln_ _Sh_ - A Number of - series - averaged 2 4 2 6 7 7 8 8 8 - Per cent - Correct - Judgments 90 89 85 87 81 76 92 72 77 - \----\/----/ \----\/----/ \----\/----/ - Average 87 81 80 - - B Number of - series - averaged 4 3 4 8 9 7 8 8 8 - Per cent - Correct - Judgments 85 70 92 84 80 83 84 74 81 - \----\/----/ \----\/----/ \----\/----/ - Average 82 82 80 - - Y Number of - series - averaged 6 6 5 11 13 12 16 16 16 - Per cent - Correct - Judgments 88 75 94 90 81 77 89 74 70 - \----\/----/ \----\/----/ \----\/----/ - Average 86 83 78 - -An analysis of the results obtained from B to show the effect of the -suggestions is given in Table XIV. - - -TABLE XIV - - _Single_ _Two_ _Three_ - _Judgments_ _Judgments_ _Judgments_ - Per cent of right suggs. - judged correctly 87 85 79 - Per cent of wrong suggs. - judged correctly 73 77 80 - -The effect of the so-called suggestions in making for correct judgments -was then quite noticeable in the case of single judgments, less so in -two judgments, and none whatever in three. This observer was able to -overcome 73% to 80% of the wrong so-called suggestions. Now, when it -is considered that only 80% to 82% of all the judgments given by B -(see Table XIII) are correct, it is very clear that their action as -suggestions was very slight. They had an influence, however. It was -shown, as expected, in a heightened attention. This was especially the -case with Y. Compare his general averages in Table XIII with those in -Table X. This rise in general averages coincides with the impression of -the experimenter during the experiment. It seemed then that this was a -distinct challenge to keen attention on the part of Y. He is a man who -intends to make impartial observations for himself, and has no notion -of being told what he is to see. That his general averages of correct -judgments stand so much farther apart in this case with heightened -attention than in either of the others (see Tables X and XII) is -indicative of an interference of the judgment processes themselves. - -Such a series of general averages as those of Y in Table XIII, as -those of B in Table X, or as those of A in Table XII, seem, in -themselves, and under the conditions of the experiment, to be pretty -clear indication of an interference of simple mental processes carried -on at the same time. The only other explanation is that suggested -above, namely, an interference of the processes of reproduction and -expression. The conditions of the experiment seem to reduce the -probability of this to a minimum. But the centre of interest, in -considering the results, does not lie in the question as to whether it -is interference of the judgment processes themselves or the processes -of their reproduction. The foreground is occupied by a prior question, -namely, whether there is any evidence here presented for interference. -For if there is interference of such processes, why does it not show -up in the results for each of the observers in each of the Tables X, -XII, and XIII? Of the nine cases here offered for comparison, only -the three above designated show what may be called clear evidence -of progressively increasing interference with increase of combined -processes proceeding at the same time. - -Under these circumstances this cannot be accepted as indisputable -evidence of interference. Such results as those of A in Table X, where -correct judgments, two at the same time, are given in 88% of the cases, -and three at the same time, in 91% of the cases, stand directly opposed -to interference. They seem to show a facilitation by combination. This -is indeed possible where three and only three sorts of judgment are -worked with. It is the limiting case, and if more than one is asked -for it is really easier to give three than to select two. A himself -remarked that this was the case. A similar explanation holds concerning -the results of B in Table XII, and those of A in Table XIII. If such -an explanation is the true one, it is manifest that the "limit of -attention," of which mention has been made above, has probably not been -reached in any of these cases. On the whole, these experiments _seem -to indicate a small degree of interference of simple mental processes -going on at the same time_. But such interference _cannot be considered -proved_ by these experiments. - - -THE QUESTION OF SYNERGY - -In connection with these last experiments, where the comparative -judgments all proceed from one definite perceptive act, and where -therefore the conditions are most accurately controlled for showing the -effect of interference, if it is a fact, there is yet another means -of looking into that question. This is afforded by the _similarity_ -of the _means of expressing_ the different kinds of judgment. In -connection with the current emphasis given to the motor side of mental -processes, it is often urged that mental processes go on at the same -time when they are working together toward one and the same motor -out-go. Otherwise they are likely, at least, to hinder each other, -and to take their turns. If such is the case, the similarity of motor -out-go which is present in these cases, where all three judgments are -plus, or all minus, or all equal, ought to produce a larger percentage -of correct judgments than is found in cases where there are two or -three kinds of expression. Furthermore, if there is no interference -of the judgment processes as such, but, as supposed possible above, -the impaired accuracy of judgment in the combination of judgments is -due to the imperfection of the memory, this too will be diminished by -similarity of expression of the three judgments. In fact similarity -should reduce this source of error to a minimum. The results presented -in Tables X, XII, and XIII, for three combined judgments, were worked -over, so far as possible, and all cases where the three judgments, if -correctly made, would have been expressed similarly, were separated -out. The total number of such cases, and all those where the judgments -would have been properly expressed dissimilarly, are recorded for -each observer in Table XV. The number actually given correctly under -each class is also recorded, as well as the _percentage_ of correct -judgments in each class for each observer. - - -TABLE XV - - KEY: TN = Total Number - CJ = Correct Judgments - N = Number - % = Per cent - - _Judgments expressed_ _Judgments expressed_ - _Similarly_ _Dissimilarly_ - _Obs._ _TN_ _CJ_ _TN_ _CJ_ - _N_ _%_ _N_ _%_ - A 222 172 77 561 479 85 - B 195 153 78 498 356 71 - Y 372 277 74 863 572 66 - -If the results of B and Y were presented alone, they would seem to -indicate synergy of similarly expressed judgments. But those of A -are most strongly contradictory of such a working together of such -judgments. This is very surprising to me, as A had such a facility in -expressing these similar judgments, especially "equal, equal, equal," -that it suggested this comparison. But the apparent facile expression -is here shown to have attended a diminished accuracy. No conclusion -can be drawn with respect to synergic influence from the similarity of -expression of judgments. - - -RELATION OF OBJECTIVE AND SUBJECTIVE SIMULTANEITY - -Reviewing this work in combination of judgments with reference to its -bearing upon the complication results, and the interval discrimination -results, it seems that interference of simple mental processes going -on at the same time, though it appears to be a fact, showing itself in -impaired accuracy of processes combined, is yet quite inadequate to -explain the whole, or indeed, any considerable part of the synchronism, -as we may call the "click first" "click last" interval of Tables IV, -V, and VI. The slight amount of interference of such processes as -the auditory and visual perceptions, tending to proceed at the same -time, would tend to a very slight displacement of one with regard -to the other. It is true, for reasons already discussed, that this -time-difference is so slight and so difficult of seizure that it cannot -be measured, and so no measure is offered. We cannot, therefore, be -certain _how much_ of the non-detectable interval is due to this cause. -But the evidence offered in the above tables of results is ample -justification for the statement that _interference_ can be responsible -for only a _very small part_ of the "click first" "click last" interval. - -In the case of this interval, as in that of an interval between any -disparate stimuli, a part of it must be due to the different resistance -or inertia of the sense-organs. The eye is undoubtedly slower than the -ear. This would at once suggest itself as the cause of the interval -between the threshold mean and the visual stimulus in the results -shown in Tables IV, V, and VI above. That is, vision being slower, an -auditory stimulus given at the same time as a visual will appear to be -earlier, and it may be given considerably later and yet appear earlier. -In general, therefore, so far as this cause is active, one would expect -that the interval, at which a sound must precede a visual stimulus -in order to be certainly distinguished as coming before the latter, -would be much shorter than the interval, at which a sound coming -after a visual stimulus could be unfailingly distinguished as coming -later. In other words, the centre of gravity of the "click first" -"click last" interval, so far as this visual inertia is the cause of -its displacement with reference to the visual stimulus time, will be -_after_ the visual stimulus. - -In one case in my results, Table V, St, H middle, there is presented -an extreme where not only the centre of gravity (threshold mean) is -placed after the visual stimulus (letter), but the whole synchronous -period ("click first" "click last" interval) is after the visual -stimulus, so that a sound coming .008 sec. after the visual stimulus is -distinguished with certainty as coming before it. So also St, in Table -VI, one pair, the sound coming .006 sec. after is judged as coming -before the visual stimulus. - -But the variety of displacements of the threshold mean in different -observers, and more particularly in the same observer under different -experimental conditions, indicates very clearly that there are factors -other than visual inertia which are quite as important, and perhaps -equally responsible for this displacement. In Table VI, H, one pair, -for example, the threshold mean is before the visual stimulus .011 -sec. So in Table V, G, H first, and also H last, it is before the -letter .005 sec. In these cases there must be some factor or factors -quite as strong as this visual inertia, and counteractive to it. These -are, in part, the complex attention factors which have been referred -to already. Prominent among them are the rhythmic perception which -is so marked in St; the movement toward the first stimulus and the -"letting-go" of the breath, of A; the passive "striking" of the letter -by the sound, in the case of some of the observers; and the "cocking" -of the eye and the ear, of others. These all have to do with the length -and place of the "click first" "click last" interval quite as much as -does the visual inertia. But however this may be, of this inertia and -the other factors just now named, probably each has more to do with it -than does the interference of the perception processes themselves. - -But after eliminating the parts played by each and all of these -agencies in the determination of the interval, there will remain a -period of "present time," in which there are no time-differences, -and no qualitative differences which lead the subject to suspect the -existence of time-differences. The mental content of this reduced -synchronous period in experience is _one experience_. The sound was -heard and the letter was seen, but they came _together_ as aspects of -_one_ experience. In the moment of perceiving either one, it was not -possible to say that the other was already a memory. In other words, -the _primary memory_ of either, whichever came first, had lasted over -into the perception of the second. There had been no perceivable -transformation of the first since the instant of its perception. At -the moment of the inception of the second process, the first was -still, to the perceiving subject, what it was at the moment of its own -inception. Though change was probably going on in the physiological -substrata of the mental process in question, in every minutest moment -of the interval, yet a certain amount of effect of this change had to -accumulate before the observer could become aware of the change, and so -be aware of the passing of time or of temporal difference. This was, -then, only a case of the working of the law of _relativity_. And the -perception of time is a function of the duration and amount of change -of mental process. - -Looked at from this point of view, we see the whole explanation of the -existence, the amount, and the position of this synchronous period -under one rubric, if only we could grant the combination of mental -processes without interference. If mental processes go on together, -the sole ground of the imperceptibility of short periods of time -separating mental processes is in the fact that the first of these -processes _has not changed sufficiently to be known as different_, to -the perceiving subject. The minimal perceivable interval will vary -from man to man, and in the same man from time to time, inversely -as the amount of change per unit of time, in the process itself. -The same statement could be made in terms of vividness or relative -clearness. The more focal the idea or process, _i. e._, the more vivid -or relatively clear it is, the more rapid will be the changes and the -perception of those changes. Professor Münsterberg's physiological -explanation of vividness,[122] as due to the facilitation of the motor -discharge, has already found confirmation in the method of keenest -interval discrimination as outlined above. The more rapidly the first -process can get into action, the more is the discriminated interval -shortened. So in Exner's experiments, where it was known which of two -stimuli would come first, the interval was very much shorter than any -of my results, for the motor preparation could be made very complete -beforehand, as in a muscular reaction. Therefore the perceptible -change, upon perception of the stimulus, occurred in a shorter time. -Under any circumstances, the conditions, subjective or objective, which -make for rapid maturing (and by the principle of dynamogenesis maturing -means going over into action) of the mental process, make also for the -shortening of the least perceptible interval. - -These conditions are as various as the gamut of human experience is -wide. There is nothing, from the primary temperamental characteristics -to the passing wave of feeling of the present moment, which does not -affect it. Most particularly, though, is it a matter of the relations -existing among the elementary processes striving to go on together. -Among the focal and fringe elements of a given moment of experience, no -matter how carefully the practised introspectionist may strive after -an ideal condition of monoideism, there is an incessant interaction. -There are all sorts of hindrances and facilitations. Herein is the -justification of Stern's statement that the "praesenzzeit," as he calls -it, "varies with the quantity and quality of conscious content, the -direction of attention, and the strength of psychical energy," and -that it cannot be assigned a maximal value but rather what he calls -an "optimal value." All that is included, in fact, in the complex -rubrics, _attention_ and _interest_, has to do with the length of this -indiscriminable interval. - -Time-difference in consciousness is the very simplest thing in mental -life, for it is a case of the bare awareness of change. The elementary -time-judgment is mere judgment of change in content of consciousness. -In the experiment where one is asked to say which of two expected -stimuli comes first, however, the case is already complicated. -There must be a double preparation to react and to note the change -characteristic of each case, and so convert it into a time-judgment. In -the combination of two judgments, there is the same double expectancy, -preparation to react in two ways at once. In each experiment, the -preparation and shaping of expectation is the same as in reaction -experiments. In all reaction work, the short reaction comes as the -result of catching the attention wave at its most favorable point. -If the signal to react catches the idea of reaction in the mind of -the observer at the very focal point in consciousness, the shortest -reaction possible under the given conditions results. So in both the -combination experiment and the interval discrimination experiment, it -is very necessary to catch the attention wave, _equally prepared for -both or all the processes_, and at the highest crest of advancement. -Both demand the same preparation as a compound reaction. I believe it -is this inequality of balance of the attention between the various -processes that is responsible for the interference which is evidenced -in my results. This is my explanation of the appearance of impaired -accuracy for combinations for a given observer under some conditions -and the failure of any sign of impaired accuracy for the same -observer under other experimental conditions, or even under the same -experimental conditions at different times. - -In the time-interval discrimination experiment the evenness of -balance in the attention wave will make for the shortest interval -discrimination, and the proportion between the two will be direct, -so far as other factors do not interfere. But there are special -interferences here. One of these is the fact that the two mental -processes do not set off at the same moment. No matter how even the -balance in attention at the moment of impact of the first of the two -stimuli, the preparation for the other, not yet set off, cannot be held -in equal readiness while this is going off. This discharge has already -disturbed the preparation to discharge in the other direction. In the -case of a given pair of stimuli of definite qualities and intensities, -the relation will be one of mutual facilitation for one interval of -separation and one of inhibition for another interval. In one case -the first opens the path for the second, being a case similar to the -summation of stimuli, and in the other, it draws all the available -energy in its own direction. - -FOOTNOTES: - -[Footnote 108: W. Wirth: Zur Theorie des Bewusstseinsumfanges und -seiner Messung, Philos. Studien, vol. 20, p. 487, 1902.] - -[Footnote 109: Cattell: Ueber die Trägheit der Netzhaut und des -Sehcentrums, Philos. Studien, vol. 3, p. 94, 1886.] - -[Footnote 110: Gonnessiat: L'Equation personnelle, Paris, 1892.] - -[Footnote 111: Exner: Experimentelle Untersuchungen der einfachsten -psychischen Processe, Archiv. f. d. gesammte Physiologie, vol. 7, p. -601, 1873, and vol. 11, p. 581, 1875.] - -[Footnote 112: Angell and Pierce: Researches upon Attention, American -Journal of Psychology, vol. 4, p. 528.] - -[Footnote 113: Pflaum: Neue Untersuchungen u. d. Zeitverhältnisse der -Apperception einfacher Sinneseindrücke, Philos. Studien, vol. 15, p. -139.] - -[Footnote 114: Peters: Aufmerksamkeit und Zeitverschiebung in der -Auffassung disparater Sinnesreize, Zeitschrift f. Psychologie, vol. 39, -p. 401, 1905.] - -[Footnote 115: Paulhan: Revue Scientifique, vol. 39, p. 684.] - -[Footnote 116: Jastrow: American Journal of Psychology, vol. 5, p. 239.] - -[Footnote 117: Loeb: Archiv. f. gesammte Physiol., vol. 39, 1886.] - -[Footnote 118: De Sanctis: Zeitschrift f. Psy. u. Physiol. d. -Sinnesorg., vol. 17, p. 205.] - -[Footnote 119: Münsterberg: Willkürliche und unwillkürliche -Vorstellungsverbindung, Beiträge zur experimentellen Psychologie, vol. -1, pp. 64-188.] - -[Footnote 120: Wundt: Physiol. Psy., 5th ed., vol. 3, p. 351.] - -[Footnote 121: Wirth: Zur Theorie des Bewusstseinsumfanges und seiner -Messung, Philos. Studien, vol. 20, p. 487, 1902.] - -[Footnote 122: Münsterberg: Grundzüge der Psychologie, vol. 1, p. 525.] - - - - -THE ESTIMATION OF NUMBER - -BY C. T. BURNETT - - -I. There are situations not a few in life in which we find ourselves -estimating the number of objects in some group. Sometimes we desire -to know merely whether the group is large or small. Sometimes we try -to reach an absolute number that shall approximate roughly to the -real number. Sometimes, again, we only care to know whether the group -in question is more or less numerous than some other group that we -have before us or perhaps recall in memory. The public speaker finds -himself wondering whether this present scattering audience is larger -than the one that last night crowded into the front seats. The farmer -riding between adjoining orchards judges roughly the prospective yield -by a comparative estimate of the fruit in sight. The politician too -has an interest that is very notable indeed in such rough numerical -estimates. He asks himself, for example, whether the voters will be -more influenced by reports favorable to his party sent in from numerous -small towns or by such reports from a few large centres. Or perhaps he -is planning a demonstration in favor of his candidate. His problem then -is so to arrange his procession that five hundred men will look like -five thousand. Turning to another field, how is it that the enrolment -in some institutions of learning seems larger and the size of the -faculty more portentous than in other similar institutions that are -really of about the same size? - -These examples bring to mind our interest in rough numerical estimates -and at the same time suggest the probability that we are swayed back -and forth in these estimations without ever a numerical difference -occurring in the objects of our judgment. These considerations lead us -on, then, to an enquiry about the factors that can thus influence our -estimation of number. - - -II. INFLUENCE OF FACTORS IN THE SAME SENSE-FIELD AS THE OBJECTS WHOSE -RELATIVE NUMEROUSNESS IS IN QUESTION. - -The experiments described in the following pages are concerned with the -influence exerted on the judgment of a given factor by other factors -presented at the same time. The object of judgment in these studies is -visual number, which is to be submitted under varying conditions of the -objects whose number is in question, for example, varying conditions -of form, size, distribution, with the intent to discover whether -this judgment is a function of these other factors as well as of the -numerical. The scope of the enquiry includes both relative and absolute -number. - -The objects chosen as a basis for the number-judgment were bits of -paper pasted in two well-defined groups side by side upon a background -of black cardboard. This card fitted into an upright frame where it was -held in place by a pivoted spring, which allowed easy adjustment and -removal of the card. The opening of the frame, 15×20 cm. was concealed -at will from the observer by a black wooden screen that played up and -down on guiding posts, when released by a cord and lever from the -catch that held it in place before the card. It fell by gravity upon a -cushion that deadened the sound; and it was restored to its position -by the operator's thrusting his fingers beneath and lifting it till -the catch above caught and held. The entire apparatus, as well as the -operator's movements, was concealed from the observer by a large black -cardboard screen resting upon a black-covered table. The one opening in -this screen was just large enough to allow a full view of the card when -the inner wooden screen fell from sight. - -This apparatus which we will call the Two-Group Apparatus, admitted of -simultaneous exposure of the two groups of objects, and that only. At -first, to make successive exposure possible, a light wooden frame was -constructed in whose grooves two leaves of black cardboard ran like -sliding doors. By means of rods fastened to their outer edges these -leaves could be pulled apart or thrust together till their inner edges -met. When this apparatus was placed between the outer screen and the -frame bearing the card, and the inner wooden screen had been dropped -out of the way, this substitute divided screen was sufficient roughly -to accomplish the end in view. - -With this apparatus the illumination was daylight, coming through a -very large window at the back of the observers. By means of a curtain, -marked variations in the light could be prevented. - -For the length of simultaneous exposure of the groups the following -rule was adopted: Each observer was to be allowed time enough to get a -satisfactory feeling of relative number, but not time enough to admit -of counting. This time was kept constant during the work of any one -sitting. As the weeks went on, it was found possible, under the rule -laid down above, to shorten the time for some of the observers, and -to use with all the same length of exposure that had sufficed for the -speediest. The range of variation was from 1.2 sec. to 1.6 sec. Time -was measured by the ticks of a watch. Later tests showed for the time -studied that, where effective at all, the longer exposure diminished a -given tendency. Often it had no apparent effect. - -The method of control already described is not only rather rough but -does not exclude the possibility of a space error. This possibility -proved actual by experiment. So an apparatus was contrived that should -present the groups in succession at approximately the same place and -should shorten the exposure, if desirable, to a small fraction of a -second. - -This new apparatus, which we will call the One-Group Apparatus, -required artificial light and a dark room. By means of a 125 cp. -incandescent electric lamp, images of the groups of objects were -reflected through the lens of a camera and came to a focus upon its -ground-glass screen. A second screen of ground glass was placed in -front of the first and as close to it as possible, that an even -distribution of light might be obtained. The cards containing -the objects were of the same general character as in the earlier -experiments. They were held in a moveable slide whereby each group in -succession could be brought before the lens. When the slide was drawn -to the limit in one direction a single circle appeared in a black -field. This circle was used as a signal and a means for directing -the eye in the dark to that region where the groups were to appear. -The exposures were made with a camera bulb, the shutter being set -for instantaneous movement, with diaphragm 22 and length of exposure -1/26 sec. A shorter time was thought on trial to make perception too -difficult. The apparatus rested upon a table of special construction -and was enclosed as far as the glass screen with a wooden frame covered -with denim. Double curtains of this material formed this enclosure on -one side and made possible an easy adjustment of the cards between -exposures, as well as the admission of the operator's hand during a -given experiment for the adjustment of the shutter. This had to be -set, of course, before each of the three exposures constituting one -experiment. During its progress the hand was not removed at all, the -curtains falling about the arm in such a way that little light escaped. -The other hand managed the moveable slide from behind the enclosure. - -Time was measured by watch-ticks. The three exposures--dot-signal, -Group 1, Group 2--were separated from each other by intervals of 1.6 -sec. This was fixed upon as the minimum for convenient operation of the -apparatus. - -In much of the experimentation on relative number two observers were -employed at once. Their chairs were placed closely side by side on -a line about 150 cm. from the plane in which the groups appeared. -These groups were not very far from being on a level with the eye. -Each observer recorded his own judgment, against the number of that -experiment. There were three possible kinds of judgments,--equality or -either group larger. If the judgment was of difference it was recorded -in terms of the larger. - -When the dark room was used, special arrangements were required, for -convenience of the observers in making their record. After several -schemes were tested the following was adopted as least trying to their -eyes: A large, black-topped table was placed before them, bearing an -electric lamp enclosed in a black box with a small aperture that could -be closed at pleasure; or, if left open, did not let enough light -escape to disturb the perception of the groups. - -The absolute number of objects in the groups was determined, first, by -the character of the problem, and then by convenience. If we are to -learn anything about the influence exerted upon the number-judgment -by other factors than the numerical, we must eliminate all influence -of the latter. Correct judgments may be determined by this factor -alone; erroneous judgments must have been otherwise conditioned; and -these conditions it is the task of our method to isolate and study, as -modifying factors. From correct judgments we learn nothing definite -about our problem, but from erroneous everything. Other things being -equal, it is preferable to eliminate from the results the influence -of this numerical factor, just as one handles any other disturbing, -unavoidable element, by equalizing the numbers in the two groups. - -What may be called the standard number of objects in each is twenty. -This choice was governed by the purpose of using a number large enough -to make counting impossible in a brief time and yet not so large as -unnecessarily to increase the labor of preparation and the difficulty, -for the observer, of getting an idea of the groups as a whole. To the -cards containing equal groups, 20 to 20, were added others, 20 to 19, -19 to 20, for the purpose of easy variation in arrangement, by omitting -one object from a group, without making the actual numerical difference -easily perceivable. In later work these small objective differences -were dropped. Yet other cards, 23 to 17, 17 to 23, were added, to the -end that the observers might find unmistakeable number-differences, and -so not be bothered by the suspicion that the groups were all equal. -The reversal of the number-relations, as indicated above, was in the -interest of equalizing the influence of the actual numerical factor in -the two groups. - -The following proportion was kept among the numbers of observations -made upon each kind of card: 1/2 upon groups objectively equal; 5/12 -upon those differing by one from each other, where half each went to -(20 to 19) and (19 to 20); 1/12 to those showing the maximum objective -difference of six, where again half went to (17 to 23) and half to (23 -to 17). Of course the observations upon cards of this last sort are -excluded from the tables. - -As to the number of cards employed for each series of experiments, -it was found at first convenient to use seven,--3 (20 to 20), 1 (20 -to 19), 1 (19 to 20), 1 (17 to 23), 1 (23 to 17). In each group the -arrangement of objects was irregular. The use of three of the first -sort was to encourage freshness of judgment, each having its particular -irregularity. Cards were but rarely remembered, practically never -except in the case of groups differing widely in number. So far as the -observers could tell, judgment was formed afresh in all these cases. -In later experiments eight cards were used. This number was in the -interest of avoiding the distribution-error. At first it was thought -sufficient that all the groups should be merely irregular. Later it -became evident that discrimination was very fine here and so that this -factor must be eliminated by the usual precise method. - -The space- and time-errors, where likely to be present, were eliminated -in the usual way by performing an equal number of experiments with the -groups in reversed arrangement. Several methods of doing this were at -first tried; but these were all abandoned in favor of the following: -The experiments were arranged in sets of 24, in each of which the -proportion of kinds of cards was kept as indicated above. Each set -with one space- or time-order of the groups was repeated with that -arrangement reversed. - -A word must be added as to the arrangement of results in the tables. -Judgments of equality upon objectively unequal groups are entered -as overestimations of the smaller groups. The per cent of correct -judgments is equally divided between the two other classes, and for -this reason that interest centres, not in correctness at all, but in -the difference between the tendency of error in one direction and that -in the other direction. No doubtful judgments were admitted, but in -such cases another trial was allowed later, usually when the observer -was not aware that he was being given a new chance. The subjects are -divided into three classes according as the results show a tendency to -favor one or the other group or no tendency either way. A difference of -10% is arbitrarily taken as significant. - -1. _The Influence of Group-Area._ The Two-Group Apparatus was employed. -The four sets of experiments carried out with this factor differed -primarily in the material upon which the observer's judgment was based, -and secondarily in certain matters of method. The attempt in them all -was to approximate more completely to the isolation of the factor -under investigation. They are numbered in the order of approximation. -As marked results were obtained from each, they have all been offered -for consideration in the four parts of Table I. A description of the -material used in each case follows. - -_A._ Squares (1 cm.) Neutral Gray no. 1. (Bradley), arranged -irregularly in two groups with irregular outlines on a background of -black cardboard. One group was large in area, the other small, the -attempt being made to fill each space homogeneously. Groups were not -proportional in shape of area. - -_B._ As above, save that circles (11 mm. approx. in diameter) were -substituted for squares, in the interest of distinctness for the -several objects. - -_C._ The area of the groups was oblong and regular, and the sides -were proportional. (Compact 72.5 mm.: 58 mm.; scattered 110 mm.: 88 -mm. These relations were determined by the size of the frame that had -already been used and by the desire to make the difference in area -as marked as other necessary conditions would admit.) Each area was -marked by a circle in each corner. The color of the compact group -was the deepest shade of normal gray (Prang Normal Gray Darker); of -scattered group the next higher shade (Normal Gray Dark). These dark -grays were used in order to reduce to a minimum the tendency to produce -after-images. The difference in the shades of the two groups was in the -interest of avoiding the greater brightness due to the mass-effect of -the compact group. - -_D._ As in C, except that India ink outline circles (1/3 to 1/2 mm. -line) were used on a background of granite cardboard. This change was -made to avoid, as far as possible, the greater mass-stimulation due to -the reënforcing effect of the compact arrangement. The size of circles -remained as before. - - -TABLE I - - KEY: NS = Number of Subjects - AV% = Av. % of difference in favor of - - A B C D - 274 248 120 132 - _experiments_ _experiments_ _experiments_ _experiments_ - _with each_ _with each_ _with each_ _with each_ - _subject_ _subject_ _subject_ _subject_ - - _NS_ _AV%_ _NS_ _AV%_ _NS_ _AV%_ _NS_ _AV%_ - - Small 5 31.5 10 34.6 7 44.1 10 46 - Large 3 35.1 4 44.1 5 41.5 3 26.3 - No tendency 1 8.8 2 4.2 4 5.7 3 6.6 - - The per cent recorded in the no-tendency class is an average of _all_ - per cents below 10, whether in favor of the one or the other of the - two remaining classes. This is true for all the following tables. - -The following facts are presented by the several parts of Table I: (1) -The large per cents of difference show that area is to a large extent a -determinant of the judgment of relative number. (2) Different subjects -show opposite tendencies. (3) A comparison of the results of individual -subjects through the four series shows that this opposition in tendency -occurs in the same subject at different times. The introspective notes -of one of these subjects show the internal process of change from one -tendency to the other. It consists in a gradual increase of analytic -activity toward the compact group. At first glance the composition of -the scattered group was more evident; but when attention was fairly -turned toward the compact, the inability to isolate objects made them -seem very numerous. The importance of a coöperating subjective factor -is here evident. (4) Out of a possible 57 cases there are but 10 -showing no tendency. - -2. _The Influence of the Internal Arrangement._ As before, the -Two-Group Apparatus was employed; and the factor was studied in three -aspects. - -_A._ The material consisted of two groups of gray circles (Normal Gray -Darker, Prang) covering equal areas. In one group this area was filled -homogeneously, in the other the circles were gathered into nuclei. In -order that there might be exactly the same relation of parts when the -cards were reversed, each group was so arranged on a diagonal axis of -symmetry from upper left to lower right corner that each half repeated -the other in reverse order. Otherwise the arrangement of circles was -irregular. - -Six cards only were used,--four (20 to 20), one (17 to 23), and one -(23 to 17). Slight differences among them occurred in the arrangement -of the equality-cards, which might help to counteract any incipient -reasoning from sameness of appearance to sameness of number. The large -increase in the difference-values is accounted for in part by the fact -that the cards (19 to 20) and (20 to 19) were omitted, and for this -reason: that when an observer tended largely to favor a particular -group, the introduction of a card in which that group was objectively -greater would mean an increase in the number of correct judgments; -whereas the introduction of two objectively equal groups for the others -would increase considerably the number of erroneous judgments. - -_B._ The numerical character of the cards here used shows a return to -the usual. The material was like that of _A_, except for a new internal -arrangement. Here the area of one group was filled homogeneously, while -that of the other contained a pattern of this sort: An ellipse just -contained within the boundaries of the normal area; a circle in each of -the four corners of that area; and in the centre a diamond formed of -four circles. Numerical changes were always confined to the ellipse, as -less open to counting than the rest of the figure. - -_C._ Material and method repeat _B_ but with another internal -arrangement. One group, as before, showed an area homogeneously filled, -and irregularly, as usual. The other group carries to an extreme the -distinction of open and filled space made prominent in the other groups -of this table by massing the circles in an outline completely enclosing -the area and in a diagonal from upper left to lower right corner. The -outline did not show even spacing; more circles were crowded in one -part than in others, that counting might be more difficult. - -That there might be no attempt to remember cards, in all cases where -there were twenty objects in the homogeneous group the same kind of -irregular arrangement was repeated. This is a different method from -that employed in _A_. Since the length of exposure was so short and the -arrangement in the group irregular, either one is probably as good as -the other. - -_D._ The material used for _B_ and _C_ had a kind of regularity, -since definite patterns were used. The introspection of the observers -showed, however, that the patterns as such were not in question in -the judgment, but rather the vacancies and the crowding. With the -Two-Group Apparatus an arrangement in parallel lines could rather -easily be counted, but with the One-Group Apparatus and its means for -instantaneous exposure this difficulty was to some extent overcome. The -arrangement of the objects in parallel lines was therefore adopted -and matched against the irregularity of an accompanying group. The -same size of group-area was kept, but the small difference-cards were -omitted. There was no other change beyond those made necessary by the -apparatus and already indicated on an earlier page. The length of -exposure was 1/25 sec. The bearing of this time-factor on the results -will be considered in a later section. - - -TABLE II - - KEY: H = Homogeneous - N = Nucleated - P = Pattern - O = Outlined - R = Regular - I = Irregular - NT = No tendency - - A B C D - 132 132 132 88 - _Experiments_ _experiments_ _experiments_ _experiments_ - _with each_ _with each_ _with each_ _with each_ - _subject_ _subject_ _subject_ _subject_ - - H N NT H P NT H O NT R I NT - Number of - subjects 10 2 2 10 1 3 7 5 2 2 1 - Av. % of - difference - in favor of 53.23 1.5 6.1 35.7 52.8 5.3 42.7 34.8 7.9 40.3 1.2 - -The several parts of Table II give us the following facts: (1) The -judgment of relative number is very markedly a function of the internal -arrangement. (2) The marked tendency among the observers to favor -the homogeneous in _A_ and _B_ meets a check in _C_. Recalling the -direction of difference between _C_ and the other sets, that in _C_ -the gradually increasing contrast between the inner vacancies and the -filling reaches a maximum, we may suspect that these vacancies begin -to seem no longer a part of the group-situation, while the compactness -of the filling, where it does occur, is thrust prominently forward. -The notes of the observers confirm this suspicion. (3) The results of -the different subjects show that the shifting of tendencies occurs -as before. (4) As to the way in which regularity functions in the -judgment, the notes of one observer are very clear. The blank spaces -in the irregular are noticeable, he says, which is not true of the -regular, where, on the contrary, one has a feeling of compactness -of figure. I am able to confirm this character of the spaces by my -experience outside this experiment. A simple pattern is very easily -apprehended and irrelevancies of the background dismissed. Increase its -complexity to a maximum, as in the case of an irregular group, and I -am almost at a halt to isolate objects from their fellows and maintain -them apart, yet together. The background is hardly to be shut out. This -is probably due to the absence of a centrally excited image of the -group. The object and the not-object run together. (5) The position -of the single observer in the no-tendency class of _D_ was marked -subjectively by great difficulty in forming a judgment. The groups -seemed incomparable, the vividness of form excluding the perception of -number. - -3. _The Influence of Complexity in Group-Composition._ - -Complexity of group-content was attained by introducing objects of -different colors; so there was not a clean isolation of factors. By -comparing these results with those recorded in Table IV, A, we shall be -able somewhat roughly to make allowance for the factor of mere color. - -Sets of 132 experiments each from sixteen observers were obtained for -each of these factors. Unfortunately the distribution-error was not -eliminated. Later experiments showed the importance of this factor, -and, in consequence, the impossibility of interpreting the results -under consideration. So new experiments were performed under the proper -conditions, but at a time when only a few of the first observers could -be used. Their results from the earlier series are given in Table III, -A. The exclusion of the small-difference cards from the later series -(Table III, B) and the consequent increase of the number of experiments -on objective equality prevent comparison. - -The material in _A_ consisted of two groups of circles of the usual -size, one Normal Gray (Prang), the other of three colors--Red, Yellow -Orange Shade 2 (Bradley), Light Blue Blue Green (Prang). The intent -was to equalize the two groups in brightness. When the observers were -questioned about the relative brightness, supporters were found for all -three possible opinions. So it seems probable that the groups did not -differ widely in this respect. As nearly as the number-condition would -allow, the three colors were represented equally in the group; and they -were distributed so as to make the whole as homogeneous as possible. - -In _B_ the changes were the correction for distribution as described -in the introduction to this section, and the substitution of -equality-cards for those of slight numerical difference. In addition, -three other colors replaced those of _A_, in the interest of regulated -brightness and more pleasing æsthetic effect. These were, in the -Bradley system of broken spectrum scales, A-Red, medium; A-Yellow -Orange, dark; A-Blue Green, dark. With these exceptions _B_ was like -_A_. The observers were all inclined to consider the gray brighter than -the mixed. The Two-Group Apparatus was used. - - -TABLE III - - KEY: G = Gray - MC = Mixed Colors - NT = No Tendency - - A B - 132 132 - _experiments_ _experiments_ - _with each_ _with each_ - _subject_ _subject_ - - G MC NT G MC NT - Number of - subjects 3 1 3 1 - - Av. % of - difference - in favor of 17.7 2.2 19.9 6.8 - -The following facts may be gathered from Table III: (1) The tendency -to overestimate the gray is due in part at least to the additional -factor of complexity in the other group, as is shown by the markedly -changed tendencies in Table IV, A, where a solid color takes the place -of the mixed colors. The actual colors involved in the two cases are -different, to be sure, and necessarily so, and this difference may of -course be invoked as the cause, as well as a possible difference in -brightness between the gray and mixed in III, B. The introspective -notes help us here. One observer felt that he favored the gray -primarily because there was a tendency to consider but one color in the -mixed. Another was drawn toward the gray because it seemed definite and -consistent. For both of these observers æsthetic elements were involved -in favor of the gray. The latter found also that the greater brightness -of the gray gave it a larger area. With a third subject the fact of -variety was felt as decidedly important; but his notes show a conflict -between this factor and that of distribution which was the conscious -basis for his normal judgment. - -4. _The Influence of Differences in the Kind of Objects._ - -_A. The Factor of Color._ The material in A 1 consisted of two groups -of circles of the usual size, one Normal Gray (Prang), the other -Red (Bradley). The attempt was made by this choice to equalize the -brightness. The size and shape of the group-area were those of the -smaller area of Table I, C and D. In A 2 the only changes were the -correction for distribution, as described in the introduction to this -section, and the substitution of equality-cards for those of slight -numerical difference. The Two-Group Apparatus was used. - -The following results appear in Table IV, A 1 and A 2: (1) While -complexity seemed on the whole to diminish apparent number, red -noticeably increases it. Some of the observers report that group as -more vivid and interesting. One observer compensated by emphasizing the -gray in attention, as his results showed. (2) If one ask how the color -red functioned in the judgment, the reply must apparently be, by its -brightness and vividness. The mixed group functioned in a double way, -as vivid and so more numerous, as fragmentary and so fewer. - - -TABLE IV - - A1 A2 - 132 _experiments_ 132 _experiments_ - _with each subject_ _with each subject_ - - _Gray_ _Red_ _No tendency_ _Gray_ _Red_ _No tendency_ - Number of - subjects 3 1 3 1 - - Av.% of - difference - in favor of 18.3 5.4 30.3 9 - - - B C - 132 _experiments_ 132 _experiments_ - _with each subject_ _with each subject_ - - _Large_ _Small_ _No tendency_ _Circles_ _Squares_ _No tendency_ - Number of - subjects 8 3 5 8 4 4 - - Av.% of - difference - in favor of 33.6 27.5 6 28.4 18.8 3.5 - - - D1 D2 - 88 _experiments_ 132 _experiments each_ - _with two subjects_ - - _44 experiments_ - _with two subjects_ - - _exposure_ = 1/25 _sec._ _exposure_ = 1/4 _sec._ - - _Simple_ _Complex_ _No tendency_ _Simple_ _Complex_ _No tendency_ - Number of - subjects 3 1 2 - - Av.% of - difference - in favor of 30.7 5.6 21.2 - - - E - 88 _experiments_ - _with each subject_ - - _exposure_ = 1/25 _sec._ - - _Bright_ _Dark_ _No tendency_ - Number of - subjects 3 - - Av.% of - difference - in favor of 47.4 - -_B. The Factor of Size._ The Two-Group Apparatus was used, the material -consisting of India ink circles (1/3 to 1/2 mm. line) on a background -of granite paper. This paper was chosen here and for the experiments -of Table I, D, to get a suitable mean between too sharp contrast and -sufficient distinctness. The circles in the one group were ten mm. -in diameter; in the other seven mm. The two areas were approximately -equal, and of the same size as that of the more compact group in Table -I. This is in fact the standard size throughout these studies in -Relative Number, wherever area is not in question. The small-difference -cards were included. - -Two sources of possible complication must be considered. It is -unavoidable that the factor of differences in compactness should -enter and that clean results on the basis of object-size be denied. -Our interpretation must not fail to consider this fact. Because of -this, it seems unlikely that a distribution-error should arise; so -the usual precaution to eliminate it was omitted both here and in the -study of area (Table I). Distribution affects the appearance of the -vacant spaces. When differences in the _amount_ are by the conditions -inevitably prominent, differences in the _conformation_ may be safely -regarded as of minimal vividness. - -The following results appear in Table IV, B: (1) The illusion of -numerical inequality is marked for many subjects. (2) The judgment -is quite possibly a function of the two factors--object-size and -group-vacancies. If we recall the fact that the small-object group -is more scattered than the other, we shall note that the leading -class here is like the leading class in Table I, and we may fairly -reckon this factor as of importance in the issue. Of the incomplete -introspective notes on this question, those of only one observer speak -clearly for the size. He says: "There is an overpowering feeling of -predominance in case of the large and I must judge for them. The large -space covered seems an important factor. The longer I reflect upon -the relative numbers the more numerous seem the larger, that is, they -appear to increase over the small after the exposure. It is hard to -give judgments of equal in most cases." - -_C. The Factor of Form._ The material consisted of a group of circles, -each of the same size as in former material; and a group of squares, -each approximately equal to a circle of the other group. These were -made of Prang's gray paper (Normal Gray Darker) and pasted upon a -black background. The areas of the two groups were approximately equal. -The squares were set irregularly except for those in the corners, where -the edges were placed parallel to the edges of the card. The Two-Group -Apparatus was used and the small-difference cards included. - -In this material, again, the formal elimination of the -distribution-error was not attempted. The striking difference in -the conformation of the vacancies through the form-differences of -the objects probably makes the repetition of the exact positions -insignificant. Still the fact must be noted. - -The results appear in Table IV, C. (1) The illusion of numerical -inequality is here again marked for many observers. (2) The -introspective notes are not on the whole very illuminating as to the -basis of judgment. One observer, who favored circles, found that the -appearance of more orderly arrangement in squares made them seem -few. Another, who favored squares, found, on the contrary, the more -regular the more numerous, and thought that the squares may have seemed -more regular. A third, who favored circles, found the squares better -individualized, with whom a fourth agreed in both respects, who also -was influenced by the apparently greater bulkiness of the squares. -Fewer could go into a given area. A fifth, on the other hand, who -found the circles better individualized, still favored them. So we -have these observers apparently doing the same thing under opposite -conditions, and the opposite thing under the same conditions. Here -indeed is a situation for any theory. So far as we can learn from the -foregoing, the form may influence the judgment merely through its -space-characteristics, but possibly also through the vividness of -intrinsic interest. - -_D. The Factor of Complexity._ The One-Group Apparatus was used in this -work and results were obtained for two different lengths of exposure, -1/25 sec. and 1/4 sec. The material differed, in that to the centres -of the circles of one group were added small Red (Bradley) circles (6 -mm.). With the apparatus used, the color was not very effective, the -brightness contrast between dark centres and white periphery being -chiefly prominent. The total group-brightness was of course diminished -by those centres. The small-difference cards were omitted. - -The results are recorded in Table IV, D 1 and D 2. (1) The illusion -is apparently strong. (2) The amounts of the difference-values show -that the shorter exposure is more favorable to the illusion. (3) The -introspective notes indicate that both brightness and complexity -functioned in the judgment. Two observers, both of whom show large -tendencies, were not conscious of any influence of complexity. One of -these did find differences in brightness important; and in favoring -the darker group his results exactly coincide with those of Table IV, -E, where this factor is under direct consideration. A third found the -complex group interesting. With a fourth the complex group developed -in number amazingly during the few moments after exposure and had an -appearance of great intricacy, often seeming to be in active movement. -A fifth observer too felt that its numerical character depended on its -complexity. - -_E. The Factor of Brightness._ Hitherto the absolute arrangement of -the objects in any two groups compared, where this factor has not been -the object of enquiry, has been in the two cases different, though -with respect to irregularity alike. This course was governed by a -desire to avoid the substitution of a form-judgment for one on number, -through recognition of the fact that both groups had identical forms. -The resulting distribution-error I tried to eliminate in the usual -way. Tests toward the end of these studies showed that there was no -danger from this source. Errors seemed about as frequent as before. -No observer made any comment on the fact, except one who through his -official connection with the laboratory work knew that the test would -be made sometime, but not exactly when. During many of the experiments -he did not perceive the likeness of form; and when he did the numerical -judgment arose without connection with that factor, as was shown by -the feeling that the two groups were unequal in number. He called the -relative fewness of the first group a case of "perspective effect." -This must have significance for any account of the time-error; but by -no means carries with it its own interpretation. - -One welcome result of these tests was their assurance that I might -without fear further simplify the experimental conditions by avoiding -the possibility of a distribution-error. The material for these -experiments on brightness therefore profited by this possibility. Each -card had a different specific irregularity, but always in duplicate. In -choosing the degree of brightness-difference Prang's brightest shade of -normal gray was found as dark as could be conveniently perceived with -the artificial light of the One-Group Apparatus. The contrast between -this shade and white was quite evident enough for the purpose. The -small-difference cards were omitted. - -Table IV, E, shows the decisive character of the results. The observers -fall all into one class in favoring the darker group, and by a large -difference-value. The following introspection of one observer shows -the extent to which the factors of brightness and number fuse: "I -frequently lose sight of time-order. It is a question of number and -not one of light-intensity, and if called upon to state which group -came first I might not be able to answer. In equality-judgments the -difference of light comes out distinctly." - -5. _The Influence of Complexity of Environment._ - -The material prepared for these experiments certainly lays stress -upon _relative_, not _absolute_, complexity; for the conditions were -satisfied by placing 5 mm. strips of white paper, equal in length -to the width of a group, a few millimetres off at the top and the -bottom of the groups that were on one side of the cards. The One-Group -Apparatus was used and the small-difference cards omitted. - - -TABLE V - - 44 experiments with two subjects. - 88 experiments with two subjects. - - Exposure = 1/25 sec. - _Simple_ _Complex_ _No_ - _environment_ _environment_ _tendency_ - - Number of subjects 2 2 - - Av. % of difference - in favor of 15.9 8.5 - -The results are recorded in Table V. (1) The drift of tendency is -toward the group with the more complex environment. No one markedly -favors the other group. (2) The notes of the observers indicate that -the added strips functioned through their effect upon the apparent area -of their group. The observers all found the dimensions increased; but -with some, apparently by contrast, the added height brought out sharply -the narrowness. One observer found this true in general; another, -when the barred group came first. The latter says: "The unbarred -group, coming first, appears to reflect its compact character on the -barred one, when it comes, so that it does not look so attenuated and -strange." Here the image brought over to the second took the width of -the second somewhat out of relation to its illusory height, whereas in -the reverse order the contrast relation was fully maintained. - - -III. THE INFLUENCE OF FACTORS PRESENTED IN OTHER SENSE-FIELDS BY THE -OBJECTS WHOSE NUMBER IS IN QUESTION - -A very simple apparatus was employed. The objects whose number was in -question were bright steel balls (3/8 inch) thrown loosely into square -black frames, 13 cm. inside, placed side by side on a black-topped -table. The experiments were performed in series of 30. The groups were -kept equal numerically, with this exception, that into each series were -introduced four experiments where the groups were so unequal that the -observer could have no question as to the correctness of his judgment -and the existence of objective differences. This numerical superiority -was given to each group alternately, and judgments on it were, of -course, excluded from the results. The actual numbers employed in a -series varied between 35 and 60 in accordance with the following scheme: - - 1. 50 each - 2. 45 " - 3. 50 " - 4. 55 " - 5. 60 to 40 - 6. 50 each - 7. 45 " - 8. 40 " - 9. 45 " - 10. 50 " - 11. 55 " - 12. 60 " - 13. 40 to 60 - 14. 50 each - 15. 45 " - 16. 40 " - 17. 35 " - 18. 40 " - 19. 45 " - 20. 50 " - 21. 55 " - 22. 60 " - 23. 60 to 45 - 24. 50 each - 25. 45 " - 26. 50 " - 27. 60 " - 28. 55 " - 29. 50 " - 30. 45 to 60 - -The time of a single exposure--in this case two groups at once--was -3 sec. measured by a stop-watch. As to the arrangement of the balls, -care was taken that they should not be massed in one place, but -scattered somewhat homogeneously over the space within the frames. The -illumination was daylight, so managed that shadows cast by the balls -were reduced to a minimum. The observer sat close to the table with -the groups directly in front of him. He either kept his eyes closed -between experiments or held a small screen before them. Sometimes he -merely turned away. The operator worked from the opposite side of the -table, taking care to make the necessary noises as little suggestive -as possible. The observers agreed that they were not consciously -influenced by the manipulation. - -The progress of these experiments disclosed an astonishing space-error. -So far as was conveniently possible the usual technique of elimination -was employed. - -1. _The Influence of Active Pressure._ - -In this study the groups were differentiated in this way: With one hand -the observer rolled the balls of one group under his fingers, while the -other group was presented to vision only. The method of observation -consisted in rapidly and lightly rolling the balls under the fingers a -few times and then surveying both groups visually for the remainder of -the exposure, judgment being given on the visual number. - -Evidently there is much that is rough about this procedure. Pressure -and kinæsthetic factors are lumped off together; the length of the -touch-stimulus was not exactly determined; and there is the possibility -that the visual stimulation from the group touched is weakened. To be -sure the method prevents any great difference in the latter respect; -and if we are guarded in our interpretation, something of interest may -be learned. - -There appeared to be no convenient way to eliminate the space-error. -The right hand was used with the right group and the left with the -left. So here again interpretation must be circumspect. - - -TABLE VI - - A B - 52 _experiments with_ 260 _experiments with_ - _each subject_ _one and_ 208 _with the_ - _other subject_ - - _No_ _No_ _No_ - _Touch_ _touch_ _tendency_ _Uneven_ _Even_ _tendency_ - Subjects 2 1 1 - - Av. % of - difference - in favor of 7.6 10 1 - - SPACE-ERROR - - _No_ _No_ - _Right_ _Left_ _tendency_ _Right_ _Left_ _tendency_ - - Subjects 1 1 1 1 - - Av. % of - difference - in favor of 69.2 23 30.8 20.2 - - C - 145 _experiments with_ - _one and_ 260 _with the_ - _other subject_ - - _No Weight_ _No weight_ _No tendency_ - Subjects 2 - Av. % of difference - in favor of 2.4 - - SPACE-ERROR - - _Right_ _Left_ _No tendency_ - 1 1 - Av. % of difference - in favor of 32 4.4 - - -Turning to the results in Table VI, A, we find the following: (1) The -influence of the pressure-kinæsthetic complex practically does not -appear; while the space-error shows a marked tendency that, for the -two observers, is in opposite directions. (2) On the other hand, the -notes of one observer show that in his case at least the face value of -the table is erroneous. To this effect he says in substance that he can -make a more accurate estimate of the number in the group touched. He -tries to ignore these sensations of touch, but with ill success in the -case of the left hand, where clumsiness not only makes it difficult to -touch the balls gently but also to keep them under the fingers, which -often feel the ground-space. For this cause the group seems small in -number. Clearly enough, then, it is the space-error that tells the -story of the effect of the added stimuli on this observer, only it -must not be interpreted as space-error. The pressure functioned in the -judgment through its numerical aspect. But the positive effect with the -right hand was turned to a negative with the left through its emphasis -of vacancies. The high difference-value in the space-column becomes -thus a striking evidence of the effect of pressure, and the results are -accounted for without reference to the kinæsthetic factor. The other -observer felt that the active pressure was relatively indifferent. (3) -The entire absence of correct judgments on the objectively equal groups -shows to what a surprising extent other factors have modified the -numerical. - - -2. _The Influence of Unevenness in Active Pressure-Feeling._ - -In the experiments of this section the groups differed in this way, -that one rested on the smooth table-top while the other had for its -bottom a coarse wire mesh covered with black cloth. The balls of the -one rolled smoothly beneath the fingers while the other balls moved -lumpily over their mesh. Both hands were used--each for the group on -its side; and the method of observation and length of exposure agreed -with those conditions in the preceding section, except that the balls -were rolled a little more vigorously that the factor studied might -come clearly into consciousness. The groups were interchanged for half -the number of series. This could not of course completely eliminate -the space-error, since kinæsthetic differences in the limbs remained -uncompensated. In general the criticism in the preceding section is -again applicable. - -The results appear in Table VI, B. (1) One observer shows a tendency -to favor the smoothly rolling group, while the other again shows no -tendency. Both have large space-errors of the same character as in A of -this table. (2) The introspection of the observer showing no tendency -is to the effect that touch plays little or no conscious part in the -situation. The other's notes give no hint that the factor studied -here was influential; but to the effect on the judgment of touch in -general, especially with the right hand, they give clear witness. The -touch-sensations, he says, were difficult to ignore. Those from the -right hand were more vivid than those from the left; and the right -hand seemed more sensitive. Judgment was based on a general feeling of -"moreishness" which came promptly. There is nothing to contradict the -evidence of the earlier experiments that touch is again influential -through its numerical character. (3) Both observers regard factors of -distribution as of fundamental importance, though one was inclined at -first to insist that there was nothing but number in his judgment. The -significance of this unanalyzed feeling will appear in a later section. -(4) These results agree with the preceding in the approximate exclusion -of correct judgments. - - -3. _The Influence of Active Weight._ - -The variation here in question consisted in lifting one of the groups -during judgment of the relative number in the two groups. The apparatus -was made by transforming into trays the frames containing the balls, -by putting into these frames wire-mesh bottoms covered with black -cloth. They were set each upon four small wooden pillars so that the -hand could be easily thrust under the tray. At the signal a given tray -was several times raised a little way and lowered, and the judgment -formed on the same factor as before. Here again the space-error was not -entirely eliminated. Each hand was used with the group on its side, but -kinæsthetic differences peculiar to each of the limbs remained. There -was always some motion among the balls in the lifted tray, though the -gentleness of the lifting prevented the existence of much. This is a -radical defect, but one not easily avoided with maintenance of other -desirable conditions. Even more serious, as the issue proved, was the -failure to control the lifting impulse; yet, as it happens, we are not -prevented from getting an experimental answer to our question. - -The results are recorded in Table VI, C. (1) They show no apparent -effect of the weight, and with one observer the further unusual fact -of no space-error. This error is marked enough in the case of the -other, and, conforming in direction to that of the preceding sections -of this table, allows us in so far to adopt the same interpretation of -his results. (2) The introspection of one observer was to the effect -that he felt a tendency toward a modification of the number-judgment -by weight. It was especially strong when the group was lighter or -heavier than was anticipated, the light group seeming less numerous, -and the heavy group more. Occasionally he caught himself weighing the -second group mentally; and sometimes he had to recover himself from a -tendency to make judgments on a wrong basis, presumably that of mere -weight. With such a conflict of tendencies the character of the results -is not surprising. Particularly important are the opposing tendencies -lying in the factor of weight itself. The other observer reported that -a very heavy weight exerted an influence that it was hard but not -impossible to ignore, while a lighter weight did not effectively enter -the situation at all. His earlier inclination to say that there was -nothing but number in his judgment inclines one to believe that fusion -of factors may have passed beyond the stage of ready analysis. (3) -Our analysis has given us reason to believe that active weight has a -definite tendency to modify the judgment of relative number. - - -4. _The Influence of Muscular Strain in Observation._ - -The study was made from the point of view of more than one set of -experimental conditions, viz.: - - (1) Equal strain (minimum). - (_a_) Right--left. - (_b_) Up--down. - (2) Equal strain (maximum) eyes turned. - (3) Strain _vs._ ease. - (_a_) Head and eyes turned. - (_b_) Eyes turned. - -The conditions of (1) (_a_) were exactly those of the earlier -experiments with the exception that the groups were undistinguished -save by position. In (1) (_b_) one group was so placed between the -other and the observer that there might be as little increased effort -as possible in viewing the farther. In the up-down movement more -muscles are involved in the lift than in the fall of the eye. So really -we have here a case of (3) but not so marked. In (2) the groups were -put to the right and left at such distances that, when sitting between, -the observer could just take each one in without turning his head. This -brought a decided strain upon the eye-muscles. In (3) (_a_) the groups -were separated by the length of the table--a distance of 90 cm.; and -the observer placed in alternate series before each; as he was in (3) -(_b_) where the farther group was carried to the limit of vision to be -reached without turning the head. Here the strain was like that in (2), -but for one group only. - -An incompleteness in experimental analysis lies in the impossibility of -separating the factors of distance and strain. - - -TABLE VII - - A - Baldwin 46 experiments - Hutchinson 78 experiments - Equal strain (minimum) - - B - 52 experiments - with each subject - Equal strain (minimum) - - C - 52 experiments - Equal strain (maximum) - Eyes Turned - - D - 104 experiments - with each subject - Head and eyes turned - - E - 52 experiments - - A B C D E - - Right Left Lower Upper R. L. Ease Strain E. St. - - Subjects Baldwin Hutchison 2 Bald. 2 Bald. - - Av.% of - difference - in favor of 30.4 28.2 68.3 71.2 52.4 80.8 - -Here are the facts of chief interest: (1) The following tabulation -gives us a ready view of the character of the results in Table VII; and -shows the extent to which they are consistent: - - A B C D E - - Baldwin favors right {upper left {farther {nearer - {strain {strain {no-strain - left left - - Hutchison favors left {upper {farther - {strain {strain - left - -(2) The only inconsistency in the strain-distance complex is with -Baldwin in E. He reported that the more distant group appeared rather -as an undifferentiated mass whose number was not so well obtained, -while in the near the individuals were significant. He seemed to -be in the midst of these. The case seems analogous to that of the -observer whose introspection was reported under Table I, and who at -first accepted what we may call the objective analysis, by which -the scattered group gave up more distinct objects than the compact; -but later attempting voluntarily to disintegrate the compact, found -a bewildering confusion in the task that made this group seem very -numerous, and brought about in the end an exact reversal of tendency. -(3) Can we now separate in the results between the influences of strain -and of distance? So far we have regarded them as one complex. But the -introspections speak merely of the space-characters of the objects, -Hutchison agreeing with Baldwin that the more remote group is judged -as an area rather than as a collection of definite objects. (4) The -almost entire absence of correct judgments in these experiments adds -new evidence to that of the immediately preceding experiments in proof -of the insignificance of the actual numerical relation for the judgment -of relative number. - - -IV. THE INFLUENCE OF FACTORS OUTSIDE OF THE OBJECTS AND IN OTHER -SENSE-FIELDS - -The One-Group Apparatus was employed, and cards in general -corresponding to those where area was not in question,--white-circle -groups equal in size and irregular in inner distribution, which was not -duplicated on the same card, though the resulting distribution-error -was formally eliminated in the usual way. The usual care was taken -to fill the group-area homogeneously. The small-difference cards -were retained at first; but on later discovering the possibility of -duplication a few supplementary experiments were added. - - -1. _The Influence of Touch._ - -The apparatus employed to give the touch-stimulus consisted in a long -lever attached to the armature of a small electro-magnet. In the end -of the lever was inserted at right angles a wooden peg, cork-tipped. -In view of the other conditions of the experiment a convenient spot -for the application of the stimulus was found to be the forehead where -it curves backward above the right eye. The apparatus was supported -by rods and clamps upon a long upright steel rod set in an iron base -and placed behind the chairs of the observers. The same rod carried a -head-rest, designed not as a support but merely to show the observer -that he had returned to the original position after he had bent forward -to record judgment. Where two observers were used at once two sets of -this apparatus were employed, with the magnets in a single circuit -governed by a floor-button. The touch-stimulus was made to coincide as -closely as possible with the appearance of a given group. - -In view of the practical remoteness of this factor from the object of -judgment the experimentation here took two forms,--one in which the -observer was passive toward the touch-stimulus; the other in which the -effort was made closely to associate the touch with the visual group by -imagining the group to be responsible for the touch. For the passive -method the touch was given irregularly now on the first and now on the -last, but as many times on one as on the other. - -For the active method, it was given always on the last group. This -constancy was held to favor the active association of touch and -particular group. The constant time-error was guarded against by -experiments in which no modifying factor was introduced. A and B of -Table VIII present the results of the passive and active methods -respectively. C and D repeat A with duplication of groups,--C with the -usual (1/25 sec.), D with a longer, exposure. These last sets were -taken that the factor of touch might be studied when the objective -conditions of the strong distribution influence should have been -removed. It might prove that a factor swamped in the former situation -might emerge into effectiveness. - -The following summary gathers the chief facts of Table VIII: (1) -Touch appears practically without effect in A. (2) In B, the -results for touch seem again insignificant; but comparison with the -control-results, to isolate touch from time-order, while it shows no -marked change for Angier, does show for the others that touch was -effective in determining the direction of error by difference-values, -in the two cases of 10.2 and 14 per cent. The active method seems to be -slightly more favorable to the influence of touch. (3) The duplication -of the groups in C gives a large increase to the apparent effectiveness -of touch, which is considerably diminished but not destroyed by -the lengthening of the exposure in D. (4) The introspection for A -indicates that touch under these experimental conditions has little -subjective importance for the judgment of number. It is sometimes quite -unnoticed. Angier made a possible exception in its favor in cases of -great hesitancy where it added "importance" to the group with which -it occurred. Usually he felt little doubt. With Shaw the touch was at -first distracting but later indifferent. Johnston's notes indicate -rather more effect. The touch prevented strict attention to the figure -impression whereby the space-intervals in that group lost in value. -Later it lost its confusing effect. Here seems to be subjective -tendency, but not enough to predominate in results. - - -TABLE VIII - - A - 88 _experiments - with each of two - subjects._ 132 _experiments - with one - subject._ - - B - 198 _experiments - with each of two - subjects._ 110 _experiments - with one - subject._ - - C - 44 _experiments - with each subject._ - - D - 88 _experiments - with one subject - and_ 44 _with the - other_ - _Exposure_ = 1/4 _sec._ - - A B - _No _No - _Touch_ _No touch_ tendency_ _Touch_ No touch_ tendency_ - - Subjects 3 3 - - Av.% of - difference - in favor of 3.2 5.7 - - - C D - _No _No - _Touch_ _No touch_ tendency_ _Touch_ _No touch_ tendency_ - Subjects 2 2 - - Av.% of - difference - in favor of 26.1 13.7 - - Results in B for the subjects separately were as follows: Angier 4%, - Johnston 8.2%, Shaw 5%, all, so far as they went, in favor of the - touch-group. Control experiments to determine the time-error gave - the following results: Angier 6.8% in favor of the group last seen, - Johnston 2.2%, and Shaw 9% in favor of the first group. - -Some further introspective evidence appears in connection with the -active method of B. Angier confirms his earlier account exactly. -Usually the factors of distribution practically associated with number -determine the judgment promptly; but in cases of doubt the touch is -felt to add to its group something that appears as number-value. -Johnston's subjective situation seems a little complicated. I may -summarize thus: (_a_) The connection between the touch and its group -being established, that group seems smaller, as being, together with -the touch, somewhere nearly equal to the first. (_b_) The connection -established and touch failing to come, that group seems smaller. (_c_) -The connection not established and attention being concentrated on -the visual impression, the touch-group feels much larger. The curious -attitude in (_a_) results in a discounting in advance of the actual -number. This done, the touch adds numerical value to its group. In -(_c_) the effort at abstraction appears to emphasize the second (touch) -group. Later, he reported similarly that the touch-stimulus seemed -to add to the number of circles in its group even when the judgment -favored the other group; and that "any outside stimulus connected -with the one of two exposures tends to lose its own significance and -be translated into number of dots to help the accompanying exposure -to equal or exceed the first." The touch-group is felt to have more -significance through association with an idea of superior energy or -greater motor impulse. - -Of the character of the influence exerted by the touch, Shaw reported -that there seemed to be a diminution in the size of the first group -and something extra in the second. More specifically, this effect -appeared at times as an added circle at the right of the second (touch) -group. He thought that this effect was overruled by the real bases of -number-judgment which he summarized as "size, regularity, density, etc." - -These notes show a definite tendency on the part of the touch-stimulus -to break in upon the course of the number-judgment ordinarily -determined by the practical association of a specific group of factors -with number. That this result gets no more marked registration in -the percentages is apparently due to the strength of these customary -associations. - -(5) The extent to which the distribution-error complicates the -present study is shown by the prompt increase in effectiveness of the -touch-stimulus when the groups were duplicated, as in C and D. - - -2. _The Influence of Hearing._ - -The scheme of the experimentation upon this factor conformed in -general to that of Section IV, 1. But a new sort of differentiation -was possible in the auditory field, and one more readily suggestive -of numerousness, perhaps, in that by use of an electric bell a rapid -succession of sounds could be given with one group while with the other -a single sound could be produced. An actual numerical difference in the -auditory field might fuse with the factor of relative visual number -and determine the judgment to its direction. These results are set -down in B of Table IX. The same set of cards was used in the One-Group -Apparatus for these experiments as for those of Section IV, 1. In these -two sections of Table IX the observers did not know on which group -the sound or the particular sound would be given; but any possible -disturbing effect of this irregularity was formally eliminated as in -Section IV, 1. The experiments of Table IX, C, repeat those of A with -duplication of groups; and D repeats those of C with longer exposure. - -The sound for A was that of a small organ-pipe (Ut 4) blown by mouth. -As in A of the preceding table the observers did not know in a given -experiment with which group the sound would be given, but, as before, -it was given the same number of times with the first as with the last. -For B the multiplied sound was produced by an electric bell with -a wooden gong. This was adopted in preference to metal because of -the prompt ceasing of the sound after the stroke,--a very necessary -condition when this sound accompanied the first group, that it might -be clearly connected with its own group. A metal gong was used for the -single sound, that the two might not be too unequal in loudness. Its -vibrations were deadened by a rubber band, and each bell was controlled -by a floor-button. For C and D a higher sound, from the same pipe -unstopped, was used in preference to the former, for the reason that in -certain experiments performed just previously the lower sound had been -used and was presumably very familiar. So in order that the sound might -be brought, if possible, afresh to the attention, the change was made. - - -TABLE IX - - - A B - - 132 _experiments_ 44 _experiments_ - _each with_ 3 _each with_ 2 - _subjects_. 180 _subjects_. 88 - _with_ 1 _subject_ _with_ 1 _subject_ - - _Exposure_ = 1/25 _sec._ _Exposure_ = 1/25 _sec._ - - _Sound_\_No _No _Many _One _No - Sound_ tendency- Sounds_ Sound_ tendency_ - Subjects 4 1 2 - - Av.% of - difference - in favor of 5.4 18.2 2.2 - - - C D - - 44 _experiments each_ 88 _experiments each_ - - _Exposure_ = 1/25 _sec._ _Exposure_ = 1/4 _sec._ - - Sound_ _No Sound_ _No_ _Sound_ _No Sound_ _No_ - _tendency_ tendency_ - Subjects - 1 1 2 - - 20.4 4.6 2.2 - -The results of these experiments may be summarized as follows: (1) -The figures give evidence of but two cases out of eleven where sound -was influential. (2) Duplication of groups is not effective in -developing evidence of the influence of sound. (3) Increased length -of exposure works, as in former cases, to lessen the influence of the -modifying factor. (4) The introspections are to the effect that the -sound seems to be entirely without influence upon the judgment, beyond -the distraction it brings in the earlier stages of work. Sometimes it -dropped wholly out of consciousness. Sometimes the distraction seemed -to last longer. One observer reported, when D was taken, that he -felt as if the sound sometimes increased and sometimes decreased the -apparent numerousness. In some other experiments not directly upon this -point, but later to be reported, a sound was used; and one observer -reported that it seemed to become functionally connected with certain -gaps in the groups, as though the puff had blown a hole in the group. -Here its effect was of course to emphasize negative factors. It appears -thus that the sound might function in opposite directions at different -times, somewhat in accord with the particular character of the visual -presentation. We should expect, then, to have percentages that look -insignificant. (5) We shall not have failed to notice the difference -between touch and auditory stimuli in the feeling of influence upon -the number-judgment. If we seek a cause for the superior influence of -touch, we may perhaps find it in the fact that practical experience -has trained us to disregard in any case of judgment such simultaneous -presentations as were employed for auditory stimuli; while a definite -tap upon the brow is a rather unusual experience likely to attract -notice to itself in spite of attempts at abstraction. As one observer -said, who took part in both kinds of experiments, the touch seemed more -"intimate." - - -3. _The Influence of Kinæsthetic Impression._ - -The method consisted in the employment of active effort upon a fist -dynamometer or a wooden handle during the appearance of one of the -groups. The handle was preferable because noiseless. The effort was -made with the left hand because the right was used in recording. The -amount of it was left to the observer's regulation, with the one -instruction that its presence be made decidedly evident but without -too great fatigue. The cards of Section IV 1 and 2 were used in the -One-Group Apparatus. Similarly again the experiments were repeated -with the duplicate-group cards. I present no table here because the -figures show practically no influence of the effort. On one subject 176 -experiments were made; on a second 132; on a third 88. - -It is interesting to note here certain results obtained from one -observer when he was in what he described as an active attitude toward -the groups, in which he seemed to rouse himself to an unusual pitch of -concentration upon the visual situation. This was evidently a condition -of increased effort to abstract. Without abstraction he gave 26 to 6 in -favor of the effort while with abstraction this tendency had fallen off -to 30 to 17. The strength of the tendency is thus strongly indicated. -Another observer felt a kind of motor difference between the groups; -he expected the effort-group to look larger and felt additionally -excited, a scattered activity, while he was passive toward the other -group. Perhaps this account puts a little meaning into his small per -cent. That his power of abstraction was effective here is hinted by -his remark that he felt a difference in the groups even when he judged -them equal. The third observer found no subjective evidence that effort -modified his judgment. - - -V. THE "ERRORS" OF EXPERIMENTATION - -Throughout the foregoing experiments has been involved the possibility -of some one of the three "errors" of experimentation, those of time, -space, and distribution, and sometimes all three. Their effect on the -results, if it existed, was, to be sure, eliminated in the well-known -way, but their existence, if actual, would raise an interesting -problem. It was possible, in the case of every group of experiments, -to rearrange the tables in such a way as to bring out the evidence for -any tendency to overestimate, for instance, the first group as against -the second, the right as against the left, or one kind of irregular -distribution as against another. - -The distribution-error must have a word of explanation. It refers to a -tendency to give more wrong judgments in favor of one kind of irregular -distribution than of the other kind with which, in a given card, it is -mated. In the construction of a set of cards several forms of irregular -internal arrangement were used, in order that the judgment might not -be one merely of form, and of course on any given card the forms were -not the same. Elimination of the effect of these form-differences -from the results involved the appearance of any given one as many -times in connection with one of the two contrasting factors studied -in a given experiment as with the other. Thus two sets of forms were -carried through an experimental series--a source of error indeed, but -avoidable only by such means as were used to escape the effects of the -space-error. Analysis would show which, if either, of the two sets -received more judgments in its favor, resulting in further evidence as -to the extent to which the judgment of relative number is a function -of distribution, and as to the fineness of discrimination for such -differences. - -Now the tables, when thus rearranged, show that these errors exist to -a surprisingly large extent. In many cases their causes, whatever they -are, seem to be the controlling factors in the judgment of relative -number. - -Barring the experiments of Section III, in which the space-error has -largely been accounted for, I now propose to gather in one survey all -the results of those analyses that have given us the information of the -existence of these errors, and all the material of later tables that -bears on this point, and to test them by further experimentation. I -will begin with the space-error. - - -TABLE X - - _Av. % of _Av. % of _Av. % of - difference in difference in difference in - favor of_ favor of_ favor of_ - - _Cases_ _Right_ _Cases_ _Left_ _Cases_ _No tendency_ - - Angier 1 25 6 17.9 9 5.7 - Davison 5 26.4 1 10.8 6 6.2 - Dunlap 7 18.3 4 4.4 - Holt 2 13.6 7 17.6 4 3.2 - Hylan 8 23.6 7 6.7 - Meakin 2 19.2 1 29.6 8 5.5 - Meriam 2 16.5 2 12.9 7 6.8 - Moore 2 11 3 16.6 7 3.1 - Peterson 1 13.6 1 12.2 9 4.3 - Rogers 4 21.9 2 15.9 6 4.5 - Rouse 3 15.5 8 5.1 - Shaw 3 20.9 5 18 7 6.1 - Windate 1 22.8 4 19.5 7 4.5 - Yerkes 6 26.6 8 5.2 - Henry 1 10 2 16.6 3 8.1 - Woods 3 19.3 3 4.8 - -1. _The Space-Error._ - -Table X presents to us a summary of the values of the space-error -tendency. (1) Taken as a whole they fall into all the three classes -that are possible; (_a_) favoring right; (_b_) favoring left; (_c_) no -marked tendency. (2) There is no observer that does not at some time -show a fairly marked tendency. (3) All the observers fall into (_c_) -and all but five into both (_a_) and (_b_). (4) More favor the left -than the right,--50 to 35. (5) This survey makes it clear that the -observers agree neither with themselves nor with each other in the -direction of influence exerted by the causes underlying the space-error. - -_a. Special Experiments to establish the Facts._ It might be suspected -that irregularities would be more apparent where other factors such -as we have been studying enter to complicate the situation from the -point of view of pure relative position of the two groups. Table XI -presents the answer to this query. The cards used contained groups -of gray circles (Gray Darker, Prang) arranged in equal areas of the -usual size and shape. The distribution-error was eliminated, though -not by duplication, and the small-difference cards were retained. The -Two-Group Apparatus was used, with an exposure of 6/5 sec. - - -TABLE XI - - 88 _experiments with each_ - - _Right_ _Left_ _No tendency_ - - Subjects 4 7 3 - - Av. % of difference - in favor of 25.6 23.1 3.4 - -The results give us again our inevitable three classes, and in many -cases a difference-value surprisingly large when we reflect on the -simplicity of the conditions. That the omission of complicating -features was of importance is shown by the fact that more of the -observers (11 out of 14) show a marked error than in any other case. -Clearly enough the various factors introduced tend to eliminate -the space-error, but when in any case it does enter, it is even -then capable of rising to as high a degree on the whole as in the -uncomplicated series, as is shown by the fact that in but four cases -does the new value surpass the best of the old, and in three of these -by a trifling amount. - -It is interesting to note that the three cases of minimum space-error -show a well-defined tendency to be determined by distribution. - -_b. Possible Bases of this Error._ The outcome of these special -experiments is that the factors found in the groups are at least not -directly responsible for the situation that we are considering. The -divergence among the observers shows this. In hunting after the cause -for this apparent influence of side, we look first for changes in -the peripheral, and then in the central, processes that precede the -judgment. The material used for the experiments of Table XI seems -approximately to have equalized all the objective factors in the two -groups. How could there be anything further in the peripheral process -whereby group could be differentiated from group? The most evident -thing is that the visual stimulus is received in a different way from -the two groups. There is a definite peripheral mechanism whose factors -seem essentially to be two, however variously they may be combined: -(_a_) The relative amount of time given to each group; (_b_) the order -in which the groups are viewed. - -The observers were instructed and continually reminded to equalize the -amount of attention devoted to the group; but as this is not wholly -a voluntary matter, the possibility of failure to conform has to be -reckoned with. Experiment must therefore be employed to test the -influence of these factors before one can fall back upon a central -process as the cause for this tendency to favor a side. - -_c. Its Relation to Differences between the Groups in Length of Look._ -The material was the same used for the experiments of Table XI. The -method was the same with the following necessary exceptions: The longer -exposure was double the shorter (4/5 sec. to 2/5 sec.), and 2/5 sec. -elapsed between the two. Further, the experiments were so arranged as -to equalize the influence of the order of exposure with respect to both -side and relative length. The means for effecting successive exposure -took the earlier form described in the introduction to Section II. - - -TABLE XII - - _88 experiments with each_ - - _Longer_ _Shorter_ _No tendency_ - - Subjects 6 7 - - Av. % of difference - in favor of 18 6.5 - -These facts are yielded by Table XII: (1) There are but two classes of -observers, as no tendency exists to favor the group of longer exposure. -(2) The time-error shows a considerably more marked tendency than the -length of look, which is indeed somewhat surpassed by the space-error. -(3) The persistence of the space-error, even among those that reveal -a tendency in length of exposure, shows that the factor of relative -difference in length of look cannot account for it. The persistence -of it, too, when the order of exposure is controlled, even though the -conditions are not wholly adapted to the study of this latter factor, -suggest at least that the space-error is independent of even that -order; but into this we shall make special enquiry. (4) The judgment -of number is independent of the amount of eye-movement devoted to the -fixation of the objects in a group. This conclusion, so far as the -actual movement is concerned, is established by the fact that so many -observers favor the shorter look; and by all the experiments with the -One-Group Apparatus where an exposure of 1/25 sec. was used, since -that time was too short to admit of movement. That ideated movement is -likewise insignificant appears from the fact of marked error arising -in the material where the groups were duplicates. Here no motives to -different movements could lie in the material. - -_d. Its Relation to the Order in which the Groups are viewed._ Table -XIII gives us the results of the enquiry. The experimental conditions -were not changed except as to the length of exposure. Each group was -given 3/5 sec.; and half the experiments were performed in the order -right-left and half in the reverse order. - - -TABLE XIII - - _88 experiments with each_ - - _First_ _Last_ _No tendency_ - - Subjects 3 9 2 - - Av. % of difference - in favor of 17.5 28.3 1.7 - -The results may be thus summarized: (1) The order of exposure is -notably influential upon the judgment of relative number, giving the -usual three classes, with the tendency to overestimate the last group -well in the lead. (2) The persistence of the space-error under these -relatively simple conditions shows conclusively that it is not a -function of the order of exposure. The two are independent variables. - -2. _The Time-Error._ - -In pursuit of our enquiry we must survey the facts as they are given -in the various experiments already reported and later to be reported. -These facts are gathered into Table XIV, which furnishes the following -items of significance: (1) All the observers, with the exception of -Rouse, show at some time a definite tendency. One case only is given -for him in this table, but other experiments not included in the -tables from which the present is drawn confirm this fact by the ratio -29 to 30. (2) There is a rather striking consistency in the several -observers. (3) The predominance of the last group is marked. - - -TABLE XIV - - _Av. % of_ _Av. % of_ _Av. % of_ - _difference_ _difference_ _difference_ - _in favor of_ _in favor of_ _in favor of_ - - _Cases_ _First_ _Cases_ _Last_ _Cases_ _No tendency_ - - Angier 7 19.1 4 4.9 - Baldwin 4 20.5 1 3.4 - Bell 1 18.2 4 6.3 - Davison 2 31.2 - Dunlap 1 11.4 1 2.2 - Holt 10 19 2 6 - Hylan 2 16 5 25.4 5 4.9 - Johnston 2 25.2 4 35.5 4 4.2 - Meakin 2 39.7 - Meriam 1 29.6 1 2.2 - Miller 3 17.1 4 5.5 - Moore 1 11.4 1 2.2 - Olmsted 1 15.2 - Peterson 1 17 1 9 - Rogers 1 10.2 1 5.6 - Rouse 1 1.2 - Shaw 6 16.7 5 7 - Windate 1 11.4 1 1.2 - Yerkes 2 42.7 - -_a. Relation of the Error to the Absolute Length of the Total -Exposure._ Table XV is set to answer this question. It is -unsatisfactory in that but two observers took part in both XIII and XV. -The material used for judgment consisted of the same cards used in the -earlier experiment, but presented now in the One-Group Apparatus. The -time of exposure was changed from 3/5 sec. to 1/25 sec. for each group. -As the space-error was eliminated, the tendency to a time-error, if -present at all, would presumably have freer play. - -But the difference-values of the new table are for the most part very -small. We have thus the further fact about the time-error that, under -the conditions studied, it appears to be independent of the absolute -length of exposure, when the groups are equal in this respect. To -this we may add another fact drawn from Table XIV, that with the -One-Group Apparatus the time-error is greater on the whole where the -groups are differentiated by other factors. Thirdly, the values for -Table XIII show that with all complicating factors withdrawn, except -the differences in position, the error is at a maximum. This may -be significant of the effect of space-differences upon that error, -or, more probably, be due to the general difference between work by -daylight and work in a dark room by artificial light. We shall be -better able to consider this later. - - -TABLE XV - - 88 experiments with each of two subjects. - 176 experiments with one subject. - 154 experiments with one subject. - 66 experiments with one subject. - - Exposure = 1/25 sec. - - _First_ _Last_ _No tendency_ - - Subjects 1 4 - Av. % of difference - in favor of 15.2 6.8 - -3. _The Distribution-Error._ - -The last of our three "errors" of experimentation is now before us. -We may recall once more the meaning the term has had for us in these -studies. It points to a tendency discovered by the use of those -cards where all objective factors were in the course of a series -equalized,--a tendency to mass one's judgments in favor of a particular -arrangement of the circles; though each group had been constructed -with a view to filling the given area as homogeneously as an irregular -arrangement would allow. - -As in the two "errors" preceding, so here we must get possession of -the facts that gave rise to the present enquiry. Table XVI presents -them to us, gathered out of all the tables wherein such a tendency has -been technically reckoned with. But first a few words of explanation -are needed to make the new table intelligible. Two sets of results are -found in its two parts. In each set the particular group-arrangements -employed and the frequency of their appearance are exactly the same. -The two sets differ, as their headings suggest, in that the material -for the second set was formed out of the first by replacing the -small-difference cards by those having equal groups. Such a change -as this might affect the proportion of judgments given in favor of -the two sets of arrangements in a particular series, and these new -results are, therefore, no longer fully comparable with the earlier -ones. In presenting the directions of tendency in the results, it is -impossible here, as in all the similar cases throughout the tables, to -name a factor as a standard in whose favor all the judgments in the -plus column should be understood as given,--impossible for this reason -that, because the very method by which the circles were distributed -in the groups, the experimenter was unable to satisfy himself as to -the significant differences in the arrangements. All the results, -however, when analyzed on this basis, were recorded consistently, so -that consistencies and agreements among the observers might be readily -apparent. We can now understand in part what Table XVI has to say to us. - - -TABLE XVI - - A - _No_ - _Cases_ _Class 1_ _Cases_ _Class 2_ _Cases_ _tendency_ - - Angier 4 19.1 2 6.3 - Davison 3 23.1 - Dunlap 2 13.7 1 2.2 - Holt 3 15.5 1 25 2 4.5 - Hylan 1 11.4 2 14 3 6.7 - Johnston 5 30.4 - Meakin 3 34.9 - Meriam 1 16 2 6.8 - Miller 5 32.1 - Moore 1 39.8 2 5.7 - Olmsted 1 27.2 - Peterson 3 42.1 - Rogers 1 11.4 2 5.7 - Rouse 2 14.2 - Shaw 6 29.1 - Windate 3 30 - Yerkes 3 17.8 - - B - _No_ - _Cases_ _Class 1_ _Cases_ _Class 2_ _Cases_ _tendency_ - - Angier 3 2.9 - Davison - Dunlap - Holt 1 22 1 21.6 2 3.1 - Hylan 2 50.8 1 11.4 1 8.4 - Johnston - Meakin - Meriam - Miller - Moore - Olmsted - Peterson - Rogers - Rouse - Shaw 2 26 1 0 - Windate - Yerkes - - Here as elsewhere the per cents recorded indicate the average per - cent of difference in favor of a given class. - -Here are the facts, first of A: (1) The only lapses from consistency -are confined to two observers; and in both these cases there is but a -single break in a uniform trend. (2) With three exceptions all agree -in the trend of their difference-values. Of these three--Holt, Hylan, -and Moore--the last furnishes but one significant value, and so must be -left out of the reckoning on this point. (3) Of the 64 cases, 50 rise -above 10%, some far beyond, showing the importance for the judgment of -relative number of this factor of distribution. (4) Of the 50 cases, -45 agree in tendency. (5) That with this surprising agreement we -have still a few exceptions, adds another item to the growing array -of evidence on behalf of the importance of some subjective factor for -the number-judgment. As to the nature of this factor we are yet in -the dark. (6) To these facts B of this same table adds the further -information that the observers inconsistent in the old are not -consistent in the new, while the consistent still maintain their record. - -_a. Analysis of the Experimental Conditions of Distribution._ At once -we are interested to enquire for the factors underlying these results. -To put ourselves upon the right track we must first consider what -factors are involved in any such arrangement of objects as we have used -in the material for these studies, and then, more precisely, we may ask -in what way such arrangements could differ significantly. Finally, by -an experimental trial-and-error process, we may solve our problem. - -The groups of objects in our material were arranged in an area marked -out in each corner by a circle. Within this area the circles were set -irregularly, with the result that the group, as a mass of objects -distinguished from a homogeneous background, had a more or less -irregular outline whose irregularity varied with different internal -arrangements. Within its outlines this area presented a mixed pattern -of bright and dark. While the total enclosure marked off by the corner -circles was always the same and theoretically the relative amounts of -brightness and darkness in equal groups was likewise the same, yet -practically differences, more or less slight, might enter through the -changing character of the rude outlines whose ideal completeness could -scarcely be brought out of a black background by the uninitiated. The -amount of this difference is sometimes surprising to one whose chief -thought of the group has been as vignetted in process of construction. -As the objects are pushed toward the edges the central spaces open out; -as they are withdrawn toward the interior gaps appear in the margin. - -It is not a very easy task to fill an area with objects in irregular -arrangement in such a way that no sections of vacancy or filling -stand out by contrast against the remainder of the same element. To -succeed in this is to fill the area homogeneously. But the chances -are good that some vacant patch will get slightly the better of its -neighbors or some section of circles will gather a little more closely -than the surrounding circles; or perhaps a gap in the outline will be -unexpectedly intrusive. Now in a given area the circles of one part -cannot become more thickly massed without a corresponding enlargement -of the vacancies of the other parts, and of course the converse is -as true; but this theoretical situation may be quite out of ken at -the moment when the group is seen. Either member of this pair of -complements may stand out vividly in the field and its fellow quite -escape perception. The very nicety with which in practical affairs we -have to make a reliable comparison of this sort shows what suspicion -of accuracy the off-hand judgment has bred. And further, the widening -of a gap or thickening of the filling in one small part of a group may -give a complementary loss to the rest of the group small enough to be -unperceived when distributed throughout the larger section. - -Two factors must therefore be considered as possibly significant in -moving the judgment,--vacancies and filling; and with the former must -be reckoned indrawing of the outline. Psychologically, increase in -the prominence of either of these factors would be all one with their -objective increase. With respect to the direction of their influence -upon the judgment of number the increase of vacancies must signify the -waning, and the increase of filling the waxing, of the objective number -in the group. - -It is in advance altogether probable that the results gathered into -Table XVI were brought about by these two factors, at least in large -part. And we have also in these factors the possibility of two types; -for as we saw above, increased vacancies in one part involves increase -of filling in another, and conversely. So the interesting question -turns upon the altogether disproportional representation of types. -Which is the type of the majority? - -_b. Experimental Test of Hypotheses._ The question was put to the test -of experiment. This was done by using groups in which now vacancies -and now filling were objectively emphasized in contrast with the usual -homogeneous group. First the vacancies. A set of cards was prepared -after the method previously used to eliminate the distribution-error -without duplication of groups on any one card. (See Section II.) In the -present case, however, the two sets of arrangements were definitely -differentiated as already indicated. One set had a homogeneously -filled area, the other a prominent vacancy within or gap in the edge. -The size of these variations was kept pretty close to the limit of -noticeableness, that the increase in compactness of the other portions -might be as slight as possible. It was experimentally necessary to -free the material as far as might be from ambiguity, and practically -important to avoid rousing the suspicions of the observers and the -resulting reflections. It seemed very likely that the strength of the -tendency shown by the distribution-error was due to its appearance -in situations where the observers knew that other factors were being -tested. - -The general method already described was used in preparing the groups -that gave objective prominence to compacted parts of the filling. To -fulfil the conditions outlined above was here even more difficult -than in the first set; and the cause will appear in the sequel. The -small-difference cards were omitted and the One-Group Apparatus used. - -A further attempt was made to head off reflection by a subterfuge. -It had been found that, among the factors whose influence on the -judgment had been studied, hearing had been as little effective as -any. So the small stopped pipe used for those experiments was again -brought into service and the error resulting eliminated in the usual -way. Incidentally our new tables will thus give us further information -about the effect of this factor, though of course under conditions that -are theoretically highly unfavorable, since we are forcing upon the -attention of the observers other factors that experience has shown them -only too ready to seize upon. So if a tendency traceable to the factor -of hearing should appear, we ought perhaps to give it somewhat more -than its face value. - - -TABLE XVII - - A. - - _Exposure = 1/25 sec._ - - _Homogeneous_ _Vacant_ _No tendency_ - - Angier [1]50 - Baldwin [2]53.4 - Bell [1]52.2 - Holt [2]44.4 - Hylan [2]51.2 - Johnston [1]56.8 - Miller [2]4.2 - Shaw [1]29.6 - - B. - - _Exposure = 1/4 sec._ - - _Homogeneous_ _Vacant_ _No tendency_ - - Angier [2]51.2 - Baldwin [2]55.6 - Bell - Holt [1]13.6 - Hylan [1]52.2 - Johnston [2]62.6 - Miller [1]25 - Shaw [2]14.8 - - C. - - _88 experiments each_ - _Exposure = 1/25 sec._ - - _Homogeneous_ _Compact_ _No tendency_ - - Angier 39.6 - Baldwin 35.2 - Bell 3.4 - Holt 27.2 - Hylan 39.6 - Johnston 44.4 - Miller 16 - Shaw 2.2 - - [1] 44 Experiments. - [2] 88 Experiments. - - The per cents recorded indicate the average per cent of difference in - favor of a given factor. - -Now we are ready to inspect the results. Table XVII, A is the outcome -of the attempt to emphasize vacancies. Its experiments with 1/25 sec. -exposure were repeated with one of 1/4 sec. as Table XVII, B, shows. -In Table XVII, C, the emphasis of compactness is concerned. - -For convenience we may again resort to a summary outline in extracting -the meaning from these tables. First Table XVII, A. (1) All the -observers but one agree in favoring the homogeneous, most of them -with very high difference-values. (2) Miller alone gives no tendency, -and his notes show a conflict between the increased vacancy and the -increased compactness. In other words, his discrimination was too keen -for the material. Under the circumstances he constitutes no exception -to the conclusion that the vacancy objectively emphasized was the cause -for an underestimation of its group. - -From Table XVII, B, we learn the following: (1) All the observers save -one favor the homogeneous group, in most cases by large values. (2) The -difference in the length of exposure seems to have no significance for -this tendency, since, while Holt and Shaw decline, Miller rises in the -scale. - -Table XVII, C, gives us these facts: (1) The difference-values have -noticeably fallen off. (2) We have again the customary three classes, -but with homogeneous leading as in the earlier tables. (3) By his -present favoring of the compact, Miller has now appeared in all three -classes, while Holt has developed the preference for the compact -that was budding in XVII, B. (4) The presence of four well-marked -preferences for the homogeneous shows that the vacancies in the -compact group were more significant for the number-judgment than -was the increased compactness of the filling, and that in spite of -the experimental effort to the contrary. (5) The decrease of this -tendency and the growth of the opposing, indicates that the judgment is -determined in either case by the more vivid factor. - -The conclusions to be drawn from these facts lie close at hand. (_a_) -The results in Table XVI, with their disproportionate division into -classes, were evidently due to the tendency of three observers to note -the filling and of the rest to be concerned with the vacancies. (_b_) -The judgment of relative number under these conditions is primarily -a judgment of vacancies. (_c_) The subjective factor of vividness -determines the direction of error, and may attach to either vacancies -or filling, though it usually attaches to the former. - -It may not be out of place here to speculate a bit as to the probable -cause for so close a dependence of the number-judgment upon what has no -number, so to say; upon an object that has no standing in the official -conclusion. The situation seems to be fundamentally based upon the -conditions that determine contrast. In a homogeneous field no part -stands out. Introduce a small object quite different in brightness or -complementary in color and the attention is drawn instantly to it, -but internal differences in its content are quite lost in the common -quality by which it differs from the ground. A case somewhat analogous -is furnished by our material, particularly in the One- and Two-Group -Apparatus. The small group is so unified by its contrast with the field -that internal differences must be made out with relative effort. Now -internal differences are necessary to the numerical character demanded -of it, and they can be brought out in no way save by attending to the -vacancies and so isolating parts in the threatening unity, each in a -kind of space-matrix. The most careful observer could not do better on -his way to truth; and that is why the error was so much larger when the -factor of space-differences was studied. - -That group is normally the more numerous in which the vacancies are -less completely developed under observation. We say "normally" here -by virtue of the speculation just completed as to the best method of -attaining a judgment objectively true. For a man thus proceeding, -our proposition is a sound statement of fact, to which the following -results of our experiments bear witness. (_a_) The experiments -recorded in Table XII on Relative Difference in Length of Look shows -no exception of a value equal to 10% to the general statement that all -tendencies, when any existed, were in the direction of favoring the -shorter group. The shorter the time of exposure the less completely -would the vacancies develop. (_b_) Table IV, E, shows that without -exception the darker group tends to be judged the more numerous. -(_c_) Table XXI shows for each subject that in a shorter exposure the -absolute number seems considerably greater than in a longer exposure. - -No comment seems necessary to concentrate the force of such evidence. -If we carry our proposition to the detailed results of our separate -studies in factors of distribution, we shall find that it helps us to -understand those few exceptions to the general trend of observers as -they appear in Tables II and XVII. The exceptions there favored the -groups in which compactness of parts went along with certain large -vacancies. Possibly enough they refused to fall in with the objective -analysis, and, disregarding the prominent vacancies, devoted themselves -to a development of the vacancies within the compacted parts. - -_c. The Factor of Hearing._ The time-error analyses of the experiments -of Table XVII have already contributed their facts to the special -section dealing with that error. But one or two interesting facts have -remained unnoticed in the sound-analysis. In the experiments of Table -XVII, A, there is a single case of marked tendency to favor the sound -group. With the lengthened exposure of B, this tendency, as usual, -disappears; but returns in C to some extent and two other observers -share it. A fourth markedly favors the group without sound. So the -experiments of this last table present as marked external evidence as -we have for the influence of hearing upon the judgment. These facts are -presented in Table XVIII. - - -TABLE XVIII - - A - _44 experiments with_ - _each of 4 subjects,_ - _88 with each of 3._ - - _Exposure = 1/25 sec._ - - _No-_ _No_ - _Sound_ _Sound_ _tendency_ - Subjects 1 6 - - Av. % of - difference - in favor of 27.2 4.1 - - B - _88 experiments with_ - _each of 3 subjects,_ - _44 with each of 3._ - - _Exposure = 1/4 sec._ - - _No-_ _No_ - _Sound_ _Sound_ _tendency_ - Subjects 6 - - Av. % of - difference - in favor of 5.9 - - C - _88 experiments each_ - - _Exposure = 1/25 sec._ - - _No-_ _No_ - _Sound_ _Sound_ _tendency_ - Subjects 3 1 3 - - Av. % of - difference - in favor of 12.9 20.4 4.5 - -It is a further curious fact, well sustained by these same experiments, -that where there is some confusion, each of the factors present has a -better chance to determine the judgment. The values for both time-error -and sound rise higher for the majority in C than in A or B. - - -VI. THE INFLUENCE OF FACTORS IN THE SAME SENSE-FIELD UPON THE JUDGMENT -OF ABSOLUTE NUMBER - -The nature of the enquiry that we have been pursuing through so many -pages is such that it may be raised exactly as well in the case of -absolute as in that of relative number. There appears to be no reason -why in this new field the results should not be exactly comparable -with those in the old, to be taken indeed as a kind of test for the -interpretation to be put upon the old. Without a single exception, -unless it were imposed by a technical difficulty, all the earlier -factors could be studied with the new purpose. Our practical interest -to go to such lengths would depend pretty largely upon the results of -first attempts. If wholly confirmatory, these would probably suffice. - -The experimental conditions were of the simplest. The 3-8 in. steel -balls of Section III were again pressed into service as objects for the -number-judgment. They were thrown loosely into a fixed black frame, 20 -cm. square. To avoid suggestive noises, its undersurface was made of -a thick piece of felt covered with black cloth; and the whole rested -of course on a black-topped table. The exposures were 2 sec. long, -timed by watch-ticks. Between experiments the observer held a cardboard -screen between him and the objects. When conditions were ready for a -new judgment, closing his eyes he lowered the screen, opening his eyes -again at the word of command and shutting them at the close of the -experiment. - -Of course the observers felt that their judgments were for the most -part extremely vague. With small numbers they had a greater feeling of -confidence. Yet altogether it was surprising with what readiness an -absolute number-judgment would spring up in the presence of any given -collection whatever within the limits set by the experimental series. -Sometimes the observers thought that they made rough calculations on -the basis of the filling in a unit of area. So far as this held it -would tend to cut off the more astonishing departures from correctness, -and it would probably advantage the smaller groups more than the large. -Still it was entirely too rough a method to prevent the influence of -the factors introduced, as the results will show. There was no time -for systematic counting, which, in any case, the observers knew to be -forbidden. - -The figures in which the observers reported their judgments of -absolute number have a value that is chiefly qualitative. The marked -inconsistencies and disagreements are our guarantee for this statement. -With all the observers there was but the loosest association between -group-appearance and number-name. The innumerable variations in -internal space-relations were of course responsible. For one observer a -particular name probably had a quantitative significance far in excess -of its value for another observer in this respect. To one man 100 might -have meant about the same as 60, for example, to his neighbor. On the -whole they were parsimonious; but Baldwin decidedly not. - -A more or less constant influence was exerted on any given judgment by -the comparison of the presented group with the traces of the preceding -still in mind. The observers felt, however, that the judgment was -largely independent of such comparison, and its fluctuations give some -credence to this feeling. - -The numbers chosen ranged by fives, from 25 to 100. In four cases a -number was immediately repeated that rough suggestions as to the -definiteness of the judgment and its dependence upon the actual number -might be gained. These were indeed but rough suggestions, since, -with certain exceptions to be noticed later, the arrangement was -disturbed between times; but they made possible a closer watch upon the -flickering of the judgment than could be kept by a mere repetition of -the series. In the latter case it might be unstable and yet relatively -firm in the other. A standard series is here recorded. Its order was -determined by drawing the numbers out of a heap, but the repetitions -were inserted arbitrarily. - - 1. 95 - 2. 25 - 3. 35 - 4. 65 - 5. No change - 6. 30 - 7. 90 - 8. 85 - 9. 45 - 10. 100 - 11. 50 - 12. No change - 13. 60 - 14. 40 - 15. No change - 16. 70 - 17. 80 - 18. 55 - 19. 75 - 20. No change - -1. _Absolute Number under Standard Conditions._ - -An indispensable preliminary for the present study is the establishment -of a standard. Unless we know something in advance about the -characteristics of the judgment of absolute number in relatively simple -conditions, we shall be unable to tell what influence, if any, to -attribute to the modifying factor in later experiments. Having then -decided as to the general conditions under which we will study the -problem we must make these the standard conditions of our work; and -having discovered the nature of the judgments given under them, measure -up to these results in all that is to follow. These standard conditions -have already been set forth in the introduction to this section. The -results are recorded in Tables XIX and XX. - - -TABLE XIX - - KEY: St = Standard - Sc = Scattered - Co = Compact - - _Subject_ = _Baldwin_ _Subject_ = _Miller_ - - _Trials with_ - _each number_ 6 3 3 4 2 3 - - _Original_ - _Numbers_ _St_ _Sc_ _Co_ _St_ _Sc_ _Co_ - - 25 1 0 -6 -10 -6 -4 - 30 3 5 -5 -12 -7 -6 - 35 10 7 -3 -14 -4 -7 - 40 10 13 -8 -15 -8 -11 - 40 10 8 -8 -14 -10 -12 - 45 10 18 -3 -21 -13 -10 - 50 17 23 2 -19 -15 -17 - 50 15 22 2 -17 -15 -14 - 55 27 40 0 -18 -3 -12 - 60 19 33 5 -20 -23 -17 - 65 27 53 2 -18 -3 -7 - 65 24 57 5 -13 -13 2 - 70 38 77 0 -19 8 -8 - 75 31 73 0 -24 10 -20 - 75 28 78 -5 -24 8 -8 - 80 36 83 -5 -14 5 -18 - 85 54 85 5 -19 -8 0 - 90 54 90 5 -13 8 -3 - 95 48 73 5 -30 20 -15 - 100 61 87 7 -13 10 -7 - - The figures recorded are the average of the algebraic sums of other - figures that represent the difference between the actual and the - estimated number. Fractions are replaced by an added unit, if the - value is 1/2 or over. - - Baldwin never underestimated the scattered group, and only once the - standard; but 31 times the compact. Miller only once overestimated - the standard group, and but 6 times the compact; but 13 times the - scattered. - -Turning to these tables we notice at once, as characteristic of all -the observers, the following facts: (1) Wide variation from objective -correctness. (2) A far wider discrepancy with the larger numbers than -with the smaller. Miller does not wholly agree here. His judgments by -series show inconstancy, tending at first to follow the rule, but in -the last two series to a maximum error near the middle. Certain remarks -of this observer suggest that possibly in the latter case reflection -as to the convenience of certain actual numbers for manipulation may -have had influence. The three earlier series of Hutchison conform to -the rule. The remainder, on the contrary, show no definite progression -in tendency. It should be noted here that both Miller and Hutchison -were more inclined than the other two observers to rough calculation. -The effect of its adoption or of increased practice in it is shown by -the disappearance of the characteristics of the earlier series. We -have thus in these two cases a doubleness of standard that we must not -fail to consider in our later comparisons. (3) There is a pronounced -instability of judgment, as shown by the fluctuations for the same -number in different series, and especially in successive judgments, -of the same in any given series. (4) There is a general tendency to -judge in multiples of five. That there should be any splitting of -fives, particularly in the large numbers, might be regarded as mere -caprice. Not so did it seem to the observers. They were conscious of -an apparent absurdity in it where judgments were necessarily so vague; -but they insisted that this stood for a kind of qualitative shading -in the perception which threw out the choice of the round numbers just -above and below. (5) The number is on the whole underestimated, three -observers agreeing in this respect; but the fourth shows a very large -and consistent tendency in the opposite direction. - -In spite of the manifold special inconstancies and disagreements, these -general tendencies are decidedly well-featured in the results. We may -say that we have found a kind of standard illusion that will serve us -for a guide through our later studies. - -2. _The Influence of Distribution._ - - -TABLE XX - - _Subject_ = _Hutchison_ _Subject_ = _Olmsted_ - _Trials_ - _with_ - _each_ - _number_ 3 2 4 - _First_ _Second_ - _Original_ _Standard_ _Standard_ _Mixed_ _Small_ - _numbers_ _Series_ _Series_ _Sizes_ _Sizes_ - 25 -5 -2 -3 -1 - 30 -4 0 -5 0 - 35 -6 -5 10 1 - 40 -11 -5 -5 -13 - 40 -12 -9 -13 -11 - 45 -7 -4 -15 -10 - 50 -14 -10 -20 -12 - 50 -13 -8 -15 -15 - 55 -10 -7 -20 -11 - 60 -19 -18 -25 -20 - 65 -15 -7 -20 -5 - 65 -15 -10 -10 -18 - 70 -14 -3 -15 -20 - 75 -21 -17 -28 -23 - 75 -25 -20 -20 -24 - 80 -24 -17 -30 -19 - 85 -17 -13 -35 -13 - 90 -13 -7 -25 -20 - 95 -25 -13 -40 -23 - 100 -22 -13 -35 -24 - - - 6 2 3 - _Mixed _Small_ - _Standard_ _Sizes_ _Sizes_ - -8 -8 -12 - -11 -14 -16 - -8 -5 -14 - -18 -17 -20 - -13 -18 -22 - -18 -20 -18 - -19 -18 -23 - -22 -15 -27 - -24 -28 -23 - -22 -23 -27 - -28 -28 -33 - -22 -28 -23 - -27 -30 -28 - -32 -23 -27 - -33 -25 -32 - -27 -23 -33 - -27 -38 -38 - -33 -40 -37 - -39 -55 -40 - -36 -15 -37 - - For the meaning of these figures see under Table XIX. Hutchison - overestimated the standard group only 5 times, never the mixed-size - group, and 9 times the small-size group. Olmsted never overestimates - at any time. - -The first of the modifying factors to be considered has to do with the -arrangement of the objects. Hitherto they had been thrown loosely into -the frame. Now in successive studies they were, first, well scattered -over the surface and, second, brought together into several compact -nuclei. The last arrangement was adopted in preference to that of a -single mass as being less open to comparison with preceding judgments -and to judgment on the basis of form and size of group. - -The results are shown in Table XIX: (1) The effect of scattering the -objects is very markedly to raise the apparent number. Baldwin's -preceding overestimations soar still higher; while Miller's former -tendency to underestimation is checked to such an extent that 13 -overestimations appear. (2) The effect of compacting the objects -is just as markedly in the opposite direction. Baldwin gives 31 -underestimations, and Miller reverts in a measure to his former type. -(3) When similar arrangements were up for study in relative number we -found two classes of observers, one favoring the compact, the other the -scattered. The present results of Baldwin and Miller put them into the -latter class. - -3. _The Influence of Complexity of Group-Content._ - -This new factor of complexity in the content of the group was realized -experimentally by making up the collection out of steel balls of two -sizes, 1/8 in. and 3/8 in. The former looked almost infinitesimal -beside the latter. The same objective numbers were still maintained and -divided between the two sizes except where in so doing a five must be -broken. In such a case the extra five went to the larger balls. - -The results are found in Table XX. Olmsted shows no definite influence -of the new factor. Hutchison, however, shows a very evident decrease -in his estimations, when comparison is made with his second standard -series. With the earlier series the new results rather closely -correspond. That the latter are not simply a vacillating reversion -seems fairly clear from this observer's account of his method. The -small balls, he says, did not distinctly come in visually. To his -judgment of the large he added an amount based on a very insecure -estimate of the small. The number of the latter seemed from time to -time pretty constant. - -This situation corresponds very fully to that in the investigation -of the same factor by use of a group of mixed colors, where relative -number was in question. (Section II.) The tendency there discovered was -to neglect the other colors in favor of one which thus surpassed the -others in vividness. There as here the mixed group seemed smaller. - -4. _The Influence of Size of Objects._ - -A study of this factor was made possible by substituting for the -usual objects steel balls of a smaller size, 1-4 in. The results are -contained in Table XX. They are not so striking as those obtained in -our study of distribution. Still the influence of this new factor is -evident, in the reduction of the apparent number. Olmsted shows this -more generally for the smaller numbers. We find it in Hutchison when we -compare the new results with the second standard series. This tendency -to underestimation increases in the two final series of the present -set. At the beginning of these two he remarked that he thought he had -been overestimating the group. This tendency of smaller size to reduce -apparent number was found true for the majority of observers in our -earlier study of relative number. - -5. _The Influence of the Length of Exposure._ - -I found that in relative number the shorter the look the more marked -was the influence of certain factors. Reports of the observers making -this seem highly probable happened in this way: When working with the -One-Group Apparatus in relative number the shutter of the camera would -occasionally stick, leaving a group exposed beyond its usual time. -The effect of this upon some but not all the observers was to cause a -noticeable shrinking in numerousness. Of those questioned, the only one -failing to notice this effect is included among the observers in this -new study. - -To test this possibility resort was had to the One-Group Apparatus as -affording a more satisfactory means for getting different lengths of -exposure of small absolute magnitude. Cards were prepared containing -a single group of larger area (67 × 82 mm.) than had been used for -relative number. The objects were the usual white circles. Each corner -was marked as usual; and, by reason of the number involved, the outline -of the area was more regular than had been true in the earlier work. -The number of circles on each card varied by steps of two from 16 to -30, giving eight cards in all. The series was arranged irregularly as -before, and two of the cards repeated immediately upon their first -presentation, making ten experiments in one set. The order of the -series follows: - - 1. 24 - 2. 22 - 3. 26 - 4. No change - 5. 18 - 6. 28 - 7. 16 - 8. 20 - 9. 30 - 10. No change - -Two time-magnitudes were used for comparison,--1-25 sec. and 1 sec. The -latter was managed with bulb exposure. All the experiments with the -shorter time were made before those with the longer had been begun. The -results are given in Table XXI. So far as the material is comparable, -we may include in our comparison the standard experiments of Tables XIX -and XX with 2 sec. exposure. - - -TABLE XXI - - KEY: A = 1/25 sec. - B = 1 sec. - - _Baldwin_ _Miller_ _Hutchison_ _Olmsted_ - _Actual_ - _Numbers_ A B A B A B A B - _Number of_ - _trials with_ - _each number_ 5 6 5 5 5 4 4 4 - 16 6 9 -2 -3 11 -1 2 -5 - 18 8 10 -4 -1 12 -1 -3 -5 - 20 34 19 1 3 19 1 1 1 - 22 37 17 6 6 14 6 4 -2 - 24 49 26 12 5 14 10 5 0 - 26 70 33 15 8 12 9 5 4 - 26 79 37 21 9 14 4 9 4 - 28 93 42 29 11 18 7 8 7 - 30 106 52 38 12 18 5 19 10 - 30 103 50 45 11 20 4 19 4 - - For the meaning of these figures see note under Table XIX. - -The outcome may be thus summarized: (1) The apparent number is -inversely proportional to the length of exposure. The tables show a -perfectly clear progression from 2 sec. to 1-25 sec. All those that -formerly underestimated are brought into the opposite class. (2) The -results of the earlier experiments are confirmed on the whole with -respect to the occurrence of greater errors with the larger numbers. -(3) Baldwin's overestimation reaches astonishing heights. (4) These new -facts for absolute number are quite in accord with Table XII, where, -under the conditions of interpretation laid down, the tendencies were -wholly in favor of the shorter look. - -The issue of these tentative experiments in absolute number confirms -the teaching of our studies in the related field. Absolute number, like -relative, has been found largely subject to a modifying influence of -certain factors. In the new field, too, distribution has asserted its -supremacy among these, and similar effects of shortening exposure have -been observed. There has been variation among the observers and some -shifting of tendency, both of which point as before to the coöperation -of some subjective factor in our results. Indeed the whole situation, -as opened by these preliminary studies, indicates a theoretical -interpretation that for both fields is at bottom one. So to an attempt -to reach such an interpretation the next section will be devoted. - - -VII. THEORETICAL DISCUSSION - -1. _The Fact of Modification._ - -That such an influence upon the judgment of number should have been -exercised by the factors considered seems in many cases to receive -an adequate account on the principle of association. Our practical -experience in the simultaneous variability of number and certain other -characteristics of a group of objects has been such as to lead us -into illusions when the two no longer vary together. In such a case, -when we have no time to count, we are actually led to _see_ a group -as smaller or larger in accordance with the variations perceived in -the associated factor. This interpretation is supported by the fact -that on the whole the space-factors were more markedly influential in -creating illusions than were any others. For those cases, however, -in which the modification was effected by a factor unconnected with -number, as color, or the simultaneous stimulation of other senses by -irrelevant objects, it appears that the mere occurrence of greater -total stimulation during the appearance of one group is sufficient to -create illusion, either through failure of the observer to discriminate -between the relevant and the irrelevant, or because he is led through -fear of disturbance to overemphasize the other group. - -2. _The Direction of Modification._ - -The foregoing account of the general fact throws no light upon the -_direction_ of the influence. Why should a given factor make a group -seem more numerous and not less? Why should it affect one man in one -way and his neighbor in another? Why should it vary with the same man -at different times? Appearances no less contradictory than these are -what we must face in carrying a theoretical account to completion. -The following propositions with appended commentary are offered in -satisfaction of these requirements. - -_a._ Differences in vividness among the factors determine differences -in number. - -Our study of the factor of distribution in Table XVII, where it was -possible in a measure to control the vividness, furnishes evidence for -this proposition. Introspective reports in other cases confirm this -view by showing that the direction of the attention, the popular way of -stating our proposition, was the determining feature. This will receive -further support in our discussion of the following proposition. - -_b._ If the vivid factor or complex be positive, _i. e._, associated -in experience with the numerous, or if it be neutral, its group will -seem the more numerous. If negative, _i. e._, associated in experience -with the few, its group will seem the less numerous. - -The experiments upon the effect of distribution support this -proposition, especially as set out in Table XVII. When the vacancies in -a given group were made vivid, the other group seemed more numerous; -when its filling surpassed in vividness, the judgment was given for -it. We have other confirmation in the fact that lengthening the time -of exposure reduced the absolute number. Take also this note of one -observer on the material in Table II, C: - -"I noticed that I had set the open spaces in the outlined group over -against the lack of them in the homogeneous, without paying much -attention to the nearness together of the spots in the lines of the -outlined. Then for a time my attitude was quite vacillating. I found my -attention drawn to the nearness together of the spots in part of the -outlined group so strongly that if I did not turn it voluntarily to the -fact that the other was filled without any large open spaces, I was led -to call almost any outlined group the larger. Toward the end of the -experiment I got back into my original attitude, in which the outlined -group seemed to have its spots hardly more thickly arranged in any part -than the homogeneous, and to have also the bare spots and so to be the -fewer." - -That the vividness of a neutral factor or complex increases the -apparent number was suggested by comments of the observers. One -observer reported of the material in Table IV: "The greater brightness -of red gave it more importance. The natural thing seemed to be to give -the red the judgment. The gray fought more for recognition." And again: -"The red seems a vitalized space and the dots more omnipresent, also -the red lasts longer in memory and is there more vivid, so that often -in cases of doubt, where the decisive comparison was made in memory, -the red may have been given the vote. Often there was an immediate -unanalyzed feeling that if the groups had been both of the same color, -the judgment would have been for the gray." In both cases his results -showed this tendency. Another observer, whose results agree with the -former, found that his eye was directed involuntarily toward the red. - -This fact was put to a special test. In the material of Table II, -B, a card, in which the pattern group had an appearance strikingly -different from the normal, was introduced, the two groups being -objectively equal. With three observers the effect was overestimation -of this group, and with a fourth, the suppression to equality of a -previous overestimation of the opposite group. This fact, together -with the observers' comments, seems to justify the conclusion that the -vividness of a neutral factor or complex was the determining condition -of the judgment. That the observers did not all show positive results -in this experiment may be set down to the difficulty in controlling -the subjective conditions of vividness. Of course the space-relations -within the new pattern were different from those in the old. The only -justification for taking no account of these is the character of the -introspections themselves. - -It should be said of the red group that beside its vividness it had -characters mentioned by other observers that might independently have -made its number seem greater. It was called "dazzling," "blurred," and -its area seemed increased. In this respect the effect of the color -should be discussed as a special case of distribution or object-size. - -The vividness tested in this special way seems due to contrast, in -the one case with surroundings, in the other case with the expected. -Such a judgment is very far removed from the normal bases, rather more -so, it would seem, than even those where a group had sound or touch -accompaniment; for in the latter case there could be no question about -the "moreness"; the only doubt could be about its legitimacy. Of the -precise extent to which this cause of vividness has operated throughout -our studies, even where spatial differences have been concerned, we -cannot be sure. The patterns of the materials in B and C of Table II -seem to offer that possibility. That it should enter anywhere opens, -indeed, the entire field. - -_c._ The observers fall into the following classes on the basis of the -character of the association: - -(1) Relatively fixed association, - - (_a_) involving correct adjustment to objects (vividness of relevant - factors); - - (_b_) involving incorrect adjustment to objects (vividness of - irrelevant factors). - -(2) Relatively unstable association. - -It will be remembered that in the case of nearly every factor studied -under Relative Number, we found three classes of observers,--those -favoring one group, those favoring the other group, and a so-called -"no-tendency" class. The bases of classification were, first, the -relative constancy in the character of the error, and, secondly, its -direction. In this third or "no-tendency" class were really lumped off -two kinds of observers, not separated at the time because our special -interest did not demand it. Along with those that gave large errors -in both directions was a much smaller class that gave a relatively -large proportion of correct judgments; but could never claim any one -observer all the time. In the new classification of Proposition _c_ -this mixed composition is recognized by dividing it between (1) (_a_) -and (2). The prime condition of correct judgment is asserted to be one -in principle with that of the illusion,--namely, vividness, but in this -case vividness of relevant factors. Our original "tendency" classes -both fall under (1) (_b_). - -Proposition _c_ is merely an attempt to apply the principles of -association and vividness to an organization of our results. The types -in question have no hard-and-fast connection with any particular -observer; they rather represent a kind of ideal fixation of opposite -tendencies playing through all. - -3. _The Time-Error._ - -So far the time-error has been left without interpretation. The chief -facts to be considered were: (_a_) Divergence of error and general -trend in favor of last. (_b_) Individual inconsistencies. (_c_) -Occasional absence. - -We are in a position now to invoke at once the principle of vividness -to account for the existence of the error and the vividness of recency -to account for the predominant tendency to favor the last of the two -groups exposed. In this respect this error may be classed with the -effect of red. That is to say, a factor or complex, directly through -its vividness and not indirectly through its association with the -numerous or the few, draws the judgment after it. Here the content of -the group is the effective thing, not the character of the vacancies. - -But the observers do not all agree in the direction of the time-error -nor are they always consistent. Here we shall get help from a -proposition offered in the discussion of the distribution-error in -which it is asserted that the group seems the more numerous in which -the vacancies are less developed under observation. We have already -noted a decided tendency to depend in judging upon the vacancies. Let -us suppose that the two groups presented in succession differ with -respect to the success of the observer in developing these vacancies. -If this be true, that difference may well depend upon the occurrence -of maximal attention during the exposure of but one of the groups. The -tendency of the majority to overestimate the second group suggests -that the attention is likely to be at a maximum when the experiment -begins. If, on the other hand, it ripen later, or if the observer seek -to rescue the second group from relative unclearness, then we should -have the first group overestimated. The time-error would disappear for -those that could attend alike to both. Clearly enough this account is -decidedly hypothetical. - -4. _The Space-Error._ - -Our attempt to reduce this error to one of time in some form was -proven a failure. The facts brought out indicate that at the bottom -is some subjective factor thus far not isolated. This factor is not -a preference going directly with right- or left-handedness because -on the surface at least it runs in the observers independent of such -asymmetry. A single bit of available introspection would seem, however, -to point to some relation of that sort; for one observer, who favored -the left, felt that a group on that side gained an importance that was -somehow due to the greater absolute value of a weight in the left than -in the right hand. Even if this be decisive for him it will still be -inapplicable to errors in the opposite direction unless we assume that -with variations in bodily energy the emphasis is cast now in one, now -in the other, direction, after the analogy of those two types of man -to be found in our social experience, for whom respectively mountains -are molehills and molehills mountains. Such successive differences in -type in a single individual would then find an intelligible account in -the shifting tides of that bodily energy. It is to be noted that the -observer just quoted once, but only once, made a decisive reversal of -his error from left to right. - -It may occur to some one that the use of two observers sitting side by -side may have given them a preference for one position of the groups. -In the first place care was taken that both groups should be as readily -seen from one point of view as from the other. Secondly and chiefly, -there is no regularity among the observers in this respect. - -It is not unlikely that a chance aspect of a particular group develops -an emphasis that gives the mechanism of subjective adjustment a -particular bent that for a time is relatively independent of the -objective situation. Still the fact that there are some cases of -persistence in type is rather damaging to this assumption and speaks -rather for the earlier one. That one, if true, seems indeed adequate to -account for the situation. As an hypothesis it accords with analogous -physiological facts; but its weakness lies in imposing the burden of a -strong tendency upon asymmetrical differences that may be in comparison -relatively slight. Finally, these studies furnish no proof that the -bodily condition of an observer of a particular type corresponds to the -demands of the hypothesis. - -_Summary:_ 1. The estimation of relative number in the visual field is -modified by group-area, internal distribution, order, and complexity in -group-composition; by the size, form, color, brightness, and complexity -of the individual members; and by the character of the environment. -It is further modified by factors contributed by the objects through -other senses, as in active pressure, special differences in pressure -character, active weight, and that complex of muscular and spatial -factors arising when a group is observed under the condition of -eye-muscle strain. The judgment is also influenced by factors outside -the group in the field of touch, but not in that of kinæsthetic -impressions. - -2. On the whole the most influential factors were those lying in the -space-characters of the groups; while those of least moment were -contributed by other objects in other fields of sensation. Hearing was -very nearly ineffectual. - -3. In very many cases the observers fell into three groups, one of -no-tendency, and a second and third showing opposite tendencies with -respect to the factor investigated. - -4. With a majority of observers there is a tendency to underestimation -in the judgment of absolute number, though with a single observer the -tendency is directly the reverse. Scattering the objects increases, -and compacting diminishes, the apparent number. The smaller the size -of the objects the fewer, under conditions, do they appear; while -heterogeneity in group-composition lessens the number for one observer -and has no apparent effect upon the other. - -5. The apparent absolute number of objects is inversely proportional to -the length of exposure of a group; and in relative number the influence -of a factor was on the whole greater for shorter exposures. - -6. The marked tendency to a space-error was found to be independent of -differences between the groups in the length of look, and of the order -in which they were viewed. - -7. The distribution-error is grounded in a fundamental tendency to base -the judgment of relative number upon the character of the vacancies -in a group; though a secondary tendency to depend upon the filling -was shown to exist. The subjective factor of vividness, attaching -now to one and now to the other of the foregoing factors, determines -which shall be operative, though it usually is joined to the first. -The ground for the primary tendency may very well be the necessities -imposed upon discrimination by the material. The contrast effect -between the large black background and the brighter objects tends to -unify the latter, which, to be discriminated as a number, must be split -up by an emphasis of the vacancies. - -8. The time-error is possibly due to differences in power to dismember -the groups exposed in succession in one experiment, while its -variations in direction seem adequately accounted for by differences in -the time at which attention becomes maximal during the progress of a -single test. - -9. The ground for these facts of modification is found in the strength -of the association between these several factors and the elements that -signify number. - -10. The basis for the different tendencies found among the observers -is the differing vividness among several factors. If the vivid factor -is associated with the idea of numerousness, or is in this respect -neutral, its group will seem more numerous. If it has been associated -with the idea of fewness, its group will seem less numerous. The -difference between the two classes of "tendency" and "no-tendency" lies -in the fact that for the latter either only correct clues are vivid, -or else there is so frequent an alternation in vividness of opposing -incorrect clues that through any given series no tendency appears, -while for the "tendency" class misleading clues are without shifting in -the ascendant. - -At the time when these experiments were completed, no work precisely -upon this problem had been published. Since then, however, Dr. J. F. -Messenger has issued a monograph entitled The Perception of Number -(Psych. Rev., Mono. Supp., vol. 5, no. 5), of which certain parts fall -within the scope of the present studies. He was concerned with the -estimation of absolute number and was primarily interested to discover -the nature of the number-judgment. The reader of both articles will -find agreement between the results and interpretations here recorded -and such part of Messenger's work as has been a common object of -study,--viz., the factors of distribution and size. - -FOOTNOTES: - -[Footnote 123: 44 experiments.] - -[Footnote 124: 88 experiments.] - - - - -TIME-ESTIMATION IN ITS RELATIONS TO SEX, AGE, AND PHYSIOLOGICAL RHYTHMS - -BY ROBERT M. YERKES AND F. M. URBAN - - -The desirability of a statistical study of time-estimation was -suggested to us by a note concerning "sex-differences in the sense -of time" which was published in Science recently by Prof. Robert -MacDougall.[125] By comparing the time-estimates of groups of men and -women consisting of fifteen individuals each, MacDougall discovered -that for intervals of from one quarter of a minute to a minute and -a half, the women exhibited a far stronger tendency to overestimate -than did the men, and were at the same time markedly less accurate. -The nature and extent of the overestimation discovered by MacDougall -are indicated by the results presented in the accompanying table from -Science. The numerals, 1, 2, 3, and 4 refer to different fillings of -the intervals (listening to reading, marking letters, etc.), the signs -+ and - to over- and under-estimation respectively. - - Period, One Minute. - - Sex 1 2 3 4 - Men +29" + 1.3" +22" - 3.5" - Women +66 +22.0 +80 +24.0 - -These apparent sex-differences in time-estimation demand further -attention, first, because the number of individuals studied by -MacDougall, as he recognized, is too small to establish the fact of the -existence of such differences, and, second, because if the differences -really do exist they should be studied in their relations to age and -the fundamental physiological rhythms.[126] - -It seemed probable that further investigation of this subject might -reveal some important facts concerning the development of the ability -to estimate time in the individual, the significance of various -conditions for time-estimation, the psychology of sex, and the -relations of rhythms to personal affinities, antipathies, and motor -capacities. - -In this report the results of a statistical study of the -sex-differences in time-estimation are discussed, and in later papers -we shall present the results of investigations of the relations of -time-estimation to age and to individual and sex rhythms, and attempt -to work out a convenient and serviceable rhythm-formula. The need of -such a formula for expressing individual rhythms is obvious, as is also -the need of comparative studies of individual and sex rhythms. - - -TIME ESTIMATION - - Name Place - Age Date - - ORDER OF TESTS TIME IN SECONDS - - _Time of_ _Male_ _Female_ - _Intervals._ (_17 years_) (_17 years_) - No. 1 No. 9 - - 1. Idleness _108̋_ _70̋_ _120̋_ - 2. Reading _36_ _30_ _118_ - 3. Writing _72_ _36_ _60_ - 4. Estimating _18_ _15_ _30_ - 5. Reading _108_ _90_ _68_ - 6. Idleness _36_ _35_ _60_ - 7. Writing _18_ _10_ _10_ - 8. Estimating _108_ _100_ _125_ - 9. Reading _72_ _100_ _66_ - 10. Idleness _72_ _75_ _58_ - 11. Writing _36_ _25_ _22_ - 12. Estimating _72_ _60_ _60_ - 13. Reading _18_ _14_ _15_ - 14. Writing _108_ _130_ _59_ - 15. Estimating _36_ _30_ _41_ - 16. Idleness _18_ _10_ _18_ - - How did you estimate the interval when you were asked to estimate it - as accurately as you could? - - n o f e y m i q r s a d r g d e s t k n w e r a x u p x z y o n d f n - o d c a e h p m a l g s r w y t b c k p s o n q a r v q c o m p v r i - c p k t o s n q z r l x m i h u v o q g P p f u t o i c n g s c a r n - o t c d a a o b i a r s a d e r w o a i e r g l c r t h f s o r a e n - s i o c r b x g r z b h o w l t s - - Number of letters counted 85 88 - Pulse-rate 72 81 - -The experimental data now to be considered were obtained as follows. -Record-sheets of the form reproduced above were printed, with blanks -for age and name of subject, place, date, for sixteen judgments of -time-intervals (numerals 1 to 16), for a statement of the subject's -method of estimating time, for the number of letters counted in thirty -seconds, and for the pulse-rate. Four intervals were used, 18, 36, 72, -and 108 seconds, and for each of these intervals judgments were taken -under the four conditions designated on the record-sheet as idleness, -reading, writing, and estimating. In the experiments the intervals -were not given in order of regular increase or decrease of the length -of interval, nor were all the judgments for any one interval taken -together, but instead, for the purpose of avoiding the influence of -expectation of a particular interval or filling, they were arranged -irregularly in the order of column two of the record-sheet. This -column, as also columns three and four, which are specimen series of -judgments for a male and a female respectively, of course were not -printed on the record-sheets which were supplied to the subjects. - -The experimental procedure was as follows: - -(1) Each subject was given a record-sheet. - -(2) The experimenter was provided with a record-sheet on which the time -of the intervals numbered from 1 to 16 was given. Care was taken that -the subjects should not know the length of the intervals before the -experiments. - -(3) The beginning of each interval was indicated to the subjects by the -word "start" uttered distinctly by the experimenter; the end, by the -word "stop." - -(4) Before beginning the sixteen tests the experimenter gave a -thirty-second interval as a standard of judgment. The experiment then -proceeded with only sufficient pause between judgments to allow of the -recording of estimates by the subjects. - -(5) During the filling called "idleness" the subject did not pay -special attention to the estimation of the time, but instead permitted -his attention to wander. - -(6) During "reading" the experimenter read aloud to the subjects. - -(7) During "writing" the subjects wrote from the dictation of the -experimenter. - -(8) During "estimating" the subjects judged the interval as accurately -as they could, by whatever method they chose except the use of a -time-piece. - -(9) Each subject recorded his judgment of the length of an interval in -seconds at the appropriate place on the record-sheet as soon as the -interval was ended. - -(10) The question following judgment number 16 on the sheet was -answered as soon as the sixteen judgments had been recorded. - -(11) The number of letters counted in thirty seconds was determined -by the use of the lines of letters at the bottom of the sheet. The -subjects began at the left of each line and counted singly as many -letters as they could between the "start" and "stop" signals of the -experimenter. They then marked the last letter counted and immediately -recorded, in the place provided on the record-sheet, the number of -letters counted. - -(12) The pulse was counted by the experimenter immediately after the -experiment when possible and the rate recorded on the sheet. - -(13) The experimenter avoided delays, interruptions, or other -irregularities in the course of the series of experiments. - -The materials for our discussion of the sex-differences in -time-estimation consist of the judgments of 251 males and 274 -females. The majority of the males were students in Harvard College, -the majority of the females, in Radcliffe and Smith Colleges. The -remainder of the records were obtained in Ohio State University, Pomona -College, and West Chester State Normal School. The authors gratefully -acknowledge their indebtedness for assistance in the obtaining of -records to Professors A. H. Pierce, T. H. Haines, W. H. Scott, D. R. -Major, A. M. Smith, H. A. Miller, and B. T. Baldwin. The males ranged -in age from 17 to 23 years, the females from 17 to 20. The total number -of judgments, the distribution of which among the various ages is shown -in Table 1, is 4014 for the males, 4375 for the females. - -Despite the fact that our experiments are open to the criticisms of all -work done under variable conditions and by different experimenters, it -cannot be doubted that the results indicate certain sex-differences in -time-estimation which suggest additional problems. For the present we -refrain from interpretations for the most part and state merely the -statistical results of the investigation. - -Previous studies of the "time-sense" and the conditions which influence -time-estimation suggested to us the desirability of examining our -data with reference to (1) sex-differences in estimates of intervals, -(2) age-differences, (3) the influence of different fillings, and (4) -differences dependent upon the length of the interval. The results have -been studied, therefore, with reference to the significance of sex, -age, filling, and length of interval, but as no marked age-differences -appeared, the detailed tables which were constructed to exhibit the -results for the subjects of each year of age have not been printed. - -In all the tables the results for males and females are presented -separately. The judgments for the sixteen intervals are arranged with -reference to the length of the interval, not in the order in which they -were taken; all the 18̋ intervals, for example, are grouped (Table 2). -The letters I, E, R, W, refer to the fillings of the intervals. - - -TABLE 1 - -NUMBER OF SUBJECTS, AGE, SEX, AND NUMBER OF JUDGMENTS - - _Males_ - - _Age_ _No. of subjects_ _No. of judgments_ - - 17 yrs. 16 256 - 18 27 432 - 19 40 639 - 20 67 1071 - 21 50 800 - 22 35 560 - 23 16 256 - - Totals 251 4014 - - _Interval_ _No. of judgments_ - - 18" 1004 - 36" 1003 - 72" 1003 - 108" 1004 - - Total 4014 - - _Females_ - - _Age_ _No. of subjects_ _No. of judgments_ - - 17 yrs. 73 1160 - 18 57 911 - 19 64 1024 - 20 80 1280 - - Totals 274 4375 - - _Interval_ _No. of judgments_ - - 18" 1092 - 36" 1094 - 72" 1096 - 108" 1093 - - Total 4375 - -A general survey of the individual records, all of which for any one -year and sex were tabulated, for convenience of examination, on a -single large sheet of coördinate paper, showed that the judgments vary -within a wide range and are very inexact. Table 2 exhibits the number -of correct judgments for each sex, interval, and filling. Of the -4014 male judgments only 96 (2.39%) were correct; of the 4375 female -judgments only 46 (1.05%) were correct. The number of correct judgments -decreases as the length of the interval increases. For the 18-second -intervals there were 7.37% for the males, 2.48% for the females, -while for the 108-second intervals there were only 0.10% and 0.37% -respectively. - - -TABLE 2 - -FREQUENCY OF OCCURRENCE OF CORRECT JUDGMENTS - - _Males_ - - 18̋ 36̋ 72̋ 108̋ - I E R W I E R W I E R W I E R W Σ % - 29 26 11 8 5 6 3 0 3 3 0 1 0 1 0 0 96 2.39 - Totals 74 = 7.37% 14 = 1.40% 7 = 0.70% 1 =0.10% 96 2.39 - - _Females_ - - 7 15 1 4 2 4 1 0 2 5 0 1 2 1 0 1 46 1.05 - Totals 27 = 2.48% 7 = 0.62% 8 = 0.73% 4 = 0.37% 46 1.05 - - _List of abbreviations which occur in the tables._ - - Σ always designates the sum of the results of the column which it - heads. - - I, E, R, W refer respectively to the intervals of idleness, - estimating, reading, and writing. - - The % sign refers to the value of the result in question in terms of - the total number of judgments. - - C refers to the results of the letter-counting test. - -The male judgments for the 108-second intervals range from 11 to 300 -seconds. If random guesses be made within these limits the probability -of the occurrence of right guesses (108") would be 1 in 290; therefore -among 1004 guesses (the number of male judgments for 108-second -intervals) 3.5 would be right. In the experiment only one judgment of -the 1004 was correct. For the other intervals, with the exception of -18 seconds, the number of correct judgments is only slightly greater -than random guessing would have given. Both males and females, however, -show considerably more correct judgments for 18-second intervals than -the number of probable right guesses. Within the range of the male -judgments and for their number 16.9 right guesses might be expected, -for the females 10.9. In contrast with these numbers the experiments -furnished 74 and 27 correct judgments respectively. - -It is noteworthy that for those intervals which are most frequently -correctly judged, not only is the number of correct judgments greater -for the males than for the females (the ratio of the percentages is -about 3 to 1), but the ratio of the number of correct judgments to the -probable number of right guesses is also greater for the males. - -The female judgments vary within a wider range and are less often -correct than the male. For the latter the total number of correct -judgments is more than twice that for the former. - -Another interesting fact concerning the judgments of the time-intervals -is that certain numerals occur in the last place of a judgment more -frequently than we should expect if their occurrence depended on random -guessing. Tables 3 and 4 exhibit the results of an analysis of the data -made for the purpose of studying this fact. In Table 3 the frequency -of occurrence of the digits 0, 1, 2, 3, etc., in the last place of the -male judgments is given for each filling under the four intervals. For -example, the digit 0 occurred in the last place of the male judgments -for the interval reading 36 seconds 98 times, as we learn by referring -to the first line and third row of the second column of Table 3. - -Examination of Tables 3 and 4 shows at once the marked preference of -the subjects for 0 and 5. The percentage of male judgments which end in -0 is 41.50; of female 58.51. Similarly the percentages of occurrence of -the digit 5 for the males is 24.41, and for the females 23.11. Only two -of the other digits (2 and 8) occur with a frequency of over 5%. - -Among the 4014 male judgments 0 occurred as a final digit 1666 times, -5, 980 times. Among the 4375 female judgments 0 occurred 2560 times, 5, -1011 times. In the male judgments 0 occurred about four times as often -as it would in random guessing; in the female, almost six times as -often. - -Comparison of Tables 3 and 4 indicates that the occurrence of 0 is -17.10% greater for the females, while that of 5 is 1.30% greater for -the males. The sum of the percentages of occurrence of 0 and 5 for the -males is 65.91, therefore the probability that a male judgment ends in -one of these digits is almost twice that in favor of any other digit. -For the females the sum of the same percentages is 81.62, and the -probability of occurrence of 0 or 5 is therefore more than four times -that of the other eight digits. - -Tables 3 and 4 show that even numbers occur more frequently than uneven -as final digits. Of the total number of judgments 2461 (3063)[127] end -with even digits and 1553 (1312) with uneven. - - -TABLE 3. FREQUENCY OF OCCURRENCE OF THE NUMERALS (0 TO 9) AS FINAL -DIGIT OF THE JUDGMENTS COMBINED RESULTS FOR ALL MALES - - 18̋ 36̋ 72̋ - I E R W I E R W I E R W - - 0 70 57 72 76 131 77 98 90 124 74 120 125 - 1 5 11 9 9 10 9 8 7 1 18 5 2 - 2 20 15 21 18 5 19 16 15 11 20 5 14 - 3 9 17 14 10 8 11 10 8 6 14 12 4 - 4 8 12 14 9 3 14 12 3 4 14 8 7 - 5 67 58 56 63 62 54 60 85 72 59 62 73 - 6 13 17 12 13 9 14 11 6 10 9 7 7 - 7 15 22 14 12 6 15 11 10 5 14 13 4 - 8 36 30 29 31 15 19 16 20 11 17 11 11 - 9 8 12 10 10 2 18 9 7 7 12 8 3 - - 108̋ - I E R W Σ % C - - 0 151 121 127 153 1666 41.504 21.92 - 1 4 11 10 2 121 3.014 7.57 - 2 9 12 9 8 217 5.406 13.15 - 3 3 12 14 3 155 3.861 7.17 - 4 6 18 9 3 144 3.587 7.57 - 5 54 45 52 58 980 24.414 10.36 - 6 8 7 6 4 153 3.812 8.76 - 7 4 7 10 8 170 4.235 7.17 - 8 8 13 5 9 281 7.004 8.76 - 9 4 5 9 3 127 3.164 7.57 - - -TABLE 4. FREQUENCY OF OCCURRENCE OF THE NUMERALS (0 TO 9) AS FINAL -DIGIT OF THE JUDGMENTS COMBINED RESULTS FOR ALL FEMALES - - 18̋ 36̋ 72̋ - I E R W I E R W I E R W - - 0 120 117 106 126 169 124 182 151 176 145 175 194 - 1 4 8 3 2 6 7 1 3 2 3 2 1 - 2 17 18 12 13 9 22 7 11 7 11 3 4 - 3 4 9 9 11 5 9 3 7 6 15 10 4 - 4 2 11 13 10 1 6 4 2 9 14 3 1 - 5 89 63 91 85 62 61 60 79 56 55 65 63 - 6 9 12 11 6 5 13 7 5 4 6 3 3 - 7 5 5 7 7 4 9 5 3 2 7 3 3 - 8 16 22 17 12 10 13 5 10 10 9 6 1 - 9 5 9 5 1 3 9 0 2 2 9 4 0 - - 108̋ - I E R W Σ % C - - 0 226 197 196 186 2560 58.515 26.14 - 1 1 5 2 0 50 1.143 9.09 - 2 4 11 6 3 158 3.611 5.30 - 3 3 7 4 7 113 2.583 5.68 - 4 2 4 2 2 86 1.966 11.36 - 5 32 44 49 57 1011 23.109 14.39 - 6 0 9 3 1 97 2.217 6.44 - 7 0 5 2 5 72 1.646 6.44 - 8 5 11 8 7 162 3.703 10.61 - 9 1 10 2 4 66 1.508 4.55 - -In order that the probability of the occurrence of even and uneven -numbers may be calculated, those judgments which end in 0 and 5 must be -subtracted from the total number of judgments, for the occurrence of -these two digits is apparently due to a constant influence. The problem -may be formulated thus. First, what is the probability that a judgment -is determined by the constant influence in favor of 0 and 5? Second, -what is the probability of even and uneven numbers, when the influence -in favor of 0 and 5 is eliminated? The calculated probability of 0 -or 5 is 0.65919 (0.81622) and therefore the probability that a given -judgment is not determined by this influence is 0.34081 (0.18378). The -probable limits of these numbers are 0.00505 (0.00395). - -After the subtraction of those judgments which end in 0 or 5, there -remain 1368 (804), of which 795 (503) are even and 573 (301) uneven. -The probability of an even number is 0.58115 (0.62562) and the inverse -probability of an uneven number is 0.41885 (0.37438). The probable -limits of these numbers are 0.00900 (0.01027). There are therefore even -chances that the percentage of occurrence of even numbers is between -the limits 57.215 and 59.015 (61.535 and 63.589), or outside these -limits.[128] - -Statistical studies have already proved that in random guessing even -numbers occur somewhat more frequently than uneven. It is therefore -worthy of notice that in these results the frequencies of even numbers -are not uniformly greater than that of uneven; for with the exception -of the digit 6 in the female judgments, the digits next to 0 and 5, _i. -e._, 9 and 1, 4 and 6, occur with least frequency. - -In the case of the number of letters counted in a half minute, also, it -appears (see last column (C) of Tables 3 and 4) that 0 and 5 occur more -frequently in the last place than chance would lead us to expect. In -contrast with the results for the time-judgments, in the same tables, -the percentages of occurrence of the various digits in counting present -less marked differences. For the males 3 and 7 occur least frequently, -for the females 2 and 9. - -To sum up the results of our examination of the materials with -reference to the occurrence of digits in the final place of the -judgments, the order of decreasing frequency of the various digits is -0, 5, 8, and 2. Of the others 3 and 7 occur more frequently than 4 and -6, with one exception. The statement that even numbers in general occur -more frequently than odd must be modified by the statement that in -these results the digits next to 0 and 5, namely, 9, 1, 4, and 6 occur -with least frequency. These statements hold for both males and females, -but for the latter the frequency of occurrence of 0 is far greater than -for the males. - -These results clearly indicate that the judgments are not random -guesses. In seeking further for some explanation of the surprising -frequency of occurrence of judgments which end in 0 or 5, we discovered -that certain numbers occur very frequently, namely, the multiples of -15, 30, and 60. In order to exhibit this tendency quantitatively Tables -5 and 6 have been constructed. - -In these tables will be found tabulated the number of times 15 and -multiples of it which are not also multiples of 30 or 60 occur for any -given interval and filling. Likewise are tabulated the frequencies of -occurrence of 30 and multiples of it which are not multiples of 60, and -finally, of 60 and its multiples. The numbers as they occurred in the -three categories run as follows: - - 15 30 60 - 45 90 120 - 75 150 180 - 105 210 240 - 135 270 300 - 165 330 360 - 195 390 420 - -Fifteen and its multiples, as given above, are arranged in one division -of the tables, thirty and sixty each in its own separate division. -The line at the bottom of the tables marked Σ gives the frequency of -occurrence of these three groups of numbers for all the subjects and -for each interval and filling. - -As is shown by the percentage of frequency columns of the tables, in no -instance do the multiples of 15 constitute less than 19.52% of the male -judgments and 23.81% of the female judgments. The lowest frequency for -any of the four intervals is 20.32% of the total number of judgments. -The maximum frequency for the males (43.03%) and for the females -(56.57%) is for the interval idleness 108 seconds. That the male and -female maxima should fall on the same interval is interesting. - - -TABLE 5 - -FREQUENCY OF OCCURRENCE OF 15, 30, 60, AND THEIR MULTIPLES - -_Males_ - - 15 30 60 Σ % _Average_ - - {I 48 5 0 53 21.12 - {E 42 9 0 51 20.32 - 18̋ {R 43 8 0 51 20.32 20.32 - {W 45 4 0 49 19.52 - - {I 29 60 7 96 38.25 - {E 17 41 5 63 25.20 - 36̋ {R 22 41 6 69 27.41 29.57 - {W 36 28 5 69 27.41 - - {I 29 18 46 93 37.05 - {E 25 7 34 66 26.29 - 72̋ {R 28 26 33 87 34.66 34.70 - {W 28 42 32 102 40.80 - - {I 25 31 52 108 43.03 - {E 16 23 20 59 23.51 - 108̋ {R 22 30 39 91 36.25 36.16 - {W 25 37 43 105 41.83 - - Σ 480 410 322 1212 - % 11.96 10.21 8.02 30.12 - - -TABLE 6 - -FREQUENCY OF OCCURRENCE OF 15, 30, 60, AND THEIR MULTIPLES - -_Females_ - - 15 30 60 Σ % _Average_ - - {I 58 30 0 88 32.47 - {E 30 35 8 73 26.64 - 18̋ {R 56 26 3 85 31.02 28.48 - {W 41 24 0 65 23.81 - - {I 31 55 39 125 45.62 - {E 21 36 17 74 27.21 - 36̋ {R 31 63 33 127 46.35 38.86 - {W 41 45 13 99 36.26 - - {I 29 28 60 117 42.70 - {E 17 18 52 87 31.75 - 72̋ {R 26 37 52 115 41.97 41.60 - {W 30 51 56 137 50.00 - - {I 12 45 98 155 56.57 - {E 21 27 58 106 38.83 - 108̋ {R 23 36 84 143 52.19 47.83 - {W 24 31 64 119 43.75 - - Σ 491 587 637 1715 - % 11.22 13.42 14.56 39.22 - -If no influence worked in favor of the multiples of 15 in these -experiments only one judgment in thirty would be 15 (3.33%) and only -one in sixty, 30 or 60 (1.67%). For the probability of the occurrence -of 15, 30, and 60 is 1/60 + 1/60 + 1/30 = 1/15, as is obvious from the -fact that among sixty consecutive numbers (1 to 60) there are four -which are multiples of 15. According to probability we should expect -multiples of 15, 30, and 60 to occur 268 times among the 4014 male -judgments and 292 times among the 4375 female judgments. As a matter of -fact there are 1212 such judgments for the males, 1715 for the females. -The probability that a male judgment is a multiple of 15, 30, or 60 is -0.3012 (probable error 0.0049); for a female judgment the probability -is 0.39199 (probable error 0.0050). - -These statistics indicate that the subjects are constantly and strongly -influenced in favor of judgments which are simple fractions of a -minute. Closer inspection of the tables gives some suggestion of the -nature of this influence. - -Comparison of the four intervals (Tables 5 and 6) with respect to the -occurrence of simple fractions of a minute shows that the frequency of -such numbers increases rapidly as the length of the interval increases. -The various percentages of frequency for males and females and for the -four intervals are again presented here for convenience of comparison. - - 18̋ 36̋ 72̋ 108̋ - - _Males_ 20.32% 29.57% 34.70% 36.16% - _Females_ 28.48 38.86 41.60 47.83 - -As is obvious from these figures both frequency and rate of increase -are far higher for the females than for the males. - -Examination of the percentages (totals) at the bottom of Tables 5 and -6 reveals another remarkable sex-difference; for the frequency of -occurrence of 15 and its multiples regularly decreases for males from -the 15 to the 60 class, whereas for females it regularly increases. - -Undoubtedly the time-judgments of these experiments were strongly -influenced by thought of the conventional time-unit, the minute, for -in all quantitative work there are errors in favor of the standard of -measurement and simple fractions thereof. In the present instance this -tendency to favor the unit was strengthened, perhaps, by the giving of -a half-minute interval as a standard for comparison at the beginning of -the tests. - -Two explanations of the sex-differences above mentioned are suggested -by our study of the data. One is the fact that the females are less -exact than the males; the other that they generally overestimate the -intervals, whereas the males often underestimate them. One's estimate -of an interval is determined partly by confidence of accuracy. The -longer an interval the less we feel able to estimate it accurately, -and, as a consequence, the more frequently it is judged as the same as -the time-unit or a simple fraction of that unit. The females are less -exact in their estimates than the males, and less exact for long than -for short intervals, and as an accompaniment of their inexactitude we -find the frequent occurrence of multiples of 15, 30, and 60. - -But confidence of ability to estimate accurately must be considered in -connection with the fact which suggests our second explanation, namely, -that the female estimates are higher than the male. Tables 7 and 8 -show that the females almost invariably overestimate the intervals -rather largely, while the males sometimes underestimate considerably. -The range of the male judgments is from 1 to 300, of the female from -1 to 400. Obviously the chance of occurrence of 15, 30, 60, and their -multiples varies with the range. The greater the range the greater -the probable frequency of 30 and 60 in comparison with 15. In random -guessing the probabilities of the occurrence of 15, 30, and 60 for long -and short intervals is the same, but our results show that this is not -true in the case of these time-estimation judgments. It seems possible, -therefore, that the sex-differences referred to are due to the fact -that the intervals seem longer to the females, and that, therefore, -a feeling of greater inexactitude than would be felt for shorter -intervals leads to the choice of simple fractions of a minute more -frequently than in the male judgments and more frequently for the long -than for the short intervals. - -It is of interest in this connection to note that the length of a -second is usually underestimated by females, overestimated by males. -The average number of seconds counted in half a minute by twenty men -and twenty women was as follows: - - _Men._ M. 30.4, M.V. 8.7, R.V. 34.94. - _Women._ M. 38.9, M.V. 10.6, R.V. 36.70 - -These figures would seem to indicate that the overestimation of the -intervals of these experiments by the females is due to the use of a -time-unit which is shorter than that of the males (although presumably -of the same length). - -We cannot with certainty say whether inaccuracy of judgment stands in -the relation of condition or consequence of the occurrence of simple -fractions of a minute, but it would appear that the female tendency to -overestimate is responsible for the sex-differences already noted. For -whatever be the facts concerning longer intervals the second as judged -by the female is considerably shorter than that of the male. - -Since a complicated periodicity of frequency in the distribution of -the judgments is exhibited in the results of Tables 3-6 it is obvious -that the distribution-curve will have a tertiary mode for each number -ending in 0 or 5, a secondary mode for 15, 30, 60, and their multiples, -and a primary mode which may or may not coincide with one of the -secondary or tertiary modes. Extreme irregularity is characteristic of -the distribution-curve. Different groups of judgments, as, for example, -those for the two sexes, those for the different intervals, etc., -give somewhat different forms of distribution, for the frequency of -occurrence of 0 and 5, as well as of the multiples of 15, is variable. - -These facts are important in connection with the selection of an -interval for the construction of the distribution-curves, in that they -indicate how large the interval or class of the distribution-curves and -tables should be. - -It is clear from the results of Tables 3 and 4 that the smallest -interval which can be of value is 10 seconds, for a smaller interval -would necessarily exhibit irregularities due to the greater frequency -of 0 than of 5. The question is whether the interval can be so -enlarged, without the loss of all details of the nature of the -distribution, that every class will represent the influence of the -same conditions. For this purpose only three intervals are possible: -10, 30, and 60 seconds. Of these 30 and 60 are undesirable because the -interval 60 gives classes which are so large that all details of the -distribution are lost, while 30 exhibits only a few details without -doing away with the periodicity due to the preference for multiples of -60. - -The further question remains, with which digit should the interval end, -in order that uniformity of conditions for the various classes may be -gained? Theoretically there are ten possibilities, but of these all -except two, 0 and 5, are excluded by reason of the unequal frequency -of the various digits already discussed. In favor of 0 is the fact -that all the classes thus formed are of equal size, _i. e._ 1-10, -11-20, etc., whereas for 5 the first class would differ from the others -in being only half as large, 1-5. This, however, is only a slight -disadvantage, for there are very few judgments which fall in this -class. On the other hand, since 0 is the final digit of most frequent -occurrence, classes ending in 5 have the advantage of placing the value -of greatest weight in the middle. On the whole it seemed desirable to -arrange the judgments in 10 second classes, beginning with the class -1-10. But for purposes of comparison the male judgments have been -distributed in classes of 10 seconds, which end in 5, 1-5, 6-15, 16-25, -etc.[129] - - -TABLE 7 - -DISTRIBUTION OF MALE JUDGMENTS IN 10" CLASSES - - _Classes_ 18̋ 36̋ 72̋ 108̋ C - I E R W I E R W I E R W I E R W - - 1 - 10" 31 16 69 136 3 1 4 18 1 1 1 4 0 0 0 0 0 - 11 - 20 174 179 142 108 40 34 45 97 4 2 5 23 1 2 1 7 0 - 21 - 30 34 47 35 7 99 106 98 82 15 9 26 65 5 0 6 23 0 - 31 - 40 7 7 3 56 69 69 28 25 16 34 47 10 2 6 31 1 - 41 - 50 4 2 2 37 23 22 18 41 43 54 33 20 9 19 28 0 - 51 - 60 1 9 13 9 6 64 68 53 35 31 17 27 32 7 - 61 - 70 5 3 0 0 37 42 28 18 27 26 22 19 8 - 71 - 80 0 1 3 1 23 34 16 9 33 34 35 20 34 - 81 - 90 1 1 1 15 15 15 8 30 40 43 29 58 - 91 -100 0 9 8 7 1 23 35 25 17 65 - 101 -110 0 2 6 3 3 10 26 17 6 33 - 111 -120 0 8 5 5 2 29 16 17 16 29 - 121 -130 0 3 1 2 0 5 15 7 8 10 - 131 -140 0 1 1 1 1 6 9 5 0 4 - 141 -150 1 0 1 0 5 5 8 4 1 - 151 -160 1 0 2 3 2 2 1 - 161 -170 1 0 2 1 0 2 - 171 -180 1 1 5 4 5 2 - 181 -190 0 1 2 1 - 191 -200 3 2 2 2 - 201 -210 0 1 1 0 - 211 -220 0 0 0 0 - 221 -230 1 1 0 0 - 231 -240 2 0 1 0 - 241 -250 1 1 1 - 251 -260 0 0 - 261 -270 0 0 - 271 -280 0 0 - 281 -290 0 0 - 291 -300 1 1 - - Totals - 251 251 251 251 251 250 251 251 251 251 251 250 251 251 251 251 251 - -As a result of these groupings of the male judgments it appeared -that the former method gives a far more regular distribution than -the latter. In view of this result and the above considerations, -Tables 7 and 8 were constructed by the use of 10-second classes, -beginning with 1-10. In these tables (column C) the distribution of the -letter-counting results has been included for convenience of comparison -of the two kinds of judgments as to form of distribution. - -As instances of the general form of distribution of the judgments the -curves have been plotted for letter-counting, Fig. 1 _A_. (Males ----, -Females, ... ,) for idleness 36 seconds, Fig. 1 _B_, and for idleness -108 seconds, Fig. 2. The distribution of the letter-counting judgments -in classes of 10 is very regular in comparison with that of the several -time-estimation judgments. For idleness 36 seconds there are several -fairly distinct modes, and for idleness 108 seconds the modes are still -more numerous and more marked. - -[Illustration: Fig. 1_A_. Distribution of the Results of the -Letter-Counting Test. Males ----, Females ....] - -[Illustration: Fig. 1_B_. Distribution of the Time-Estimation Judgments -for the Interval Idleness 36̋. Males ----, Females ....] - -[Illustration: Fig. 2. Distribution of the Time-Estimation Judgments -for the Interval Idleness 108̋. Males ----, Females ....] - - -TABLE 8 - -DISTRIBUTION OF FEMALE JUDGMENTS IN 10̋ CLASSES - - 18̋ 36̋ 72̋ 108̋ - _Classes_ - I E R W I E R W I E R W I E R W C - - 1 - 10 72 20 88 133 5 6 5 33 2 0 1 6 0 1 0 2 0 - 11 - 20 114 119 109 94 33 29 40 83 7 5 15 25 2 2 7 10 0 - 21 - 30 50 87 54 29 70 57 73 74 16 13 25 52 4 1 3 27 0 - 31 - 40 17 17 10 6 51 87 53 30 24 21 24 30 2 1 11 14 0 - 41 - 50 10 14 7 4 40 35 39 20 35 18 37 32 14 6 17 34 2 - 51 - 60 2 10 3 1 43 30 40 14 48 44 47 53 30 18 35 36 5 - 61 - 70 1 3 0 3 11 7 5 2 28 50 20 21 8 11 23 22 18 - 71 - 80 3 2 1 2 5 8 2 10 29 32 23 14 14 21 20 14 57 - 81 - 90 0 0 1 1 9 3 6 2 27 29 28 14 41 35 35 19 67 - 91 -100 0 2 0 1 4 2 1 16 11 15 5 25 35 17 11 50 - 101 -110 0 0 0 1 1 1 4 7 6 0 9 24 7 6 25 - 111 -120 0 0 2 3 6 3 17 20 10 8 52 38 33 16 19 - 121 -130 2 0 0 1 0 3 4 3 3 4 15 6 8 13 - 131 -140 0 1 1 0 1 2 1 4 6 9 6 6 5 - 141 -150 0 1 0 1 5 4 4 2 15 13 16 7 1 - 151 -160 1 1 0 0 0 4 2 0 3 7 2 2 2 - 161 -170 0 0 0 1 1 0 0 3 2 0 1 - 171 -180 1 0 0 7 4 7 4 22 14 16 22 - 181 -190 0 0 1 0 1 0 2 2 3 0 - 191 -200 0 0 1 1 3 0 3 5 6 6 - 201 -210 1 0 0 0 0 0 1 0 1 0 - 211 -220 0 0 1 0 0 1 2 0 0 - 221 -230 0 0 1 0 0 1 0 6 2 - 231 -240 0 2 1 0 1 3 3 2 4 - 241 -250 0 1 0 0 3 0 0 - 251 -260 0 0 2 0 0 1 - 261 -270 0 0 1 0 0 0 - 271 -280 0 0 0 0 0 0 - 281 -290 0 0 0 0 0 0 - 291 -300 1 2 4 2 1 1 - 301 -310 0 0 0 0 - 311 -320 1 0 0 0 - 321 -330 0 0 0 0 - 331 -340 1 0 0 1 - 341 -350 0 0 - 351 -360 1 1 - 361 -370 0 - 371 -380 0 - 381 -390 0 - 391 -400 2 - - Totals - 271 274 274 273 274 273 274 273 274 274 274 274 274 273 274 272 264 - -Tables 7 and 8 show that the range of the judgments increases with the -length of the interval judged, and that the modal class is always much -nearer the lower than the upper limit. Asymmetry is characteristic of -the distribution of organic data, and in certain instances, as for -example writing 18 seconds, males, the choice of a 10-second class -interval results in extreme asymmetry, and one is reminded of the -tables which Fechner gave as examples of his logarithmic method in -statistics.[130] - -It is not to be expected that a method of grouping should be found -which will give regularity of distribution throughout, but it is -important that there should be regularity about the mode. In the table -of distribution for the males (Table 7) all the intervals from idleness -18 seconds to reading 72 seconds are regular.[131] The remaining -intervals, with the exception of estimating 108 seconds, are irregular. - -Trial proves that for these intervals increase of the size of the -class to 30 seconds is sufficient to give regular distributions, as is -obvious from Table 9. Grouping by 30-second classes gives regularity -for most of the female judgments, but for idleness 108 seconds and -writing 108 seconds there are still slight irregularities, as Table 10 -indicates. - -Tables 7 and 8 show that the distribution is far less regular for -the females than for the males. The fact that it becomes regular -when the class interval is increased to 30 seconds suggests that the -irregularities of distribution which appear in the tables are due to -those influences which favor simple fractions of a minute and not to -the small number of judgments. - -Having now noted certain important characteristics of the -time-estimation judgments and the nature of their distribution, we -may examine the arithmetical means and other statistical quantities -which have been determined for our data. Those quantities which have -been determined for the several ages, intervals, and fillings as well -as for the sexes are: (1) The Mean (_M._ in tables), (2) the average -variability (_M. V._), (3) the positive variability (+ _V._), (4) -the number of judgments with positive variation (No. + _V._), (5) -the negative variability (- _V._), (6) the number of judgments with -negative variation (No. - _V._), (7) the relative variability (_R. V._) -= _M_ + _V_/_M_ × 100. - -Since the sums of the positive and the negative variations are equal, -it is possible to make certain of the accuracy of the means and -average variabilities by comparison of the + _V._ and - _V._ As this -was done in all cases we feel confident of the reliability of the -statistical quantities presented in the tables. - -In Table 11 have been arranged the various quantities as determined for -the males and females for each interval. The values given in this table -are averages of the determinations made for the several ages separately. - - -TABLE 9 - -DISTRIBUTION OF CERTAIN MALE JUDGMENTS IN 30̋ CLASSES - - _Classes._ W. 72̋ I. 108̋ R. 108̋ W. 108̋ - - 1- 30 92 6 7 30 - 31- 60 115 61 52 91 - 61- 90 35 90 100 68 - 91-120 6 62 59 39 - 121-150 1 16 20 12 - 151-180 1 9 7 6 - 181-210 3 5 3 - 211-240 3 1 0 - 241-270 1 1 - 271-300 1 - - 250 251 251 251 - - -TABLE 10 - -DISTRIBUTION OF FEMALE JUDGMENTS IN 30̋ CLASSES - - 18̋ 36̋ 72̋ 108̋ - _Classes_ I E R W I E R W I E R W I E R W - 1- 30 236 226 251 256 108 92 118 190 25 18 41 83 6 4 10 39 - 31- 60 29 41 20 11 134 152 132 64 107 83 108 115 46 25 63 84 - 61- 90 4 5 2 6 25 18 13 14 84 111 71 49 63 67 78 55 - 91-120 0 2 0 3 8 9 5 37 38 31 13 86 97 57 33 - 121-150 2 0 2 2 1 9 10 8 9 25 37 28 21 - 151-180 1 2 0 0 8 9 9 4 28 23 18 25 - 181-210 1 0 2 1 4 0 6 7 10 6 - 211-240 0 2 3 0 1 5 5 8 6 - 241-270 0 1 0 3 3 0 1 - 271-300 1 2 4 2 1 1 - 301-330 1 0 0 0 - 331-360 1 1 1 1 - 361-390 0 - 391-420 2 - - Totals 271 274 274 273 274 273 274 273 274 274 274 274 274 273 274 272 - - -TABLE 11 - -MEANS, ETC., FOR EACH SEX, INTERVAL AND FILLING - - KEY: Ma. = _Males_ - Fe. = _Females_ - - M. M. V. +V. No. +V. - Ma. Fe. Ma. Fe. Ma. Fe. Ma. Fe. - - {I 17.7 20.74 5.4 10.35 5.8 15.48 15.9 22.75 - 18" {E 19.5 25.55 4.9 9.84 6.0 13.98 16.9 23.75 - {R 15.5 18.46 4.9 9.14 6.3 13.03 14.6 24.25 - {W 11.5 15.58 3.7 8.56 4.6 11.83 14.3 25.75 - - {I 33.3 42.81 9.1 16.55 12.6 20.63 14.2 28.00 - 36" {E 33.1 41.54 8.4 15.23 10.7 23.34 14.2 23.00 - {R 32.1 41.71 8.4 16.42 9.7 20.78 16.3 27.75 - {W 24.7 30.10 9.0 14.71 10.9 22.08 14.4 23.50 - - {I 63.3 73.00 17.2 27.20 20.9 33.72 15.7 27.75 - 72" {E 63.1 77.13 16.0 26.56 18.8 37.27 16.9 24.75 - {R 57.9 70.78 17.3 30.30 20.9 39.28 15.2 26.75 - {W 51.2 54.93 19.8 24.21 23.7 29.47 15.0 38.25 - - {I 92.7 113.37 29.8 40.13 35.3 44.08 15.2 32.00 - 108"{E 99.8 114.88 26.3 36.38 29.3 49.26 14.9 26.25 - {R 90.1 100.47 28.3 40.18 33.9 47.90 15.3 34.25 - {W 75.5 87.45 32.4 45.33 40.8 61.12 14.9 34.25 - - -V. No. -V. R. V. - Ma. Fe. Ma. Fe. Ma. Fe. - - {I 5.7 7.78 20.0 45.00 30 49.83 - 18" {E 4.4 7.69 19.0 44.75 25 39.10 - {R 4.4 7.07 21.2 44.25 31 49.26 - {W 3.2 7.14 21.6 42.50 33 54.55 - - {I 8.1 14.01 21.7 40.50 27 38.32 - 36" {E 7.2 11.57 21.7 45.25 25 36.66 - {R 7.5 13.84 19.6 40.75 26 38.84 - {W 8.7 11.24 21.5 44.75 36 48.64 - - {I 15.5 22.83 20.2 40.75 27 36.87 - 72" {E 14.7 20.98 19.0 43.75 27 34.43 - {R 15.7 24.91 20.7 41.75 30 42.77 - {W 16.0 21.26 20.9 36.75 37 43.84 - - {I 25.9 37.87 20.7 36.50 32 35.34 - 108"{E 24.4 29.51 19.9 42.00 26 31.57 - {R 24.8 34.60 20.6 39.75 31 39.95 - {W 27.5 35.86 19.9 42.75 42 51.67 - -The following facts are revealed by comparison of the results for the -two sexes.[132] Without exception the means for the females are larger -than those for the males. All but one of the sixteen intervals (E 18̋) -are underestimated by the males, whereas all but six are overestimated -by the females. The amount of over- and under-estimation is given in -Table 12. In every instance the females overestimate in comparison with -the males. The mean variability is very much greater for the females, -as is also the relative variability. If variability be taken as a -measure of reliability of judgment the males are far superior to the -females. - -As is obvious from Table 12, both under- and over-estimation increase -with increase in the length of the interval. For 18̋ intervals they are -least, for 108" intervals greatest. - -The influence of the fillings is marked. The writing intervals without -exception are judged as shortest; reading gives the next shortest -intervals, while sometimes idleness, sometimes estimating, comes third. -In order of increasing length of average estimates of the intervals the -fillings stand: writing, reading, idleness, estimating. As a rule the -averages for the idleness and the estimating intervals are nearly the -same, but it is worthy of note that the females always overestimate -to a greater extent when estimating than when idle. This is another -indication of the discrepancy between the female time-unit and the -objective unit. - -About ninety per cent of the subjects estimated by some counting -method. The methods most frequently used were "counting seconds," -counting "1 and 2 and 3 and 4, etc.," counting the swings of a -pendulum, tapping, and counting imaginary watch-ticks. - -The above statements might suggest that the overestimation -characteristic of the female judgments is due to a more rapid counting -rhythm. This, however, is not true, for the letter-counting tests -indicate a slightly more rapid rhythm for the males, 93.42 as opposed -to 91.89. - - -TABLE 12 - -AMOUNT OF OVER- AND UNDER-ESTIMATION OF INTERVALS - - _Males._ _Females._ _Males._ - {I - 0.3 + 2.74 Age 17 18 19 20 21 22 23 - {E + 1.5 + 7.55 Over- or under- -8.55 - 18̋ {R - 2.5 + 0.46 estimation -3.60 -7.50 -13.02 -13.49 -8.71 -13.20 - {W - 6.5 - 2.42 No. + 6 2 2 0 2 2 2 - - {I - 2.7 + 6.81 No. - 10 14 14 16 14 14 14 - {E - 2.9 + 5.54 - 36̋ {R - 3.9 + 5.71 - {W -11.3 - 5.90 _Females._ - - {I - 8.7 + 1.00 - {E - 8.9 + 5.13 Age 17 18 19 20 - 72̋ {R -18.1 - 1.22 Over- or under- - {W -24.8 -17.07 estimation + 2.38 - 4.16 - 2.57 + 2.55 - - {I -15.3 + 5.37 No. + 11 8 8 12 - {E - 8.2 + 6.88 No. - 5 8 8 4 - 108̋{R -17.9 - 7.53 + = overestimation - {W -32.5 -20.55 - = underestimation - -In Table 13 are the means, variabilities, errors, etc., for the -letter-counting tests. In this table we have presented the values of -the various statistical quantities for the several ages of both males -and females, for there are certain interesting differences which -should be noted. Similar age-tables have been prepared for all of the -other results, but in no case have noteworthy differences appeared. -From Table 13 it will be observed that the males on the average -count more letters in thirty seconds than do the females, and at the -same time make more errors. The mean and relative variabilities for -the sex-groups are almost the same. Curiously enough the number of -letters counted as well as the accuracy of counting decrease for the -females with age (17 to 20 years being the age-limits of the group -under consideration). The males within the same age-limits increase in -rapidity of counting, but decrease in accuracy. In the examination of -Table 13 it is to be remembered that the 17 and 23 year groups of males -contain only 16 individuals each, and therefore cannot be compared to -advantage with the other groups. Both mean and relative variabilities -decrease from 17 to 20 years for the females, whereas for the males -there is no constancy in the direction of the change. - - -TABLE 13 - -MEANS, ETC., FOR LETTER-COUNTING - - _Males._ - - _Age_ 17 18 19 20 21 22 23 _Average_ - M. 92.81 92.48 94.00 95.87 92.66 97.06 89.06 93.42 - M. V. 10.29 15.31 16.50 12.90 7.81 13.04 19.20 13.58 - +V. 11.76 22.96 16.50 11.70 8.13 16.30 21.94 15.61 - No. +V. 7 9 20 37 24 14 7 16.96 - -V. 9.15 11.48 16.50 14.40 7.51 10.87 17.09 12.57 - No. -V. 9 18 20 30 26 21 9 19.00 - R. V. 11.1 16.5 17.6 13.5 8.4 13.4 21.6 14.59 - Errors 0.88 1.04 2.10 3.03 1.70 0.89 2.75 1.77 - - _Females._ - - _Age_ 17 18 19 20 _Average_ - M. 97.74 95.51 89.21 85.09 91.89 - M. V. 17.06 14.56 11.30 11.28 13.55 - +V 18.67 18.49 12.06 14.56 15.94 - No. +V. 32 21 30 31 28.50 - -V. 15.71 12.14 11.66 9.21 12.18 - No. -V. 38 32 31 49 37.50 - R. V. 17.5 15.2 12.7 13.3 14.70 - Errors 1.35 1.46 1.49 1.65 1.47 - - -SUMMARY - -(1) The length of a second is slightly overestimated by men, greatly -underestimated by women. - -(2) Intervals of from 18 to 108 seconds are usually slightly -underestimated by men (ages 17 to 23 years), and greatly overestimated -by women (ages 17 to 20 years). - -(3) The time-estimates of women are far more variable than those of -men, and on the whole markedly less accurate. - -(4) Both men and women favor estimates which end in 0 or 5, as well as -simple fractions of a minute, but the tendency is stronger in women -than in men. Over one third of the estimates reported in this paper -were 15 seconds or simple multiples thereof. - -(5) In letter-counting the groups of subjects studied (251 men and -274 women) exhibited differences just the opposite of those in -time-estimation, for the men counted more rapidly and less accurately -than did the women. - -(6) Of the four fillings for the intervals used in the experiments, -"writing" gave the smallest estimates of the intervals, listening to -"reading" next, while "idleness" and "estimating" were conditions in -which the intervals seemed much longer to both men and women. - -(7) This preliminary study of sex-differences in time-estimation, by -which it has been learned that women overestimate and are notably -inaccurate in comparison with men, is to be followed and supplemented -by the results of an investigation now in progress concerning -the relations of sex-differences in time-estimation to age and -physiological rhythms. - -FOOTNOTES: - -[Footnote 125: Science, N.S., vol. 19, pp. 708-709, 1904.] - -[Footnote 126: E. Mach (Analyse der Empfindungen, 1900, p. 161) thinks -that his physiological time-unit has become larger with age. And he has -also noted that the time-sense differs in animals of the same species -which differ in size.] - -[Footnote 127: The unbracketed number is that for the males, the -bracketed that for the females.] - -[Footnote 128: It may be asked in connection with the above statistics, -what is the probability that even and uneven digits have unequal -chances of occurrence? The analytic treatment of this problem -indicates that the probability is ½[1+φ(4.25)] = 0.99999999891 for -the males and ½[1+φ(15.93)] for the females. It is therefore almost -certain, theoretically, that even and uneven numbers have not the same -frequency. See Czuber, Wahrscheinlichkeitsrechnung, 1903, pp. 158-161. -The constants of this problem are in Czuber's denotation, _a_ = 52.308 -and _b_ = 222.] - -[Footnote 129: The judgments might be grouped in 10 second classes -beginning with the lowest number in the experiments, but this would -have the disadvantage of rendering the distribution tables or curves -for different groups of judgments incomparable.] - -[Footnote 130: G. Th. Fechner, Collectivmaasslehre, pp. 338-346, 1897. -Compare the asymmetry of writing 18 seconds for both males and females -with Fechner's Table III, p. 442.] - -[Footnote 131: The distribution may be called regular if the -classes increase to a maximum, the mode, and then decrease without -interruption. (See Fechner, Collectivmaasslehre, pp. 121-122.)] - -[Footnote 132: The values of the means and variabilities was determined -to the second decimal for the females, but only to the first for the -males; consequently the relative variability could be computed exactly -to the first decimal for the females and to the unit only for the -males.] - - - - -ASSOCIATIONS UNDER THE INFLUENCE OF DIFFERENT IDEAS - -BY BIRD T. BALDWIN - - -The purpose of the following investigation was to study the influence -of two or more starting-points on the train of associated ideas. It -was begun in October, 1902, and concluded in January, 1905. Nineteen -graduate students acted as subjects, and the experiments were conducted -with each individually for one hour per week, except in a few instances -where two subjects were present together. Occasionally the experimenter -acted as subject in order to get a clearer insight into introspective -data. There are recorded here thirteen groups of one hundred and eight -sections, including eight hundred and fifty-five separate experiments, -with a sum total of eleven thousand, one hundred and thirty-five named -associations. - -So far the field has not been studied experimentally, although -Cordes,[133] while attempting to observe the effect of an unconscious -intermediating factor in 'mediate association,' noticed that the -accompanying factor (particularly with a tone) sometimes combined with -the starting-point in determining the associated series. The fact is -simply mentioned, and Scripture's[134] conclusions from the same are -inadequate when he states, "In general we may say that two simultaneous -ideas have an effect that depends on their relative masses; if one of -the ideas is over-poweringly weighty the next idea will be chiefly -influenced by it, but if the two are nearly balanced the next idea will -be the result of the two." Miss Calkins[135] makes a near approach to -the problem in a study of "Mental Combination," where auditory words -were given as nearly simultaneously as possible and the subject was -required to remain for four seconds in silence and then to write the -train of imagery which passed in six following seconds; the words as -auditory starting-points were finally excluded from the experiments -"because the first word pronounced tends often to establish itself so -firmly that its association-images are proof against the intrusion of -the second word, which has therefore no chance to be grasped with the -first." These results differ from the ones here recorded which were -obtained independently and under different conditions. In her valuable -monograph on Association[136] there is in one instance a suggestion of -the problem, but no results are given. - -The two or more starting-points were nonsense syllables, concrete or -abstract words, pronounced by the investigator or shown on cards, or -finally, pictures. The associations continued for a period of fifty -seconds unless otherwise indicated. The same letters denote the same -subjects throughout all the experiments, K. and R. being women. In the -examples given, Roman numbers have been used, in place of the letters, -as it was found impossible to get representative series which were -entirely devoid of personal references. - -After the associations had been "jotted down," the subjects in each -case copied them, noting also the suggesting ideas, and giving, in many -cases, a number of introspective notes. It is important to mention that -in all of the work these records of suggesting ideas were made by the -subjects without any questions on the part of the investigator. - - -GROUP I. TWO NONSENSE SYLLABLES - -In order that a standard might be obtained that would serve as a basis -for subsequent experiments, two nonsense syllables were pronounced with -equal emphasis, as starting-points, and the subject was asked merely to -wait until both had entered consciousness and not to favor nor inhibit -either. If the subject stated that associations arose between the -pronunciation of the starting-points the results were discarded. - -Turning to the notes we find that K. reported, "The first just hovered -around," and the associations followed the second, or as V. states -it, "Sof was carried subconsciously for a while without influence," -while By. frequently noticed that "The first may be in the background -on the point of breaking in but be inhibited involuntarily," or in -another, "It was frequently present but exerting no influence." A. -"forgot what the other word was, but felt it trying to get a hand in." -Ro. goes further and states in terms similar to A., "The words which -might have been suggested by 'taf' were wholly inhibited, though I -am sure 'taf' was present to me throughout the series, but was not -efficacious as against the other syllable." It is unnecessary to -multiply instances to show that the wraith, so to speak, of one may -linger for a short time, or occasionally for the entire series, but -that the associations are determined by the other. Or the lingering -wraith of a starting-point may hover ineffectively in consciousness -and exert no determining influence on the series until toward its -close; then, however, although both starting-points still persist, -they exchange places so far as effectiveness is concerned, and the -former wraith becomes the primary factor in effecting the series of -associations. For example, "The two syllables were present all the way -through, but the former exhausted itself as a word-suggester after -a few words." Again Ro. gives examples where "One alone may be in -consciousness and determine the associations when the other may enter -without effect upon the series, or may determine the series, the first -persisting but losing its effect"; and a case of both ideas persisting -and each alternately exerting an influence was noted by M. These last -two conditions are exceptional. - -Studying carefully the notes and graphic representations as given in -the tables, it is apparent that one starting-point may be followed -independently and exclusively; we find "'fef' suggesting 'theft,' and -the subsequent associations monopolizing the field of consciousness -and 'tuz' not again appearing." (V.) The results show that in the one -hundred and seven experiments one was followed exclusively only twenty -times. The following would be an example: - - -III. Naf-Tam - - --tambour tam - --experiment tambour - --psychology experiment - --laboratory experiment - --space psychology - --time space - --ego space and time - --Ebbinghaus ego - --discussion psychology - --posted notice psychology - --door posted notice - --gray door - --stairs door - --fishes laboratory - --water fishes - --decay fishes - --animal fishes - --meat fishes - --odor meat - -In other cases one starting-point may be followed and then the -other for a few or many associations, each "occupying the mind to -the exclusion of the other for a number of words, when suddenly the -other appears and suggests a new series," which V. calls "a curious -zigzagging in consciousness." This may take place at any point along -the series. As Ro. indicates, "There was rivalry here; 'yud' wholly -inhibited all the 'zid' associations, even 'zid' itself for the time, -then, 'yud' apparently being exhausted, 'zid' entered again into the -focus." - -In contrast to the above forms, the tables indicate and the notes -verify that while the associations primarily follow one there can be -traced the modifying effect of the other; "The nature of the words -was influenced by a fringe of consciousness which contains the other -starting-point," M.'s comment runs, while J. adds, "The other helped -in the mental picture but had no special significance." There are no -experiments in the first group where this partial fusion took place -throughout the series, and there are only six examples where it took -place before the sixth word and continued to the end. While there are -no cases here of alternating partial fusion, yet it sometimes happens, -that is, the predominating influence is sometimes transferred from one -to the other. The modifying influence may reach such a degree at any -point in the series that the identity of each point of departure of the -association is lost and there is total fusion, resulting in one idea or -one train of thought. For example, 'rel' and 'mem' gave 'realm' for V.; -for Ht. 'fef' and 'tuz' gave 'fezz'; for M. they gave 'fez'; for Ro. -'fuz.' - -Of the twenty-one experiments where one starting-point was followed -exclusively, there were two cases for the first and nineteen for the -second. There were but two cases of alternating groups, a third one -being unique in that after the first three words there was a persistent -alternation between two apparently independent series of inter-related -words and inter-related visual images. There were three cases of -complete fusion throughout the series and nine where total fusion -started before the fifth word and continued. - -In a number of cases the initial starting-points were forgotten before -the end of the series and the subjects were sometimes unable to recall -them. - -As the subjects were kept ignorant of the characteristic persistence -of either starting-point in forming separate associations, and of the -tendency towards fusion, as well as of the preponderance of influence -of one over the other, it is to the tabulated results that we must -look for quantitative measurement of these. 76.2% of the associations -are due to the independent influence of one or the other of the -starting-points; 23.9% are due to the combined influence; for the first -starting-point we have 18.7%, for the second 57.5%. In 15.3% of all the -associations the combined influence was the result of total fusion; in -4.1%, the result of a union where the first starting-point predominated -in influence; in 4.4%, the second predominated. The following graphic -representation indicates the order of influences for the first pair of -syllables. The table gives the results for the ten pairs. - - -TABLE I. TWO NONSENSE SYLLABLES SPOKEN - - Time--50 seconds. - - Characters: | represents the influence of the first, - the second, + - complete fusion, α fusion with the first predominating, β fusion with - the second predominating. - - 1) Taf--Coz - - M. | - - - - | | | | | - - - - - F. - - | | + + + + | | | + + β β β β β β - H. - | | | | | | | | | | | | | | | - R. | - - - - - - - - - - - - - - - - K. - - - - - - - - V. | | - - - - | - - | + + + + - Ro. | | | - - - - - - - - - - - - - - - - - Bl. - - - - - - - - - - - - - - - - By. | - | | | - - - - - - - - - - - - - - - - - - - - Bs. - - - - - - - - - - - - - - - - Ht. - - | | | | | | | | | | | | | - - Starting-points: - - (1) Taf--Coz. - (2) Cim--Bef. - (3) Yud--Zid. - (4) Sof--Deb. - (5) Naf--Tam. - (6) Fef--Tuz. - (7) Sar--Nef. - (8) Sek--Lub. - (9) Hov--Bes. - (10) Rel--Mem. - - | - + α β - - M. { 20 69 26 4 3 - { 16.5% 56.6% 21.2% 3.3% 2.4% - - F. { 28 22 37 0 39 - { 22.2% 17.5% 29.4% 30.9% - - H. { 39 98 0 11 0 - { 26.3% 66.2% 7.5% - - R. { 9 102 32 0 0 - { 6.3% 71.4% 22.3% - - K. { 47 58 1 14 0 - { 39.1% 48.3% .7% 11.9% - - V. { 30 79 54 0 0 - { 18.4% 48.4% 33.2% - - Ro. { 32 111 0 5 0 - { 21.4% 75.1% 3.5% - - Bl. { 5 131 15 15 0 - { 3.1% 78.9% 9.0% 9.0% - - By. { 43 102 23 15 22 - { 16.8% 52.6% 11.7% 7.7% 11.2% - - Bs. { 9 72 31 0 6 - { 11.4% 58.5% 25.3% 4.8% - - Ht. { 32 58 20 0 0 - { 29.0% 52.8% 18.2% - - Totals{294 902 239 64 70 - { 18.7% 57.5% 15.3% 4.1% 4.4% - - Number of subjects, 11; number of sections, 10; number of - experiments, 110; number of associations, 1569. - - -GROUP II - -Two concrete nouns with apparently equivalent connotation were -pronounced. In order that the subject get no clue as to the -preponderance of one starting-point over the other, the nine sections -were given at irregular intervals in connection with other experiments. - -The tables show few cases of fusion, there being but one case in the -eighty experiments where all the associations were the result of the -combined influence of both starting-points. There was no other instance -where complete fusion took place before the sixth association and -continued throughout, and only six cases where any form of fusion took -place in the eighty experiments within the first five words (7.6%), -while in the one hundred and seven experiments of Group I there were -twenty-five (23.9%). - -The tables show a tendency which was noted when two syllables were -used and which is emphatically brought out here, namely, it is the -position or sequence which determines which of the two equivalent -starting-points shall produce the greater influence. When the two -starting-points are given in immediate succession, it is the second -which predominates in influence. This preponderance may be clearly -demonstrated by the tables alone, though there are many notes which -show "the greater influence of one" (the second). A. seems to have -realized this when he wrote, "While the first was uppermost the second -hovered in subconsciousness, resting content, knowing that it would -have its turn soon." In corroboration the tables give--abstracting from -all cases of fusion--268 words (23.2%) for the first, 721 words (62.3%) -for the second. In fifty-five of the eighty experiments the last had -full control at the end of the series. Taking the cases where one -was followed exclusively throughout the series, starting between the -first and the sixth named association, we find eight for the first and -twenty-nine for the second. This greater influence is again to be found -in the cases of partial fusion; the first predominating in 2.6%, and -the second in 4.3%. - -The results of both groups show that the starting-points tend in a high -degree toward independent influence, and also that such a method of -presentation is one of sequence rather than simultaneity, as the two -words show unequal influence. The former must in a manner be reproduced -to become a point of departure for associations, while the latter acts -directly. Is it then a condition of mind that when similar impressions -are presented the one in the presence of which consciousness is -reacting directly has a greater influence in arousing associations than -one which is just past? This we are forced to conclude is the case, but -the proof of the conclusion will be supplemented by later results. - - -TABLE II. TWO WORDS SPOKEN - - Time--50 seconds. - Characters--same as Table I. - - (1) Library--River - - M. | + + β - - - - - - - - - - - - - F. | - - - - - - - - - | | | | - H. - - - - - - - - - - - - - - - - - Ro. | | | | - - - - - - - - - - J. | - | | | | - - - - - - - - - - - - - - - - Bl. | | - - - - | | | | | | | | | - - / - By. - - - - - - - - - - - - - - - - - - - - - - - Bos. | - - - - - - - - Bur. - + - - - - - - - - - - - - - (1) Library--River. - (2) Hat--Road. - (3) Newspaper--Medicine. - (4) Bicycle--Drum. - (5) Theatre--Magazine. - (6) Store--Church. - (7) Soldier--House. - (8) Ship--Boy. - (9) Furniture--Tree. - - -TABLE II.--_continued_ - - | - + α β - - M. {32 66 26 0 13 - {23.4% 48.2% 18.9% 9.5% - - F. {32 67 13 5 1 - {27.2% 56.7% 11.0% 4.3% .8% - - H. {59 79 5 0 0 - {41.3% 55.2% 3.5% - - Ro. {44 85 0 0 0 - {34.1% 65.9% - - J. {21 121 8 5 0 - {13.5% 78. % 5.3% 3.2% - - Bl. {22 83 6 0 1 - {19.7% 74.1% 5.4% .8% - - By. {16 97 18 14 23 - { 9.5% 57.8% 10.7% 8.3% 13.7% - - Bs. {26 64 3 7 1 - {25.8% 63.5% 2.9% 6.9% .9% - - Bur. {16 59 8 0 10 - {17.2% 63.4% 8.6% 0 10.8% - - Total {268 721 87 31 49 - { 23.2% 62.3% 7.6% 2.6% 4.3% - - Number of subjects, 9; number of sections, 19; number of - experiments, 80; number of associations, 1156. - - -GROUP III - -For two syllables and like words the second strongly predominates in -awakening associations; will the same be true when two simple outline -pictures are shown in the same order? The following results show in -attestation of the above conclusion percentages remarkably similar -to those of the words. There are 23.7% for the first and 61% for the -second; 84.7% of the associations show no sign of fusion and only 15.3% -for fusion and the different forms of partial fusion, the second still -holding the ascendency. When the two pictures did fuse, R. tells us, -"All the associations were more elaborate pictures than when mere words -were given." - -A comparative study, inadequate though it is, offers a partial -parallelism between the predominating memory type and stimulation. The -subjects who are preëminently of the visual, K., visual motor, M., H., -V., and visual lingual motor, Ht., find the pictures more suggestive -than the syllables, while those of the pure motor, F. and By., reverse -the order and find that the syllables offer more numerous and "more -vivid" (F.) associations. - -Common experience, however, immediately shows the limitations of -reaching conclusions, when considering prolificacy as criteria of -suggestiveness, inasmuch as starting-points which are abundantly rich -in associations tend to produce so many points of departure that they -tend to inhibit one another. Again there is to be considered the kind -of associations, those of the syllables being of a very elementary -character and in serial form. - -A few experiments were given in which colored slips of paper were used -as starting-points. These proved very suggestive for the subjects. Also -a few tones were given, but these were soon discontinued, as other -tones, which could not be recorded, were frequently suggested. The -sentence which forms a very satisfactory starting-point where one is -used could not be used to an advantage where several were given. As we -are here interested in the mutual influence of the starting-points, -our remaining study will be confined to a quantitative and qualitative -variation of the forms used in the previous groups. - - -TABLE III. TWO PICTURES SHOWN - - Time--50 seconds. - Characters--same as Table I. - - (1) Boy Rolling Hoop--Blacksmith - - M. | | | - - - - - - | | | | | - F. | | - - | + + - H. - - - - - - - - - - - - - R. - - - - - - - - - - - - - - - - - K. - - - - - - - - - - - - - - - - - - V. - - | | + + + + + + + + + + + + + + - S. - - - - - - - - - | | | | | | | - By. | - - - - - - - - - - - - - - - - - - - - - - Bs. - - - - - - - - - - Ht. | | - - - - - - - - - - (1) Boy Rolling Hoop--Blacksmith. - (2) Old Man With Umbrella--Bird House. - (3) Carpenter--Mower. - (4) Children Playing--Boy with Basket. - (5) Horse--Dog House. - (6) Shoemaker--Fisherman. - (7) Little Girl--A Chicken. - (8) Boy--A Sheep. - - | - + α β - - M. {41 65 2 0 1 - {37.6% 59.7% 1.8% .9% - - F. {11 42 21 0 5 - {13.9% 53.2% 26.6% 6.3% - - H. {37 52 11 26 9 - {27.4% 38.5% 8.1% 19.3% 6.7% - - R. {41 58 8 0 15 - {33.4% 48% 6.5% 12.1% - - K. {32 82 0 0 0 - {27.1% 72.9% - - V. {12 95 21 3 5 - { 8.8% 70% 15.4% 2.1% 3.7% - - S. {36 44 0 0 0 - {45% 55% - - By. { 8 111 12 0 13 - { 5.4% 77.2% 8.3% 9.1% - - Bs. {13 40 7 0 0 - {21.7% 66.7% 11.6% - - Ht. {22 72 7 0 4 - {20.9% 68.6% 6.7% 3.8% - - Totals {253 661 89 29 52 - { 23.7% 61% 8.2% 2.7% 4.4% - - Number of subjects, 10; number of sections, 8; number of experiments, - 76; number of associations, 1084. - - -GROUP IV - -The previous experiments suggest the conclusion that that -starting-point in the presence of which consciousness is reacting -exerts a greater influence than one just past. The proof of this -anticipated result is supplemented by subsequent consectary data. - -It is necessary to test the outcome when the nature of the impressions -is varied and the starting-points are given simultaneously. An outline -picture and a word may be so given. These experiments verify from a -different standpoint the statement that the picture establishes itself -more permanently and is more influential, there being 47.8% of the -associations produced by the picture alone, 14.8% by the words alone, -25% of a fusion of the two, and 12.4% of a uniting influence with -the first predominating. The subject R. is an exception in that she -favors the word when not favoring a combination of the two, a fact -which I am unable to explain except to add that the subject stated -that the æsthetic pleasure connected with the picture was sufficient -to inhibit the associations. K. has 100% for the pictures, which is -partially explained by the fact that she is a remarkable visualizer who -reproduces all situations in visual terms. - - -TABLE IV. PICTURE SHOWN AND WORD SPOKEN - - Time--50 seconds. - Characters same as Table I. - - (1) (a rabbit)--Table - - M. | - - | | | | | | | + - - - - - R. + + + + + + + + + + + + + + + + + + - K. | | | | | | | | | | | | | | | - S. | | | | | - | | | | | - J. | - - | | | | | | | | | - - - | | | | | | | | | - Ht. | - | | | | | | | | | | | | - - - - - - (1) (a rabbit)--Table. - (2) (horse)--Book. - (3) (boy)--Dish. - (4) (duck)--Iron. - (5) (dog)--Paper. - - | - + α β - M. { 38 9 16 6 0 - { 55.0% 13.1% 23.3% 8.6% - - R. { 1 20 55 0 0 - { 1.3% 26.3% 72.4% - - K. { 65 0 0 0 0 - {100.0% - - S. { 29 15 3 10 0 - { 50.8% 26.3% 5.3% 17.6% - - J. { 75 19 14 9 0 - { 64.2% 16.3% 11.9% 7.6% - - Ht. { 17 7 30 33 0 - { 19.5% 8.1% 34.5% 37.9% - - Totals {225 70 118 58 0 - { 47.8% 14.8% 25.0% 12.4% - - Number of subjects, 6; number of sections, 5; number of experiments, - 30; number of associations, 471. - - -GROUP V - -The character of the starting-points determines which shall be followed -in a simultaneous presentation; can the character of two immediately -successive starting-points be so varied as to overcome the factor of -temporal difference? The few experiments in this group show an attempt -to shift and measure this influence, selecting as variants words of -general and specific character, the first being a term of everyday -experience with the subjects, of wide connotation, and therefore -presumably rich in associations, and the second, which had the -advantage of position, one of more limited and specific connotation, -thus in a measure making it possible to test the stability of the -second in establishing itself as a word-suggester. For the words -"Gymnasium--Stamens" the second still strongly predominates. There is a -slight increase in the amount of fusion (24.5% in all), the explanation -of which would probably lie in the fact that the first is more -assertive than before and offers more elements common to the two. There -was one case of total fusion, one case where fusion started before the -sixth word and continued, no cases of alternating fusion, four cases of -partial fusion, five cases where the second was followed throughout, no -case where the first was followed throughout, five cases of alternation -between the first and the second. In 75.5%, the influence was exerted -without fusion. Eight of the nine subjects favor the specific term. - - -TABLE V. GENERAL AND FAMILIAR WORD--SPECIFIC WORD SPOKEN - - Time--50 seconds. - Characters--same as Table I. - - (1) Laboratory--Rake - - M. | | | | | - - - - - - - - - - - - - - - - - F. | - - - - - - - - - - H. + + + + + + + + + + + - V. | - - - - - - - - - - - - - | | | | | - S. - - - - - - - - - - | | | | - Bl. - - - - - - - - - - - - - - - - - - By. | - - | | | | | | | | | - Bs. - Ht. - - - - - - - - - J. | | β β β β β β β β β β β β | | | | | - - (1) Laboratory--Rake. - (2) Experiment--Butterfly. - (3) Gymnasium--Stamens. - - -TABLE V.--_continued_ - - { 22 25 4 6 0 - M. { 38.6% 43.9% 7.0% 10.5% - - { 4 19 0 0 0 - F. { 17.4% 82.6% - - { 4 25 13 0 0 - H. { 9.5% 59.6% 30.9% - - { 7 38 2 0 7 - V. { 12.8% 70.7% 3.7% 12.8% - - { 11 34 0 0 0 - S. { 24.4% 75.6% - - { 0 36 0 0 0 - Bl. { 100.0% - - { 11 16 7 0 9 - By. { 25.5% 37.1% 16.5% 20.9% - - { 0 9 12 2 - Bs. { 39.1% 52.2% 8.7% - - { 10 11 10 - Ht. { 32.3% 35.4% 32.3% - - { 17 8 15 0 13 - J. { 32.1% 15.1% 28.3% 24.5% - - { 86 221 63 8 29 - Totals { 21.2% 54.3% 15.4% 1.9% 7.2% - - Number of subjects, 10; number of sections, 3; number of experiments, - 27; number of associations, 407. - - -GROUP VI - -What modification of influence takes place when an auditory impression -in the form of a word of abstract nature (the pure abstract words are -taken later) is given in comparison with a concrete noun? The tables -indicate that we are now able partly to overcome the disadvantage -of first position by the advantage of concrete content. 24% of the -associations are the result of total fusion; there are eight cases of -total fusion throughout the series, and seven where total fusion took -place before the third word and continued. There are two cases where -the first was followed throughout, and but one where the second was -followed exclusively. The tables indicate that there were very few -words. Some of the subjects claim, "These words did not seem equally -rich in associations. I was not at all conscious of the one while the -other was in consciousness." (H.) The most characteristic feature here -was, as Br. also indicates, "Great amount of rivalry at the beginning -of the series"; while Bs. states, "There was a lot of confusion and -a feeling of groping for words." Br. adds later, "For some seconds -association seemed obstructed. Then by an effort the process was -started which followed an involuntary course. A kind of confused -presence of both words." Another subject adds, "There was a long blank -after the words were said in which both words were balancing off in -the fringe of consciousness and the mind expectant, passively waiting -for an association to turn up. The hesitant period seemed marked by an -attempt at a synthesis of these two words in some way." - - -SUBJECT XIX - - Lamp--Justice. - - | chimney lamp. - | white lamp chimney. - | yellow white chimney. - | flame yellow. - | nickel lamp plus the other words. - - scales justice. - - purple robe justice. - -As the tables indicate, there was frequently a strong tendency here for -the abstract terms to fuse. As H. noticed, "It does not tend to call up -associations of its own stripe, but in some way becomes concrete." - - -TABLE VI. TWO WORDS: CONCRETE--ABSTRACT SPOKEN - - Time--15 seconds. - Characters--same as Table I. - - (I) Desert--Hate - - A. | | | + + + - M. | | | | - - - F. + + + - H. | - | | | | | | | - Ro. | | - - | | | | - Bl. + + + + + + + - By. | | | + + + + + + - Bs. - | | | | | - Br. | | | + + - - (1) Desert--Hate. - (2) Lamp--Justice. - (3) Pen--Fatigue, - (4) Gate--Fear. - TABLE VI--_continued_ - - | - + α β - A. { 10 2 6 0 0 - { 55.5% 11.2% 33.3% - - M. { 7 8 10 0 0 - { 28.0% 32.0% 40.0% - - F. { 3 8 5 0 0 - { 18.7% 50.1% 31.2% - - H. { 17 16 1 0 0 - { 50.0% 47.1% 2.9% - - Ro. { 15 11 0 0 0 - { 57.7% 42.3% - - Bl. { 4 15 7 2 0 - { 14.2% 53.5% 25.1% 7.2% - - By. { 4 21 8 0 1 - { 11.8% 61.8% 23.5% 2.9% - - Bs. { 5 1 15 0 2 - { 21.8% 4.3% 65.2% 8.7% - - Br. { 11 8 2 0 0 - { 52.3% 38.1% 9.6% - - Totals { 76 90 54 2 3 - { 33.8% 40.0% 24.0% .8% 1.4% - - Number of subjects, 9; number of sections, 4; number of experiments, - 34; number of associations, 225. - -Reversing the order by placing the concrete noun second, it gains in -influence. We are told by the subjects at this point, "The choice seems -to be determined by the concreteness of the word." (H.) "The abstract -soon exhausted itself as a word-suggester." (Ro.) There was fusion in -24% of the associations of the first group, and 22.2% in the second. -There are six cases where the second alone prevails, two for the first -starting-point and four for the second. There are eleven cases of -fusion beginning before the sixth word and continuing throughout the -series. There is much partial fusion, with the second predominating in -influence. - -The results again emphasize the fact that the influence is -transferable, also that normally the second has the advantage; -furthermore, they illustrate the preponderance of the concrete word as -a starter of associations, and that the abstract term when it exerts -an influence tends to fuse rather than persist in having separate -associations; all of which shows that concrete terms produce more vivid -impressions than abstract ones, and would, when it is possible to use -them, be of direct aid to the learner. - - -TABLE VII. TWO WORDS: ABSTRACT--CONCRETE SPOKEN - - Time--15 seconds. - Characters--same as Table I. - - (1) Honesty--Tide - - A. - | - - - - - M. - - - - | | | | - F. | - - - - - - H. | - - - - Ro. | | - - - - - Bl. | - - - - - - - By. - - + + - Bs. - - - - - - - - J. - + + + + + + - - (1) Honesty--Tide. - (2) Skill--Coal. - (3) Terror--Sky. - (4) Refined--Flag. - - | - + α β - A. { 2 7 11 0 4 - { 8.4% 29.2% 45.8% 16.6% - - M. { 4 11 10 1 5 - {12.9% 35.5% 32.3% 3.2% 16.1% - - F. { 2 8 9 0 0 - {10.5% 42.2% 47.3% - - H. { 8 11 1 3 0 - {39.2% 43.5% 4.1% 13.2% - - Ro. {10 13 3 0 0 - {38.4% 50.0% 11.6% - - Bl. {15 10 0 0 0 - {60.0% 40.0% - - By. { 2 20 3 0 0 - { 8.0% 80.0% 12.0% - - Bs. { 1 11 6 0 2 - { 5.0% 55.0% 30.0% 10.0% - - J. { 6 16 6 0 0 - {21.4% 57.2% 21.4% - - Totals {50 107 49 4 11 - {22.6% 48.4% 22.2% 1.9% 4.9% - - Number of subjects, 9; number of sections, 4; number of experiments, - 36; number of associations, 221. - -Increasing the disparateness by making the one a proper name and the -other a pure abstract noun, we find the name dominates consciousness, -almost to the exclusion of the abstract term. The tables confirm the -conclusions that the abstract term, even when given the advantage of -position, exerts little influence, for in the first group of eighteen -experiments of two hundred and eighty-four associations there are 13.4 -times as many associations for the first as for the second, or two -hundred and fifteen words for the first (75.8%) and sixteen (5.5%) for -the second. - -Reversing the order, the burden of influence swings back to -thirty-eight (12.8%) for the first and one hundred and fifty-six -(52.7%) for the second with an amount of fusion increased to -ninety-nine (33.4%). - - -TABLE VIII. TWO WORDS: PROPER NOUN--ABSTRACT NOUN SPOKEN - - Time--50 seconds. - Characters--same as Table I. - - (1) Lowell--Liberty - - M. | | | | α α α | | | | | | - R. | α α | | | | | | | | | | | | | - K. | | | | | | | | | | | | | | - J. | | | + + + α α α α α α α α α α α α α - S. | | | | | - | | | | | | | - Ht. - - | | | | | | | | | | | | | | - - (1) Lowell--Liberty. - (2) Roosevelt--Fidelity. - (3) Eliot--Integrity. - - | - + α β - - M. { 29 3 2 7 0 - { 70.7% 7.4% 4.8% 17.1% - - R. { 30 0 17 2 0 - { 61.2% 34.7% 4.1% - - K. { 43 2 0 0 0 - { 95.5% 4.5% - - J. { 42 0 8 13 0 - { 66.6% 12.7% 20.7% - - S. { 40 2 0 0 0 - { 95.2% 4.8% - - Ht. { 31 9 3 1 0 - { 70.4% 20.4% 6.9% 2.3% - - Totals {215 16 30 23 0 - { 75.8% 5.5% 10.7% 8.0% - - Number of subjects, 6; number of sections, 3; number of experiments, - 18; number of associations, 284. - - -TABLE IX. TWO WORDS: ABSTRACT NOUN--PROPER NOUN SPOKEN - - Time--50 seconds. - Characters--same as Table I. - - (1) Individuality--Lincoln - - M. | + | + + + + + + + + + + + + - R. - - - - - - - - - - - - - - - - - K. - - - - - - - - - - - - - J. | - - - - - - - - - - - | | | | | | | | | | - S. - - - - - - - - - - - - - - - - Ht. - - - - - - - - - - - - - - - - - - - - (1) Individuality--Lincoln. - (2) Brevity--Webster. - (3) Justice--Hanus. - - | - + α β - - M. { 4 19 25 0 0 - { 8.3% 39.6% 52.1% - - R. { 5 31 12 0 0 - {10.4% 64.5% 25.1% - - K. {14 31 0 0 0 - {31.2% 68.8% - - J. {13 11 44 0 0 - {19.1% 16.1% 64.8% - - S. { 2 40 0 0 0 - { 4.8% 95.2% - - Ht. { 0 24 18 0 3 - { 53.4% 40.0% 6.6% - - Totals {38 156 99 0 3 - {12.8% 52.7% 33.4% 1.1% - - Number of subjects, 6; number of sections, 3; number of experiments, - 18; number of associations, 296. - - -GROUP VII - -Occasional experiments of the previous groups indicated an abnormal -influence of those ideas which were accentuated by the special -interests of the subjects. We ask therefore: What is the relation of -the newly aroused associations to the present content of consciousness? -May the present content of consciousness be so varied as to reënforce -or inhibit the characteristic influence of the individual impressions -successively presented? In order to test this, words or a sentence were -pronounced just previous to the presentation of the two starting-points -related to them as follows; in the first divisions the preparatory -words lead to the second, in the second divisions to the first, in the -third divisions to neither, in the fourth divisions to both, and in the -last we have a slight change in the marginal setting and a sentence -leads to the second. - -The following are examples of the first and second divisions: - - Quartz--Granite--Shale. - HORN--SLATE. - Dog--Sheep--Horse. - SQUIRREL--TELEGRAM. - - -SUBJECT XVIII - - --slate slate - --slate ledge (Col.) slate - --Great Falls, Mont. quartz, granite, shale - --geology quartz, granite, shale, G. F. - --Will B. geology - --State University Will B. - --Sexton James State University - --Mrs. J. Sexton James - --C. S. J. Mrs. J. - --Indian School C. S. J. - --Fort Shaw School Indian School - --Mrs. C. Ft. Shaw School - --Mrs. E. Mrs. C. - --Seattle, Wash Mrs. F. - --Miss M. Seattle, Wash. - --Everyman Miss M. - --Cousin V. Everyman - --theatre Cousin V. - - -SUBJECT XII - - | hunt squirrel (and dog) - | pasture sheep, horse, and hunt - | yard squirrel and pasture - | Harvard yard - | Freshman Harvard - | themes Freshman and squirrel - | hunting themes, dog, " - | George hunting - | squirrel George - | creatures squirrel - | animals creatures - | activity " animals - | agility " " - | grace " " - | cuteness " " - | pets " " - | civilisation creatures - | vs. cats " - | enemies cats - -That one starting-point establishes itself more firmly, and offers -more dominant associations with an increased degree of suggestiveness -is intimated by various expressions of the subjects who state, "the -preparatory words called forth associations connected with this or that -starting-point"; or "there was a felt fusion of all"; "a summation of -all"; or "the preparatory words had an influence throughout"; "they -strengthened this or that starting-point"; "they affected one and not -the other"; and many similar expressions. - -The influence of these preparatory marginal settings was also indicated -very often by the nature or kind of words in the series. - -Turning to the tables which collectively represent in a graphic and -quantitative form the notes of the subject, and which are in harmony -with the above, we find they demonstrate that there is a very intimate -and definite relationship. When the state of mind immediately preceding -the moment of the formation of the associated series is conditioned by -the preparatory words leading to the second, the amount to which that -starting-point dominates consciousness in arousing associations is -greater than in any previous case where the words of like nature are -pronounced. - -With the preparatory words leading to the second starting-point, we -have 11.5% of the influence for the first, 69.2% for the second; with -them leading to the first, 58.2% for first, 17.2% for second; with -them leading to neither, 40.6% for first, 44.2% for second; with them -leading to both, 16.1% for first, 54.8% for second; with a preparatory -sentence leading to second, 12.9% for first, 59.7% for second. - -A few experiments were made where one word was given as a setting and -four or eight starting-points were shown, but the starting-points were -so numerous that they tended to confuse the subject's introspective -account. - - -TABLE X. TWO WORDS SHOWN: THREE PREPARATORY WORDS SPOKEN LEADING TO THE -SECOND - - Time--50 seconds. - Characters--same as Table I. - - Corn, Wheat, Oats. (1) MOB--HAY - - M. + + + - + + - - - - - R. - - - | + + α + β - - - - - - K. - - - - - - - - - - - - - - - S. + + + + - - - - - - - - - - - - - J. + + + + + + β β - - - - - - - - Ht. - + + + + β β β β β β β β - - (1) Corn, Wheat, Oats. MOB--HAY. - (2) Cloud, Mist, Dew. ORATION--CANOE. - (3) Turtle, Fish, Frog. KEY--NET. - (4) Quartz, Granite, Shale. HORN--SLATE. - (5) Geometry, Plane, Rectangle. CASE--CUBE. - - | - + α β - - { 10 41 17 0 7 - M. { 13.3% 54.7% 22.7% 9.3% - - { 15 37 21 1 4 - R. { 19.3% 47.4% 26.9% 1.2% 5.2% - - { 0 55 0 0 0 - K. { 100.0% - - { 8 64 4 0 0 - S. { 10.5% 84.2% 5.3% - - { 17 69 6 0 2 - J. { 18.1% 73.4% 6.3% 2.2% - - { 2 45 17 0 8 - Ht. { 2.8% 62.5% 23.6% 11.1% - - { 52 311 65 1 21 - Totals { 11.5% 69.2% 14.4% .2% 4.7% - - Number of subjects, 6; number of sections, 5; number of experiments, - 29; number of associations, 449. - - -TABLE XI. TWO WORDS SHOWN. THREE PREPARATORY WORDS SPOKEN LEADING TO -THE FIRST - - Time--50 seconds. - Characters--same as Table I. - - Dog, Sheep, Horse. (1) SQUIRREL--TELEGRAM - - M. | | | | | | | | | | | | | | - R. | | | | | | | | | | | | | | | - K. | | | | | | | | | | | | | - S. | | - - - - - - - - - - - J. | | | | | | | | | | | | | | | | | | | - Ht. | | | | | | | | | | - - - - - - - - - - (1) Dog, Sheep, Horse. SQUIRREL--TELEGRAM. - (2) Pineapple, Banana, Orange. FRUIT-STAND--ELECTRIC LIGHT. - (3) Justice, Truth, Beauty. CHARITY--PHOTOGRAPH. - (4) Gold, Copper, Silver. DIME--SKULL. - - M. {28 3 15 0 8 - {51.8% 5.5% 27.9% 14.8% - - R. {16 9 23 0 11 - {27.2% 15.3% 38.9% 18.6% - - K. {56 2 0 0 0 - {96.5% 3.5% - - S. {36 24 0 0 0 - {60.0% 40.0% - - J. {38 4 24 1 7 - {51.4% 5.4% 32.4% 1.4% 9.4% - - Ht. {37 20 0 0 0 - {64.9% 35.1% - - Totals {211 62 62 1 26 - {58.2% 17.2% 17.2% .2% 7.2% - - Number of subjects, 6; number of sections, 4; number of experiments, - 24; number of associations, 362. - - -TABLE XII. TWO WORDS SHOWN. THREE PREPARATORY WORDS SPOKEN LEADING TO -NEITHER - - Time--50 seconds. - Characters--same as Table I. - - Botany, Statue, Postal. (1) CHOCOLATE--BANNER - - M. | | - - - - - - - - - - - - - | - R. - | | | | | | | | | | | | | | | | | | | | - K. | - | | | - | - | - | - | - S. | | - - - - - - - - - - - - - - - - - J. | | | | | | | - - - - - - - - - - - - - - - - Ht. - - + + + - - - - - - - - - - - - - (1) Botany, Statue, Postal. CHOCOLATE--BANNER. - (2) Idea, Proposition, Syllogism. SILVER--GAME. - - | - + α β - - M. {3 28 0 0 0 - {9.6% 90.4% - - M. {22 1 2 0 14 - {56.5% 2.5% 5.2% 35.8% - - K. {28 5 0 0 0 - {84.8% 15.2% - - S. {13 20 0 0 0 - {89.4% 60.6% - - J. { 17 22 0 0 0 - { 43.6% 56.4% - - Ht. { 0 14 8 7 0 - { 48.3% 27.6% 24.1% - - Totals { 83 90 10 7 14 - { 40.6% 44.2% 4.9% 3.4% 6.9% - - Number of subjects, 6; number of sections, 2; number of experiments, - 12; number of associations, 204. - - -TABLE XIII. TWO WORDS SHOWN. THREE PREPARATORY WORDS SPOKEN LEADING TO -BOTH - - Time--50 seconds. - Characters--same as Table I. - - Tree, Shrub, Grass. (1) TEA--FERN - - M. + + α α α α α α α - - - R. + + + + + + + + + + + + - K. - - - - - - - - - - - - - - - - - S. - - - - - - - - - - - - - J. | - - - - - - - - - - - - - - - - - - - - - Ht. + + α α α α α α | | | | | - - (1) Tree, Shrub, Grass. TEA--FERN. - (2) Fox, Wolf, Moose. DEER--DOVE. - - | - + α β - - M. { 2 12 4 8 0 - { 7.6% 46.3% 15.3% 30.8% - - R. { 0 0 25 0 0 - { 100.0% - - K. { 1 30 0 0 0 - { 3.2% 96.8% - - S. { 8 12 0 4 0 - { 33.3% 50.0% 16.7% - - J. { 8 26 0 0 0 - { 23.5% 76.5% - - Ht. { 8 12 2 6 0 - { 28.5% 42.8% 7.2% 21.5% - - Totals { 27 92 31 18 0 - { 16.1% 54.8% 18.4% 10.7% - - Number of subjects, 6; number of sections, 2; number of experiments, - 12; number of associations, 168. - - -TABLE XIV. TWO WORDS SHOWN (AUTHORS)--WITH A PREPARATORY SENTENCE -LEADING TO THE SECOND - - Time--50 seconds. - Characters--same as Table I. - - "God's in His Heaven--all's right with the world." - - (1) BURNS--BROWNING - - M. + - - - - - - - - - | | | | | | - R. | - - - - - - - - - - - - K. + + + + + + + + + + + + + - S. | - - - - - - - - - - - - - | | | - J. | | - - - - - - - - - - - - - - - - - - - Ht. - - - - - - - - - - - - (1) "God's in His Heaven--all's right with the world." - BURNS--BROWNING. - - (2) "All that glistens is not gold." - BYRON--SHAKSPERE. - - (3) "Hitch your wagon to a star." - SPENCER--EMERSON. - - | - + α β - - M. { 9 15 15 0 4 - {20.9% 34.8% 34.8% 9.5% - - R. { 1 47 0 0 0 - { 2.1% 97.9% - - K. {15 0 26 0 0 - {36.5% 63.5% - - S. { 6 34 0 0 0 - {15.0% 85.0% - - J. { 3 43 14 0 0 - { 5.1% 71.6% 23.3% - - Ht. { 0 18 13 0 0 - { 58.1% 41.9% - - Totals {34 157 68 0 4 - {12.9% 59.7% 25.8% 1.6% - - Number of subjects, 6; number of sections, 3; number of experiments, - 18; number of associations, 263. - - -GROUP VIII - -The aim here is to test the effect of interruption in the series of -associations, and to throw further light on the relation of the series -to the present content of consciousness when this content is a series -of associations and the new content is a pronounced word which is to -act as a point of departure for new associations. - -There are three divisions. The time in all is fifty seconds; in the -first a word of general connotation is given and after an interim of -ten seconds a second more specific word is pronounced. In the second -three similar words are given at an interval of fifteen seconds; the -third four words with an interval of ten seconds. The following are -examples of the first and third divisions: - - -SUBJECT III - - Commencement--Sieve - - commencement - | college commencement - | cap college - | gown cap - | boys commencement - | confetti commencement - - sieve - - holes sieve - - water sieve - - flour sieve - - space holes - - concept space - - Royce concept - - time concept - - eternity time - - damnation eternity - - Hamlet "Consummation," etc - - Shakspere Hamlet - - -SUBJECT VII - - Wax--Jug--Tar--Sod - - wax - | Charley wax - | picnic Charley - | horse Charley - | saddle horse - - jug - - ink jug - - clay jug - - Hegel jug - - tar - / 'old tar' tar - / ship 'old tar' - / Bermuda 'old tar' - - sod - \ grave sod - \ graveyard grave - \ house graveyard - \ church house - \ music church - \ white church - -In all the experiments the subject simply knew that possibly more than -one starting-point would be given. There was of course the conscious -recognition on the part of the subjects that the pronounced words were -starting-points, which would imply an attentive consciousness, but they -were cautioned neither to favor nor inhibit the newly pronounced word -nor an association in progress. - -The notes are uniform in showing that often one, two or three words -of the former association-series are written after the new word is -pronounced. "The momentum," says F., "was great enough to carry the -associations two or three words beyond the pronounced word"; while Bl. -found "a tendency for the trend of associations to persist, though -not strong enough to overcome the new influence." By.'s experience -was slightly different. As stated before, he often wrote the word as -it came into consciousness. "On hearing a new word it gets precedence -over the next associations not yet formed, and there is considerable -confusion and lost time unless the motor discharge of writing the -pronounced word is permitted to have free expression." The tables -verify the same, and also show that there are more associations during -the first interval. - -Does a former starting-point regain its influence? In the first -division there are two cases where the first and second fuse, but no -place where the first independently forms an association; in the second -but one word for subject Bl. in "Quill--Bench--Chalk," and in the third -not any. There was a small amount of fusion in all, since but two words -are due to the combined influence of the first and third, five to the -combined influence of the first and fourth, with three starting-points, -and one to the combined influence of the first and third with four -starting-points. - -The train of associations is inhibited by a new starting-point which -dominates in influence. No mention is made in any note that a former -starting-point remains in consciousness for the series, but M. -emphatically writes, "Absolutely no influence of the preceding word -or words when the next is taken up"; and later, "As soon as the new -one is pronounced the old word and the series it had brought up were -immediately suppressed." Bl. comments, "How remarkable it is that each -new word crowds the old trend of associations out and starts new ones"; -and the graphic representation, one of which only is given here on -account of lack of space, shows that there is no return to the original -series. - -The tables are indicative of the tendency. In the first division of -the group there are three possible lines of fusion, in the second six -possible lines, and in the third twelve possible lines, but we find -only 13.2% for all forms of fusion in the first, 7.9% for the second, -and 10.5% for the third. In the eighty-seven experiments of the series -there is but one absolute return to the previous starting-point. (See -Group IX, sec. 2, Bl.) The tables show the varying degrees of fusion, -and while the percentages have little meaning, as there is a variable -time-element, the numbers do show accurately the number of words and -the relative and continued influence of each starting-point. - -We conclude that, when the present content of consciousness is a -series of associations, the newly given impression establishes itself -sufficiently to inhibit the associations of the previous series. - - -TABLE XV. TWO WORDS--GENERAL AND PARTICULAR--SPOKEN - - Time--50 seconds, with an interval of 10 seconds between 1 and 2. - Characters--same as Table I. - - (1) Commencement--Sieve - - M. | | | - - - - - - - - - - - - - - - F. | | | | | | + + + + + + + - H. | | | | | - - - - - - - - - - - - - V. | | | | | - - - - - - - - - - - - - S. | | | | | | | | - - - - - E. | | | - - - - - - - - - - Bs.| | | - - - - - - - - - - - - - - - Ht.| | - + + + + + + - By. - - | - + α β - M. { 3 14 0 0 0 - {17.6% 82.4% - - F. { 6 7 - {46.2% 0 53.8% 0 0 - - H. { 5 12 0 0 0 - {29.4% 70.6% - - V. { 5 12 0 0 0 - {29.4% 70.6% - - S. { 8 4 0 0 0 - {66.6% 33.4% - - E. { 3 9 0 0 0 - {25.0% 75.0% - - Bs. { 3 14 0 0 0 - {17.6% 82.4% - - Ht. { 2 1 6 0 0 - {22.2% 11.2% 66.6% - - By. 0 0 0 0 0 - - - Totals {35 66 13 0 0 - {31.4% 55.4% 13.2% - - Number of subjects, 9; number of groups, 1; number of experiments, 8; - number of associations, 114. - - -TABLE XVI. THREE WORDS SPOKEN - - Time--50 seconds. Interval, 15 seconds. - - Characters: | first, - second, / third, + partial fusion between - first and second, α partial fusion between first and second with - first predominating, β partial fusion between first and second with - second predominating, γ partial fusion between first and third, δ - partial fusion between second and third, ε partial fusion between - first and third with third predominating. - - (1) Gun--Bug--Jaw - - M. | | | | | | | | - - - - - - / / / / / / - F. | | | | | - - - δ δ δ - H. | | | | | | - - - - / / / / / - V. | | | | | | | | - - - - - - / / / / / / - Bl. | | | | | | - - - - - / / / / / / / - By. | | | | | | | | | - - - - - - / / / / / / - Bs. | | | | | + + + + / / / / / - Ht. | | | | | | | α | | | δ - - - - - Ro. | | | | | | - - - - - - / / / / / / - - (1) Gun--Bug--Jaw - (2) Quill--Bench--Chalk - (3) Hall--Moss--Leather - - | - / + α β γ δ ε - - M. {20 14 18 1 0 0 0 0 0 - {37.8% 26.4% 33.9% 1.9% - - F. {15 11 15 0 0 0 2 3 0 - {32.6% 23.9% 32.6% 4.4% 6.5% - - H. {19 11 15 0 0 0 0 0 0 - {42.3% 24.4% 33.3% - - V. {24 15 21 1 0 4 0 0 0 - {36.9% 23.1% 32.3% 1.5% 6.2% - - Bl. {15 9 9 0 0 0 0 0 0 - {45.4% 27.3% 27.3% - - By. {23 8 14 3 0 4 0 3 0 - {41.8% 14.5% 25.5% 5.5% 7.2% 5.5% - - Bs. {13 10 10 4 0 0 0 0 5 - {30.9% 23.8% 23.8% 9.6% 11.9% - - Ht. {23 11 10 1 1 2 0 1 0 - {46.9% 22.5% 20.5% 2.0% 2.0% 4.1% 2.0% - - Ro. {15 15 24 0 0 0 0 0 0 - {27.8% 27.8% 44.4% - - Totals {167 104 136 10 1 10 2 7 5 - { 37.8% 23.5% 30.8% 2.3% .2% 2.3% .4% 1.5% 1.2% - - Number of subjects, 9; number of sections, 3; number of experiments, - 27; number of associations, 442. - - -TABLE XVII. FOUR WORDS SPOKEN - - Time--50 seconds. Interval, 10 seconds. - - Characters -- same as Table XVI, with addition of \ representing the - fourth, ς partial fusion between first and fourth, η partial fusion - between second and fourth, θ partial fusion between third and fourth, - ☐ total fusion between first, second, third, and fourth, ι partial - fusion between first, third, and fourth, κ partial fusion between - second, third, and fourth, λ partial fusion between third and fourth, - with fourth predominating, [ partial fusion between first, second, - and third. - - (1) Den--Nag--Cot--Fan - - F. | | | | | | - - - - - - δ - - \ \ \ \ \ - H. | | | | | - - - / / / / / / \ \ \ \ \ \ \ \ \ - V. | | | | | - - - / / / / \ \ \ \ \ \ \ - Bl. | | | | - - - - / / / \ \ \ \ - By. | | | | | | - - - - - δ δ δ \ \ \ \ \ - Bs. | | | - - / / / \ \ \ \ \ - Ht. | | | | | - - - - - / / / / \ \ \ \ - Ro. | | | | - - - - / / / / \ \ \ \ \ - - (1) Den--Nag--Cot--Fan - (2) Tax--Fan--Map--Dog - (3) Paw--Wand--Box--Mug - (4) Bud--Car--Cub--Mat - (5) Wax--Jug--Tar--Sod - (6) Cur--Elk--Pug--Man - (7) Rope--Wig--Ink--Grass - - (_Table on page 460_) - - -GROUP IX - -The aim here was to see if it were possible to have the first -starting-point such that the conditions would be similar to the results -obtained by using preparatory marginal settings, but include rather -than inhibit the second starting-point. A review of the tendency toward -mental combination in the former experiments suggested that the words -be in the relation of the whole and part. The "part" was given the -position of predominating influence in order to see to just what extent -it would persist in combining. - - | -- / \ + γ δ ς η θ - - F. { 29 19 11 19 3 0 4 0 0 11 - { 30.3% 19.8% 11.4% 19.8% 3.1% 4.2% 11.4% - - H. { 31 18 24 25 3 0 0 0 0 8 - { 28.5% 16.5% 22.1% 22.9% 2.7% 73% - - V. { 28 28 21 50 0 0 0 0 0 0 - { 22.0% 22.0% 16.6% 39.4% - - Bl. { 18 17 17 29 0 0 0 0 0 0 - { 21.6% 20.5% 20.5% 34.9% - - By. { 36 22 9 24 2 4 3 0 6 2 - { 32.1% 19.6% 8.0% 21.4% 1.8% 3.7% 2.6% 5.3% 1.8% - - Bs. { 22 13 17 18 4 1 0 1 0 6 - { 24.2% 14.3% 18.7% 19.8% 4.4% 1.1% 1.1% 6.6% - - Ht. { 30 18 10 21 3 0 0 0 2 1 - { 34.4% 20.6% 11.4% 24.2% 3.4% 2.4% 1.2% - - Ro. { 24 22 16 48 0 0 3 0 0 0 - { 21.3% 19.4% 14.2% 42.4% 2.7% - - Totals{218 157 125 234 15 5 10 1 8 28 - { 26.6% 19.2% 15.2% 28.5% 1.9% .6% 1.3% .2% .9% 3.4% - - ☐ ι β κ λ [ - - F. 0 0 0 0 0 0 - - H. 0 0 0 0 0 0 - - V. 0 0 0 0 0 0 - - Bl. 0 0 0 2 0 0 - 2.5% - - By. 4 0 0 0 0 0 - - Bs. 0 3 1 0 5 0 - 3.3% 1.1% 0 5.4% 0 - - Ht. 0 0 0 0 0 2 - 2.4% - - Ro. 0 0 0 0 0 0 - - Totals{ 4 3 1 2 5 2 - { .4% .3% .2% .3% .7% .3% - - Number of subjects, 8; number of sections, 7; number of experiments, - 52; number of associations, 819. - -In the light of the interpretation of previous facts and the subsequent -results of this group of experiments, we are now in a position to -conclude that, if the present content of consciousness on the reception -of a new impression is such that the reactions are not antagonistic -but reënforce each other, the second will not persist in independent -influence, but will be rather included in and supplementary to the -influence of the first, which otherwise would be less assertive. The -results below show that while the first of the two starting-points has -a decided disadvantage of position, and therefore has little influence -in arousing associations, it here is responsible for 43.2% and the -second for but 9.5%, while there is a combined influence of 47.3%, the -first strongly predominating in partial fusion. There is but one case -where the second was followed exclusively. - -The explanation of this, extended to an hypothesis, would rest in -the fact that each word has definite characteristic reactions and -that the fusion of two words or lines of thought means that the motor -accompaniments are such that they unite and reënforce each other, or -that the one includes the other. There are few antagonistic impulses. - - -TABLE XVIII - -TWO WORDS--WHOLE AND PART--SPOKEN - - Time--15 seconds. - Characters--same as Table I. - - (1) Crowd--Man - - A. | + + - M. + + + + + + + + + - F. + + + + + - H. - J. | | | | | | + + + - S. - - - - - V. + + + α α α α α α - E. | + + + - L. | | | | - Bs. α α α α α α - Br. | | | | | + + - - (1) Crowd--Man - (2) Ton--Pound - (3) Moose--Horn - (4) Engine--Whistle - (5) Book--Page - (6) Music--Octave - - | - + α β - - A. { 4 3 24 0 0 - { 12.9% 9.6% 77.5% - - M. { 13 0 27 2 0 - { 30.9% 64.2% 4.9% - - F. { 7 3 22 1 0 - { 20.6% 8.8% 64.8% 5.8% - - H. { 28 5 0 0 5 - { 73.6% 13.2% 13.2% - - J. { 21 1 17 6 0 - { 46.6% 2.3% 37.8% 13.3% - - S. { 25 12 0 0 0 - { 67.5% 32.5% - - V. { 4 2 16 10 0 - { 12.5% 6.3% 50.1% 31.1% - - E. { 11 3 9 5 0 - { 39.2% 10.8% 32.2% 17.8% - - L. { 14 6 4 0 0 - { 58.4% 25.0% 16.6% - - Bs. { 15 2 11 6 0 - { 44.2% 5.8% 32.4% 17.6% - - Br. { 25 0 9 9 0 - { 58.2% 20.9% 20.9% - - Totals { 167 37 139 39 5 - { 43.2% 9.5% 35.9% 10.0% 1.4% - - Number of subjects, 11; number of sections, 6; number of experiments, - 62; number of associations, 387. - - -GROUP X - -In the last group the words were called whole and part, although -the reader no doubt observed that this was not always strictly the -case, but rather that the more complex was more influential as a -word-suggester than the simple and often tended to include it. Can -this be demonstrated in another way? Attention was called in Group of -Experiments IV (two pictures shown) that picture no. 3 (a man sawing -wood), although first, had more than the normal number of associations, -the explanation of which might lie in the fact that it contained more -objects. We here attempt to test this by comparing a comparatively -complex and a comparatively simple picture as starting-points. It has -been clearly proven that the second picture to be presented has a -decided advantage of position. The simple picture is here given the -advantage of position. The notes show the first to be more important, -while there is no suggestion of the first including the second, on -account of there being less fusion than for words and more independent -associations for the second starting-point; the averages are 38.5% for -the first, 30.5% for the second, 31.0% fusion. - - (a) Picture of Blacksmith shoeing horse - (b) Picture of a Sheep. - | shop (a) - | nails shop - | shoe shop and (a) - | blacksmith shop and shoe and (a) - | Longfellow blacksmith - - pasture (b) - - sheep pasture - - lambs pasture and sheep - - grass pasture and lambs - - hillsides grass - - brook pasture and hillsides - | iron shop-shoe - | hammering iron - | soldier iron-hammering and first group - | battle soldier - | shoe battle - | horse-shoe nail iron, hammering, soldier, battle - | anvil horse-shoe nail - - -TABLE XIX. TWO PICTURES SHOWN - - Time--50 seconds. - Characters--same as Table I. - - (1) (a) Blacksmith shoeing Horse - (b) A Sheep - - J. | | | | | - - - - - - | | | | | | | - E. | + + - - | | | - W. | - | - - - | | | | | | | - V. | | + + + + + + + + + + + + + - L. - | | | | | | | | - Ht. - - α α | | | | - + + + + + - - - (1) (a) Blacksmith shoeing Horse - (b) A Sheep - - (2) (a) Girl and Boy - (b) A Bird - - (3) (a) Three Children - (b) A Duck - - (4) (a) A Sower - (b) A Dog - - | - + α β - - J. { 30 23 9 18 0 - { 37.5% 28.8% 11.2% 22.5% - - E. { 28 10 2 0 0 - { 70.0% 25.0% 5.0% - - W. { 14 18 5 0 0 - { 37.8% 48.7% 13.5% - - V. { 6 11 37 0 13 - { 8.9% 16.4% 55.3% 19.4% - - L. { 27 4 1 0 0 - { 84.3% 12.5% 3.2% - - Ht. { 16 30 6 6 0 - { 27.6% 51.8% 10.3% 10.3% - - Totals {121 96 60 24 13 - { 38.5% 30.5% 19.2% 7.6% 4.2% - - Number of subjects, 6; number of sections, 4; number of experiments, - 24; number of associations, 314. - - -GROUP XI - -Three words spoken, one immediately following the other, are given -in this group in order to test the span of consciousness and the -influence of an immediate interruption, as one was given immediately -following the other in such a way that all associations were checked -until after the third starting-point. If we attempt to follow the -initial starting-points we see they may disappear after the first few -associations and reappear in the series; or each remain as initial -starting-points for a few associations; or one alone control the whole -series, while the others are present without influence; or there may be -an alternation of independent influences; or an influence which shows -a modifying effect of one or both of the other starting-points, which -may reach such a degree that all fuse, and in so doing get an advantage -over the single words. The starting-points are to a large extent -disparate and there is very little fusion; we find only .5% total -fusion and 18.7% partial fusion. - -An example would be as follows: - - -SUBJECT VIII - -FROG--ICE--TABLE - - - snow ice - | bench table - | fish frog - | pole fish - | boat fish - | line fish - | bait fish - | weeds fish - - skating ice - - sleds ice - - coasting sleds - - girls coasting - -There were no cases of the total fusion of all the starting-points -throughout the series, no cases of total fusion of the first and -second, and two cases for the second and third. There were two cases of -partial fusion of the first, second, and third throughout. The first -was followed exclusively in two cases, the third in one. The first and -third were followed intermittently in four cases, the second and third -in eleven, the first, second, and third in thirty-five. - -The second starting-point has the ascendency of influence. This is -not due to habits formed in earlier experiments, as the two groups -of experiments with two words were given in connection with other -experiments. This group informs us that in immediate interruption the -new impression has not sufficient power to establish itself more firmly -than a past impression which is just past, and must in a manner be -reproduced to start associations. The influence of the first has been -somewhat destroyed, but the second is greater than the third. - - -TABLE XX. THREE WORDS SPOKEN - - Time--50 seconds. - - Characters--same as Table XVI, with the addition of [ representing - total fusion between the first, second, and third, μ partial fusion - between first, second, and third with first predominating, ν partial - fusion between first, second, and third with first and third - predominating. - - (1) Frog--Ice--Table - - A. / - - - - - - M. - | | γ γ γ γ γ γ γ γ γ - F. - - - - - / / | | | | / / / - - - - H. | - - - - - | | | | / / / - - - - J. | - - / / / / - + + + + + + + + - Bl. - / | | | | | | - - - - - By. | / / / / / / - - - - - - - - - - - - - - - - - Bs. - | | | - - - / / - Ro. | | - - / / / / / / / / / / / - Br. - / / / δ δ δ δ δ δ - - (1) Frog--Ice--Table - (2) Key--Shoe--Knife - (3) Desk--Park--Glove - (4) College--Church--Cafe - (5) Boston--Elevator--Lake - (6) Skate--Book--Theatre - (7) Bridge--Sleigh--Ticket - (8) Gun--Lamp--Watch - - | - / + α β γ δ [ μ ν - A. { 26 32 30 0 0 0 0 0 2 10 0 - { 26% 32% 30% 2% 10% - - M. { 25 36 21 3 0 0 10 1 1 0 6 - { 24.3% 34.9% 20.5% 2.9% 9.8% .9% .9% 5.8% - - F. { 15 23 24 8 11 0 7 6 0 0 0 - { 15.9% 24.5% 25.5% 8.5% 11.8% 7.4% 6.4% - - H. { 31 68 31 0 0 0 0 0 0 0 0 - { 23.8% 52.4% 23.8% - - J. { 19 18 48 15 0 0 0 22 1 0 0 - { 15.5% 14.6% 39.1% 12.2% 17.8% .8% - - Bl. { 23 33 16 5 0 0 0 22 0 0 0 - { 23.2% 33.2% 16.0% 5.0% 22.6% - - By. { 13 56 48 15 0 1 17 2 0 0 0 - { 8.7% 36.8% 31.5% 9.8% .6% 11.2% 1.4% - - Bs. { 19 13 19 9 0 0 0 19 2 0 0 - { 23.4% 16.0% 23.4% 11.2% 23.5% 2.5% - - Ro. { 32 33 33 0 0 0 0 0 0 0 0 - { 32.6% 33.7% 33.7% - - Br. { 12 24 38 0 0 0 6 0 0 0 0 - { 15.0% 30.0% 47.5% 7.5% - - Totals{215 336 308 55 11 1 40 72 6 10 6 - { 20.3% 31.1% 29.1% 5.2% 1.1% .9% 3.6% 6.8% .5% .9% .5% - - Number of subjects, 10; number of sections, 8; number of experiments, - 79; number of associations, 1060. - - -GROUP XII - -In order to test the relative influence and to throw more light on the -problem of immediate interruption four words were shown and the subject -was directed to read from left to right. There were few experiments -and most of the subjects were new. The results show that the third -starting-point has a decided disadvantage, having an influence of only -7.8%. The second and fourth are almost equal, while the first is again -less. - - -TABLE XXI. FOUR WORDS SHOWN - - Time--50 seconds. - - Characters--same as Table XVII, with the addition of ξ partial fusion - between the second, third, and fourth with the second predominating. - - (1) Gun--Car--Ink--Fan - - M. \ \ \ - - - - - / / / / / / - R. \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ - K. \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ - S. - | / - - - - - - - - - J. | | | - - - - - - - - - - - - Ht. + + α α α | | | | | | | | | - - (1) Gun--Car--Ink--Fan - (2) Brain--Umbrella--Telephone--Chain - (3) Book--Money--Hour--Chart - - | - / \ + γ θ α κ ξ - M. {14 6 9 4 0 6 0 0 0 0 - {35.9% 15.4% 23.0% 10.3% 15.4% - - R. {16 0 0 30 0 0 0 0 0 0 - {34.8% 65.2% - - K. { 0 35 0 16 0 0 0 0 0 0 - { 68.6% 31.4% - - S. { 5 15 7 4 0 0 0 0 0 0 - {16.2% 48.4% 22.5% 12.9% - - J. {13 13 4 15 2 0 0 0 0 0 - {27.7% 27.7% 8.5% 31.9% 4.2% - - Ht. {15 9 0 5 2 0 7 3 1 1 - {34.8% 20.9% 11.6% 4.7% 16.3% 6.9% 2.4% 2.4% - - Totals{63 78 20 74 4 6 7 3 1 1 - {24.5% 30.4% 7.8% 28.5% 1.6% 2.4% 2.6% 1.4% .4% .4% - - Number of subjects, 6; number of sections, 3; number of experiments, - 18; number of associations, 257. - - -GROUP XIII - -Four similar words were pronounced in immediate succession, the results -of which show that we are correct in calling the above a case of -succession and also to establish clearly and definitely that there is -a difference of degree between immediate and postponed interruption. -The third starting-point has again a decided disadvantage of influence -and exerts no apparent influence in thirty-seven of the fifty-two -experiments. The last starting-point exerts the greatest influence. - - -TABLE XXII. FOUR WORDS SPOKEN - - Time--50 seconds. - - Characters--same as Table XVII with the addition of ο partial fusion - between first, second, and third with first and second predominating. - - (1) Cow--Roof--Fence--Girl - (2) Cathedral--River--Elevator--Newspaper - (3) Cane--Harness--Box--Coat - (4) Book--Snow--Rope--Stone - (5) Wire--Flower--Horse--Paper - (6) Gun--Wharf--Chair--Stove - - | - / \ + λ δ η θ ☐ ι ο ε β - M. { 35 3 6 32 0 3 17 0 9 0 0 0 0 0 - { 33.4% 2.8% 5.8% 30.4% 2.8% 16.2% 8.6% - - F. { 16 11 1 35 0 3 0 0 1 2 1 0 5 0 - { 21.3% 14.6% 1.4% 46.6% 4.0% 1.4% 2.7% 1.4% 6.6% - - H. { 21 38 11 30 0 0 0 0 0 0 0 1 0 1 - { 20.6% 37.3% 10.8% 29.5% .9% .9% - - V. { 16 16 0 36 2 2 9 0 1 0 1 0 0 0 - { 19.3% 19.3% 43.3% 2.4% 2.4% 10.9% 1.2% 1.2% - - Bl.{ 36 8 10 19 0 0 4 0 0 0 0 0 0 0 - { 46.8% 10.3% 12.9% 24.8% 5.2% - - By.{ 23 30 3 36 1 0 0 0 1 0 0 0 0 0 - {24.5% 31.9% 3.3% 38.3% 1.0% 1.0% - - Bs.{ 22 14 1 20 1 0 0 7 0 1 0 0 0 0 - {33.3% 21.3% 1.6% 30.0% 1.6% 10.6% 1.6% - - Ht.{ 9 19 4 31 0 0 0 0 1 14 0 0 0 0 - {11.5% 24.3% 5.2% 39.8% 1.3% 17.9% - - Ro.{ 26 23 6 16 0 0 0 0 0 0 0 0 0 0 - {36.6% 32.4% 8.4% 22.6% - - Totals - {204 162 42 255 4 8 30 7 13 17 2 1 5 1 - {27.2% 21.6% 5.4% 33.9% .5% 1.1% 3.9% .9% 1.8% 2.3% .3% .2% .7% .2% - - Number of subjects, 9; number of sections, 6; number of experiments, - 52; number of associations, 751. - -We ask finally how far our results and notes point to a theoretical -understanding of the mechanism of associations. Previous work, -especially that of James, Cordes, Calkins, and Scripture, as well as -the accumulated notes of my subjects, confirm that the transition -may be made by means of total, partial, and focal recall, and that -in partial and focal recall the prominent persisting elements are -surrounded in the formation of a new idea by other new elements. - -If a latent idea remains in the margin of consciousness and exerts -an influence, which not merely modifies but determines the series of -associations, and leads up to the focalisation of the latent idea, -we have a case of predetermined association, which, when noted by -investigators, has invariably become confused with mediate association. -Here there is an element or group of elements, persisting in the margin -of consciousness, which is gradually maturing and becoming focalised -into groups of elements comprising an idea which ultimately dominates -consciousness. In some cases three, four, and five ideas have been -named before this takes place, and we have here a reversed form of -association. Four subjects noted the experience on different occasions, -and it is not to be confused with the common experience of apprehending -the present contents of consciousness as part of a larger whole where -we are conscious of its existence but not of what it is. - -The notes further show that the common conscious elements may be -predominantly visual, auditory, olfactory, gustatory, or kinæsthetic, -or a complex or compound of these in character, while to this may be -added an indication of the fact that the transition, incipient as it -is, may in many cases be reduced to a condition which is in the last -analysis one of the motor nervous system. Ht., for instance, finds -that the words all pass over into innervations of the organs of speech -and "are accompanied by the impulse to make the sound," stating later, -"they hang on the tongue." The following is one of the series given -which represents rather an extreme case, Taft, taffy, toffy; tough, -rough, ruff; buff, bluff, tough; muff, duff, tuff. Br., who also gave a -large percentage of verbal associations, finds that "some part of each -word seems to linger on the tongue with motor sensations till the next -comes." "I am subject," he adds, "more or less frequently to verbal -automatism of this auditory incipient motor type." Ro., who has many -auditory associations, reports "they are always accompanied by motor -images, together with many associations." A changing of orientation is -a common accompaniment, with statements of the feeling of the impulse -to turn in various directions. For F., who is predominantly of the -motor type, we have an example where the rhythmic ticking of a clock -fades into the rhythmic watching of a boat rising and falling on the -water. - -The notes would seem to indicate that there is no idea without a -motor fringe, and also that these elements of incipient impulses to -movement may accompany the elements of transition, and are observed -introspectively by the subjects. They are therefore data for -psychology. Do they influence or direct the associations? In short, are -they the processes which connect and which determine the associations? - -F. states, "There seem to have been waves of motor sensations. Such -waves may start with a word and carry one in faint mimicry through -the whole succession of bodily sensations that one experienced in -that event, and then may come a relapse until other stronger currents -appear." Here we are face to face with the dynamics of association, -the most fundamental and important problem of brain association. Have -these phenomena of ideational images "acquired by contact a kind of -magnetism which causes the one to attract the other and have, so to -speak, become magnetic?" (Zanotti.) Or are they on the other hand -independent of all force and "merely ideas of antecedence and sequence -only?" (Mill.) While there is no mention of a magnetic force, the notes -and results all show that the ideas are systematically conditioned in -a way which cannot be explained by the contiguity of the objects. The -motor elements play the deciding role. Ht. emphasises the influence -of ideated movement when he writes, "Kinæsthetic. Slow regular -tramping on snowshoes brought up the characteristic swing of arms, -and therewith the idea (sensations of weight) of the stick (or stock) -which I have generally carried on Norwegian snowshoes. Transition from -Vermont to the Black Forest by association with snowshoeing in both -places. Real sensations in play were free breath, movements in chest -(kinæsthetic), fresh air (olfactory), cold (thermal), and emotion -of emotional strength." Again, "Looking up at sun suggested general -ideas of expansion of attention and with this breath comes the idea, -breezes"; another subject adds, "A tendency to imitate the sounds of -syllables and this leads on to a train of associations"; another, "A -slight feeling of sudden changed impulse"; another, "A sort of motor -after-image came back and took the foreground"; and F. goes further -when he states, "Ideationally my hand wandered to the upper right-hand -corner of the page, then suddenly the auditory image of 47 came up as -if whispered to me." All of which indicate that some ideas at least -depend for their entrance into consciousness upon motor reactions. - -Passing to the more refined reactions expressed in emotions we find -that they are not merely accompanying coloring influences, but also -often actual determining factors. All of the subjects notice at some -time a coloring atmosphere from an emotion, but others find that "the -growing word is rather felt emotionally than definitely formulated," -and we have "a nameless idea, largely feeling-tone" (Ht.); or the words -may "all come as parts of a growing feeling, an indistinct though -strong state of mind." (J.) The same subject observed, "The previous -word may create a mood or feeling which in the main determines the -associations; a group of words is dependent upon strong accompanying -feeling--there is a summation and a discharge while the next word has -been accumulating force" (J.), and we have a form of summation; or -in other words, "a general mood accumulated while several words were -in mind at once, then all dropped and another general feeling came -to the front with an accumulation of other words." (F.) Here we have -a typical example of constellation where all the words and ideas are -implicitly present as a total attitude or disposition, the elements of -which become successively focalised into a series of associated images. -The last subject finds that "the emotional atmosphere often controls -the associations." Indeed, it would seem that occasionally for some -subjects this strong accompanying undercurrent of undifferentiated -emotional feeling is capable of bringing about trains of thought -independent of any logical connection. K. finds "the feeling to carry -one on"; H. finds the "point of departure the interesting idea"; all -find that the words change with the disposition, as may be verified by -a study of the lists of associations. - -We are forced to conclude that the impulses to movement or other -emotional attitudes may act as determining factors in association, -which extended to an hypothesis would mean that the mode of transition -in the associated series is in the last analysis to be found in -delicate incipient motor tendencies to action, the psychic concomitants -of which are observable; that psychic states are both as to their unity -and organisation consequences of motor reactions which are implicitly -present as parts of a total reaction to the present situation. It is -these motor tendencies to action which determine what idea shall enter -consciousness. Just in so far as they become released they become -prolonged, accentuated, and form a nucleus for the new idea. To speak -of association independent of motor elements is merely to make an -empirical classification of successive states of consciousness. - -There remains a psychical phenomenon which must be satisfactorily -accounted for before we go farther. An element of an idea, an idea or -a series of ideas may occupy consciousness to the exclusion of others. -If the second starting-point were not given, the associations would -undoubtedly follow the given one. Inhibition must then be one form of -"obstructed association," the inhibiting ideas being present to the -exclusion of the inhibited. But are we thus forced to say inhibition -is the "negative side of the association process," claiming that -all ideas not in consciousness are inhibited, and thus being forced -to conclude the conscious idea is inhibiting an unconscious idea, -which cannot exist (by the very definition and presuppositions of -psychology) until it is an object of consciousness. This would mean -that content of consciousness and inhibition are identical. On the -other hand, the notes and exemplifying facts of the tables show Dr. -Breese's fallacious position when he concludes that "because, obeying -the laws of association, the train of ideas takes one direction -rather than another can hardly be considered sufficient ground to -hold that the other possible train of ideas is inhibited."[137] He -has overlooked the possibility of two or more trains of associations -having been started and the associations of one starting-point are -excluded from entering the focus of consciousness by the direction -of the given series. Inhibition would then be the negative side of -fusion. The explanation must, as has already been demonstrated, be -psycho-physical in character. If these impulses to action have actually -been observed by the subjects we are justified in concluding that just -as in physiological inhibition one action excludes another, so the -correlative tendencies to movement of one idea exclude others. - -By. observed that the image of the starting-point lingered and -inhibited subsequent ideas. The implication here, from our previous -reasoning, would be that not the ideational images, as such, but the -physiological motor concomitants, persisted and excluded others, and -this is why disparate terms give a "shock to the nervous system" -(A.), "require different lines of expression" (A.); and "one has more -momentum," as so many report. This would explain why the associations -of a new starting-point inhibit the associations of a former one; for -as the motor nervous impulses tend to work themselves out into action, -the reaction of the previous impulse will be suppressed by those of a -new impulse which enters, by the conditions of these experiments, an -attentive consciousness. Thus the prepotent impulses to action are the -conditioning factors in mental inhibition. - -All this indicates that the basis of habit which has been the universal -principle of explanation of associations is inadequate. As Münsterberg -has pointed out, contrary to what we mean by habit, either idea may -bring to consciousness the other, in a manner independent of the order -of the original presentation. Extending our hypothesis to include the -formation of associations, the conclusion will be that in order for -two ideas to become associated they must be together in consciousness, -each as parts of a total experience, a total attitude; the motor -reactions of the ideas must be parts of a more comprehensive reaction -which includes both as simultaneous correlated motor impulses: when, -in future time, the reactions of the one are reëxperienced, there is -a sequence of infinitely delicate and complex impulses to movement, -and any tendency toward such reaction tends to reproduce the whole of -which it is a part, as each reaction is more or less bound up in the -integrity of the whole central nervous system. - -FOOTNOTES: - -[Footnote 133: Cordes, G.: Experimentelle Untersuchung über -Association, Phil. Studien, vol. 17, p. 30.] - -[Footnote 134: Scripture, E. W.: Elements of Experimental Phonetics, p. -142.] - -[Footnote 135: Calkins, M. W.: Memory and Association, Psychol. Rev., -vol. 5, p. 451.] - -[Footnote 136: Calkins, M. W.: Association, Psy. Monograph, no. 2, p. -46.] - -[Footnote 137: Breese, B. B.: On Inhibition, Psy. Rev. Monograph, vol. -3, p. 15.] - - - - -DISSOCIATION - -BY C. H. TOLL - - -The purpose of this investigation, of which the following gives a -preliminary report, was to compare the tendency to associate by -contiguity, with the tendency to associate by similarity. - -In every series of stimuli to which one gives attention there is -tendency to association by contiguity. But some similarity among -certain elements of the series may produce a dissociation of the given -elements into two series with some bond of similarity in each. This -is a matter of common experience, as when you find you can read your -newspaper and listen to your neighbors' conversation at the same time, -understanding both, although the actual order in which the several -words are perceived would form a meaningless mixture. - -We may say dissociation is always accomplished by a tendency to -association by similarity overcoming the constant tendency to -association by contiguity. Study of the relative efficacy of the two -may therefore be called a study of dissociation. The tendency to -associate by contiguity might be measured in two ways. - -First, when one attempts to learn a series in exactly the given order, -the number of errors in the series as recollected may be taken as an -inverse indication of the strength of association by contiguity. The -three kinds of error possible in nearly all of the experiments were -Omissions, Displacements, and Imperfections. All of these three have -been tabulated. But the number of elements omitted seems considerably -the most reliable as an indication of the degree of inadequacy of the -associative tendency. The cases of displaced or imperfect elements are -comparatively few: moreover, Displacements and Imperfections are not -mutually exclusive categories. A single element may be both imperfectly -recollected and wrongly placed in the recollected series. On the whole, -it seems that the number of given elements which were omitted in the -recalled series is the most positive and reliable of the errors. Our -conclusions are based on the Omissions. - -Second, when one makes no attempt to learn the series, simply giving -attention to each element as it comes, and afterward lets the elements -recur spontaneously, the number of cases in which a recollected element -is followed by an element given contiguously may be taken as a direct -indication of the strength of association by contiguity. - -Tendency to association by similarity can evidently be measured in -the same two ways, by counting errors when one purposes to learn the -series as two groups of similar elements, and by counting sequences of -similar elements when one avoids any effort to learn the series and -recollection is spontaneous. - -In the first seven experiments we used the first method. The errors -made when the purpose is to associate by contiguity can then be -compared with the errors made when the purpose is to associate by -similarity, an equal number of series, given under the same conditions, -and of identical character, being given in each case. - -In the last four experiments we have used the second method. The number -of sequences of elements given contiguously can then be compared with -the number of sequences of similar elements. - -Five subjects have coöperated in this, but the experiments were -strictly individual, one observer being alone in the room with the -experimenter. Each test lasted about an hour. As a matter of course, -the results have been calculated for each of the five subjects and -their agreements and disagreements have been carefully considered. But -as this first report is to indicate merely the general tendency, we -give here at first only the average of the five persons. - -The experiments have varied as to the kind of elements used, the manner -of presentation, the time allowed, and the manner of recording the -recollected series. But throughout each experiment the series were of -one identical type, while the individual elements were altered in each -series. - -In the experiments where the series were to be learned, some in the -given order, some dissociated by similarity, it was found rather -confusing to turn from one method to the other; so several consecutive -series were learned by one method, and then several by the other, four -alternations being made each hour to neutralize any effect of practice -or of fatigue. - -The series were of course different in kind in the several experiments, -but were usually of eight or of ten elements. Half of this number had -some distinct characteristic in common, the other half some other -characteristic. In some experiments these elements were alternated, in -some arranged irregularly. - -In the first eight experiments the subject wrote down the elements -recalled, as soon as the series had been given. In the last three the -subject spoke the elements recalled. - -In all cases where the first method of measurement was used, the time -allowed for learning the series was made a little too short to permit -of learning the series perfectly. Since comparison of the number of -mistakes was our method, we naturally had to make sure there would be -mistakes to compare. - -The details of the several experiments were as follows: - -(1) The elements were letters and numbers. They were about 12×8 mm. in -size and were printed on white cards 15×30 mm. - -Five letters and five numbers were placed, alternately, in a straight -row on a sheet of white cardboard. The series was then exposed to -the subject by turning up the small tin shutter of a screen that was -clamped to the table-edge. - -The time of exposure was measured with a stop-watch and was constant -throughout the hour for each individual subject. Four seconds proved -the best time for most of them, but in one case it was necessary -to allow only three seconds. Twenty series were presented during -each hour, ten for each method of memorizing. There were duplicates -of all the numbers, and of eight letters, but not more than two -of any element. Selection in forming the series was by chance. In -dissociating, the letters were separated from the numbers. - -As soon as the exposure was ended, the subject wrote down the elements -recollected, trying to preserve their relative order. This recollected -list was then copied beside the operator's record of the given series, -so making the errors apparent. - -(2) The elements were all letters, printed as before, and the alternate -cards were placed half their length out of alignment with the original -row. - -The method of presentation, the length of exposure, the number of -elements presented, etc., were as in no. 1. In dissociating, the -letters on one level were separated from those on the other. - -(3) The elements were all letters, printed as before, and five of the -ten elements presented were placed out of alignment. But the disaligned -cards were at irregular intervals and often in groups, and were only a -quarter of an inch out of alignment. This order was varied each time, -but without any system. - -The other details were as in no. 1. - -During this experiment I came to notice the effect produced by the -natural tendency to learn the five elements of the dissociated series -in a rhythmical form, thereby increasing the ability to retain them; -while there appeared to be no natural tendency to apply any such -inclusive rhythm to the ten elements of the series when learned in the -given order. To counteract this effect the subjects were instructed -to consider the series, when learned in the given order, as two -consecutive series of five elements each, and to use the same natural -rhythm in learning these as they did in the dissociating. But this -correction was not made in the first two hours, nor very perfectly in -the rest. - -(4) The elements were all numbers, printed as before, five of the ten -being placed a quarter of an inch out of alignment, and in irregular -groups, precisely as in the last experiment. - -The time was reduced to three seconds for some and two seconds for the -others. Details of presentation were as described in no. 1. - -This time all the subjects tried to neutralize the effect of the -instinctive rhythm for the five-element series by learning the -ten-element series in two groups of five elements each. - -(5) The elements were all nonsense syllables, each consisting of a -vowel between two consonants, printed on white cards 20×20 mm. Eight -of these were placed in an even row on a sheet of white cardboard, and -four of them were marked by laying a quarter-inch strip of blue paper -over the bottom of the card. The serial position of the marked cards -was irregular, and was altered each time. - -Ten seconds was given to some subjects, eight to the others. Other -details of exposure, etc., were as in no. 1. - -In learning the series in the given order, the blue markings were -ignored; but in dissociating, the marked and unmarked syllables were -learned in separate groups. - -There seemed to be no rhythmical tendency; but to be safe the subjects -were instructed to learn the straight series in groups of fours. - -Seven series were given to be learned in each method during the hour -with each subject. - -(6) The elements were one-syllable nouns, alternated with nonsense -syllables, all spoken by the operator. The nonsense syllables were all -different from those used in the preceding experiment: the nouns were -ordinary words, and were so arranged as to avoid any obvious sequence -or relation among them. Very few, if any, were used twice in one hour. -Five nouns and five syllables were given in each series. - -The elements were spoken at the rate of forty-six a minute, timed by a -metronome which was muffled in a heavily padded box so that its sound -was no disturbing factor. The speaker sat within three feet of the -subject and enunciated as distinctly as possible. - -Dissociation was performed as previously: in each hour eight series -were dissociated, and eight learned in the given order. - -(7) The elements were one-syllable nouns, spoken as before, alternated -with nonsense syllables, printed on small white cards. The nouns were -all different from those used in the previous experiment: the nonsense -syllables were the same, but were this time printed, in letters 10 mm. -high, on cards 40 mm. square. They were exposed by sliding them, one at -a time, in front of an opening in a cardboard screen which was fastened -to the table-edge. - -The optimum rate for presenting the elements was found to be about -forty a minute, measured with the metronome. - -Five nouns and five nonsense syllables were given in each series. Eight -series were given to be learned in the given order, and eight to be -dissociated into separate series of nouns and of syllables. - -(8) The elements were names of mammals, alternated with names of cities -of the United States, all spoken. The names were all fairly familiar. -Ten elements were given in each series. - -The interval in reading was planned to be long enough for some -appreciation of the meaning of the words, but not enough to permit -mental repetition of the preceding elements. Any mechanical -time-measurement was found impracticable. - -The subjects were instructed to avoid any effort to memorize the -series, simply receiving each element as given. - -After the last element there was a pause of about two seconds, to -decrease the mere sound-recollection of the last few elements. Then the -operator repeated, in an altered tone, one of the given elements. The -subject at once wrote down the first element that came to mind, then -the next, and so on. - -In the seven preceding experiments the set of series presented had been -different for each subject, though of course identical in character. -But in this experiment and the following ones the lists of words were -identical as read to each subject. The same element was repeated for -each. Sixteen lists were given. - -(9) The elements were nouns. In each series five names of similar -objects were alternated with five names of a different sort of objects, -_e. g._, names of fishes with names of poets. All were read, as before. -In each series new sorts of objects were chosen. The subject never knew -what sort of words were to be given; the subjects agreed this was not a -disturbing factor to them, and it obviated the tendency to think what -words would probably be given, as is natural when the general character -of the series is announced beforehand. - -The subjects were instructed to be passive during the reading, and -during the four-second pause that followed, avoiding mental repetition -of the words. Then the operator gave a signal and the subject repeated -aloud the words as they happened to be remembered. The words being -numbered on the list from which they were read, the operator was able -to record the words as fast as spoken. - -The subjects were instructed to give the word which they found to be -foremost after they had spoken the preceding one, rather than to try to -repeat a group of words which usually appeared simultaneously at the -first effort of recollection, but which usually faded while one of them -was being spoken. - -The same sixteen series, of ten elements each, were given to each -subject. - -(10) The elements were nouns, the ten presented in each series all -being names of similar objects, _e. g._, flowers. Five were spoken, -alternated with five printed on small cards which were shoved in -front of a 10×10 cm. opening in a cardboard screen fastened to the -table-edge. Cards were 40 mm. square, the words printed by hand, but -carefully, in letters 10 mm. high. - -A series was given in about 13 seconds, but the time was not -mechanically measured; it was at a rate which some practice showed to -give a fair time to comprehend each element. - -As before, the subjects were told to be passive until, after a -four-second pause at the end of the series, the operator gave a signal. -Then the recollected words were spoken. - -The class of nouns was different in each series. - -(11) The elements were nouns. In each series five of some familiar -class were alternated with five of some other familiar class. The -classes were different in each of the twelve series given. - -From this regular series of ten, five were chosen irregularly, and -were printed on cards as in no. 9. The remaining five, of course also -irregularly placed in the series, were spoken. This irregularity was -different in each series. Thus some words of one kind were spoken, -the rest printed; some words of the other kind were spoken, the rest -printed. - -The other conditions were exactly as in the last experiment. - - * * * * * - -A table for the individual subjects, indicating not only the omitted -but also the displaced and imperfect objects would have, for instance, -the following character: C indicates that the effort was made to -associate by Contiguity, S by Similarity. - - -SPOKEN NOUNS, ALTERNATED WITH PRINTED NONSENSE SYLLABLES - - Nouns Omitted Syll. Omitted Displaced Imperfect - C S C S C S C S - Turley 13 16 21 14 7 13 6 10 - Emerson 4 5 26 16 7 4 4 13 - Miss Kent 5 8 15 8 18 5 9 4 - Flexner 4 6 10 9 7 3 8 16 - Toll 8 7 8 2 10 12 8 3 - - Total 34 42 80 49 49 37 35 46 - -If we consider total results only, and among them only the omitted -elements, we come to the following percentages. They give the -percentage of the errors of omissions among the elements recalled. - - 1. Letters and numbers alternated C 26. S 10.8 - 2. Letters, alternatingly disaligned C 21.2 S 15. - 3. Letters irregularly disaligned C 23.8 S 22.4 - 4. Numbers irregularly disaligned C 7. S 20. - 5. Nonsense Syllables, irregularly marked C 27.5 S 27.5 - 6. Nouns and Nonsense Syllables alternated, spoken C 35. S 37.2 - 7. Nouns and Nonsense Syllables alternated, nouns spoken, - syllables printed C 28.5 S 22.7 - -In the second group, experiments 8 to 11, not the errors of omission, -but, as explained above, the different kinds of reproduced elements, -had to be analyzed with special reference to the question whether a -sequence linked two contiguous or two similar objects. In the following -table the total number of recalled sequences is taken as basis and -the different kinds of sequences are given in percentages of it. The -elements themselves are described above. B means a break, that is, a -sequence without similarity or contiguity. - - 8. Dissimilar elements, similarly presented S 45 C 28 B 28 - 9. Dissimilar elements, different kind in each series S 53 C 25 B 21 - 10. Similar elements, dissimilarly presented S 54 C 20 B 26 - 11. Dissimilar elements, dissimilarly presented - S (Meaning) 27 C 7 B 8 - S (Presentation) 13. - -The results by the first method of measurement may be summarized -as follows, though the first and third conclusions are weakened by -disagreement among the individual subjects. - -_A._ When the only dissociating factor is some slight unessential -feature (a bit of color on the card, a slight disalignment), this -similarity and contiguity are nearly equally efficient. No. 3 and no. 5. - -As this unessential feature is made more striking (disalignment half a -card-length), the strength of similarity increases, only three fourths -as many errors being made in dissociation as in contiguous association. -No. 2. - -The case of no. 4 (all numbers) is of little or no value. The time -allowed for learning had to be made short enough to ensure the -appearance of some errors; perfect recollection would obviously give -no basis for comparison. And the time had to be so short in this -case (only two seconds for some of the subjects) that the additional -eye-motions and adjustments necessary in dissociating took time enough -to spoil the results. - -_B._ When the only dissociating factor is in the meaning of the -elements (letters and numbers), this similarity is stronger than -contiguity, only one half as many errors being made. No. 1. - -The results of no. 6 do not support this proportion, but its results -are not consistent, while those of no. 1 are. - -_C._ When both meaning and manner of presentation are combined as -dissociating factors (nouns and nonsense syllables, seen and heard), -this similarity is stronger than contiguity, only three fourths as many -errors being made. - -But this method of measurement is not well adapted to series of -auditory elements, so this experiment is unsatisfactory. No. 7. - -The results by the second method of measurement may be summarized as -follows: - -_A._ When the only dissociating factor is in the meaning of the -elements (names of different sorts of objects), this similarity is -stronger than contiguity, twice as many similarity sequences as -contiguity sequences being recalled. No. 8 and no. 9. - -_B._ When the only dissociating factor is in the manner of presentation -(to sight and hearing), this similarity is stronger than contiguity, -nearly three times as many similarity sequences being recalled. No. 10. - -_C._ When both meaning and manner of presentation are dissociating -factors, these similarities are much stronger than contiguity, more -than four times as many similarity sequences being recalled. - -_D._ When these two dissociating factors are opposed to each other: -(1) Four of the subjects show similarity of meaning much stronger -than similarity of presentation, from two to five times as many -similarity-of-meaning sequences being recalled. (2) One subject is -strongly and consistently otherwise, giving nearly three times as many -similarity-of-presentation sequences. No. 11. - - - - -MOTOR IMPULSES - - - - -THE ACCURACY OF LINEAR MOVEMENT - -BY B.A. LENFEST - - -The starting-point for our investigation was the observation of -Woodworth[138] that there is a certain rhythm in which a certain -hand-movement is made with the maximum of exactitude, and which -represents thus an optimum for the periodical discharge of the -particular motor centre. Our question was whether this rhythm is a -constant one for all parts of the body, or whether different groups of -muscles produce the greatest exactitude in different periods; further, -whether secondary factors, like complexity of movement, resistance by -weight, fatigue, etc., influence this psycho-physiological optimum. - -The investigation, however, showed soon the necessity to consider the -whole problem of the accuracy of rhythmical linear movements, and the -experiments are thus not always directly related to our starting-point. - -There is very little material published that can be collected under -the subject head, accuracy of voluntary movement, and still less when -the enquiry is confined to the accuracy of straight lines or linear -movements. - -The most suggestive contribution is that of Dr. Woodworth on the -accuracy of voluntary movement. He has collected consistently what can -be found up to the date of his publication, and the reader is referred -to pages 7-16 of his monograph for the most reliable collection of -authorities. - -It must be said, as we run over the list from Goldscheider on the -threshold of perceptible movement, through the results of Hall, -Hartwell, Loeb, and Delabarre on "bilateral asymmetry" and comparisons -of right and left hands; consider Fullerton and Cattell in their -suggestive results, and Münsterberg's studies of movements; and finally -take the testimony of Bryan as to the growth of accuracy of movement -in children, that the vast accumulation of material bearing on reaction -time--and similar phenomena would be of more value if concerned more -with the accuracy and less with the production or perception of -movement. - -A paper by Miss M. K. Smith, in the Philosophische Studien for 1900, -with the title, Rhythmus und Arbeit, concerns the influence of -rhythmical action upon the quality and quantity of work performed. The -method was to commit to memory nonsense syllables and letters. - -The results show a tendency to take up a certain rhythm, especially -in the later results and after practice; easier memorizing if rhythm -is present; motor reactions, as tapping, nodding, or swaying of body -are noted frequently; the feeling of pleasure accompanies rhythmic -reactions. While there are no data as to accuracy, there is suggestive -matter bearing on the optimal rate and on the relations of compound and -simple movements of the hand. - -As far as the writer knows, he is the first to present systematic -results as to the head and foot movement. The purposes of this enquiry -may be briefly stated as - -(1) the collection of a large body of facts, bearing on the actual and -relative accuracy of straight-line movements possible with various -parts of the body, such as hands, arms, head, legs, and feet; - -(Something like 340,000 lines have been drawn and calculated.) - -(2) to introduce certain variations in the conditions attending the -production of ruled lines, such as - -(_a_) to rule with the eyes opened and eyes closed, with other -conditions the same; - -(_b_) to change the rate of ruling or interval between the production -of ruled lines; the rates chosen were 20, 30, 40, 50, 60, 70, 80, 100, -120, 140, 160, 180, and 200 beats per minute; - -(_c_) to change the length of the normal or first line; the lengths -used were 14, 10, and 1 cm.; - -(_d_) to impose a weight on the ruling hand to either retard or -accelerate the movement, choosing a weight of such magnitude that it -would be perceptible, but would not have mass enough to cause pain or -fatigue; 260 grams was used; - -(_e_) to introduce a simultaneous movement of the free hand; _i. e._, -the one that did not carry the recording pencil, of a similar character -and extent but of opposite direction to the ruling hand; - -(_f_) to record movements of both hands, of the head and of both feet; - -(_g_) to conduct a series of experiments of similar character, as -regards time-rate and extent of movement, to the series presented by -Dr. Woodworth, with the idea of corroborating or disproving the results -of his investigations; lines of 140 cm. were accordingly chosen; - -(_h_) to conduct a series of experiments where the subject chooses his -own rhythm or rate at which the easiest and best lines, subjectively -speaking, could be ruled; - -(_i_) to find the rates of respiration and pulse-beats and find the -connection, if any, between them and the linear records. - -(3) To examine, by variations of the number of lines ruled, the -questions of fatigue and persistence of the memory-image; series of -50 lines for the first year and of 20 lines for the second year, were -accordingly selected. - -(4) To find the relations, if any, between constant errors and mean -variations, so called. - - -THE APPARATUS - -It is proposed to give the briefest possible discussion or explanation -of the apparatus required for the investigation, it being desired at a -later stage to enter into a comparison of the method adopted here with -that of the only other investigation at all comparable to this one: the -research problem of Dr. Woodworth, already referred to. - -The underlying principle has been to avoid complication in apparatus, -partly because of the delay and expense involved in working out, and -making up elaborate schemes for apparatus, but mainly because of the -advantage in duplicating this series of experiments, or of carrying -on related investigations, to be derived from a choice of such -parts, entering into the complete apparatus, as are at hand in any -psychological laboratory, or that can be obtained and set up at small -expense. - -The use of smoked paper has been avoided, because a short preliminary -series, using the usual smoked-paper records, was found to give no -better results than did the method here adopted of ruling on white -paper with a soft pencil, and the labor was thus considerably reduced. - -To the objection that the pencil-ruling is more difficult, and involves -more loss in friction and more complicated adjustments on the part of -the subjects, only one of fourteen subjects admits that this is the -case; and even if the testimony was unanimous as to the greater ease -of production of the smoked records, it would be no reason for its -adoption, since one of the first rules for all experimental work is -uniformity of conditions, and this is equally well attained in either -case. - -The apparatus for free hand-movements and for the compound movements of -both hands consists: - -(1) Of an adjustable wooden rest (see Fig. _A_) with a base (_a_) about -40 × 60 cm. hinged to a vertically adjustable flat board (_b_), called -the arm-rest, about 40 × 70 cm., and having on its upper edge two brass -pins or plates (_c_) about 30 cm. apart. - -The pencil is started from one of these pins, depending on the hand -used, and moved until it comes in contact with a wooden rod that is -held against the opposite pin and which is of the right length to give -a movement of the pencil of 1, 10, or 14 cm., as desired. - -The operator holds this rod in place for the first line ruled and then -instantly removes it, so that the second and all later lines are ruled -by memory of the first one, as closely in length to the first, or -so-called normal line, as is possible. - -(2) The apparatus for actuating and taking care of the paper. - -This consists of two drums (_d_ and _d´_, Fig. _B_) 20 cm. diameter -by 40 cm. wide, mounted on suitable supports about 1 metre apart, and -fastened to a table, with axes parallel. - -The drum upon which the record is to be made (_d_) is adjusted close -to the arm-rest, so that each ruled line will be carried down and out -of sight before the next one is ruled, the pencil being held in the -position (_e_); note that the arrow shows the direction of rotation. - -The second drum (_d´_) is actuated by a motor (_F_) through a round -belt (_g_), this motor being a clockwork type, with gear-changes and -adjustable vanes for varying the speed, and having the power derived -from a suspended weight (_w_). - -The recording paper (_h_) transmits motion from (_d´_) to (_d_). This -paper consists of a strip about six metres long by twenty-eight cm. -wide, with one end pasted to (_d_), and then wound upon (_d_), leaving -enough to be carried to (_d´_) and pasted to the latter. As the paper -is unwound from (_d_), it is wound upon (_d´_), and, both to keep -the paper tight and to prevent too rapid unwinding of (_d_), it is -necessary to apply a friction-brake to the shaft of (_d_). - -(3) A metronome, capable of being used for a range of 20 to 200 beats, -and a stop-watch, to enable the operator correctly to time the subject, -are in constant use. - -[Illustration] - -The metronome is set in vibration and the subject is permitted to take -his own time to start the ruling, the operator holding the wooden -rod in place with one hand, while the other hand holds the stop-watch -ready to start it the instant the subject's pencil is moved. There is -thus a personal equation for the length of period, but this is of no -consequence, as will be apparent when the method of calculation and the -use of the planimeter is considered. - -In the series of records with the weight, it is impossible to run the -speed about 80 to 100 beats, unless the modification in apparatus shown -in Fig. _C_ is used; for the vibration of the string running from the -hand to the weight around a pulley is violent enough either to throw -the string off the pulley or cause the weight to jump so severely as to -render the records useless. - -This is entirely obviated by the given method of using a heavy weight -acting with a small leverage (about 1 cm.) and thus moving only a short -distance, so that it is capable of operating at the highest speeds with -no perceptible shock or jump; the string is led to the hand or wrist -from a grooved pulley of about 12 cm. radius, so the highest velocity -of the weight is only about one twelfth that of the hand. This method -makes it possible to carry the weighted records to the highest speeds. - -This same method is used for the head and foot records, with the -following additional apparatus; the string (Fig. _C_), shown leading to -the hand, is led horizontally over to and around a similar large pulley -on the opposite side of the table and either down to the foot or in a -diagonally upward direction to the head; so that movements of the head -or foot are faithfully recorded on the drum by means of a pencil held -in a block of wood, this block of wood being fastened on the horizontal -string in a suitable position for recording on the drum paper. The -pencil is kept against the paper by a light spring or elastic band. - -The foot is connected to the string by a stirrup that prevents any -movement of the feet at all, unless the same is recorded by the pencil. - -The head is furnished with a skull cap or harness consisting of -non-elastic webbing and stiffened, where the string is attached, by -a strip of sheet brass formed to fit the forehead or the back of the -head, as the case may be. The object of the brass strip is to prevent -a lost motion in the flexible webbing, that is found troublesome -otherwise. - -It will be evident, then, that the weight is continually acting as an -accelerating or retarding influence in all records for head and feet, -but it is not considered objectionable, for it is a constant throughout -the series. - -The other plan would require a circuit of cord leading in both -directions from the head or feet in a complete circuit, and would cause -in the opinion of the writer too much complication of apparatus. - -The pulse-beats were taken by the stop-watch and wrist method so -familiar to the physician, while the respiration results were obtained -by the usual tambour apparatus for registering the chest expansion upon -smoked paper. - - -THE METHOD OF CALCULATION - -Suppose that the drums have been set in rotation and that the paper is -unwinding from (_d_) and being wound on (_d´_), Fig. _B_, and suppose -that the subject has ruled series of 20 to 50 lines, as may be desired, -regulated by the stop-watch in the hands of the operator. The records -will appear much as Fig. 5 under the planimeter discussion, there being -for each speed one normal line to start and a series of lines following -and intended to be of the same length as the normal line. A series of -records, then, consists of 13 records of 20 or 50 lines, each running -from 20 to 200 beats per minute, the complete series having not less -than 260 and not more than 650 lines. - -It should be added that the operator holds a pencil-point on the end -of each normal line just after the record of 20 or 50 lines is made -and turns the drum (_d_), thus marking a line nearly perpendicular -to the ruled lines and at the average or normal distance from the -starting-point; an absolutely correct record would show all ruled lines -ending on this line. - -The calculation of this series of records by the ordinary method of -measuring each line, adding the lines of the series, averaging for the -constant error, and repeating the operation in a slightly different -form for the mean error or mean variation is of such enormous labor for -an extended investigation as to be beyond the capacity of one or of -several students; it is fortunate that the planimeter is at hand to be -employed in averaging each series, and this instrument has therefore -been selected as overcoming this difficulty. - -It is desirable to consider the method employed by Dr. Woodworth to -overcome this danger of excessive computation, and it will now be -subjected to a critical and comparative examination. - -He says, page 19 of his monograph on the Accuracy of Voluntary -Movement, that the subject's sole duty was to make the present line -equal to that immediately preceding, and the width of the slot was -so adjusted that the subject could see only the line just ruled. -After discussing certain matters of memory and its relation to the -memory-image, in the attempt to support this changing normal plan, -he confesses, on page 20, that this device is advantageous in much -simplifying the most tedious part of the graphic method, that of -computation. - -While this is undoubtedly true, it needs careful scrutiny before -adoption, for, on the same page, he says that one source of error in -the method of making each line equal to the preceding one is that the -different movements in the same series are not comparable, but the -positive constant error is cumulative in its effect, and the normal -tends to become longer and longer. - -Some relation between this source of error and such a record as shown -on page 29, Fig. 2, is evident, for, while it should be noted that this -cumulative effect is peculiar to a series of lines for one speed, it -has further a tendency to produce overruling at all speeds, and the -natural result is to increase the error unduly and unnaturally for the -higher speeds or as the speed increases, because there is then less -time for the discrimination and choice that will tend to shorten the -ruled line. It may be predicted, then, that Dr. Woodworth's method -will show a slight lengthening of normal between lines at slow speeds -and a much greater one at high speeds, the effect being to introduce -a variable factor that would have no existence were a better plan -adopted. The computation required for the average error is simple, -being dependent only on the first and last lines of a series, and it -is suspected that this very simplicity has led to its adoption and the -consequent neglect of certain serious sources of error. - -He tells us, on page 20, that the constant and variable error may -well be isolated and studied separately, but indicates that they must -"somehow" be considered combined as nature has made them; that is, -analysis is desirable, but the synthetic method is more scientific. - -This investigation will present data suggesting that - -(1) Such a curve as that on page 29 of his monograph is not a -characteristic one and relations of length of ruled line, as well as -effects of weight, make it impossible to apply Weber's law or even the -law of Fullerton and Cattell in the way proposed by Dr. Woodworth. - -(2) There is no relation, mathematical or other, between constant and -mean errors, and they not only may be but must be isolated and studied -separately, if an investigation is to be conducted in the interests of -scientific exactness. - -It will be necessary to reject the method of Dr. Woodworth if the -most reliable results are desired, in which case the planimeter is a -necessity. - -The theory of the planimeter cannot be developed at this place; every -physicist and engineer is acquainted with it. The writer believes he -was the first to apply the planimeter to the calculation of results -from psycho-physical data for averaging both mean and variable errors. -More than 340,000 lines were involved, each demanding two measurements. -The best type of planimeter for general use and the one used here is -the Amsler adjustable-arm form. - -In Fig. _D_ is shown a record taken at twenty beats per minute that -will both explain the method of computation and show how the planimeter -has been used to find the constant and mean errors. - -[Illustration: Fig. D - -Hylan-20 beats. L.H.E.c.-2-13-Ό1.] - -The record, as made and ready for computation, is not provided with the -line _cd_ or with the dotted lines that connect the ends of the ruled -lines. The line _ab_ is drawn by turning the drum of the apparatus with -a pencil held at the end of the normal or left-hand line _af_, which -was here 100 mm. long. - -The tracing-point of the planimeter being placed at _a_, a reading -is taken, which was in this case 1486; after following with the -tracing-point the dotted path to _g_ and returning, via _gb_ and _ba_, -a second reading is taken, which was 1248; subtracting gives 238, -which should be read 2380 square mm. for the area of the space _agba;_ -dividing by the distance _ab_, in this case 119 mm., gives the average -height, which is + 20.0 mm., the plus sign suggesting that the distance -thus found, which is the constant error for the series, be laid off in -addition to or beyond _Fa_. - -This being done, a line _cd_ is drawn parallel to and 20.0 mm. from -_ab_, as the mean line of constant errors. - -To find the mean error of the series a slightly different method is -necessary. - -Place the tracing-point of the planimeter at _c_ and read vernier, -giving 1916; follow the dotted path from _c_ to _h_, the straight line -from _h_ to _i_, the dotted path from _i_ to _k_, the straight line -from _k_ to _l_, the dotted path from _l_ to _m_, the straight lines -from _m_ to _n_ and _n_ to _g_, the dotted path from _g_ to _m_, the -straight line from _m_ to _l_, the dotted path from _l_ to _k_, the -straight line from _k_ to _i_, the dotted path from _i_ to _n_, and the -straight line from _h_ to _c_, when a second reading is taken, which -was in this case, 1806. Divide the difference of these two readings, -1100 mm., by the length of _cd_, 119 mm., and the result is 9.1 mm., or -the mean error (mean variation). - -It will be noted that this method gives the sum of the errors from -the mean line _cd;_ that is, the same result would be obtained if the -tracing-point were (1) carried from _c_ around all the area below _cd_, -and this area were calculated as before; (2) carried from _c_ around -all the area above _cd_ and the area measured as in other cases; and -(3) these two results added and averaged. - -To apply the method for _ab_, or constant error computation, to _cd_ -should give equal readings at _c_ or a 0 mean error, a result evidently -incorrect in the record selected. - -After averaging results by the planimeter, the collection of data has -been arranged by months; the record for one month only can be presented -here, but the method of tabulation is the same throughout. - -Each figure given for N, M, c and v, in the accompanying typical table -for the month of May, 1904 (pages 495-499), is the average from 20 or -50 lines, ruled as already shown, Fig. _D_. - - -RESULTS - -It is necessary to observe that the limits of space imposed on the -writer preclude all but the barest outline of the deductions to be -drawn from the investigation, and to this fact is due whatever of -dogmatism is inherent in the argument; for it is manifestly impossible -to present all the material, and the writer asks, then, the indulgence -of the reader when he claims to have impartially examined and presented -the evidence. - - -HAND MOVEMENTS - - Simple movements - Lines 14 cm. long. - - -TYPICAL SERIES FOR THE MONTH - - Key. - v = mean error. - R.H. = right hand. - R.F. = right foot. - E.O. = eyes open. - si. = simple motion - N = normal line. - Unit = 1 mm. - L.H. = left hand. - L.F. = left foot. - E.C. = eyes closed. - co. = compound motion. - M = mean line. - b = beats per minute. - c = constant error. - - See Beats per minute. - Day. Subject. Key. 20 30 40 50 60 70 80 100 120 - - - 6 Hylan. N 10 10.5 11 11 10 10 10 12 10 - L.F.E.O. M 16.1 13.5 12.1 13.8 13.1 10.0 10.0 11.2 12.5 - c +6.1 +3.0 +1.1 +2.8 +3.1 0.0 0.0 -0.8 +2.5 - v 2.8 3.5 1.9 0.9 1.6 4.6 2.0 2.7 1.2 - - 140 160 180 200 - - 12 10 11 11 - 12.0 6.1 11.0 14.21 - 0.0 -3.9 0.0 +3.2 - 1.0 1.3 2.1 4.0 - - - Hylan. N 10 11 10 12 10 12 11 11 11 - L.F.E.C. M 8.9 10.5 10.9 11.4 13.1 10.3 11.8 13.1 13.9 - c -1.1 -0.5 +0.9 -0.6 +3.1 -1.3 +0.8 +2.1 +2.9 - v 2.7 6.4 2.2 1.4 2.7 1.6 2.3 1.6 4.9 - - 11 11.5 11 11 - 15.8 11.0 15.0 17.8 - +4.8 -0.5 +4.0 +6.8 - 2.9 2.3 2.3 2.5 - - - George. N 10.5 10 10 10 10 10 10 10 11 - L.F.E.O. M 14.6 9.7 7.1 6.4 7.7 8.3 8.0 10.0 11.0 - c +4.1 -0.3 -2.9 -3.6 -2.3 -1.7 -2.O 0.0 0.0 - v 2.1 1.6 1.8 2.3 0.8 0.7 1.4 1.7 0.8 - - 10 10 11 11 - 9.0 10.0 8.0 12.5 - -1.0 0.0 -2.0 +1.5 - 1.0 1.3 1.6 0.4 - - - George. N 10 9 9 10 11 9.5 9 10 8 - L.F.E.C. M 11.7 9.2 10.2 12.6 13.2 11.5 12.2 6.6 5.0 - c +1.7 +0.2 +1.2 +2.6 +2.2 +2.0 +3.2 -3.4 -3.0 - v 2.0 2.9 2.5 0.7 0.5 1.0 0.8 2.0 4.1 - - 10 9 9 10 - 8.0 7.6 8.0 11.0 - -2.0 -1.4 -1.0 +1.0 - 3.1 2.5 2.1 3.7 - - - Moore. N 10 10 10 10 11 11 11 10 10 - L.F.E.O. M 15.7 18.8 17.7 16.7 18.3 18.5 16.5 15.6 16.0 - c +5.7 +8.8 +7.7 +6.7 +7.3 +7.5 +5.5 +5.6 +6.0 - v 3.5 3.8 1.1 0.8 3.6 2.1 2.7 0.6 2.4 - - 10 11 10 10 - 16.2 16.3 16.4 18.8 - +6.2 +5.3 +6.4 +3.8 - 0.5 3.5 2.2 3.8 - - - N 10 10 10 10 11 10 10 9 - Moore. M 19.6 15.3 15.3 14.3 14.9 13.5 6.7 13.4 - L.F.E.C. c +9.6 +5.3 +5.3 +4.3 +3.9 +3.5 -3.3 +4.4 - v 2.6 2.5 2.4 0.4 2.0 6.4 0.7 4.1 - - 9.5 11 11 10 10.5 - 20.0 14.3 14.5 16.9 17.9 - +10.5 +3.3 +3.5 +6.9 +7.4 - 2.6 3.8 1.1 3.1 2.8 - - - N 10 10 9 10 10 9.5 10 10 - 9 Angier. M 13.6 12.5 11.6 11.6 11.5 11.7 13.0 12.9 - R.F.E.O. c +3.6 +2.5 +2.6 +1.6 +1.5 +2.2 +3.0 +2.9 - v 2.9 2.3 1.8 2.3 1.7 1.6 2.0 2.7 - - 11 10 10 10 10 - 12.2 12.2 13.5 22.1 16.5 - +1.2 +2.2 +3.5 +12.1 +6.5 - 3.3 1.5 1.5 6.7 1.5 - - - - N 10 10 10 9.5 10 9 10 10 - Angier M 11.4 7.7 13.8 8.3 11.4 11.5 11.0 10.3 - R.F.E.C. c +1.4 -2.3 +3.8 -1.2 +1.4 +2.5 +1.0 +0.3 - v 4.8 1.3 3.0 2.6 1.4 1.7 1.8 1.7 - - 140 beats - - 9 10 10 11 10 10 - 9.9 12.8 16.7 17.7 12.4 12.0 - +0.9 +2.8 +6.7 +6.7 +2.4 +2.0 - 1.8 1.4 1.7 4.2 2.1 1.7 - - - N 11 10 10 9 10 11 10 10 - Huggins. M 12.5 8.5 12.6 9.7 9.7 16.6 15.7 18.7 - R.F.E.O. c +1.5 -1.5 +2.6 +0.7 -0.3 +5.6 +5.7 +8.7 - v 3.6 2.6 2.7 2.8 3.3 3.2 3.3 3.6 - - 10 11 11 11 10 - 13.6 15.8 9.3 18.3 14.3 - +3.6 +4.8 -0.7 +7.3 +4.3 - 3.1 2.7 2.9 3.8 3.0 - - - N 11 8 10 10 11 10 10 10 - Huggins. M 6.5 10.5 10.7 8.8 12.6 12.9 12.2 22.3 - R.F.E.C. c -4.5 +2.5 +0.7 -1.2 +1.6 +2.9 +2.2 +12.3 - v 1.4 2.1 1.8 1.6 3.7 3.1 2.0 4.1 - - 10.5 10 10 10 10 - 9.9 21.8 12.0 12.5 16.3 - -0.6 +11.8 +2.0 +2.5 +6.3 - 1.4 5.0 2.3 3.6 1.8 - - - N 9 9 9 9 9.5 8 7 10 - 13 Lenfest. M 12.7 11.9 11.1 11.3 12.1 8.7 11.6 12.6 - R.F.E.O. c +3.7 +2.9 +2.1 +2.3 +2.6 +0.7 +4.6 +2.6 - v 3.7 2.4 1.9 2.3 2.8 0.2 2.8 2.1 - - 10 10 9 8 10 - 9.0 8.6 11.7 7.0 11.8 - -1.0 -1.4 +2.7 -1.0 +1.8 - 2.0 2.1 3.2 1.4 4.1 - - - N 12 11 11 10 10 10.5 11 11 - Lenfest. M 14.9 14.7 12.2 13.5 12.6 11.9 12.6 8.7 - R.F.E.C. c +2.9 +3.7 +1.2 +3.5 +2.6 +1.4 +1.6 -2.3 - v 3.3 2.2 3.5 3.5 3.2 3.0 2.6 1.7 - - 11 11 10 10 10 - 9.1 8.9 8.4 14.1 6.9 - -1.9 -3.1 -1.6 +4.1 -3.1 - 2.4 2.8 2.9 4.1 2.3 - - - N 12 11 11 11 11 10 11 10 - George. M 8.3 9.0 8.6 8.8 8.7 7.0 7.4 7.9 - R.F.E.O. c -3.7 -2.0 -2.4 -2.2 -3.3 -3.0 -3.6 -2.1 - v 5.0 3.3 2.3 0.1 3.3 2.9 2.4 3.1 - - 11 10.5 11 10 10 - 6.8 9.7 9.0 5.8 11.0 - -4.2 -0.8 -2.0 -4.2 +1.0 - 1.5 4.6 2.9 2.9 3.9 - - - N 12 11 12 11 11 11 10.5 11 - George. M 7.0 7.7 14.1 8.3 10.3 8.4 8.7 7.8 - R.F.E.C. c -5.0 -3.3 +2.1 -2.7 -0.7 -2.6 -1.8 -3.2 - v 2.5 2.6 2.4 3.7 2.9 2.3 1.6 2.1 - - 10 10.5 11 10 10 - 6.4 10.0 9.0 7.9 7.3 - -3.6 -0.5 -2.0 -2.1 -2.7 - 1.9 3.7 2.9 1.8 3.8 - - - N 11 11 11 11 12 10 9 11 - Moore. M 14.5 16.6 16.5 9.0 17.0 10.7 10.4 11.9 - R.F.E.O. c +3.5 +5.6 +5.5 -2.0 +5.0 +0.7 +1.4 +0.9 - v 1.7 2.2 1.9 1.8 1.3 2.2 2.6 2.2 - - 10 10.0 10.5 11 9.5 - 11.5 12.5 12.5 15.1 12.6 - +1.5 +2.5 +2.0 +4.1 +3.1 - 2.2 2.5 2.5 1.4 0.8 - - - N 11 10 11 11 11 10 10 9 - Moore. M 14.3 13.2 15.9 12.3 17.9 10.0 11.3 15.9 - R.F.E.C. c +3.3 +3.2 +4.9 +1.3 +6.9 0.0 +1.3 +6.9 - v 1.8 2.8 1.6 2.1 1.7 2.4 3.2 2.2 - - 11 11.0 10 10 10 - 14.8 15.5 13.4 11.8 12.2 - +3.8 +4.5 +3.4 +1.8 +2.2 - 2.7 1.4 2.2 1.8 2.2 - - - N 11 11 10 11 10 10 10 11 - 16 Angier. M 14.3 13.5 9.3 14.4 14.1 9.5 15.1 12.7 - R.F.E.O. c +3.3 +2.5 -0.7 +3.4 +4.1 -0.5 +5.1 +1.7 - v 1.7 1.9 2.0 2.4 2.0 1.1 2.4 2.8 - - 10 11 10 11 11 - 11.1 12.6 13.7 11.0 16.6 - +1.1 +1.6 +3.7 0.0 +5.6 - 2.0 2.0 2.7 1.3 3.5 - - - N 11 10 10 9 10 10.5 10 10 - Angier. M 14.4 4.8 2.5 3.6 5.8 6.7 8.0 11.0 - R.F.E.C. c +3.4 -5.2 -7.5 -5.4 -4.2 -3.8 -2.0 +1.0 - v 3.2 2.7 2.3 3.6 2.7 2.3 1.3 2.8 - - 11 10 11 11 11 - 13.5 11.1 13.9 10.1 11.0 - +2.5 +1.1 +2.9 -0.9 0.0 - 2.8 1.4 2.4 1.8 2.2 - - - N 97 97 98 97 98 99 97 98 - Huggins. M 107.6 107.8 100.4 114.2 98.0 110.3 89.4 102.5 - L.F.E.O. c +10.6 +10.8 +2.4 +17.2 0.0 +11.3 -7.6 +4.5 - v 5.9 0.6 4.8 6.5 5.3 6.7 6.4 5.5 - - 95 98 99 99 100 - 99.2 100.8 106.4 101.5 108.9 - +4.2 +2.8 +7.4 +2.5 +8.9 - 7.8 6.0 4.7 7.0 12.7 - - - N 97 98 100 97 95 95 99 99 - Huggins. M 102.8 104.3 115.1 101.4 94.1 102.0 106.4 93.4 - L.F.E.C. c +5.8 +6.3 +15.1 +4.4 -0.9 +7.0 +7.4 -5.6 - v 5.8 8.6 10.8 9.9 7.9 10.4 8.1 6.8 - - 97 98 99 99 100 - 87.7 98.7 108.4 97.7 110.8 - -9.3 +0.7 +9.4 -1.3 +10.8 - 9.4 5.8 6.9 5.3 6.1 - - - N 11 11 10 10 10 10 10 10 - 20 Lenfest. M 16.1 13.5 11.6 10.9 10.9 14.2 11.7 10.5 - L.F.E.O. c +5.1 +2.5 +1.6 +0.9 +0.9 +4.2 +1.7 +0.5 - v 2.8 3.0 3.0 3.0 1.2 1.9 1.0 1.6 - - 11 10 11 11 10 - 12.4 11.1 12.2 8.7 12.9 - +1.4 +1.1 +1.2 -2.3 +2.9 - 3.2 5.1 1.9 1.7 4.2 - - - N 12 11 10 10 10 11 10 10 - Lenfest. M 20.4 16.8 11.6 11.2 11.8 14.0 9.0 9.3 - L.F.E.C. c +8.4 +5.8 +1.6 +1.2 +1.8 +3.0 -1.0 -0.7 - v 2.5 3.6 3.0 1.9 1.6 2.0 3.0 1.2 - - 10 10 11 11 10 - 6.2 10.0 8.5 5.1 8.3 - -3.8 0.0 -1.5 -5.9 -1.7 - 1.9 0.3 1.8 1.7 0.8 - - - - N 98 97 94 98 98 97 98 98 - George. M 104.0 100.4 102.6 99.3 105.1 111.1 101.9 100.5 - L.F.E.O. c +6.0 +3.4 +8.6 +1.3 +7.1 +14.1 +3.9 +2.5 - v 6.4 11.3 9.6 7.7 5.3 8.0 3.7 5.6 - - 97 96 98 98 97 - 96.4 102.0 97.4 94.2 95.8 - -0.6 +6.0 -0.6 -3.8 -1.2 - 5.7 5.7 9.1 7.8 3.6 - - - N 98 97 94 97 97 98 98 97 - George. M 93.6 81.2 94.7 92.7 104.2 99.3 93.4 89.6 - L.F.E.C. c -4.4 -15.8 +0.7 -4.3 +7.2 +1.3 -4.6 -7.4 - v 9.1 8.9 5.5 4.6 5.8 6.9 4.9 6.6 - - 96 98 98 99 100 - 96.4 93.0 87.3 101.8 87.4 - +0.4 -5.0 -9.7 +2.8 -12.6 - 7.8 4.8 7.7 5.6 5.7 - - - N 97 99 98 97 96 96 97 98 - Moore. M 106.1 106.9 105.2 103.0 104.7 108.6 102.7 106.9 - L.F.E.O. c +9.1 +7.9 +7.2 +6.0 +8.7 +12.6 +5.7 +8.9 - v 4.3 5.6 4.6 5.2 8.0 6.0 7.4 6.9 - - 99 98 99 99 99 - 110.9 105.7 111.2 99.9 93.0 - +11.9 +7.7 +12.2 +0.9 -6.0 - 4.8 9.0 4.7 11.4 1.8 - - - N 96 97 97 97 96 97 96 97 - Moore. M 119.2 79.8 87.3 79.6 81.6 91.2 96.5 106.2 - L.F.E.C. c +23.2 -17.2 -9.7 -17.4 -14.4 -5.8 +0.5 +9.2 - v 16.1 6.7 11.6 7.2 7.5 4.1 4.0 6.6 - - 99 98 97 98 99 - 100.4 91.9 104.0 88.6 80.9 - +1.4 -6.1 +7.0 -9.4 -18.1 - 4.0 6.1 5.4 6.6 8.2 - - - N 98 97 95 96 96 97 99 97 - 23 Lenfest. M 105.7 110.8 97.4 93.8 97.8 100.2 99.9 92.9 - L.F.E.O. c +7.7 +13.8 +2.4 -2.2 +1.8 +3.2 +0.9 -4.1 - v 9.3 1.5 3.6 5.1 3.6 4.4 2.9 3.3 - - 97 98 98 98 99 - 86.1 96.6 91.9 80.9 83.0 - -10.9 -1.4 -6.1 -17.1 -16.0 - 6.7 5.0 8.2 6.0 7.8 - - - N 96 94 96 96 96 94 96 97 - Lenfest. M 111.3 95.0 98.3 101.7 101.7 110.1 98.8 79.0 - L.F.E.C. c +15.3 +1.0 +2.3 +5.7 +5.7 +16.1 +2.8 -80.0 - v 7.1 5.1 5.8 2.7 5.4 7.8 12.1 3.7 - - 97 97 100 100 100 - 88.9 72.7 88.4 69.7 80.8 - -8.1 -24.3 -11.6 -30.3 -19.2 - 5.6 8.0 7.4 8.4 7.0 - - - N 96 97 96 96 98 98 97 97 - Huggins. M 113.5 105.7 105.5 97.7 92.5 98.4 92.5 102.0 - L.H.E.O. c +17.5 +8.7 +9.5 +1.7 -5.5 +0.4 -4.5 +5.0 - v 4.2 2.4 3.6 5.0 3.5 3.1 4.2 5.8 - - 95 98 98 99 97 - 95.0 112.3 104.5 108.7 95.7 - 0.0 +14.3 +6.5 +9.7 -1.3 - 4.7 6.4 5.8 7.1 4.4 - - - N 98 97 97 97 97 99 99 97 - Huggins. M 103.5 82.8 86.1 87.8 87.7 94.2 92.1 94.5 - L.H.E.C. c +5.5 -14.2 -10.9 -9.2 -9.3 -4.8 -6.9 -2.5 - v 8.4 6.7 5.4 3.5 6.7 5.4 6.0 5.8 - - 97 97 98 98 96 - 99.9 111.5 101.3 113.7 95.1 - +2.9 +14.5 +3.3 +15.7 -0.9 - 4.8 13.3 4.7 9.6 2.6 - - - N 96 95 96 96 96 97 96 - 27 Lenfest. M 101.6 93.4 91.2 90.0 97.5 93.2 93.4 - R.F.E.O. c +5.6 -1.6 -4.8 -6.0 +1.5 -3.8 -2.6 - v 6.2 5.1 3.4 2.8 5.5 4.5 3.7 - - 96 99 102 101 100 - 89.8 97.5 88.6 96.8 66.2 - -6.2 -1.5 -13.4 -4.2 -33.8 - 5.5 3.6 4.3 4.9 8.1 - - - N 96 96 97 97 97 98 98 - Lenfest. M 103.8 101.2 94.0 100.3 96.4 101.2 105.0 - R.F.E.C. c +7.8 +5.2 -3.0 +3.3 -2.6 +3.2 +7.0 - v 6.2 7.4 4.5 3.8 3.5 4.7 2.4 - - 95 98 100 99 100 - 78.0 98.5 88.8 85.1 65.8 - -17.0 +0.5 -11.2 -13.9 -34.2 - 4.7 4.3 7.0 6.9 5.9 - -The records are averaged for nine subjects, three of them being -left-handed. For the right hand we find, for mean error, a reduced -error with visual control. - -For constant errors, a similar result is apparent; when following the -eyes-closed curve one may note a large negative error 20-50 beats, and -a similar but larger positive error 70-160 beats, with a falling to a -negative error again at 200 beats. - -This may be interpreted to mean a groping for the correct length of -line at the lower speeds when some time for reflective processes is -allowed, and an inhibitory effect on the motor discharge; later the -speed prevents this discrimination, and introspective testimony goes -to show that a mental conception of a barrier, beyond which one cannot -carry the pencil, is set up and kept more or less constant through the -help of the joint and muscular sensations. It would follow, then, that -this muscular stop is overestimated where reflection is not possible. - -Finally, the falling-off of the length of the line is probably due to -physical inability to rule a line of the full length of 140 mm. at 200 -beats per minute and an examination of some individual cases confirms -this opinion, for the lines may be started some distance away from the -origin apparently in order to end them at the correct point. - -Curve inclinations are upward, for mean errors, with visual control, -while the eyes-closed records show no increase in error for the -increased speeds. - -For constant errors, with visual control, there is a similar -inclination downward for both hands, with a 0 error at about 120 beats. -It should be noted that this opposite tendency in mean and constant -errors suggests that they should be kept separate in all computation. - -The left-handed subjects have much better control of their left hand -than have the right-handed subjects, and they may dispense with visual -control to a large extent. - -On the other hand, for right-hand records we find much the same -increase in irregularity and error for both left- and right-handed -subjects; they all must depend on visual control for reduction of -errors. - -It follows that the non-visual control exerted by the left-handed -subjects on the right hand is as good or as great as for the -right-handed subjects; while they have the hand in which they may be -expected to excel under much better control. - -It is not intended to present this as an argument for teaching -left-handedness, but it is certainly suggestive when considering the -question that ambidexterity be taught in early life. - -It should be noted that two of the three left-handed subjects might be -expected, because of special training, to show marked manual dexterity, -while only one of the four right-handed subjects has had special -training along this line. - -No extended discussion is appropriate here as to the question of what -portion of this extra ability of the left-handed subjects to react -accurately is due to practice and habit, _i. e._, is automatic, and -accomplished without reference to the sensory motor by-path to the -cerebral cortex; and on the other hand, as to whether the direct -sensory motor path via spinal cord or medulla is not cut off entirely. - -For 140 mm. averages and free motion, we find in general - -(1) a reduced error and greater uniformity of result at all speeds -where visual control is added, in the case of both mean and constant -errors and for all subjects; - -(2) the mean errors for visual-control records show a rise along a -line whose equation is approximately _y_ = _px_, or the equation of a -straight line, where _p_ is an undetermined constant. - -On the other hand, - -(3) the eyes-closed mean errors show no increase or decrease in value -during the entire series; - -(4) the constant errors for visual-control records show a drop from -positive errors to negative errors, along a line whose equation is -approximately _y_ = _qx_ or the equation of a straight line, where _q_ -is an unknown constant, somewhat less in value than _p_ in the case of -mean errors; the constant error becomes 0 at about 120 beats; - -(5) the eyes-closed constant errors follow the same equation for -left-handed subjects, using the left hand, but all other cases suggest -a curve of the parabolic form, having 0 constant errors at 60 and 180 -beats and being convex upward. - -Considering individual records for 14 cm. - -A general survey of the charts suggests certain irregularities that -call for explanation, for there will be sudden large increases in -errors, that are explicable on the hypothesis that the subject has -temporarily lost control of the moving hand, that is, that fatigue is -to be noted. - -While the purpose of the investigation has been to allow no lines to be -ruled while the subject was conscious of any such feeling, there being -a pause of any desired length to permit time for rest, it is to be -noted that a considerable amount of recorded data as to fatigue shows -that it is an unconscious or subconscious phenomena. - -Further, the series of records have been arranged to occur from 20 -to 200 beats and never in the reverse order, because of subjective -limitations, so it is reasonable to expect that during the period of -twenty minutes to one half an hour required for a series of records, -there will be lapses of volitional control entirely beyond the ken of -the subjects. It is to this cause rather than to pure chance that the -results will be attributed. With this exception, the individual records -show close agreement with their average. - -The results obtained from a consideration of free hand-movements of 1, -10, and 14 cm. length are: - -For 14 cm. lines - -for the average of nine subjects: - -The mean errors, - -(1) increase with speed for eyes open; - -(2) do not change in error with speed-change for eyes closed; - -(3) visual control reduces errors for right hand, but does not for the -left; - -(4) right-handed subjects alone gain from visual control. - -The constant errors, - -(1) decrease with speed in visual cases; - -(2) increase with speed to the middle and then reduce to 200 beats for -eyes closed; - -(3) left-handed subjects are more accurate for the left hand and can -dispense with visual control; - -(4) all subjects need visual control for the right hand; - -(5) left-handed subjects show less error throughout for non-visual. - -For the individual cases, - -the mean errors - -(1) show evidences of loss of control or fatigue for some speeds, and -the average results are confirmed. - -The constant errors show that the average deductions are confirmed. - -Lines 10 cm. long: - -Averages for seven subjects as regards mean errors have especial -interest for l.h.e.c. records, which alone show a rise of error with -speed-increase. - -Noting that the records are overwhelmingly averages of right-handed -subjects (six to one), it is of interest to examine this record. - -We may say, then, that for right-handed subjects, the voluntary control -for the right hand is not much improved by the introduction of visual -assistance; it is more marked for speeds of 100 beats or less than for -the high speeds. And in the latter case, it is under 10%; but when the -left hand is considered, a marked gain or 40 or 50% is apparent, when -the eyes are used except for the two lowest speeds. - -As far as it is possible to offer any hypothesis from the few -facts tabulated, it may be said that right-handedness implies a -high development of muscular control, but slightly improved by the -introduction of the visual element, as far as the right hand is -concerned; but for the left hand muscular control comparable to the -right-hand control can be obtained only with visual control; in short, -I fail to find evidences of cross-education, where the visual element -is absent, nearer than about 50% of the mean error. - -No clearly marked gain through visual control can be pointed to in -the case of constant errors; there is, to be sure, a slight gain in -steadiness and error-reduction, where eyes help in the case of both -hands, but not 5% in magnitude of the difference noted with mean errors. - -Individual records show fatigue-points at 40 to 80 beats and again -above 140 beats, but there is no perceptible loss of control during a -series of lines ruled at only one speed. - -It is apparent, when comparing with the 140 mm. records, that there is -no physiological reason why the subjects may not rule the full length -of a 10 cm. line at 200 beats, and the limit of movement for high -speeds is probably between 10 and 14 cm. - -The constant errors are in general positive and only Me. shows a -tendency to underrule lines at high speeds. - -For 10 cm. lines, - -for the average record, - -(1) the mean-error curve is horizontal for l.h.e.o., but otherwise -rises with speed-increase; - -(2) visual control is a 10% gain for right hand and 40 to 50% for the -left, so right-handedness is prominent for the eyes-closed series; - -(3) the constant-error curve for r.h.e.c. rises, but all others show -reduction of error as rate increases; - -(4) visual-control gains are not over 5%. - -The individual curves show, - -for mean errors, - -(1) marked-fatigue points for l.h.e.o; - -(2) r.h.e.o. curve is horizontal, but all others rise; - -(3) l.h.e.o. curve is about the same as r.h.e.o., but there is more -loss for non-visual series with left hand. - -For constant errors, - -(1) r.h.e.c. curve rises, but all others are horizontal; - -(2) the eyes reduce errors especially for the left hand; - -(3) overruling is prominent even at high speeds, for there is no -evidence that the lines are shortened at high speeds. - -Lines 1 cm. long: - -Averages are made for nine subjects, three being left-handed. - -The eyes are effective in reducing mean errors and to a less extent for -constant errors. - -A noteworthy feature of the constant-error record is that the errors -are positive with one exception, that of 20 beats with l.h.e.c. and -even this curve jumps rapidly above the 0 line. - -In all cases the motor discharge is of sufficient magnitude to cause -overruling in cases of normal lines of one cm. The assistance afforded -by the eyes is not marked. - -Certain evidence of an introspective character, that most of the -subjects offer, is to the effect that, "when I would do good, evil -is present with me"; that, where there is a decided feeling that the -muscular limit, if such a term be permitted, is exceeded, yet the -subject's will-power is not sufficient to inhibit the overruling; there -is a more or less vivid conscious error in the 10 mm. series for the -hands. - -In regard to the relation of mean and constant errors, there is more -close uniformity than with the 140 mm. lines, but it is to be noted -that there is no comparison to be drawn between maximum or minimum -points; for example, at 100 beats the minimum points for r.h.e.o. agree -closely, but the maximum constant error matches the minimum mean error -at 100 beats for r.h.e.c. - -We cannot predict, then, that a subject capable of closely ruling to -the normal will be able also to rule each line of the same length as -the rest of the series, or _vice versa_. - -As in the case of mean errors in general note that subjects show a less -constant error and more regularity for their more dexterous member; -it is not true for the left hand that for left-handed subjects visual -control is a hindrance for accurate work; otherwise the same gain, by -use of the eyes, is to be noted for the rest of the records. - -Individual records show close correspondence with the average of -results, and the latter may be considered fairly representative. - -Almost the whole series shows the constant error positive, the most -consistent example being for J. with l.h.e.o.; this tendency to -overrun the 1 cm. lines is consistently uniform and has been elsewhere -commented on, so it may be left with the observation that the log shows -that the subjects were frequently conscious of this overruling, but -confessed inability to correct it. - -Only in the case of Y. for the three left-handed subjects and for W. -among the six right-handed men does the left hand show less mean error -than the right hand, and all other cases show such an interweaving of -curves as to render it difficult to perceive any advantage that the -more dexterous hand possesses on the score of accuracy. - -For constant errors: - -For individual cases it is to be noted that for the left-handed -subjects J. is better for the right hand, Le. is indifferent, and Y. -prefers the left hand; while three of the six right-handed subjects -prefer the left hand and one is indifferent; thus giving still further -proof that a more dexterous hand is a fiction on the score of the right -or left-handed theory, when accuracy of straight-line movement is to be -considered. - - For 1 cm. lines, - for the average, note - for the mean errors: - -(1) visual control reduces errors; - -(2) errors increase for eyes open, but decrease for eyes closed, as -speed increases when considering right hand, but left-hand errors are -constant; - -(3) as left-handed subjects are better for r.h.e.o. than right-handed -subjects, but not for eyes closed, it is suggested that visual control -equalizes differences in the subject's less trained hand. - -For constant errors: - -(1) visual control reduces errors; - -(2) curves are horizontal in all cases; - -(3) all errors are positive, showing consistent overruling; - -(4) as visual control of the left hand is a gain for right-handed but -a hindrance for the left-handed subjects, the more practised hand is -probably able to dispense with visual control, and depend largely on -the muscular sense. - -Mean and constant errors are not comparable. For the individual -cases we find a corroboration of the above and for mean errors: more -dexterous hand does not excel, and evidence against ambidexterity is -conflicting; for constant errors: overruling is consciously done. - -Constrained hand-movements for lines 14 and 1 cm. long and for the -weight, both accelerating and retarding the movement, are to be next -considered. - -Constrained motions are of two general types as examined by the writer. -Series of the records for the hands were taken at 140 mm. and 10 mm. -bases with a weight hung on the finger or fingers of the hand under -investigation; in one series the weight acted as a pull or accelerating -effect on the ruled line and in the other series the weight was imposed -as a retarding effect, tending to restrain the movement of the hand. - -This weight was in all cases 260 grams, this weight being chosen as of -sufficient amount to have a perceptible effect, but not large enough to -cause feelings of pain or fatigue in any case. - -The average for seven subjects, three being left-handed, is as follows: - -In general, the mean errors for the right hand are less, and less -variable as compared with the left hand. The left-hand records are very -close to the corresponding right-hand curves, especially the portions -of the eyes-closed records 20 to 120 beats. - -This may be said for both mean and constant errors. In general, mean -errors are reduced, and curves are more nearly straight lines when the -weight is added; also the weight reduces constant errors, and gains -more regular records at all speeds. It is to be noted as a point of -unusual interest that there is no apparent shortening of the line ruled -when the weight is hung on the hand, for the negative errors are less, -not more when the weight is applied. - -In general, then, the imposition of a weight that will be small enough -not to cause pain or fatigue shows that both mean and constant errors -are reduced; that the amount of error is less variable over the range -of speeds used; that the records show no retarding effect, but that -the subject is both able to move the hand just as far as without the -weight, and do it with much greater accuracy. - -Individual records for 14 cm. and weight-retarding show a marked -reduction in both mean and constant errors, and a less marked gain -in uniformity in every case. This tends to confirm the introspective -opinion of W. subject that the imposition of a retarding weight tends -to reduce errors of both classes and to cause greater steadiness. - -It should be added that there is evidence of an occasional letting-go -of voluntary control, so to speak, resulting in a large increase in -mean error, as already pointed out, or a large increase in negative -constant error, as shown on all individual records, and it would -seem then that the matter of cortical control is more vital and -indispensable for the restricted movements. - -The effect of weight-retardation on visual records is to reduce the -error and steady the ruling of the less dexterous hand to a much more -marked degree than for the well-trained hand. - -In the l.h.e.c. records the lack of corrective effect of visual -control is marked, as in the case of free movements, but the dip in -the curve at 30 to 70 is not noted in the free ruling and should be -considered as a distinct shortening due to weight-retardation before -discriminative processes have oriented the subject. - -Without considering the accelerating weight-records in detail note that: - -The effect of weights (less than that necessary to cause pain or -fatigue), either tending to accelerate or retard motions, is to reduce -both mean and constant errors and to render more uniform or more -uniformly increasing or decreasing such errors, except in the case -of l.h.e.c., where constant errors are greater positively with the -weight-pulling and greater negatively with the weight-retarding, than -for free motions; that is, the effect of the weight is natural, and -shows no signs of inhibition in this particular case. - -There is no such marked fluctuation in error for the pull-records -as was noted for the weighted curves, and it is further noted that -the individual pull-records are more bunched or consolidated about -some mean than are the free-movement curves. This suggests that the -accelerating weight is a decided help for accuracy and regularity, and -it would seem to call for less voluntary control than for either of the -other movements. - -Further, as the effect of pulling weights is to equalize the accuracy -of movement of the hands, the hypothesis is proposed that weights -either accelerating or retarding the movements of the hand tend to -equalize their accuracy or to promote ambidexterity as far as accuracy -of straight-line mean errors is concerned. - -L.h.e.c. rise for Ha., are horizontal for J., W., and Y., and slope -downward for the other subjects, the net effect being a slight downward -slope. The loss of accuracy and regularity when the visual sense is -inhibited is to be noted in every case, it being especially marked for -Bo., Li., and W. - -As compared with the r.h.e.c., there is not sufficient evidence to -lead to the conclusion that the right hand is a more accurate member -than the left, but on the contrary the left-hand record for non-visual -control is lower for both weighted series than is the right-hand curve. -Contrasting this with the eyes-open records for free and weighted -movements, the visually aided results show a greater accuracy and -regularity for the right hand. - -This leads to a proposition that the greater dexterity on the line -of accuracy, of one hand, that is the right hand for right-handed -subjects, and the left hand for left-handed subjects, is a matter -of visual control and is in no sense due to the muscular sense or -to automatic action, for without eyes we are ambidextrous as far as -accuracy of linear movements is concerned; the proposition needs -careful scrutiny in application to the general question, but is held to -be correct within the range of experiments. - -We are tempted to extend this matter somewhat in the following way, -by saying that there is no evidence deducible from this research that -there is hereditary preponderance of activity or accuracy of one hand -or one leg (as shown later) over its mate, and the baby is brought into -the world with an equal capacity of accuracy of both members. - -It is, then, an evolutionary matter, not racial but individualistic, -and right-handedness or left-handedness is largely a development after -birth. Our system of education is responsible for the over-development -of one hand, and such a case as that of Dr. Anderson of the Yale -University Gymnasium, who in class demonstration cannot instantly tell -which hand is being used to actuate the chalk at the blackboard, is the -normal symmetrically developed man. - -The school reform for ambidextrous training is radical enough, but -seems a logical conclusion of the argument. Apologies are appended for -driving the argument beyond the limits of the investigation, but it is -hoped that the enquiry is at least suggestive. - -For 14 cm. lines, - -weight-retarding movements: - -For the average of nine subjects: - -The weight reduces errors and promotes regularity in the case of both -mean and constant errors, nor does it tend to cause underruling, save -in the case of left-handed subjects for l.h.e.c. records. There is a -gain, in general, when the visual factor is introduced. - -For mean errors, - -(1) right-hand curves are horizontal, while the visual records show -increasing error and l.h.e.c. a reduction of errors; - -(2) the right hand gives slightly better results; - -(3) note that l.h.e.c. record is equally good for free or weighted -movements. - -For constant errors, - -(1) r.h.e.o. and l.h.e.o. curve downward, while both non-visual curves -slope upward; - -(2) the left hand seems equally efficient, as compared with the right -hand. - -For individual cases, - -note (1) fatigue-spots are more numerous than for free movements, -especially for the left hand; - -(2) weight reduces both mean and constant errors and to a less extent -even records. - -For mean errors, - -(1) visual control reduces errors; - -(2) the weight tends to equalize the accuracy of the right and left -hands. - -For constant errors, - -(1) there is no general testimony showing shortening of lines at high -speeds; - -(2) the less trained hand is more helped by the weight, especially for -non-visual work. - -The evidence for right- and left-handed subjects is inconclusive, and -we cannot finally say that the more trained hand is capable of greater -accuracy. - -Weight-accelerating movements: - -The average of seven subjects: - -The accelerating weight reduces mean and constant errors, and improves -regularity of curves, except for l.h.e.c. constant-error record. There -is some evidence that a pull causes overruling, while a retarding -weight causes underruling, but there are exceptions enough to warrant -care in finally accepting this statement. Visual control with -accelerating weight reduces error more than the weight acting alone. - -For mean errors, - -(1) weight reduces errors for r.h.e.o. and l.h.e.c. as compared with -free-movement records, while the other two curves are inconclusive; - -(2) visual sense helps in accurate ruling; - -(3) non-visual records are not reduced, as a rule, from the results of -free motion. - -For constant errors, - -(1) the accelerating weight tends to greater accuracy, with an -exception for the-non-visual records. - -No testimony of marked importance is to be noted in comparison of -right-handed and left-handed subjects; the more trained hand shows -greater accuracy in some cases, but fails to excel in others; so the -data is inconclusive. - -For individual cases we find: - -(1) the acceleration records are more accurate and regular, and present -fewer lapses than the free or retardation results, suggesting greater -ease with weight assisting; - -(2) visual control is prominent throughout, and evidence shows that -this sense is the greatest factor in the predominance of the more -trained hand; the non-visual records should and do show no marked -difference in the hands; - -(3) a weight tends to equalize accuracy of hands; - -(4) the overruling effect of weight is over-corrected in some cases for -constant error of low rates. - -Constrained movements of 1 cm.: - -The average is of seven subjects, three of them being left-handed: - -With weight-retarding movement, there is no reduction of mean error -with visual control of right hand, but there is with the left. Constant -errors show little reduction for either hand with eyes open. - -The facts would seem to warrant the hypothesis that, for the left hand, -a movement uncontrolled visually, whether restricted by a weight or -not, can be made with greater accuracy, when time is permitted for -discriminative and reflective processes and visual-control results in -about the same error whatever the speed, while the right-hand motions -show no such evening effect of visual control with the weight-records -or even reduction of error; the free movement, however, does show a -reduction of error. - -A general statement may be deduced that, for lines of 10 mm. in length, -there is no difference in either mean or constant errors, when a weight -is imposed to cause retardation, provided the weight is not large -enough to cause pain or fatigue. - -By separating the averages for right- and left-handed subjects, it may -be further said that: - -Visual control is not efficient to reduce the error and no particular -gain in regularity can be noted. The left-handed subjects show, for the -left hand, much better results without visual control as far as the -free motion is concerned. - -While somewhat contradictory, it may be stated that constant errors -are reduced by the weight addition, and there is some evidence leading -to the belief that the ruled line is shorter when the weight acts as a -retarding influence. - - -INDIVIDUAL RECORDS - -Considering lines 10 mm. long with a retarding weight: - -A glance over the seven individual records shows some considerable -increase in both constant- and mean-error irregularities, as compared -with the free-motion curves, as well as in actual errors; there are -distinct losses of volitional control for both classes of errors, -especially at or near the ends of the series. - -There are cases of very low mean error to be found on all records, -where the value is 1/4 mm. or less, and, while the same phenomenon -is found with free motion, it is more marked here and occurs more -frequently; in most cases it seems as a drop from errors of larger -values rather than a gradual matter, as if the subject realized the -large error and exerted unusual volitional control to correct and -produce a very accurate record, but found that the attention needed was -beyond his will-power, as shown by the immediate lapse of accuracy. - -There is an indirect confirmation of this view from the introspective -testimony of the subjects. - -The visual element steadies but does not reduce mean errors when weight -is retarding. - -The general shape of curve for eyes closed is downward 20-40 beats, -and rising for the rest of the series; it is less regular, but more -accurate than the visual results. - -The fact that constant errors are mostly positive leads to a denial of -any inhibitory effect of the retarding weight. - -For 1 cm. lines, - -weight-retarding movements: - -For the average of seven subjects we find: - -(1) visual control does not improve accuracy or regularity as in free -movements; - -(2) a retarding weight tends to make errors constant whatever the -speed-rate; - -(3) the testimony goes to show that the free-movement records are more -accurate than the retardation ones. - -Mean errors are: - -(1) no more accurate and perhaps less regular, when the weight is -imposed; - -(2) right- and left-handed subjects are equally accurate. - -Constant errors: - -(1) the more dexterous hand is superior for coördinations requiring -accuracy; - -(2) ruled lines are slightly shortened in some cases; - -(3) weight-records do not give more accurate results as compared with -free movements. - -For individual records we find: - -(1) retarding weights increase errors and irregularity; - -(2) fatigue-points are more marked and frequent than for free movements. - -Mean errors, - -(1) the visual factor is of some value, but the testimony is varied; -right hand for increased regularity only, and left hand for greater -accuracy only; - -(2) curves are horizontal or reducing with speed-increase. - -Constant errors, - -(1) the more dexterous hand coördinates better; - -(2) all errors are positive; - -(3) visual control helps only for regularity; - -(4) curves are horizontal or rising. - -With weight-accelerating movements, the average record shows a -sudden rise in mean error at both ends, not in evidence with free or -retardation results. - -In general it is to be noted: - -(1) that the visual element is of no value for reducing the error, and -of little value for promoting regularity; - -(2) that the pull-records are closely comparable to the free-motion -records, and the accelerating influence of the weight is imperceptible; - -(3) that the pull-records are more regular and closer to the -free-motion curves than are the weighted records, especially at the -ends of the left-hand curves. - -For constant errors: - -It is more in accord with the facts to say that the imposition of a -weight tends to reduce the constant error, and this is more marked when -the weight acts in pulling or to accelerate the motion. - -Comparing with the weighted curve, we find the same general type of -rising curve, similarly located, and the same is true when compared -with the free-motion curve. Constant errors are reduced, but slightly, -and visual control is rendered nil, when the weight acts either to -accelerate or retard the movement, and of the two, the accelerating -effect is more marked, as reducing errors and promoting regularity. - -There is no appreciable tendency for the weight to reduce the ruled -lines when retarding motion, nor is the weight as accelerating, able to -extend the line beyond the point set in the free motion. - -When contrasting averages from right- and left-handed subjects it may -be said: - -As compared with free motions there is a slight reduction of error and -irregularity more marked with the left-handed subjects, but a general -close correspondence of results. - -The question is now appropriate, why should the right-handed men show a -reduced error for speed-increase, while the left-handed subjects show -the reverse? Bearing in mind that the right hand is the more dexterous -or better trained in the former case, it may be suggested that the -order of record from 20 toward 200 beats is such as to cause more -accurate results at the upper limit, in spite of the fact that less -time is allowed for discrimination and adjustments; on the other hand, -left-handed subjects have much less advantage of practice and habit in -their use of the right hand, and will show the predominance of error, -when the ruling is too rapid for careful discrimination. - -It becomes a struggle between automatism, or semi-automatism, on the -one hand, and discriminative processes on the other. - -Visual control is not an advantage in the case of accelerating weight, -and the large reduction in error with visual control for the free -movements is not evident with weighted motions. - -For the left-handed subjects we find that the eyes-closed record shows -closer work than does the eyes-open curve; it is lower and nearer the -line of 0 error; in this respect, it shows the same effect as with -the free-motion curve, and to a less extent as for the retardation -weight-record. The accelerating record is, however, more accurate and -regular than either of the other curves. - -It will be clear, then, as observed, that for constant errors, visual -control tends to reduce errors and steady records whatever the -speed-increase, as far as right-handed subjects are concerned, but this -effect is not noted for left-handed subjects using the right hand, and, -with their left hand, visual control is a disturbing element. - -Further this erratic effect of visual control is less marked but clear -when the weight acts as a retarding factor, but is much more noticeable -for the free-motion record. - -Individual records show few lapses of control for either errors. - -The bulk of the evidence is that the weight imposition, whether acting -as a retarding or accelerating influence, is effective in rendering the -results more accurate and regular, though at least one subject exhibits -the opposite effect for the accelerating weight. - -The left hand is better for J., Le., and W., but is less regular for -all subjects, save Le. and W., showing again a somewhat complex mass of -testimony, from which we may conclude that the right hand is the more -accurate member for right-handed subjects, and to a much less extent -the left hand is preferred by the left-handed subjects. - -Visual control is to be noted as effective for accuracy and regularity, -except for Ha., where the curves closely intertwine, and for J., where -the eyes-closed record is much better. - -Weight-accelerating movements: - -For the average of seven subjects we find - -visual control is of doubtful advantage, for left-handed subjects, but -shows a clearly marked reduction of error for right-handed subjects. - -Mean errors are: - -(1) similar in all respects to free-movement results; - -(2) acceleration-curves are closer to free-movement results than are -retardation records; - -(3) the more trained hand shows reducing error for speed-increase, -while the other hand shows increasing errors, because of superiority -of practice-effects over the native tendency to increase error as -speed-rate rises, for the more dexterous hand alone. - -Constant errors: - -(1) there is no tendency to overrule, as compared with free movements, -when weight acts to accelerate movements, for there are even cases of -lines being shortened with accelerating weights; - -(2) a weight seems to negate the results of visual control, as a rule. - -For individual records we find: - -(1) fatigue-points, for the right hand only, are to be found in a few -cases; - -(2) weight promotes regularity and accuracy; - -(3) visual control is effective only for reducing variations of error; - -(4) the better trained hand is the more accurate in the records, to a -slight extent; - -(5) there are evidences of semi-hypnotic or dreamy states in the -non-visual series. - - -COMPOUND MOTIONS - -Series of records were taken at 100 mm. and 10 mm. bases for the hands, -with what is called compound motion. This consisted in an additional -movement of the hand that was not ruling with the pencil, in a similar -manner, as regards the amplitude and general character of the motion, -but in an opposite direction. - -For example, suppose the left hand is ruling a 100 mm. line outward, -or to the left; coincident with this movement would be a similar motion -of the right hand outward or to the right. The origin of both motions, -or the starting-ends of actual and imaginary ruled lines, was optional, -it being desired to bring out the effect of such additional motion, as -little complicated as possible with restrictions, as to its position -or extent. Actually this distance varied from about 10 mm. where both -motions were outward to 600 mm. for inward motions. - -A comparison of such compound motions with single-hand records shows in -general the following: - -For 10 cm. lines: - -The case for mean errors may be summed up by saying: - -(1) left-hand records are less accurate and regular than the right-hand -curves; - -(2) visual control reduces error and irregularity in all cases, but is -more marked with the left hand; - -(3) errors increase with speed-increase; - -(4) compound-motion records show little increase in error or -irregularity, as compared with the simple motions. - -For constant errors: - -No marked peculiarities are to be noted, but in general, - -(1) left-hand records are less accurate and regular; - -(2) visual control reduces errors and irregularity; - -(3) errors reduce with increase of speed, except for compound motion -uncontrolled visually; - -(4) compound-motion errors are not much greater, nor is the -irregularity increased. - - -INDIVIDUAL CASES - -100 mm. hand with compound motions. - -A glance at the charts shows for individual records a few examples of -inhibition of voluntary control for both constant and mean errors, it -being much more marked in the case of mean errors. - -These lapses of control appear for constant errors for A. with l.h.e.c. -at 160 and 180 beats, for mean errors for G. with l.h.e.c. at 200 -and with r.h.e.c. at 180 beats; for Le. with l.h.e.c. at 50 and with -r.h.e.c. at 160 beats; for A. with l.h.e.c. at 200 beats; thus giving -evidence that the visual element has a steadying effect, and that the -left hand is less reliable save for Le. - -There seems reason for contending that the compound motion can be -carried out, as arranged, without loss of accuracy or regularity on -the part of the ruling hand, and further that the subjects are pretty -generally apt to react to a given stimulus within certain rather narrow -limits of accuracy. - -The evidence is here pretty conclusive that the right-handed subjects, -as a whole, show greater accuracy by about 25% for the more dexterous -hand; but it will be wise to consider the individual cases on this -point. - -Greater regularity and accuracy for the right hand is attained by all -right-handed subjects, while the preference of Le. for the left hand is -clear but much less definite. - -For individual cases: - -The evidence again is fairly well marked that the more practised hand -will give a better account of itself even when visual control is not -called on. - -The results for compound movements of the hand for 1 and 10 cm. lines -are summarized as follows: - -It should be kept in mind that the compound records were in all cases -taken in connection with a duplicate series of lines for one hand, and -called simple movements. These simple movements correspond with the -free-movement records that have been considered already. - -The purpose has been to bring out the modification of results that a -compound movement introduces, rather than to bear heavily on intrinsic -phenomena, _i. e._, comparison is deemed more important. - -For lines 10 cm. long: - -Average of seven subjects: - -We find for mean and constant errors: - -(1) left-hand records are less accurate and uniform; - -(2) visual control increases accuracy and regularity, especially for -the left hand; - -(3) there is an increase as the speed increases for mean errors, and a -decrease for constant errors; - -(4) compound movements are practically as accurate and regular as the -simple ones for constant errors. - -For individual cases: - -(1) a few lapses of control or fatigue-spots more marked for mean -errors with the l.h.e.c., for the visual sense steadies ruling, and the -left hand is less reliable; - -(2) compound and simple records show close agreement; - -(3) the more trained hand reacts more accurately, and with greater -regularity; - -(4) non-visual records show a cautionary shortening of line at low -speeds, and another at the upper limit, the latter being due to -physiological limitations. - -For 1 cm. lines: - -As far as averages are considered: - -We may say, then, for mean errors: - -(1) that visual control is effective for reducing errors, and -increasing steadiness in both sets of records, being more marked with -the less trained hand, the left; - -(2) only in the case of the l.h.e.c. curves is the movement of the free -hand noted as appreciably affecting the accuracy or steadiness of the -record. - -(3) eyes-closed records in general show a considerably greater error at -20 beats that practice rapidly reduces up to 40 to 60 beats. - -We may note for constant errors: - -(1) all errors are positive and confirm the earlier deductions on this -point; - -(2) visual control reduces error and improves steadiness of record; - -(3) the free hand-movement does not affect either the accuracy or -uniformity of results; - -(4) errors do not increase with speed. - -For individual records: - -Comparing the individual cases of simple and compound movement, there -is no particular reason for concluding that the compound movement -is a disturbing influence as far as the records of all subjects are -concerned, save possibly the lapse of G. at 20 beats, and on the other -hand a case of greater accuracy and evenness for compound movements for -Mo. with r.h.e.c. constant error. - -It is, then, possible to extend the conclusion of the 10 cm. records, -and say that both lengths of lines are ruled with a fairly constant -limit of error, whether the movement be simple or complicated by -movement of the free hand. - -Individually there is testimony in favor of the gain in accuracy with -visual control for Hu., Hy., and Le., while the crossing of curves for -the other subjects shows that there is no difference in eyes-open and -eyes-closed results, the general conclusion being in favor of the value -of the eyes for accurate results. - -For mean errors the right hand is more efficient in the case of A., -Hu., Hy., and Me., while the reverse is the case for the rest, and the -evidence goes to suggest that greater accuracy can be attained with the -more practised hand. - -For constant errors the right hand is more accurate in the case of A., -G., Hy., only; Me. and Mo. are equally accurate with the hands, and the -rest show a marked preference for the left hand, the evidence being -thus conflicting, pointing to the theory of ambidextrous development on -the lines of accuracy. - -L.h.e.c. records are horizontal for all subjects except Hu., Me., and -Mo., who show an upward slope to the curve. Evidences of visual control -as giving greater accuracy are noted in general above 70 beats and -individually for Hy. and Mo., only, the remaining records being so -intertwined that no difference can be noted, all suggesting that the -eyes are of but little assistance when the left hand is considered. The -right hand is preferred with eyes closed by A., Hu., and Le., while -four right-handed subjects testify that the less trained hand is more -accurate. - -The testimony here seems conclusive as pointing to a denial of the -current notion as to the greater accuracy of the right hand for -right-handed subjects, and of the left hand for left-handed subjects, -and further suggests that visual control is a large factor in the -supposed superior excellence of the hand mentioned. - - -SUMMARIZING - -For lines 1 cm. long: - -Average of seven subjects: - -It may be said that: - -(1) visual control reduces both mean and constant errors, especially -for left hand; - -(2) errors are constant whatever the speed; - -(3) constant errors are positive showing overruling in all cases; - -(4) there is no disturbance created by the second-hand movement, save -for r.h.e.c. mean errors, where the accuracy is less for the compound -records; this is probably due to the fact that this record shows the -least evidence of voluntary control, and is thus most subject to -disturbances; - -(5) there is a marked reduction of mean error 20-50 beats, probably due -to practice. - -For individual cases note: - -(1) fatigue-spots for non-visual mean errors only; - -(2) the equality of result of both types of movements is noted for all -cases; - -(3) the non-visual right-hand records for some subjects are more -accurate; - -(4) the more trained hand is not, as a rule and subject to exceptions, -the more accurate one, especially for the non-visual records; and - -(5) there is evidence that the superior accuracy of the right hand for -right-handed subjects is largely a matter of visual control. - - -HEAD-RECORDS - -There was no attempt made to differentiate the visual element because -the very movements of the head prevent the full use of the eyes; as a -matter of fact, the subject's attempt to make use of the eyes and the -aid is more marked at slow speeds and upon facing the apparatus. It -is to be noted here that the visual element, as reducing the error at -low speeds, is equally marked whether the eyes are directed toward the -recording pencil or not. This raises an interesting question as to the -direction the eyes must take for the optimal result; must the eyes be -fixed on the moving pencil, on its immediate surroundings, or may they -wander at will about the surrounding objects? - -My own introspective testimony, corroborated by others, who have acted -as subjects for this investigation, is that the eyes are most effective -when gathering spatial relations in a gross way, and it may be expected -that the effects of visual control as reducing errors will be equally -efficient, whether the recording pencil be screened or visible, -provided it be possible to bring on the retina objects that are grouped -about the centre of attraction, the pencil, but not in its immediate -neighborhood. - -The records show that there is underruling at the higher speeds because -of physiological limitations; but this shortening is greater for the -backward movements, for the position of the subject is such as to lead -to greater uncertainty as to the exact length of ruled line, and it is -probable that a cautionary or inhibitory feeling is the cause of this -shortening beyond what will be clearly due to inability to perform the -desired movement. - -Further, visual control is effective, in the case of constant errors, -in lengthening the ruled lines at high speeds, and thus reducing the -negative constant error. - -While the muscular control of the head is a constant, whether the -movement be forward or backward, it is less effective for constant -error reduction when the head is moved backward. Consequently, while -the backward and forward curves are fairly well in correspondence, -there is some reason for offering the proposition that either the -eyes are of assistance in forward movements to reduce mean errors at -high speeds, and they are of no such value for backward movements, or -the muscular control of the platysma myoides, trapezius and associated -muscles of the neck group is more nearly perfect for movements of the -head forward than for backward motions, the latter being to my mind the -better hypothesis. - -The results for head-movements for lines 1 and 10 cm. long are -summarized: - -For lines of 10 cm. length: - -Average of six subjects: - -For mean errors: - -(1) the curve for head-forward and head-backward closely corresponds -to l.h.e.c. record; the errors increase by 50% with increase of -speed-rate, suggesting that - -(_a_) visual control is negligible, as far as seeing the moving pencil -is concerned; - -(_b_) control of head for forward equals that for backward movements. - -For constant errors: - -(1) there is underruling at high speeds because of the usual -physiological limitations, and this is more marked for head backward -results, suggesting that - -(_a_) spatial relations are obtained, when the apparatus is visible, -that tend to correct underruling, or - -(_b_) an extra inhibitory effect, due to lack of knowledge of spatial -relations, is added to the normal physical shortening and the subject -moves the head a less distance than is naturally possible; or - -(_c_) the muscular control is less complete for movements of the head -backward. - -For individual cases we find: - -(1) fatigue-lapses are less in magnitude than for the hands, because -the head-movement can be only a fraction of the forearm-movement; - -(2) mean errors increase and constant errors decrease with speed-rise; - -(3) similarity of individual head-forward and head-backward curves is -suggestive, taken with the fact that no typical form of curve is to be -found; - -(4) head-backward constant errors are greater and less regular in all -cases, suggesting that the eyes, in head-forward records, by getting -spatial relations, are more efficient. - -For lines 1 cm. long: - -Average of six subjects: - -For mean errors note: - -(1) the head-backward records are less regular than the head-forward -ones, and rise a little with speed-increase, showing visual assistance -for accuracy or better muscular control for the forward movements or -both; - -(2) the constant errors show shortening of ruled lines at high speeds a -little more marked for the head-forward results; - -(3) there is constant overruling. - -Individual cases suggest: - -(1) fatigue-spots are apparent, especially for head-backward movements; - -(2) errors do not increase with speed; - -(3) the movements of the head forward are under better control. - - -FOOT-RECORDS - -10 cm. records show that - -(1) the eyes are of no assistance as to increasing accuracy but help in -promoting regularity of error; - -(2) a shortening of ruled lines with speed-increase is noticeable, and -is probably due to the usual physiological reason; - -(3) the feet are capable of less accurate motion than the hands, but -show better results than the head; - -(4) mean errors increase but constant errors decrease with -speed-increase. - -Individual records show: - -(1) less violent fluctuations of errors in all respects than do the -results of head or hands, for vertical foot-movements are of less -extreme extent than are arm- or head-motions; - -(2) that for visual control with mean errors, no foot is the more -accurate, and there is no reason to believe that the feet are unequally -educated. - -1 cm. records show, as far as mean errors are concerned, that: - -(1) visual control is of no value as either reducing actual errors or -as effecting greater regularity; - -(2) Errors for foot-movements are no less, but considerably more -regular than for head-motions; - -(3) errors for hand-movements are more regular, and only 50% of the -results for either head- or foot-movements; - -(4) all curves are horizontal; - -(5) there is no appreciable advantage as to accuracy or regularity that -can be attributed to either foot. The evidence goes to show that the -subjects are ambipedalous, if it be permitted to coin such a word. - -In general, we find that, as far as constant errors are concerned, - -(1) visual control does not help to reduce actual errors or promote -uniformity; - -(2) errors for foot-movements are less than the head records, and but -little greater than the hand results, while the regularity for the feet -is comparable to the hand, and much greater than for the head; - -(3) all curves are horizontal; - -(4) there is no particular advantage that either foot has over the -other either as to accuracy or regularity. - -The evidence is that the subjects were ambipedalous, as far as ability -to reach a certain point equally well by either foot is concerned. -The popular notion has been to the contrary, and it is a point of -considerable importance to note the last point. - -For example, in kicking, as developed by football trainers, it is -commonly assumed that the right foot for right-handed subjects should -be developed, and the opposite foot for left-handed men. Or again, in -the case of a person lost in the woods and walking in a circle, it is -observed that right-handed persons will turn to the left; probably -because of the pace of the right foot being slightly longer than the -left. My reply to this evidence will be that the data herein presented -is for vertical movements of the foot, starting from the floor in every -case, the subject being seated in a chair. - -On the other hand, it is an entirely different movement, calling for a -much different and greater muscular control in the case of kicking or -walking that must be considered. For this reason the evidence, while -conclusive within its range, is not offered as more than suggesting -that the feet are equally well trained for the usual adjustments, and -only an exhaustive investigation covering all possible foot-movements -will settle the question. - -The result for foot-movements for lines 1 and 10 cm. long is here -summarized. - -For lines 10 cm. in length: - -Average of seven subjects: - -Note in general that - -(1) l.f.e.c. mean error is most erratic, while the same curve is the -most accurate, as far as constant errors are concerned; - -(2) the left foot mean and constant errors are slightly greater than -those for the right foot, for visual records; - -(3) mean errors increase and constant errors reduce with speed-increase; - -(4) the visual sense improves regularity, but does not reduce errors; - -(5) there is a physiological reason for the shortening of lines at high -speeds; - -(6) the feet are more under control than the head, but less than the -hands. - -For individual records: - -(1) fatigue-lapses, all for non-visual, are less numerous and of less -magnitude than for the hands and head, for the vertical movement of -foot is likely to be of less extent than that of head and hands for the -particular motion required here; - -(2) there is no foot capable of being called more accurate than its -mate; - -(3) the eyes appear to be of no value for reducing or regulating errors -for foot-movements. - -For lines 1 cm. long: - -Average of six subjects: - -It may be said in general that - -(1) the visual sense is valueless for promoting accuracy or regularity -of curve; - -(2) errors of foot-movements are more regular and, for the constant -errors, more accurate than for the head-records; - -(3) errors of foot-movements are less and less regular by 50% as -compared with records for the hands; - -(4) errors do not increase or decrease with speed-changes; - -(5) the feet are equally accurate. - -For individual results: - -(1) fatigue-lapses and cases of large error-increases are noted in a -number of subjects, both for visual and non-visual records; - -(2) further, evidence is available as to the indifference to visual -control; - -(3) no preference for either foot is to be discovered. - -The results for individual choice of rhythm. - -In this series of records, the metronome was dispensed with, and -the subject was permitted to react as he desired, taking the speed -preferred because of ease, pleasure, or other reason. - -Records were obtained for six subjects for feet, head, and hands, both -single-hand and double-hand movements, all for lengths of line 1 and 10 -cm. The charts for individual choice were plotted for a comparison of -speeds rather than for accuracy. - -It was noted for the hands: - -(1) that every subject reacts more rapidly with the left hand; - -(2) the eyes had little effect as to changing the speed-rate; - -(3) single and double hand-movements were equally rapid. - -Some subjects, as A., react more rapidly for the shorter lines, though -no clearly marked evidence of this speed-increase is to be noted. - -For the head, the results for both eyes opened and closed show the -impossibility of separating the optimal or preferred rate of speed on -the score of visual assistance or because of direction of head-movement. - -There is a close agreement of the subject as to his best speed, and -this is independent of special conditions; for example, - -A. selects 50-57 beats per minute for 1 cm. and 48-68 for 10 cm.; G. -has a preference for 61-66 and 56-71; Hu. rises to 103-125 for 10 cm. -and selects 68-82 for 1 cm.; Le. 52-55 for 1 cm. and 45-52 for 10 cm., -and so on. - -We may say, then, that free rate-choice for head-movements results in -a selection of some rate of speed that is not affected by the visual -sense or direction of movement, and is strictly individualistic, -covering a range of 50-130 beats per minute, and not increasing as the -amplitude of movement is reduced. - -Turning to individual choice of speed-rate, for the feet it will be -seen that - -(1) the non-visual records closely correspond as to chosen speed, and -there is a less close correspondence of visual speeds; - -(2) the visual records are ruled at a lower rate in some cases, but A., -G., and Mo. show little difference; - -(3) there is a tendency to speed up as the series progresses; - -(4) the shorter lines are ruled with greater speed as a rule, though G. -and Le. fail to show this phenomenon; - -(5) The left-foot records show a higher speed-rate for all cases. - -Among many interesting points that cannot be examined in this -connection, such as relation of voluntary choice of rate to the main -line of metronome records as regards accuracy, the fact of the higher -rate of ruling for the left hand and foot stands most prominent. - -Whether a record of head-movements to right or left, or other devices -to compare the sides of the body or to contrast arm and leg speeds, -will bear out this testimony is as yet unknown, so that the writer -prefers to announce the result and not now fit theory to data. It may -be said that the records were taken in reverse order and rearranged, -as regards right and left foot or hand, and, in addition, the initial -foot-movement varied with the subject, some being right and some left. - -We ask finally: Is the time in which the greatest exactitude is -produced, the same for every group of muscles; that is, has every -motor apparatus the same natural rhythm? and: Is this natural rhythm a -constant rapidity for all motor nerve-centres or does it depend upon -the complexity and character of the movement? - -The comparison will fall first on the averages and finally on the -individual records. - -The hand-movements show the following results: - -Constant errors for 14 cm.: - -For simple and weight accelerating and retarding motions, there is a -close agreement about 120 beats for the minimum error for visual and -right-hand non-visual records; left-hand non-visual records are spread -more, but will also average the same. - -For 10 cm. simple and compound movements the visual minimum errors are -at 180-200 beats, while with the eyes closed the results are grouped -about 60 beats; one record, that for l.h.e.c., has two minimum points -at 60 and 180 beats, the latter being clearly a crossing of the 0 -error-line, because of physiological limitations. - -For 1 cm. simple and weighted minimum errors are grouped between 20 and -60 beats, while the simple and compound group show less regularity and -a tendency to group minimum errors at 100 beats. - -The head-movements show for both 1 and 10 cm. lines a minimum error at -180-200 beats, there being, however, one exception at 100 beats for 10 -cm. head-backward movements. - -The foot-movements show minimum errors at 80 beats for the right -foot, and 180 and 100 beats for the left foot, visual and non-visual -respectively. - -Bearing in mind for a moment the individual choice records, there seems -here a suggestion that the left foot is capable not merely of higher -speeds, but of minimum errors at the higher rates as compared with the -right foot. - -No such differentiation of the hands can be discovered, however. - -Mean errors: - -For the hands: - -For 14 cm. for simple and weighted results we find that the right-hand -and left-hand eyes-open minimum errors are at 180 beats, but the -non-visual left-hand minimums are at 30 beats. - -For 10 cm. simple and compound records we find all minimum errors are -between 160 and 200 beats. - -For 1 cm. simple and weighted results there is a scattering of minimum -errors from 20 to 200 beats, with a heavy preponderance at 200, and the -same is true for the simple-compound series. - -The head-movements minimum errors are at 40 beats without exception. - -The foot minimum errors are distributed from 20-30 beats for the left -foot to 160-180 for the right. - -It is thus evident that each group of muscles and each motor centre has -its own optimum, and that the conditions of complexity, resistance, -etc., influence greatly the accuracy of the periodic movement impulse. - -FOOTNOTE: - -[Footnote 138: Woodworth: The Accuracy of Voluntary Movements, -Psychological Review Monographs, no. 13, 1899.] - - - - -THE MOTOR POWER OF COMPLEXITY - -BY C. L. VAUGHAN - - -A. COUNTING OF SIMPLE AND COMPLEX VISUAL OBJECTS - -If every sensory stimulus has a motor reaction, then a simple figure -perceived in any way ought to produce a somewhat different response -from a more complex figure similarly perceived. Of course if only one -figure of each kind is given it is difficult to measure in any way -this difference, since it is so small. But we might make it measurable -by multiplying the process. Therefore I have cut out a row of similar -figures in a strip of cardboard and on another strip another series of -a different pattern. Now if these rows are counted figure by figure -each figure has a certain motor effect which influences the speed of -counting, so that the time of counting (measured by the chronoscope) -should give some indication of the comparative motor power of the -figures in question. - -In the accompanying illustration nine cards of various patterns are -shown. Cards 1, 2, and 3 are comparatively simple patterns while 4, 5, -and 6 are comparatively complex, Card 6 having the added complication -of different kinds of figures on the same card. Cards 7, 8, and 9 form -another group, Card 7 having the same letter throughout, Card 8 having -letters composing a sentence and Card 9 a series of the letters, mostly -consonants, mixed promiscuously. In order to prevent the subject from -knowing the exact number, and thus, perhaps, bring in another influence -at the end of the row, most of the different cards have different -numbers of figures, but this difference is not great and some cards -have the same number. The subject usually forgets, from one experiment -to the next, the number on each card. - -At first the experiment was performed with the figures in a straight -row, instead of in the broken line which is seen in the illustration. -In counting the straight rows, the observers found it hard to keep the -place in the line. A subject would become confused and count some spot -twice or else he would omit it altogether. Furthermore this disturbance -was found to be much greater with some figures than with others, with -Card 1, for example, more than with Card 2. Therefore the device was -adopted of diversifying the line, both by placing some of the figures -above and some below the line and by making the distances from one -figure to the next, different in the different cases. And in order to -prevent the subject from associating any peculiar turn in the line -with a certain number counted, it was decided to have the arrangement -on the different cards different. But it was still necessary to have -the intervals between figures about the same in all the cards, and -therefore the row was divided into sections of six figures each and -these sections were used as units, variously arranged, in constructing -the other rows. For example the first unit of Card 3 is the same as the -second of Card 4. Sometimes this six-figure unit is turned end for end -or upside down, and thus, though the same spaces are used, the cards -appear dissimilar. - -[Illustration: FIG. 1] - -The subject would be seated at the table with one hand resting lightly -on the key which sets the chronoscope in motion, his eyes raised so -that the table in front of him is not seen. One of the cards would -then be put in the proper position in front of him (always the same), -and he is told that all is ready. He looks down at the card and as -soon as he begins to count the first figures in the line he presses -the chronoscope key, and when he has reached the end of the line he -releases the key. The time for the operation is then noted. The whole -series of cards is thus gone through. An extra card of which no record -is taken is used for the first few tests so that the subject may be in -the proper state when the first test to be noted down is taken. Also -the order of the series is changed from one experiment to the next, -each card taking its turn at being first and last. It was hoped in this -way to distribute among the different cards the effects of practice and -fatigue, and also to guard against any expectations on the part of the -subject as to the character of the next card. - -The subject is told to count as fast as he can, with a reasonable -feeling of certainty as to his correctness, the main object being to -have a uniform principle, in counting the different series. Wrong -counts were excluded, but later on the same cards given again so as to -keep the tables even. Subjects were not allowed to count the figures -by groups, but one by one. At first a certain amount of difficulty was -found in the fact that subjects in counting would repeat the numbers -to themselves, and as they seemed to be retarded by this, especially -in those numbers whose corresponding names have 2 or 3 syllables, the -result was that we were getting the speed with which subjects could -count the numbers from 1 up to 38 or 39 and this would be practically -the same whatever the figure. But all the subjects were finally trained -merely to think the number, or at least to have as little vocal -adjustment as possible. When this was done the subject no longer felt -that it was the speed with which he could count that was being measured -but the rate at which he could take in the different figures on the -card, one at a time. - -Between three and four hundred tests were made of the counting of the -figures on the nine cards, the work being divided among seven subjects, -though not in exactly equal amounts. Since the number of figures on the -different cards are different, I have found the time it takes to count -one figure by dividing the total time by the number of figures on a -card. The following table shows the average time taken by each subject -for one figure on each card, time given in thousandths of seconds. -_A.M.V._ stands for average mean variation. - - _A._ _A.M.V._ _B._ _A.M.V._ _C._ _A.M.V._ _D._ _A.M.V._ _E._ - 1 279.69 11.47 186.87 13.22 247.62 14.89 193.08 12.38 262.77 - 2 270.60 12.47 180.55 11.88 249.21 18.00 190.51 11.82 257.56 - 3 274.43 9.87 180.89 11.57 247.59 15.51 192.07 7.87 259.96 - 4 286.82 12.47 190.39 12.56 255.20 16.78 200.53 10.72 267.11 - 5 290.29 11.89 195.41 12.36 262.27 19.73 199.89 9.27 271.06 - 6 293.06 12.21 185.33 11.51 275.40 18.13 199.20 7.92 264.59 - 7 273.32 15.54 192.23 13.73 229.26 19.30 185.60 9.83 265.56 - 8 279.77 13.86 185.23 12.69 246.66 18.86 193.39 9.81 277.52 - 9 285.09 11.97 197 04 12.28 269.96 19.95 186.30 9.05 259.72 - - _A.M.V._ _F._ _A.M.V._ _G._ _A.M.V._ - 20.20 217.00 12.32 442.63 36.51 - 16.03 195.00 9.50 431.00 24.39 - 17.41 191.50 11.03 434.83 24.28 - 20.31 226.40 29.11 445.71 14.58 - 20.86 233.50 20.46 459.17 18.92 - 15.00 220.80 14.92 432.17 26.87 - 19.20 189.20 30.31 402.13 21.34 - 14.93 220.70 21.79 388.77 27.48 - 14.27 210.34 11.71 419.57 18.22 - -A, B, C, D, E, F, G are the different subjects, and 1, 2, 3, 4, etc., -refer to the cards with the different patterns. It is seen at a glance -that great differences exist between the rates with which the different -subjects count. Subject G had much fewer tests than the others, and -thus, not having as much training, his average is higher in comparison -than it would be had he had the same training. - -Now if we compare the counting of the first three or relatively simple -patterns with that of the next three or comparatively complex ones, we -notice at once that the simple figures are almost invariably counted -in less time than the complex, there being only two exceptions. B -counts 6 a little faster than 1, and G counts 6 faster than 1 and 3. -Even these apparent exceptions are easily explained. As noted already, -subjects are much more apt to lose their place in counting certain -cards than others. This is especially true of Card 1 even after the -line is broken. Now Card 6 is arranged on a different plan from the -others, for it has many kinds of figures on it. This is a great help -in keeping one's proper place in the counting of the series, and since -wavering between two figures is avoided, the series is counted more -rapidly. But B is the most rapid in counting, of all the subjects, and -it is natural that any differences in the ease of keeping place should -show themselves here, since the more rapid the counting the easier it -is to lose the proper position. This cannot be said of G, who is a -slow counter, but on the other hand it may be noted that he had only -a few cases, and at first the ability to keep one's position is much -less than after considerable experience. So in Cards 6 and 1 there are -two conflicting principles, degree of complexity and tendency toward -confusion of position. Of course both these principles are present in -all the other cards, but they reach a maximum in 1 and 6, in 1 extreme -simplicity with difficulty in keeping place, in 6 extreme complexity -with ease in keeping place. Card 1, it will be seen, is with nearly all -subjects a little slower than 2 and 3, while 6 is generally faster than -4 and 5. - -Therefore it would seem that the apparently small exceptions are not -real exceptions, but variations due to the presence of other factors -than mere differences in complexity of the figures used. In observing -the averages for 7, 8, and 9 we see that as a rule 7 is fastest, 8 -next, and 9 the slowest. The tables are not quite so regular as for the -cards just given. B and G count 8 faster than 7, and E counts 9 faster -than 7. The most of these cards have on them 36, 37, 38, or 39 figures. -Card 8 has 43 letters. The subjects report that the last three on this -card are counted much faster. They know, as soon as they reach 40, just -how many there are, and it is hard to keep from counting the rest in -a group. Otherwise they do not feel any difference in counting Cards -8 and 9. Arranging the letters in words does not affect the speed of -counting, so far as they can see, for in counting they do not notice -the words at all. - -When we average the records of all the subjects giving equal weight -to each subject, though the number of tests may be different with the -different men, we get the following table. Time given in thousandths of -seconds. - - (1) 261.38 - (2) 253.49 - (3) 254.54 - (4) 267.46 - (5) 273.08 - (6) 267.22 - (7) 248.19 - (8) 256.01 - (9) 261.15 - -It is seen, from looking at this table, that all divergences from the -general rule have stopped. Cards 1, 2, and 3 each take less time than -any of the 4, 5, 6 group, and 7 is faster than 8 and 9. So the evidence -seems very strong that it takes longer to count complex than simple -figures. Should one object that the difference is extremely small, a -few thousandths of a second, and that thus a slight error in one test -might invalidate the result, we reply that the time which is given -is the time in which we count just one figure of the given pattern, -and that thus of course the difference between counting two different -figures must be very small. Moreover there has been a remarkable -agreement of the tests taken at different times. It is not a case of -finding 1, 2, and 3 counted faster one day and 4, 5, and 6 counted -faster the next, but 1, 2, and 3 are counted faster nearly every time. -Occasionally 1 will take longer than one of the 4, 5, 6 group. And -extremely seldom is there a case where the average of 1, 2, and 3 is -not less than that of 4, 5, and 6. - -The experiment seems to have proven that it takes a longer time to -count a row of complex figures than a similar row of simple figures. -_The complex figure exercises a retarding effect upon the eye as it -sweeps along._ There is a greater amount of sensory stimulation, -consequently a greater amount of motor excitement. This motor -excitement does not act in harmony with the motor activity which impels -the eyes along, but has a somewhat antagonistic effect. The eye is -held more by the complex figure; it is a greater effort to withdraw -the gaze to look at the next figure. A certain interest, as we say, -on the psychological side tends to hold one to the figure looked at. -This interest is greater (other things being equal) the greater the -complexity of the figure. The nervous processes involved in counting, -though admittedly in very small degree, are thus inhibited by the -complexity of the figure and act more slowly. - - -B. REACTIONS TO SIMPLE AND COMPLEX OPTICAL IMPRESSIONS - -Since the preceding experiments seem to show that reactions on optical -impressions are different according as the figures are more or less -complex, it would seem that we ought to be able to measure by graphic -methods the reactions to visual fields of varying grades of complexity -and in this way to demonstrate their different motor powers. - -A Porter kymograph was used on which to register the reactions. -Resting on the top of the drum, and revolving with it, was a circular -band of white paper, upon which were pasted the different figures -to be observed. A screen was placed in front of the kymograph, thus -concealing the figures; but at their level was a little square window -in the screen, which, when the eye was placed in the proper position, -allowed the subject to see one of the figures but nothing more. A few -inches in front of this window was an eye-rest which kept the eye -properly placed. A tambour received the movement from the subject and -communicated it to a straw which made a scratch on the smoked paper -which covered the drum. - -The figures used in this experiment form two series, one, composed of -geometrical figures, varying in complexity from a circle to a very -complex figure consisting of many overlapping squares, triangles, etc., -and the other composed of colored figures varying in complexity from a -simple square of one color to a very complex mixture of various colors. -The area of the visual field is about the same in all cases,--an -inch square. The geometrical figures were formed of black lines on -a white background. The figures used are shown in the accompanying -illustrations. - -The subject would be seated in front of the screen, his eye at the -eye-rest a few inches in front of the window in the screen, and the -forefinger of the right hand on the tambour, which is to the right of -and behind the screen, and thus not seen while the eye is at the rest. -Then as the drum revolves and brings a figure in front of the window, -the subject observes this figure carefully, and when it is all in the -field of vision he presses down with his forefinger, thus producing a -curve on the drum surface. _He tries to make the same finger-movement -every time_, whatever the figure at the window may be. But his -attention is not to be too much taken up with the making of the -movement, for he must be closely observing the figure. If he looks at -the figure until he observes its characteristics clearly and then turns -his attention from this to the finger-movement, it is evident that the -optical sensation would not have much effect upon the movement. The -movement must be performed while his interest in the figure is highest. -Now, after a little practice, any one can accustom himself to make a -certain definite movement in about the same way every time, and he can -then agree that he shall make this movement as a reaction to a given -stimulation. Then when the stimulus comes he makes the movement without -any longer thinking of the character of the movement. It has become, to -a certain extent, automatic and can look out for itself. - -This is the state into which I have tried to get my subjects. Their -whole attention is to be taken up with the seeing of the figures in -the window, and to these figures they are to react as automatically as -possible. Thus, though finger-movements are usually voluntary, all the -capricious character of voluntary action will be removed here, and if -the stimulus is the same in all cases, the reaction tends to assume -the form of a uniform movement. There is, then, a chance to see the -influence of different optical stimuli upon this action. - -[Illustration: FIG. 2] - -Six different geometrical figures were seen at each revolution of the -drum and six reactions given by the subject. Between figures a white -surface would occupy the field of vision. The simple and complex -figures were distributed so that the subject never knew what kind of a -figure would come next. The purpose of the experiment was kept as much -as possible from the knowledge of the subjects; but some, knowing my -general problem, surmised quite correctly my main object here. - -Ten revolutions were made at each sitting, thus causing the subject to -react ten times to each figure. Then a new drum paper was taken and the -case with the colored figures placed upon it. This had five colored -figures, and ten revolutions were made also in this case. Thus, in all, -in any one day, the subject would make one hundred and ten of these -finger-movements. - -Since we have in all these experiments tried to find out in the -different figures merely differences in the _amount_ of the reaction, -and not differences in the character of the reaction, we shall keep up -this method here. Now a stronger reaction makes a higher curve, and -since the drum is all the while revolving, and since the higher the -curve, other things being equal, the longer it takes, the stronger -reaction will also make a wider curve. So it would seem that if we wish -to observe the differences in the amounts of reaction the most natural -course to pursue would be to measure the heights and widths of the -curves we have registered. This accordingly has been done. - -In our discussion of these measurements let us, then, first, take up -the curve heights, and of these, those of the geometrical figures -which we call _U_, _V_, _W_, _X_, _Y_, _Z_. The height is measured -from a base-line [drawn by revolving the drum after the subject has -taken his finger from the tambour] to the highest point reached. These -measurements are taken from two hundred reactions to each figure, -divided among seven different subjects. - - _Heights of Curves_ - _U_ _V_ _W_ _X_ _Y_ _Z_ - _Subject_ A 6.83 6.68 6.59 6.55 6.63 6.79 - B 8.64 7.26 6.41 7.79 6.39 9.75 - C 6.67 6.55 6.73 6.85 5.87 8.53 - D 21.35 21.26 21.46 21.90 21.33 21.31 - E 16.13 15.77 15.17 15.85 15.29 16.08 - F 16.90 16.97 16.14 16.52 15.81 17.91 - G 11.42 11.32 11.39 11.48 11.06 11.10 - - 87.94 85.51 83.89 86.94 82.38 91.48 - - _Average_ 12.56 12.26 11.98 12.42 11.77 13.07 - - _Arranged in order of height of curve_ - _Z_ _U_ _X_ _V_ _W_ _Y_ - 13.07 12.56 12.42 12.26 11.98 11.77 - -If we put the figures in the order of strongest reaction for the -different subjects we get the following table: - - _Subject_ A _U_ _Z_ _V_ _Y_ _W_ _X_ - B _Z_ _U_ _X_ _V_ _W_ _Y_ - C _Z_ _X_ _W_ _U_ _V_ _Y_ - D _X_ _W_ _U_ _Y_ _Z_ _V_ - E _U_ _Z_ _X_ _V_ _Y_ _W_ - F _Z_ _V_ _U_ _X_ _W_ _Y_ - G _X_ _U_ _W_ _V_ _Z_ _Y_ - -It is seen from these results that, although the subjects differ, the -height of the curve varies directly with the complexity of the figure. -The order of the figures, which we get by measuring the height of the -curves and then putting that figure with the highest curve first, with -the next highest second, and so on, is exactly the same order in which -we should put them if we were asked to put the most complex first, -the next second, and so on. Though the individual subjects may vary -somewhat from this rule, when they are all grouped together there are -no exceptions. - -The variations of the reactions with the different subjects may be -shown very clearly in the following way, where the different figures -are in the left-hand side arranged in order of descending complexity. -"1st place," etc., refer to the order of arrangement of the figures -by the different subjects as shown in preceding tables. Thus, _Z_, -3 times, 1st place, means that three subjects have in the average a -higher curve for _Z_ than for any other figure. - - 1_st place_ 2_d place_ 3_d place_ 4_th place_ 5_th place_ 6_th place_ - - _Z_ 3 times 2 times 0 times 0 times 2 times 0 times - _U_ 2 times 2 times 2 times 1 time 0 times 0 times - _X_ 2 times 1 time 2 times 1 time 0 times 1 time - _V_ 0 times 1 time 1 time 3 times 1 time 1 time - _W_ 0 times 1 time 2 times 0 times 3 times 1 time - _Y_ 0 times 0 times 0 times 2 times 1 time 4 times - -One can see at a glance from this, how, as the figures decrease in -complexity, they take their position further on in the series. If a -diagonal is drawn from the upper left-hand corner to the lower right, -it will pass through or near the larger numbers in the table, thus -showing that the figures belong in the ordered series in the places -already shown. - -Next in order let us take up the measurements of the widths of curves -for the same geometrical figures which we have been considering. - - _Widths of Curves in mm._ - - _U_ _V_ _W_ _X_ _Y_ _Z_ - _Subject_ A 20.83 20.59 20.93 21.22 20.21 21.89 - B 11.18 10.77 10.46 10.31 9.92 10.79 - C 4.28 4.43 4.10 3.78 4.95 4.70 - D 21.08 19.36 18.33 18.75 18.17 21.09 - E 14.22 13.85 13.40 13.56 11.96 14.13 - F 17.00 15.26 15.92 16.52 14.52 16.47 - G 5.25 5.19 5.30 5.08 5.11 5.37 - - 93.84 89.45 88.44 89.22 84.84 94.44 - - _Average_ 13.40 12.78 12.63 12.75 12.12 13.49 - - _Order_ _Z_ _U_ _V_ _X_ _W_ _Y_ - 13.49 13.40 12.78 12.75 12.63 12.12 - -If as before we take the orders for the different subjects, we get the -following table: - - _Subject_ A _Z_ _X_ _W_ _U_ _V_ _Y_ - B _U_ _Z_ _V_ _W_ _X_ _Y_ - C _Y_ _Z_ _V_ _U_ _W_ _X_ - D _Z_ _U_ _V_ _X_ _W_ _Y_ - E _U_ _Z_ _V_ _X_ _W_ _Y_ - F _U_ _X_ _Z_ _W_ _V_ _Y_ - G _Z_ _W_ _U_ _V_ _Y_ _X_ - -Here, as before, in the case of the heights, it is seen that though -the order is different with the different subjects, yet the general -tendency is to place the most complex figures first and the simplest -last. The most simple figure _Y_ never comes in front of the fifth -place except with subject C, who places it first. This exception may be -ascribed to the fact that this subject, on account of his going away, -did not have so many tests. In fact only one day's work of 10 reactions -for each figure is recorded, and it is but natural that some variations -from the standard should occur in his case. - -If now, as before, we investigate where each figure occurs in the -series for the different subjects we get the following table: - - _Times in_ - 1_st place_ 2_d place_ 3_d place_ 4_th place_ 5_th place_ 6_th place_ - Z 3 3 1 0 0 0 - U 3 1 1 2 0 0 - V 0 0 4 1 2 0 - X 0 2 0 2 1 2 - W 0 1 1 2 3 0 - Y 1 0 0 0 1 5 - -Here we again see the large numbers on a line from the upper left-hand -to the lower right-hand corner. - -Thus we get the following order from the geometrical figures as -measured by the height and width of the curves: - - _Height_ _Z_ _U_ _X_ _V_ _W_ _Y_ - _Width_ _Z_ _U_ _V_ _X_ _W_ _Y_ - -The only difference, it is seen, is that the positions of _V_ and _X_ -are reversed in the two series. Such a change would on our principle -be fairly likely to occur, since _V_ and _X_ are figures near to each -other in complexity and the motor effects are very similar. - -[Illustration: FIG. 3] - -In the same manner, the following tables show the reactions to the -colored figures of different grades of complexity. And first, as -before, is the table of the heights of the curves for the different -subjects, given in millimetres. The numbers given represent the -averages of all reactions made. We will call the figures, for the sake -of reference, _L_, _M_, _N_, _O_, _P_. - - _L_ _M_ _N_ _O_ _P_ - _Subject_ A 5.75 6.01 5.90 5.82 5.74 - B 6.72 5.56 6.35 7.53 4.94 - C 10.92 10.90 10.76 10.52 10.99 - D 25.49 25.42 26.23 25.89 25.52 - E 20.63 20.82 20.37 20.55 20.30 - F 15.67 15.23 15.15 15.98 14.51 - - 85.18 83.94 85.26 86.29 82.00 - - _Average_ 14.20 13.99 14.21 14.38 13.67 - -Order arranged as before in a descending series according to height of -curve: - - _O_ _N_ _L_ _M_ _P_ - 14.38 14.21 14.20 13.99 13.67 - -This is exactly, as I should judge, the order of the complexity of the -figures reacted to. - -The arrangement by the individual subjects is as follows: - - _Subject_ A _M_ _N_ _O_ _L_ _P_ - B _O_ _N_ _L_ _M_ _P_ - C _P_ _L_ _M_ _N_ _O_ - D _N_ _O_ _P_ _L_ _M_ - E _M_ _L_ _M_ _N_ _P_ - F _O_ _L_ _M_ _N_ _P_ - -We see that individual differences are stronger here than in the -geometrical figures, but that the same tendency to react more strongly -to the complex is present in nearly every case. This can be brought -to the eye more clearly if we observe the table in which is shown -the position of the different figures in the series of the different -subjects. - - _Times in_ - 1_st place_ 2_d place_ 3_d place_ 4_th place_ 5_th place_ - O 2 1 2 0 1 - N 1 2 0 3 0 - L 0 3 1 2 0 - M 2 0 2 1 1 - P 1 0 1 0 4 - -_M_ here presents the principal exception, coming too often in the -first place. - -Finally we give the tables for the widths of the curves for the colored -figures; and first the table of the averages of all the subjects for -all the figures: - - _L_ _M_ _N_ _O_ _P_ - _Subject_ A 25.76 24.27 25.06 24.77 23.14 - B 9.42 9.49 9.06 9.84 8.11 - C 5.85 5.35 5.62 5.80 5.24 - D 13.68 13.53 13.18 13.26 13.38 - E 22.06 21.37 22.50 22.17 20.44 - F 16.30 15.08 16.65 16.76 15.13 - - 93.07 89.09 92.07 92.60 85.44 - - _Average_ 15.51 14.85 15.35 15.43 14.24 - -Order, arranged in a descending series according to width of curve: - - _L_ _O_ _N_ _M_ _P_ - 15.51 15.43 15.35 14.85 14.24 - -Here the order is not just the same as we got from a measurement of the -heights. The three complex figures have changed places somewhat, but -there is no exchange of a simple and a complex. - -The arrangements by the individual subjects are as follows: - - _Subject_ A _L_ _N_ _O_ _M_ _P_ - B _O_ _M_ _L_ _N_ _P_ - C _L_ _O_ _N_ _M_ _P_ - D _L_ _M_ _P_ _O_ _N_ - E _N_ _O_ _L_ _M_ _P_ - F _O_ _N_ _L_ _P_ _M_ - -The three complex figures have different places with different -subjects, but very seldom is a simple figure found among the complex, -or _vice versa_. - -This can be seen easily from the following table: - - _Times in_ - 1_st place_ 2_d place_ 3_d place_ 4_th place_ 5_th place_ - _L_ 3 0 3 0 0 - _O_ 2 2 1 1 0 - _N_ 1 2 1 1 1 - _M_ 0 2 0 3 1 - _P_ 0 0 1 1 4 - -A theoretical word may close our report. - -The growth of biology and physiology has tended to show that there -is no break in the nervous mechanism. The stimulus goes to the brain -and out through motor channels to muscles, glands, etc. The nervous -current does not wait in the brain for the permission of the mind to -leave on its journey to a muscle nor does it need mental reënforcement. -The nervous current as a whole is a unity. The nervous system is a -physiological instrument for producing the appropriate reaction to -a certain stimulus. In the unicellular organism there is no nervous -system, but the protoplasm receives the stimulus and produces the -reaction. As we go up in the animal series a differentiation is seen -to be present in the organism. Some parts are more concerned with the -receiving of stimuli and others with the approach toward or withdrawal -from the stimulating object. There is a division of labor. The nervous -system is developed as a means of rapid communication between the -different parts, but this communication is a physiological one. The -stimulus sets up a chemical action in the sensory organ which is -transmitted along the nervous path to the motor organ which is caused -to react. As we ascend the animal series the differentiation becomes -greater and greater, and consequently the means of communication must -become more and more complex. So trunk lines are formed which lead to a -centre, and from this centre again go out main lines which divide and -subdivide until the muscles are reached. The centre acts as a kind of -automatic switch-board. - -Accepting such a view of the nervous system it must be granted that -different stimulations would produce different reactions. It was my -aim in the experimental work which has been described to show that -this is true. And while much work has already been done in showing -that different kinds, or different amounts of stimulation produce -differences in reactions, it seemed important to demonstrate also -that mere differences in the complexity of the stimulus bring about -differences in the reaction. So the experiment of counting figures of -different complexity was entered upon, and we found that it took longer -to count figures the more complex they were in spite of the fact that -the act of counting seems always the same. The question is how must the -fact that counting becomes slower and slower, as the figures become -more complex, be interpreted? - -When we count a row of figures, the eyes do not move along at a regular -uniform rate, but make a quick jump from one figure to the next, halt -a moment, make another jump, and so on. Now, I think the principal -difference comes in with the figures of different complexity in the -time the eye halts at each figure. The halt is longer the more complex -the figure is. It is well known that any visual object which stimulates -the retina is brought by a reflex movement of the eye to the place of -clearest vision. Of two objects stimulating the eye at the same time, -the more pronounced one will produce the reflex and will hold the eye -longer than a weaker stimulus. Similarly here, the more complex figure -produces a stronger reflex and holds the eye longer than the simple -figure. This is repeated at every figure in the series. - -The complex figures have more features about them, all of which by way -of the retina and optic nerve are represented in the cortex and thus -more cortical cells are involved, which in turn produce a stronger -stimulation of the muscles which move the eye in the proper way to see -the figure, and thus the eye is held more strongly by the complex than -by the simple figure. - -Again in the second experiment, the subject reacts more strongly to -the complex as shown already in explaining the first experiment and -for the same reasons. It might be said that in looking at the colored -figures, _e. g._, that since the same amount of retina is stimulated, -the reaction ought to be the same. But we may presume that the complex -figure, on account of the different shapes and contrasts on its -surface, will more variously affect the same amount of retina and that -the nervous currents sent to the cortex will, many of them, be stronger -than those from the simple figure and will thus cause the cortical -cells to be more strongly excited, or by a process of irradiation the -stimulation will spread to adjoining cells and thus finally more cells -be stimulated. However this may be, the amount of discharge into motor -cells is certainly greater and the muscular reaction, therefore, also -greater. - -The interesting side of our results is thus given in the fact that -we have here two activities--counting with highest speed and making -hand-movements of certain length--which are performed every time with -exactly the same intention and with the subjective impression of -equal result, and which yet show marked differences according to the -complexity of the psycho-physical stimuli. It is a new contribution to -our knowledge of the independent motor power of ideas. - - - - -ANIMAL PSYCHOLOGY - - - - -THE MUTUAL RELATIONS OF STIMULI IN THE FROG RANA CLAMATA DAUDIN[139] - -BY ROBERT M. YERKES - - -I. ANIMAL BEHAVIOR AND THE SENSES - -Since the behavior of an animal is conditioned by its senses, it is -extremely important that the comparative psychologist should have -accurate and detailed knowledge of the sense-impressions received by -his subjects. Knowledge of the so-called "special senses" does not -suffice for the satisfactory description of behavior, for there are -several other kinds of sense-data of equal or even greater importance -than those of the five special senses. As investigation of the subject -progresses the banefulness of the notion that all sense-experience is -summed up in "the five special senses" becomes more and more evident. -For the comparative psychologist the senses are not five, six, -eight, or ten, but as numerous as are the kinds of sense-data which -condition animal activities. There can be no doubt that many of the -lower animals are largely dependent upon senses which are not included -in the conventional special sense list. The contention that certain -organs which are commonly recognized as sensory in function, the cristæ -acusticæ of the ear, for instance, are merely reflex control organs, -has little weight in this connection, for every sense-organ is part -of a motor control mechanism, and so far as we are able to judge from -available evidence each has as an accompaniment of its functioning -a mode of sensation. If there are two kinds of peripheral organs in -connection with the afferent nerves, namely, those whose functioning -has sensation for an accompaniment and those in which motor control -is the sole phenomenon, it is high time that the fact were definitely -known. - -Even a thoroughly accurate knowledge of the general condition of -the senses in a particular phylum, genus, or species may be of -trifling value in the study of the behavior of a given individual, -for within these groups the state of development and relative -importance of a sense may differ strikingly. Herrick,[140] in his -admirable investigation of the sense of taste in fishes, has rendered -comparative psychology an important service by showing that even a -highly developed sense may be of markedly different value in the -associative life of different species. The cat-fish, according to -Professor Herrick's observations, obtains its food primarily by the aid -of taste-impressions, the hake by the aid of touch, and the sea-robin -chiefly by means of vision. All three of the senses mentioned are -possessed by each of the fishes, yet their values differ so widely -that an understanding of the habits and associative processes of any -one of the species would be impossible except in the light of just -such facts as Herrick has discovered. Clearly, then, we must know the -relative importance of the various sense-impressions received by an -animal before we can discuss its behavior or psychic characteristics -intelligently. - -Furthermore, if behavior is to be serviceably described in terms of -stimuli and physiological conditions it is necessary first of all -to recognize that an animal responds to a situation, not to any one -independent and isolated stimulus. Every situation, to be sure, may be -analyzed into its component simple stimuli, but the influence of each -and all of these stimuli is conditioned by the situation. Too often in -our accounts of an animal's behavior we name some one stimulus as the -condition of the reaction and entirely neglect the situation, without -which the stimulus would have been of quite different value to the -animal. For any given stimulus other external and internal stimuli -constitute an environment. The complete description of a reaction -demands knowledge of all the stimuli which enter into the situation and -of their mutual relations of interference or supplementation. A frog -which in its native habitat and undisturbed by an unusual situation -would react violently to the light touch of a stick may give no sign -of reaction to the same stimulus when a human being stands nearby. -The influence of the tactual stimulus has been changed entirely by -the simultaneous appearance of visual, olfactory, and possibly still -other sense-data (man). The animal reacts not to the touch alone, but -to this stimulus as part of a certain situation. The general effect -of a situation we often speak of as excitement, timidity, etc. These -are words for which must be substituted in our accounts of animal -behavior accurate descriptions of the situations. Experimental studies -prove that an animal must become thoroughly accustomed to the general -situation in which it is to be observed before the influence of any -particular condition can be studied to advantage. - -Only a few of the important reactions of an animal to either external -or internal stimuli are visible to the casual observer, and many of -them can be detected only by the employment of indirect methods. -Frequently the lack of a visible motor response to a new situation is -good evidence of a fundamentally important reaction. The death-feigning -opossum, crustacean, or insect, truly reacts by becoming motionless. As -Whitman[141] has shown in the case of the leech it is as hazardous to -judge of the degree of sensitiveness of another animal solely on the -basis of our own as it is to maintain that lower animals possess only -the senses which are ours. Varied, indirect and delicate methods are -necessary in the investigation of the senses, as the results of the -experiments to be described below help to prove. - -It is my purpose in this paper to call attention to and emphasize -the importance of studying stimuli in their mutual relations of -interference and supplementation. This I shall do by presenting the -results of an investigation of the behavior of the green frog. I shall -discuss briefly, first, the sense-data received by the animal, their -relative importance, significance, and mutual relations, and, next, the -phenomena of reënforcement and inhibition. - - -II. THE SENSORY REACTIONS OF THE GREEN FROG - -The following sensory reactions have been observed in the frog, but -most of them have not been studied with care: olfactory, temperature, -visual, tactual, equilibrational, and auditory. It is my purpose to -investigate each of these senses in such fashion that we shall know the -receptive capacity of the animal. Thus far I have completed only the -work on auditory reactions, but the chemical and temperature senses and -vision will be discussed in similar fashion later. - -At present there is little known concerning the chemical senses. -Unpublished observations made by Mr. Sherwin in this laboratory -indicate the existence of olfactory sensitiveness to camphor, iodine, -and several other strong stimuli. The reactions to the stimuli were -slow, however, and there is no reason to believe that the sense of -smell is of great importance to the animal. Of taste barely more is -known than that it is present. - -There is marked sensitiveness to variations in temperature, as I -have demonstrated by preliminary test experiments, but the limits, -distribution, and significance of this sensitiveness remain to be -investigated. I am not aware that the existence of temperature spots -has been determined. In connection with a study of the reactions of -frogs to light Torelle[142] discovered that the animals suddenly become -inactive and usually attempt to bury themselves when brought into a -temperature of 8° to 10° C. This reaction is prompt and definite; its -value to an animal which hibernates is evident, yet one would scarcely -anticipate the suddenness and regularity with which it occurs. - -My studies of habit-formation and reaction-time[143] have revealed -the importance of vision in the life of the frog. Perception of -movement appears to be of far greater value to the animal than -perception of form or color. The spectral colors are discriminated in -all probability, for the animals react very differently to those of -the blue end than to those of the red. According to Torelle blue is -preferred to red. There is evidence that red has a higher stimulating -value than blue, and the apparent avoidance of red in Torelle's -experiments may be due to this fact. None of the work with which I am -familiar demonstrates that the suspected color-reactions are due to -stimulation of the eye. They may be due to stimulation of the skin, for -Parker[144] has shown that the reactions of _Rana pipiens_ to light are -due to stimulation of the sink as well as of the eyes, or they may even -be due to intensity instead of color. - -The tactual-auditory sense series is better known and also, it would -appear, better developed than the chemical series. A large portion of -the body surface of the green frog is keenly sensitive to mechanical -stimulation, and Steinach[145] by measurement of electrical changes in -the nerves of the skin has discovered the existence of "touch spots." -His method, which is ingenious, promises to be of considerable value in -the objective investigation of the senses, but it involves operations -on the subject which inevitably destroy the normal condition of the -sense. - -According to Steinach we have in the negative variation in the -electrical condition of nerves during stimulation a phenomenon which -may be used in the determination of the threshold of stimulation as -well as in the investigation of irritability. In a previous paper[146] -I have discussed the associational rôle of tactual impressions as well -as the tactual reaction-time. All my observations lead me to believe -that touch is a highly developed and important sense in the green frog. - -Of the senses intermediate between touch and hearing that of -equilibration has been most discussed. Certainly there is good reason -to suppose that the sense-organs of the semicircular canals of the ear -furnish the animal with impressions of position, movement, and possibly -also of direction. Further study of the tactual-auditory senses of -frogs may indicate the existence of conditions similar to those -discovered by Parker in certain fishes, in which, as he remarks, "the -skin, lateral line organs and ears represent, figuratively speaking, -three generations of sense-organs. The oldest is the skin stimulated -by varying pressures, such as are produced by irregular currents, and -capable of initiating equilibrational responses. From the skin have -been derived the lateral line organs stimulated by water vibrations of -low rate, and also significant for equilibration. Finally, from the -lateral line organs have come the ears stimulated by water vibrations -of a high rate and important for equilibration. The ear, unlike the -skin and lateral line organs, is differentiated for its two functions, -the sacculus for hearing, the utriculus for equilibration."[147] - -The sense of hearing remains to be considered. My attention was first -drawn to this subject by failure to obtain motor reactions to sounds in -the investigation of the time-relations of the neural processes of the -green frog. Although a large number of sounds of different qualities, -pitches, and intensities were employed, no visible motor reactions -were observed. This led me to seek the significance of what appeared -to be either a surprising lack of sensitiveness to changes in the -environment which would naturally be expected to stimulate the animal, -or an interesting and important case of the inhibition of reaction to -auditory stimuli. This suggested the question, Are frogs deaf, or do -they under certain conditions completely inhibit their usual reactions -to sound? - -In the literature on the senses and reactions of frogs I have found -nothing which contributes importantly to our knowledge of the sense -of hearing. Most of the investigations which deal with the ear are -concerned with the equilibrational and orientational functions of the -labyrinth organs, and have nothing whatever to say about hearing. -In the natural histories the existence of a well-developed sense of -hearing is usually assumed, and numerous instances of what are supposed -to be reactions to sound are cited. It is to be noted, however, that -none of the observations in these popular works furnishes satisfactory -proof of the exclusion of the influence of visual stimuli. Among the -few references to frog audition of which I have knowledge, the only -one which seems worthy of special notice is that of Gaupp in his -Anatomie des Frosches. Since his few paragraphs sum up the state of -our knowledge on the subject, while at the same time furnishing an -illustration of the assumption of hearing on the basis of analogy, -I present the substance of them in free and slightly abbreviated -translation. - -"The labyrinth organ has an acoustic and non-acoustic (static) -function. For these two functions, according to the leading if not -generally accepted view, entirely different portions of the organ are -in question, and since the non-acoustic is attributed to the three -_Cristae acusticae ampullarum_ and the three _Maculae_ (_M. recessus -utriculi_, _M. sacculi_, _M. lagenae_), there remain for the acoustic -function only the _Papilla basilaris_ and the _Macula neglecta_. It is -not certain, however, that the non-acoustic organs do not participate -in the acoustic function. - -"With regard to the acoustic sense of the frog nothing exact is known. -That it exists, and that in good development, is certain. The existence -of the drum and columella, and the fact that frogs have a voice are -unmistakeable proofs of hearing. The participation of the _Papilla -basilaris_ in acoustic functions is rendered certain by comparative -anatomical studies: the _Papilla basilaris_ is the nerve end-organ from -which, in the mammalia, the undoubtedly acoustic organ of Corti arises. -From analogy of structure we may also infer an acoustic function in -the _Macula neglecta:_ on this, as on the _Papilla basilaris_, there -is a simple tectorial membrane, and further the _Pars neglecta_, like -the _Pars basilaris_, has a strong thick wall which only in a limited -region, namely, where it approaches a part of the perilymphatic space, -is markedly thinner." (For fish Breuer (1891) has already stated that -if they really hear--which is proved--the _Macula neglecta_ alone can -come into consideration in connection with the function, for there is -no _Papilla basilaris_ in fishes, and the six other nerve end-organs -apparently serve the non-acoustic function.)[148] - -As the green frog does not respond visibly to sounds under experimental -conditions, I found it necessary to employ indirect methods in the -study of audition. By observing the influence of sounds on respiration -and on the reactions to certain electrical, tactual, and visual -stimuli, I obtained results which, since they have already been -described in detail elsewhere,[149] may be summarized here as follows: - -1. Observation of frogs in their natural habitat shows that they are -stimulated by sounds, but the sense of hearing apparently serves rather -as a warning sense which modifies reactions to other simultaneous -or succeeding stimuli than as a control for definite auditory motor -reactions. - -2. Experimental tests prove that sounds modify the frog's reactions -to visual and tactual stimuli. When the sound accompanies the visual -or tactual stimulus it serves to reënforce the reaction to the other -stimulus, but when given alone it never causes a motor reaction. - -3. The green frog responds to sounds made in the air, whether the -tympana be in the air or in water. There is some evidence that -the influence of auditory stimuli is most marked when the drum is -half-submerged in water. The influence of sounds upon tactual reactions -is evident when the frog is submerged in water to a depth of 4 cm. - -4. Sounds varying in pitch from those of 50 to 10,000 vibrations per -second affect the frog. The most striking results were obtained by -the use of an electric bell with a metal gong. With this sound in -connection with a weak tactual stimulus a maximum reaction may often be -obtained even when either stimulus alone causes no perceivable reaction. - -5. Sounds modify the reactions of the frog after tympana and columellæ -are removed. Cutting of the eighth cranial nerves causes disappearance -of the influence of sound. It is clear, then, that the reactions to -sounds are really auditory reactions and that the sense of hearing in -the frog is fairly well developed, although there is little evidence of -such a sense in the motor reactions of the animal. - -6. Experiments during the spring months show marked influence of sounds -for both males and females, whereas experiments made during the winter -indicate a much diminished sensitiveness to auditory stimuli in both -sexes, but especially in the male. - - -III. THE MUTUAL RELATIONS OF STIMULI - -In studying the various influences of complication of stimuli in the -frog, I have used two methods: the measurement of reaction-time and of -the amount of reaction. The reaction-time results will be presented -first. - -Reaction-time to electric stimulation of the skin was studied with -special attention to the influence of other stimuli which were given -in definite temporal relation to the electric stimulus. A Hipp -chronoscope, controlled by a Cattell's falling screen, served as a -time-measuring apparatus. The other essentials of the apparatus were -a reaction-box, and devices for giving the stimuli and indicating the -reaction. On the bottom of the reaction-box a series of wires were so -placed that an electric stimulus could be given to the frog resting -upon them by the closing of a key in the hands of the experimenter. -In preparation for each experiment the frog was placed upon these -open circuit wires in such a position that the weight of its body -pressed upon a delicate spring in the floor of the box, thus causing -the chronoscope circuit to be completed. The forward jump of the frog -in response to stimulation caused the breaking of this circuit by the -release of the spring upon which the animal rested. When all was in -readiness for an experiment the chronoscope was started, and a key -closed which simultaneously gave an electric stimulus to the frog and -completed a circuit which caused the chronoscope record to begin. The -stimulus consisted of a current from one or more "Mesco" dry cells. -The motor reaction of the frog broke the chronoscope circuit, thus -causing the chronoscope record to stop. It was then possible for the -experimenter to read from the dials of the chronoscope the time, in -thousandths of seconds, intervening between stimulus and reaction -(reaction-time). In case of additional stimuli in connection with the -electric, various simple devices were introduced to meet the demands -of the experiments. These will be described in connection with the -statement of results in each case. - -_Electric and photic stimuli._ A photic stimulus was given from one -to two seconds before the electric stimulus by the turning on of a -sixteen-candle-power incandescent light, which was placed thirty cm. in -front of the frog in the case of one series of experiments and fifteen -cm. above it in another. The light uniformly inhibited reaction to the -electric stimulus, as is shown by the results of Table 1. - - -TABLE 1 - - Title of investigation,--Electric-Visual (Red Light). - Experimented on,--Green Frog No. 4. - Harvard Psychological Laboratory,--9.40 A.M., Feb. 28, 1902. - Chronoscope control average, 189σ,--Electric stimulus, 1 Cell. - - NO LIGHT. - - _Number of_ - _Experiment._ _Reaction-time._ - 1 152σ - 2 145 - 3 221 - 4 327 - 5 263 - 6 271 - 7 329 - 8 215 - 9 225 - 10 216 - - LIGHT BEFORE ELECTRIC STIM. - - 11 No reaction. - 12 No reaction. - 13 No reaction. - 14 No reaction. - 15 No reaction. - - NO LIGHT. - - 16 216 - -The inhibitory influence of light depends upon the intensity of the -electric stimulus. Even a very strong light will not cause much -retardation of reaction to a three or four cell current. As the -strength of the electric stimulus decreases the delay of reaction -increases, until finally there is complete inhibition. At this point, -an electric stimulus, to which the frog would react almost invariably -when there is no disturbing condition, will fail to cause reaction in -the presence of a sudden increase in light intensity. - -Merzbacher[150] states that the leg reflex of a frog, so placed that -its legs hang free in the air, is greater in response to a given -cutaneous stimulus in darkness than in daylight.[151] - -_Electric and visual stimuli_ (moving object). For the purpose of -determining the effect upon reaction-time to an electric stimulus -of stimulation of the eye by a rapidly moving object, experiments -were made in which, as in the case of electric and photic stimuli, -reactions to electric stimulus alone and to the visual and electric -were observed alternately. Thus in the case of each pair of reactions -it was possible to note whether the visual stimulus shortened or -lengthened the reaction-time. The visual stimulus was given by quickly -moving a finger before a window in the reaction-box. - -Two series of twenty pairs of reactions each were taken with each of -two frogs. In the first series the finger was suddenly moved across the -window and the electric stimulus was given either simultaneously or -a small fraction of a second later. It was impossible to arrange for -accurate measurement of the temporal relations of the two stimuli in -the case of these tests. In the second series the finger was moved back -and forth before the opening in the reaction-box for an interval of at -least a second before the electric stimulus was given. - -These experiments, which were in the nature of preliminary tests, -yielded the following results. When the stimuli were given almost -simultaneously the visual reënforced the electric as was indicated by a -shortening of the reaction-time. As appears in the upper part of Table -2, the average time of forty reactions, twenty for each frog, to the -electric stimulus was 148^{σ},[152] and to the same stimulus when it -followed the visual 128^{σ}. Furthermore, examination of the several -pairs of reactions shows, as is indicated in the table, that there were -twenty-seven cases in which the visual stimulus caused shortening of -the reaction-time (reënforcement of the electric stimulus) to thirteen -in which it caused lengthening (inhibition). When the visual stimulus -preceded the electric by at least a second, the reaction-time to the -electric stimulus was greatly lengthened. The averages are 150^{σ} -for the electric stimulus alone, 178^{σ} when it was preceded by the -visual. In this series there are twenty-five cases of inhibition to -fourteen of reënforcement. - -_Electric and visual stimuli_ (moving red disc). The indications -of the importance of the temporal relations of stimuli, so far -as reaction-time results are concerned, furnished by these crude -preliminary observations led to a more accurate study of the subject. A -revolving disc, which moved at the rate of one revolution per minute, -was so arranged that at a certain point it closed an electric circuit -in which a magnet had been placed. This magnet attracted a steel arm -at the end of which a disc of red cardboard 12 mm. in diameter was -suspended. With the making of the circuit the steel arm was drawn -downward suddenly and the red disc, by reason of the vibrations of -the arm moved rapidly back and forth in front of a window in the -reaction-box. In this way the moving object was exposed to view about -ten cm. to the right and three cm. in front of the right eye of the -frog. The revolving disc, a fraction of a second later, completed the -electric stimulus circuit. Thus both stimuli were given automatically, -at such an interval apart as the experimenter desired. In the two -series of results now to be described the intervals were 0.1 and 0.5 -second respectively. - - -TABLE 2 - -Reaction-time to Electric Stimulation Alone, and to the Same when -preceded for 0.1, 0.5, or 1.0 Second by Visual Stimulus. - - Key: - 1 = Frog. - 2 = Electric Alone. - 3 = Visual 0.1" before elect. - 4 = Number Inhibited. - 5 = Number Reënforced. - 6 = Number Equal. - 7 = Visual 1.0" before elect. - - 1 2 3 4 5 6 2 7 4 5 6 - - Preliminary Series. Visual Stimulus Moving Finger. - Averages for 20 reactions. - No. 5. 179ˢ 158ˢ 6 14 0 163ˢ 206ˢ 14 6 0 - No. 6. 116 98 7 13 0 136 150 11 8 1 - Gen. - Aver. 148 128 13 27 0 150 178 25 14 1 - - Visual Stimulus Moving Red Disc. - Visual 0.1" before electric. Visual 0.5" before electric. - - Series I. Averages for 25 reactions. - - No. 5. 177 163 10 15 0 170 255 15 9 1 - No. 6. 148 112 6 19 0 115 178 18 7 0 - - Series II. Averages for 25 reactions. - - No. 5. 135 120 7 18 0 155 259 24 1 0 - No. 6. 128 111 6 19 0 132 227 17 7 1 - Gen. - Aver. 147 126 29 71 0 143 230 74 24 2 - -These series consisted of twenty-five pairs of reactions each, with -two animals. The results of the series are presented separately, in -the lower half of Table 2, because the experiments which constitute -them were separated by a period of three weeks. It is to be noted -that these results agree fully with those of the preliminary series. -The visual stimulus of a moving red disc, given 0.1 second before a -2 cell electric stimulus, reënforces the electric reaction, _i. e._, -it shortens the time of reaction. The same visual stimulus given 0.5 -second before tends to inhibit the electric reaction, _i. e._, it -lengthens the time of reaction. - -_Tactual and auditory stimuli._ Since in the frog auditory stimuli -under experimental conditions seldom if ever cause visible motor -reactions, the study of the influence of this mode of stimulation -upon the reactions to other simultaneous or succeeding stimuli -is of special interest. In the investigation of the relations of -auditory stimulation to other forms of reaction _amount_ of reaction -instead of _reaction-time_ was taken as a measure of the influence -of the stimulus. By a method the details of which may be most easily -understood by reference to the plan of the apparatus in Figure 1, the -influence of auditory stimuli on the leg-movement induced by tactual -stimulation was observed. - -In these experiments the frog sat astride a wooden support, held in -position by linen bands over the back and a wire screen cap over -the head. The hind legs hung free, and any movement of one of them -in response to a stimulus could be read in millimetres by reference -to a scale on the wooden support. This method of measuring the -value of a stimulus in terms of leg-reflex has been used by several -investigators--most recently by Merzbacher.[153] I have found it -desirable, as did Merzbacher, to observe the movements of a shadow of -the leg on the scale and thus read the amount of movement, rather than -to watch the leg itself and attempt to project it upon the scale. - -As is indicated in Fig. 1, the auditory and tactual stimuli were given -automatically by means of a swinging pendulum, _P_, which was held in -position by the magnet _a_ until released by the experimenter. Early in -its swing the pendulum turned the key, _m_, thus completing a circuit -which caused the auditory stimulus to be given; later in the swing the -key, _n_, was turned, and the tactual stimulus thus given through the -magnetic release of the lever, _l_. The interval between the auditory -and the tactual stimuli could be varied from 0 to 2" by changing the -position of the key, _n_. For intervals over 1" it was necessary to -arrange this key so that the tactual stimulus was given at some time -during the return swing of the pendulum. - -The auditory stimulus used was either the sound of a quick hammer blow -(momentary stimulus of Series I), or the ringing of an electric bell -for a certain length of time (prolonged stimulus of Series II). In Fig. -1 the bell is shown. It was placed eighty cm. from the frog, and in -order that the influence of vibration of the experiment table might -be avoided it was suspended from the pendulum frame. When the hammer -was used it was placed sixty cm. from the frog, on the pendulum table. -The holder for the frog and the tactual apparatus occupied a separate -table which was not disturbed by the jars of the pendulum table. - -[Illustration: Figure 1. Auditory-tactual Reënforcement-Inhibition -apparatus. _P_, pendulum; _p_, contact point of _P;_ _b_, attachment -for electro-magnet, _a;_ _m_, key for circuit of electric bell, _B;_ -_n_, key for magnet circuit of tactual apparatus; _K_, hand-key for -release of pendulum and temporary closing of electric bell circuit; -_k_{1}_, _k_{2}_, _k_{3}_, keys in circuits; _e_, _f_, _g_, magnetic -release for tactual apparatus; _l_, pivoted lever, bearing rubber cone, -_T_, and weights, _w_. (Drawn by Dr. Wm. E. Hocking.)] - -The tactual stimulus was given by a rubber cone, _T_, two mm. in -diameter at its apex. This rubber point, after the electric release -of the lever to which it was attached, struck the frog at the middle -point of a line drawn between the posterior margins of the tympana. The -intensity of the stimulus could be varied by weighting the lever, _l_, -at _w_. - -All experiments were made with the green frog, _Rana clamata_ Daudin. -The reactions were taken regularly at half-minute intervals in pairs: -first, a tactual stimulus reaction, then an auditory-tactual reaction. -Ten, fifty, or one hundred pairs constituted a series. So far as -the condition of the frog is concerned there seems to be nothing -undesirable in long series, for fatigue does not appear, and so long -as the animal is kept moist and in an unconstrained position, it -continues to react normally, and without frequent struggles to escape. -The advantage for the purposes of this investigation of taking the -reactions in pairs, rather than taking separate series of reactions -for each stimulus or combination of stimuli, is obvious. It enables us -to compare directly the reactions of each pair, in other words those -reactions which took place under most nearly identical conditions, and -to note at once whether the auditory stimulus reënforced or inhibited -the tactual reaction. - -During a series the intensity of the tactual stimulus was changed as -conditions demanded, but for any one pair of reactions it was always -the same. It not infrequently happened that an intensity which at -first caused merely a slight movement of the leg, later in the series -uniformly brought about a maximal contraction, or the reverse might -be true, and inasmuch as a maximal reaction to the tactual stimulus -alone left no opportunity for judging of the influence of the auditory -stimulus, when it was given in addition to the tactual, it was always -necessary in such cases so to alter the intensity of the tactual -stimulus that a medium reaction resulted. - -The frogs, after being placed in the saddle-like holder and held firmly -for a few seconds, seldom struggled very much, but if bound tightly -they became irresponsive to the stimuli.[154] It was, therefore, -necessary after they had quieted down to loosen the bands which held -them in position. For the purpose of excluding the influence of visual -stimuli a wire screen cap covered with black cloth was put over the -head; this served to keep the animal in position as well as to exclude -visual stimulation. - -_a. Momentary auditory stimulation._ Four frogs were used for a study -of the influence of the momentary sound produced by a hammer blow, -and for each of these animals fifty pairs of reactions were recorded -in series each day. The temporal relation of the stimuli was changed -daily during a week of experimentation: the results therefore consist -of fifty pairs of reactions with each frog for each of the following -seven intervals: (1) Auditory and tactual stimuli simultaneous, (2) -auditory .25" before tactual, (3) auditory .45" before, (4) auditory -.15" before, (5) auditory .65" before, (6) auditory .35" before, (7) -auditory .90" before. The intervals were used in the experiments in the -above order to avoid the formation of the definite habits of reaction -which regular increase in the interval would have favored. - -Typical of the results with all the animals are the following (Table -3) which were obtained with No. 1, a male. The figures in each case -indicate the average of fifty reactions. Reënforcement and inhibition -are expressed in terms of the tactual reaction, _i. e._, the -auditory-tactual reaction is so many per cent greater (reënforcement) -or less (inhibition) than the tactual. In the tables reënforcement is -indicated by the + sign; inhibition by the - sign. In the last column -of the table is given the number of reactions that were reënforced or -inhibited. This was determined by comparing directly the reactions -of each pair. Cases in which the two reactions were the same were -distributed equally between the two classes: tactual reactions -reënforced by auditory stimulus, and tactual reactions inhibited by -auditory stimulus. Assuming that the auditory stimulus was without -effect upon the tactual reaction, the number of reactions in these two -classes would be approximately the same, hence all auditory-tactual -reactions over half in a series, _i. e._, over twenty-five, which -are greater than the corresponding tactual reactions, are reënforced -reactions, and can be taken as a measure of the reënforcing influence -of the auditory stimulus. In the same manner all reactions over half -which show inhibition can be taken as a measure of the inhibitory value -of the auditory stimulus. - -As preliminary tests described in an earlier paper[155] furnished -evidence of sex-differences, it is worth while to compare the results -given by the males and females in these experiments with momentary -auditory stimulation. For purposes of comparison I have presented -in Table 4 the reënforcement-inhibition values given by the males -and females for each interval. Column one contains the value of the -auditory-tactual reaction in terms of the tactual reaction; column two, -the number of reactions in excess of half which were reënforced or -inhibited. - - -TABLE 3. FROG NO. 1. MOMENTARY AUDITORY STIMULUS, HAMMER BLOW. WEIGHT -USUALLY 5 OR 10 GRAMS - - Reaction Reaction Amount of Number of - to to Auditory Reënforc'm't reactions - Tactual and Tactual or Reënforced - Interval. Stim. Stim. Inhibition. or Inhibited. - - 0" 6.84mm. 11.08mm. +62.0% +17.0 - .15 22.22 28.96 +30.3 +17.0 - .25 16.30 21.72 +33.3 +13.0 - .35 24.90 25.32 + 1.7 + 0.5 - .45 17.56 13.64 -22.3 -10.0 - .65 17.46 15.72 -10.0 - 6.0 - .90 31.26 31.48 + 0.7 + 0.5 - - -TABLE 4. MOMENTARY AUDITORY STIMULUS, HAMMER BLOW - - _Males_ _Females_ - Nos. 1 and 3. Nos. 2 and 4. - Per centum No. of Per centum No. of - Interval Diff. Reacts. Diff. Reacts. - 0" +82.5% (Reënf't) +17.5 +58.0% +12.7 - .15 +58.1 +17.0 +25.4 + 8.5 - .25 +32.3 +12.7 +39.8 +12.7 - .35 + 4.0 + 1.2 - 9.7 - 3.2 - .45 -13.5 (Inhibition) - 7.2 -13.9 - 7.2 - .65 -12.5 - 6.2 -11.8 - 7.2 - .90 - 0.7 - 1.5 - 2.6 - 0.5 - -In these results two striking differences between the males and females -appear: first, the reënforcement is not so great for the females as -for the males; second, inhibition appears earlier and continues longer -with the females than with the males. The average reënforcement with -simultaneous stimuli is 82.5% for the males against 58.0% for the -females. Inhibition begins to appear in case of the females when the -interval between the stimuli is .25" to .35"; in case of the males it -appears between .35" and .45". Finally at .90" interval inhibition is -slightly greater for the females. - -Although the exact significance of these facts is unknown, it is -not improbable that they are indicative of fundamentally important -sex-differences in reaction to sound. The males among frogs are -usually the vocalists, although in some species the females also -croak. Moreover, in case of the green frog the tympanum of the male -is much larger than that of the female. The results presented would -seem to indicate that certain sounds stimulate the males to activity, -whereas they inhibit activity in the females. - -Graphically represented, the results of the momentary auditory stimulus -experiments with frogs Nos. 1, 2, 3, and 4 are as follows: - -[Illustration: FIG. 2. Reënforcement-Inhibition curves for momentary -auditory stimulation, based upon amount of reaction. Male No. 1 ---- -Male No. 3 ....] - -[Illustration: FIG. 3. Reënforcement-Inhibition curves for momentary -auditory stimulation, based upon amount of reaction. Female No. 2 ---- -Female No. 4 ....] - -The curves are all plotted by the method which will now be -described in connection with Fig. 2. This figure presents the -reënforcement-inhibition curves for the males No. 1 (solid line in -the figure) and No. 3 (broken line). If in this figure we let the -zero-point on the ordinates represent the value of the reaction to the -tactual stimulus when given alone, then the value of the reaction to -the auditory-tactual stimuli would be represented at some point above -the zero-point if this reaction was greater than the tactual reaction -(reënforcement), and below the zero-point if the reaction was less -than the tactual (inhibition). Since one of our chosen measures of -reënforcement and inhibition is the amount, in per cent of tactual -reaction, by which the auditory-tactual reaction exceeds or falls short -of the tactual reaction, such a curve of reënforcement-inhibition -as that of Fig. 2 (solid line) can be constructed at once from the -data given in column four of Table 3. Here the auditory stimulus, -when simultaneous with the tactual, caused 62% reënforcement, as is -indicated in the figure. The figures in the left-hand margin of the -curves indicate amount of reënforcement or inhibition in per cent of -tactual reaction; those at the bottom of the curves mark the intervals. -On the curves dots indicate the intervals used in the experiments. Each -of the curves is plotted on the basis of 700 reactions. - -[Illustration: FIG. 4. Reënforcement-Inhibition curves for momentary -auditory stimulation, based upon number of reactions. Male No. 1. ---- -Male No. 3 ....] - -[Illustration: FIG. 5. Reënforcement-Inhibition curves for momentary -auditory stimulation, based upon number of reactions. Female No. 2 ---- -Female No. 4 ....] - -In every way comparable with the curves for the males No. 1 and No. -3 in Fig. 2 are those for the females No. 2 and No. 4 of Fig. 3. The -similarity of the two curves in each figure is noteworthy. Inasmuch as -the conditions of experimentation were the same for all the animals -this would seem to indicate sex-differences which are worthy of further -investigation. The curves show clearly the greater reënforcement in the -males, and the greater inhibition in the females. - -Figures 4 and 5 are the reënforcement-inhibition curves for the same -series of experiments plotted on the basis of the _number_ of reactions -in excess of half that were reënforced or inhibited. As there were -fifty pairs of reactions with each frog for each interval, uniform -reënforcement would be represented by twenty-five reactions above -the base-line; uniform inhibition by twenty-five reactions below the -base-line. The number of reactions is indicated by the figures in -the left margin; the intervals, by those below the base-line. As an -illustration of the application of the method of plotting, the curve -for male No. 1 (solid line) of Fig. 4 is constructed from the data -of column five of Table 3. With simultaneous stimuli 17 reactions in -excess of half, _i. e._, 17 + 25, or 42, were reënforced; at .35" -interval .5 of a reaction was the average amount of reënforcement; -at .45" interval 10 reactions in excess of half, _i. e._, 35, were -inhibited, therefore the curve falls to 10 below the base-line. - -[Illustration: FIG. 6. Composite Reënforcement-Inhibition curve for -momentary auditory stimulation, based upon amount of reaction. Frogs -Nos. 1, 2, 3, 4. (Males and females.)] - -[Illustration: FIG. 7. Composite Reënforcement-Inhibition curve for -momentary auditory stimulation, based upon number of reactions. Frogs -Nos. 1, 2, 3, 4. (Males and females.)] - -Just as Figures 2 and 3 permit of direct comparison of the results -of the measurement of the _amount_ of reënforcement and inhibition -for males and females, so Figures 4 and 5 make possible comparison in -similar fashion of the _number_ of reënforced and inhibited reactions -for the sexes. It is to be noted that the two sets of curves, plotted -on the bases of _amount_ and _number_ of reaction, agree in all -important respects. - -Figure 6 is the composite curve of amount of reënforcement-inhibition -for the four animals; Figure 7 is the composite curve of the number of -reactions reënforced and inhibited. - -Summarily stated, the results of the experiments thus far described -are: (1) The auditory stimulus of a quick hammer blow produces the -maximum amount of reënforcement of tactual reaction when it is given -simultaneously with the tactual stimulus; (2) as the interval between -the auditory and the tactual stimulus approaches .35″ the amount of -reënforcement gradually decreases; (3) when given .35″ before the -tactual stimulus the auditory is practically without effect upon the -tactual reaction; (4) as the interval increases above .35″ inhibition -begins to appear; (5) the inhibitory influence of the auditory stimulus -is greatest when the interval is about .45″; (6) when the interval is -as long as .90″ the auditory stimulus is again ineffective. It thus -appears that the reënforcement-inhibition curve of this particular -stimulus under the conditions described is representative of a neural -process which completes itself, in passing through two phases, a -positive phase (reënforcement) and a negative phase (inhibition), in -about one second. - -_b. Prolonged auditory stimulation._ The experiments previously -described have proved that a momentary auditory stimulus, which when -given alone never produces a visible motor reaction, either reënforces -or inhibits the reaction to a tactual stimulus which it accompanies or -precedes. The experiments now to be described were made for the purpose -of ascertaining whether reënforcement and inhibition occur in the same -way if the auditory stimulus is prolonged, instead of momentary. - -In a trial series of experiments with frog No. 1, one hundred pairs -of reactions were recorded for each of six intervals of auditory -stimulation. The auditory stimulus was given by the ringing of an -electric bell. For all intervals the ringing of the bell continued -until the tactual stimulus was given. When the two stimuli were given -simultaneously the auditory stimulus was necessarily momentary, as -in the foregoing experiments, but for all other relationships of -the stimuli the bell rang for a certain length of time before the -tactual stimulus was given. The six relations of the stimuli were: -(1) simultaneous, (2) bell .2″ before and until tactual, (3) bell .6″ -before, (4) bell 1.05″ before, (5) bell 1.5″ before, and (6) bell 2.0″ -before. The other conditions of these experiments were the same as -those previously described, except that the auditory stimulus was here -given by the opening of the key which released the pendulum, instead -of being given by the turning of a key in the course of the pendulum -swing. This method of giving the auditory stimulus as the pendulum was -released was found unsatisfactory because of the irregularity of the -magnetic release; at one time the pendulum would start immediately, at -another time there would be a delay of as much as .1″. - -The reënforcement-inhibition curve plotted on the basis of the 1200 -reactions in this series is presented in Fig. 8. Before stopping to -consider the important features of this curve we should note the -results of certain more accurate experiments with prolonged auditory -stimulation. - -[Illustration: FIG. 8. Reënforcement-Inhibition curve for prolonged -auditory stimulation, based upon amount of reaction. Frog No. 1.] - -With two animals, No. 2, a female, and No. 3, a male, fifty pairs -of reactions were taken for nine different intervals (see Table 5) -of auditory stimulation. Each of the curves of Figures 9 and 10 -is therefore based upon 900 reactions. The conditions for these -experiments were the same as those for the momentary stimulation -series, save that the electric bell took the place of the electrically -actuated hammer, as the mechanism for auditory stimulation. - -[Illustration: FIG. 9. Reënforcement-Inhibition curves for prolonged -auditory stimulation, based upon amount of reaction. Female No. 2 ---- -Male No. 3 ....] - -The important facts exhibited by the results of these prolonged -auditory stimulation experiments in contrast with those with momentary -auditory stimulation are: (1) That whereas for the momentary -auditory stimulus of a hammer blow the reënforcement is greatest for -simultaneous stimuli, in case of the prolonged stimulation with the -electric bell, reënforcement increases during an interval of .25″ -of auditory stimulation. Hence, the two conditions of stimulation -give us different types of reënforcement-inhibition curve. For the -momentary stimulus the maximum reënforcement appears at simultaneity, -and for the prolonged stimulus at .25″; (2) that the transition from -reënforcement to inhibition occurs at 1.2″ in the prolonged stimulation -curves, while in the momentary stimulation curves it occurs at .35″; -(3) that the maximum inhibition which appears in the curves under -discussion at about 1.5″ is less in comparison with the amount of -reënforcement than that of the momentary stimulation curves; (4) that -the auditory stimulus becomes ineffective when the interval during -which it continues before tactual stimulation is 2.0″. The curves of -Figures 8, 9, and 10 are then representations of a neural process which -passes through a positive and a negative phase in about 2″. The effect -of prolongation of the auditory stimulation interval is to lengthen -the period of reënforcement; the period of inhibition shows little -modification. - -For the purpose of showing in greater detail the nature of the results -of this work the data from which the curves of Figures 9 and 10 were -constructed are presented in the accompanying Table 5. - -[Illustration: FIG. 10. Reënforcement-Inhibition curves for prolonged -auditory stimulation, based upon number of reactions. Female No. 2 ---- -Male No. 3 ....] - -Having now presented the results of my own investigation I wish to -call attention to certain of their relationships to the work of other -investigators, and to discuss briefly their significance. - - -TABLE 5. PROLONGED AUDITORY STIMULATION (ELECTRIC BELL) - - _Frog No. 2._ _Female._ _Weight usually 25 grams._ - - Auditory Number of - and Amount of Reactions, - Tactual Tactual Reënforcement Reënforced - Interval. Stimulation. Stimulation. or Inhibition. or Inhibited. - - 0″ 9.20 mm. 12.12 mm. + 31.7% +10.0 - .25 4.56 11.88 +160.5 +22.5 - .45 8.94 16.94 + 89.5 +18.5 - .65 17.18 22.50 + 31.0 +15.5 - .90 9.42 13.32 + 41.4 +14.5 - 1.20 10.54 9.64 - 8.5 - 2.5 - 1.40 24.00 20.64 - 14.0 - 6.0 - 1.58 19.16 17.80 - 7.1 - 7.0 - 1.95 14.50 15.40 + 6.2 + 5.5 - - _Frog No. 3._ _Male._ _Weight usually 5 or 10 grams._ - - 0″ 14.92 mm. 25.20 mm. + 68.9% +11.0 - .25 15.88 38.54 +142.7 +24.0 - .45 13.48 26.02 + 92.9 +13.5 - .65 18.30 27.94 + 52.6 +13.0 - .90 20.94 29.06 + 38.8 + 9.5 - 1.20 21.90 30.58 + 39.6 + 1.0 - 1.40 19.18 18.34 - 4.4 - 5.5 - 1.58 32.24 26.30 - 18.1 - 3.0 - 1.95 13.86 14.14 + 2.0 + 2.0 - - -VI. DISCUSSION OF LITERATURE AND RESULTS - -The literature on reënforcement and inhibition is large, and even -that portion of it which deals especially with the importance of the -temporal relations of stimuli in connection with reënforcement and -inhibition is so extensive that it does not seem worth while to attempt -to give a systematic résumé of it for the purposes of this paper. I -shall therefore call attention merely to those investigations which -have contributed directly to the solution of the problems with which we -are now concerned. - -Bowditch and Warren[156] discovered that knee-jerk in the human subject -is reënforced when an auditory, a visual, or a tactual stimulus -precedes the tendon blow by .1″ to .5″, whereas the same stimuli have -an inhibitory influence when they are given from .5″ to 1.0″ before the -tendon blow. - -At the suggestion of Bowditch, Cleghorn[157] undertook to investigate -the influence of complication of stimuli upon voluntary movements. In -this research graphic records taken in connection with an ergograph -indicated (1) that "a sensory stimulus" applied just as the muscle was -beginning to contract (voluntarily) caused an increase in the height of -the contraction, and (2) that the relaxation following a contraction -with intercalated sensory stimulus is quicker and more complete than -when no stimulus is given (p. 344). Cleghorn did not give special -attention to the significance of the temporal relations of the stimuli -which he employed, and his work was limited to the phenomenon of -reënforcement of voluntary action by reason of the appearance, during -the progress of his research, of an excellent paper on the interference -of stimuli by Hofbauer.[158] - -Hofbauer covered thoroughly the ground which Cleghorn had planned to -work over. The ergographic method was employed also by Hofbauer in -his very careful study of the interference of impulses in the central -nervous system of man. It was noticed that while the subject was -rhythmically contracting a certain group of muscles in response to -some prearranged signal (_e.g._, the sound of a metronome) the report -of a pistol caused the contraction which immediately followed it to be -much greater than the average of the rhythmic series, while the next -contraction was correspondingly less than the average. It thus appeared -that the sudden sound caused, first, reënforcement of the voluntary -movement, then, inhibition. The reënforcement is greatest, according -to Hofbauer, when the voluntary movement occurs immediately after the -pistol report. When the report precedes the metronome signal by .2″ -reënforcement is still marked, but thereafter it decreases rapidly in -amount, until finally at .5″ inhibition appears. When the interval -between the two stimuli is 1.0″ the first stimulus has practically -no effect upon the voluntary movement in response to the second. -(Hofbauer, p. 558.) - -What Bowditch and Warren, not to mention other students of the subject, -have described for reflex action in man, Hofbauer, Cleghorn, and others -have shown to hold true also of voluntary movements. Unfortunately my -own investigation was completed up to the point of the writing of this -paper before I read Hofbauer's work, so I have not followed methods -of dealing with my data which would make our results directly and -easily comparable. But, whatever may be the relations of our results in -detail, there can be no doubt that what he has demonstrated for man is -true in its important aspect of the reënforcement-inhibition phenomena -for the frog. - -Important in their bearings upon the phenomena of reënforcement and -inhibition which we are now considering, are the various studies of -refractory period and rhythm of nerve cell and fibre. The existence of -a refractory period in neural substance, similar to that demonstrated -for certain kinds of muscle by Marey,[159] Englemann,[160] Kaiser,[161] -Cushny and Matthews,[162] Woodworth,[163] and many others, has been -proved by Broca and Richet.[164] - -Broca and Richet found that in the normal dog the refractory period -of the nerve substance is too short to be easily detectable, they -therefore experimented with animals which were lightly chloralized and -kept at a temperature of 30 to 34° (the mean normal temperature of the -dog is about 39.5°). Under these conditions a dog, when two identical -stimuli (quality and intensity the same) were applied to the cerebral -cortex successively, exhibited the following reactions: (1) When the -stimuli were separated by .01″ they reënforced one another (addition); -(2) when the interval was .1″ they inhibited the reaction partially -(subtraction). - -Concerning this phenomenon Richet writes in his dictionary of -physiology (p.5): "Marey showed, in 1890, that the heart of the frog, -at certain moments of systole, was inexcitable. Now our experiments -prove that the cerebral apparatus, a certain time after the excitation, -also ceases to be excitable: it then has a refractory phase, and this -refractory phase is much more prolonged than that of the cardiac -muscle." In a later publication Richet[165] makes the somewhat -startling statement that a refractory period is not exhibited by the -nerves of cold-blooded animals. In the tortoise, according to his -results, reënforcement occurs so long as the interval between the -two stimuli is not greater than 2″, while for longer intervals each -stimulus to all appearances works independently. Richet seems to have -generalized from a study of the tortoise. That his generalization is -unwarranted seems to me highly probable in the light of the results -of this paper, for there are many reasons for supposing that the -reënforcement-inhibition phenomena with which we have been dealing -in case of the frog are manifestations of the existence of the same -process in the nervous system which under somewhat different conditions -of experimentation exhibits itself in the so-called refractory period. - -The researches of Richet and his students indicate that the time of -the process which conditions the phenomena of reënforcement-inhibition -is about .1″. Stimuli given at .1″ intervals do not interfere with one -another. That the process underlying the refractory period and the -reënforcement-inhibition phenomena of our experiments is a rhythmic -double-phase process is made still more probable by the following -results. Horsley and Schäfer[166] found that the rate of response of -the monkey to cortical stimulation was 12 per second, and Schäfer[167] -discovered that the maximum rate of volitional impulses in man is 10 to -12 per second. - -It was shown by Exner that certain movements of the foot of a rabbit -could be produced by stimulating either the cortex or the skin of the -foot. Simultaneous stimulation of both regions gives reënforcement. -Stimulation of the cortex, if given not more than 3″ before subliminal -stimulation of the skin, renders the latter effective. When both -stimuli are subliminal each makes the subsequent one effective if -the interval between them is not over 1/8″ (Schäfer[168]). Similarly -for the dog Exner[169] proved that cortical and cutaneous stimuli -reënforced one another, when both were subliminal, if the interval -between them was not greater than .6″. Cortical and auditory stimuli, -and auditory and cutaneous (of the skin of foot) gave similar results. - -Physiologists have long been familiar with several aspects of the -phenomena of reënforcement and inhibition in the frog, but I know of no -detailed study of the significance of the temporal relations of stimuli -in this connection. Goltz[170] called attention to the inhibition of -the croaking reflex by peripheral stimulation, as well as to several -similar phenomena. Nothnagel,[171] Lewisson,[172] and Wydensky[173] -further contributed to our knowledge of the interference effects of -stimuli in the frog. Wydensky proved that the application of an induced -current to a nerve-muscle preparation may result in either contraction -or relaxation of the muscle, according to the frequency of stimulation. - -More recently Merzbacher[174] has dealt with the influences of -complication of stimuli in the frog with the purpose of ascertaining -the relations of the sense-organs to the reflex movements of the -animal. His first paper is concerned especially with the functional -importance of the eye in connection with reflexes. Unfortunately for -the demands of this research, he did not attend particularly to the -temporal relations of his stimuli. That a visual and a cutaneous -stimulus were given either "at the same time or within a short interval -of one another" (p. 250) is not the sort of information our problems -demand. - -According to Merzbacher's very interesting results a visual stimulus -reënforces the reaction to a cutaneous stimulus. As the results of this -paper show, this is only half a truth, for the two stimuli may either -reënforce or inhibit one another's reactions. As Merzbacher observed -no evidences of reaction to auditory stimulation he presumably did not -attempt to study the influences of the ear in connection with reflexes. - -There can be no doubt that the words reënforcement and inhibition -as at present used in connection with the functions of the nervous -system cover a multitude of widely differing phenomena. We can at -once distinguish at least two important kinds of reënforcement or -inhibition: first, that which is due to the functioning of special -augmentary or inhibitory portions of the nervous system; second, -that which is the result of the complication of stimuli. Any and -every process in the nervous system may have either a reënforcing or -an inhibiting influence upon simultaneous or succeeding processes; -doubtless most processes or impulses at various times have both -effects. The nervous system is constantly being modified by impulses -from many sources, which suppress or strengthen one another according -to their relative intensity, their temporal relations, and the motor -relations of the portions of the organism which they affect. - -The existence of the so-called refractory period in brain cortex and -nerve indicates that every stimulus causes certain fundamentally -important changes in the condition of the neural substance. These -changes we may for convenience of illustration describe as modification -of excitability, or of the functional capacity of central or peripheral -tissues. Every stimulus causes a portion of the neural substance -to pass from its normal state through a condition of increased -excitability, which we may designate the positive phase, to a condition -of diminished excitability, the negative phase. There is first an -increase in the functional capacity of the tissues, then a decrease. -If during the course of the change produced by a given stimulus a -second stimulus becomes effective its result in reaction is determined -by the particular phase of the tissues upon which it intrudes. If the -nervous system is in the condition of increased excitability, and -the two stimuli act upon sensory regions whose motor connections are -not antagonistic, the reaction will be reënforced, as we say, by the -previous stimulus; if, however, the second stimulus falls upon the -negative phase of the nerve substance, the reaction will be partially -or totally inhibited. - -The facts which are most prominent as the result of this investigation -are, first, that the temporal relation of stimuli is an important -condition of certain forms of reënforcement and inhibition; second, -that the interference effects of two stimuli cannot be studied to -advantage without attention to the relations of the forms of reaction -which are appropriate to each stimulus. - - -V. SUMMARY - -1. Motor reactions of the green frog to electric stimuli are inhibited -either partially or wholly by photic stimuli. The visual stimulus of a -moving object has a like effect. It has been found, furthermore, that -the same visual stimulus may either inhibit or reënforce the motor -reaction in response to electric stimulation. When the two stimuli are -given simultaneously reënforcement occurs, when the visual stimulus -precedes the electric by half a second or more inhibition appears. - -2. An auditory stimulus, which does not produce any visible reaction -when given alone, modifies respiration and the reactions to other -stimuli when given in connection with them. - -3. The momentary auditory stimulus of a quick hammer blow when -simultaneous with tactual stimulation reënforces the reaction to the -latter stimulus. This reënforcement, or increase in the amount of -reaction, ranges from 50 to 100% of the average reaction to the tactual -stimulus alone. When the auditory stimulus is given before the tactual -reënforcement occurs in gradually decreasing amount until the interval -between the two stimuli reaches .35″; at this point the auditory -stimulus has no apparent effect upon the tactual reaction. As the -interval is still further increased inhibition appears and continues -for intervals between .35″ and .9″. Reënforcement is greatest when the -two stimuli are simultaneous; inhibition is greatest when the momentary -auditory stimulus precedes the tactual by .4″ to .6″. When the interval -reaches .9″ the first stimulus does not affect the reaction to the -second. - -4. Reënforcement is greater for the males than for the females; -inhibition appears sooner and lasts longer in case of the females. -This apparently indicates that the males are stimulated to activity by -certain auditory stimuli, whereas the females are rendered passive by -similar sounds. - -5. Prolonged auditory stimulation by means of an electric bell causes -reënforcement and inhibition, according to the temporal relations -of the stimuli, as does momentary auditory stimulation, with the -following differences: The maximum reënforcement occurs when the -tactual stimulus is given about .25″ after auditory stimulation has -begun; reënforcement continues for a period of 1.2″, _i. e._, when the -electric bell continues to ring until the tactual stimulus is given, it -reënforces the tactual reaction from simultaneity to 1.2″. Inhibition -then appears, and continues until 1.8″. Both momentary and prolonged -auditory stimulation cause first reënforcement, then inhibition of the -appropriate reaction to a tactual stimulus. - -6. The reënforcement-inhibition curves for the frog are very similar to -those for man. - -7. In case of the several pairs of stimuli whose interference effects -have been studied reënforcement-inhibition appears. The first stimulus -reënforces reaction to the second so long as the interval between them -is not more than about .4″, while it inhibits the reaction when the -interval is longer. Whether this reënforcement-inhibition curve as -given in the experiments described may similarly be obtained for any -and every pair of stimuli, no matter what their relation to reactions, -remains to be determined. - -8. In connection with the study of the mutual relations of stimuli of -which this paper gives an account certain facts concerning the sense -of hearing have been discovered. A summary statement of the results on -hearing may be found on page 551. - -FOOTNOTES: - -[Footnote 139: The results brought together in this paper have been -published in part in connection with other work in the following -papers: Inhibition and Reënforcement of Reaction in the Frog, Jour. of -Comp. Neurol. and Psychol., vol. 14, p. 124, 1904. Bahnung und Hemmung -der Reactionen auf tactile Reize durch akustische Reize beim Frosche, -Arch. f. d. ges. Physiol., vol. 107, p. 207, 1905. The Sense of Hearing -in Frogs, Jour. of Comp. Neurol. and Psychol., vol. 15, p. 279, 1905.] - -[Footnote 140: The Organ and the Sense of Taste in Fishes, Bulletin -U.S. Fish Commission for 1902, pp. 237-272.] - -[Footnote 141: Animal Behavior, Woods Hole Lecture Series, p. 300, -1899.] - -[Footnote 142: The Response of the Frog to Light, American Journal of -Physiology, vol. 9, p. 476, 1903.] - -[Footnote 143: The Instincts, Habits and Reactions of the Frog, Harvard -Psychological Studies, vol. 1, p. 590, 1903.] - -[Footnote 144: The Skin and the Eyes as Receptive Organs in the -Reactions of Frogs to Light, American Journal of Physiology, vol. 10, -p. 31, 1903.] - -[Footnote 145: Ueber die electromotorischen Erscheinungen an -Hautsinnesnerven bei adaequater Reizung, Archiv für d. ges. -Physiologie, vol. 63, p. 503, 1896.] - -[Footnote 146: Harvard Psychological Studies, vol. 1, p. 592, 1903.] - -[Footnote 147: Abstract of paper read before Section F of American -Association for the Advancement of Science in Philadelphia, 1904. -Science, vol. 21, p. 265, 1905. See also Bulletin of the U. S. Fish -Commission for 1902, pp. 45-64, and the same for 1904, pp. 183-207.] - -[Footnote 148: Anatomie des Frosches, VI, Lehre von Integument und von -den Sinnesorganen, pp. 751, 752, 1904.] - -[Footnote 149: Journal of Comparative Neurology and Psychology, vol. -15, pp. 279-304, 1905.] - -[Footnote 150: Ueber die Beziehungen der Sinnesorgane zur den -Reflexbewegungen des Frosches, Arch. f. d. ges. Physiol., vol. 81, pp. -222-262, 1900.] - -[Footnote 151: "Blendung oder blosse Lichtentziehung erhoht die -Erregbarkeit für mechanische Reize" (p. 253).] - -[Footnote 152: Thousandths of a second.] - -[Footnote 153: Arch. f. d. ges. Physiol., vol. 81, p. 227, 1900.] - -[Footnote 154: A case of inhibition.] - -[Footnote 155: Arch. f. d. ges. Physiol., vol. 107, p. 213, 1905.] - -[Footnote 156: Journal of Physiology, vol. 9, pp. 60, 61, 1890.] - -[Footnote 157: American Journal of Physiology, vol. 1, p. 336, 1898.] - -[Footnote 158: Arch. f. d. ges. Physiol., vol. 68, p. 546, 1897.] - -[Footnote 159: Travaux du Laboratoire de Marey, 1876.] - -[Footnote 160: Arch. f. d. ges. Physiol., vol 59, p. 309, 1894.] - -[Footnote 161: Zeitschr. f. Biol., vol. 32, p. 1, 1895.] - -[Footnote 162: Journal of Physiology, vol. 21, p. 213, 1897.] - -[Footnote 163: American Journal of Physiology, vol. 8, p. 213, 1902.] - -[Footnote 164: Comptes rendus, vol. 124, p. 573, 1897.] - -[Footnote 165: Nature, vol. 60, p. 629, 1899.] - -[Footnote 166: Journal of Physiology, vol. 7, p. 101, 1886.] - -[Footnote 167: Journal of Physiology, vol. 7, p. 111, 1886.] - -[Footnote 168: Text-book of Physiology, p. 841, London, 1900.] - -[Footnote 169: Arch. f. d. ges. Physiol., vol. 28, p. 495, 1882.] - -[Footnote 170: Beiträge zur Lehre von den Functionen der Nervencentren -des Frosches, p. 41, Berlin, 1869.] - -[Footnote 171: Centralb. f. d. med. Wissensch., vol. 7, p. 211, 1869.] - -[Footnote 172: Arch. f. Anat., u. Physiol., p. 259, 1869.] - -[Footnote 173: Arch. d. Physiol. norm. et pathol., vol. 4, p. 690, -1892.] - -[Footnote 174: Arch. f. d. ges. Physiol., vol. 81, p. 222, 1900.] - - - - -THE TEMPORAL RELATIONS OF NEURAL PROCESSES - -BY ROBERT M. YERKES - - -Muscle contraction-time, according to the determinations of several -investigators, varies about .0035".[175] Sanderson states that the -time for direct stimulation of the muscle is approximately .0035" and -for indirect stimulation, by means of the nerve, .007". The rate of -nerve-transmission in the frog ranges from 25 to 35 metres per second. - -Reflex reaction-time, as might be expected, varies widely with the -nature of the reaction elicited by a stimulus, the condition of -the animal, and the quality and strength of the stimulus. For many -of the simple motor reactions of the frog it ranges between 20 and -60^{σ}.[176] Whether reflex reaction-time is to be sharply contrasted -with instinctive and voluntary reaction-times, or whether they -indistinguishably merge into one another is a question of considerable -interest and importance for the student of the evolution of activity. - -Voluntary reaction-time may be as short as 150^{σ} or as long as life, -in an animal capable of profiting by experience as does the frog. It is -preëminently the delayed type of reaction-time. - -So much concerning the temporal relations of neural processes in the -frog being well established, the purpose of the present paper is -to call attention to some experimental results which indicate the -existence of clearly defined types of reaction, and suggest possible -values of reaction-time as a sign of mind. - -The specific problems to be considered are: (1) Do reaction-times, in -any given animal, range with equal frequency of occurrence from short -to long, or are there certain modes (most frequented classes) which -indicate definite types of reaction, such, for example, as the reflex, -instinctive, etc.? (2) If there is distribution of the reaction-times -about one or more modes, what are the types of reaction indicated -thereby? (3) Finally, is reaction-time of service as a sign or measure -of consciousness? - -I wish especially to call attention to the fact that this paper deals -with the reactions of the frog, not with animal reactions in general. - - -REACTIONS TO ELECTRICAL STIMULATION AND TYPES OF REACTION - -Two years ago in connection with a discussion of the reaction-time of -the green frog to electrical and tactual stimuli,[177] I presented a -curve showing the distribution of 277 reaction-times to an electrical -stimulus. The curve exhibited two clearly defined modes: one at between -60 and 70^{σ} and the other at about 160^{σ}. There was further a group -of delayed reactions ranging about 500^{σ}. This form of distribution -was interpreted, at the time, as indicative of three types of reaction, -called, respectively, the reflex, the instinctive, and the delayed. - -I have since obtained and examined with reference to form of -distribution the further data which are presented in this paper. The -reactions are all those of the green frog to electrical stimulation. -The stimulus was applied by means of wires on the reaction-board -on which the frog rested during the experiments. When reaction -occurred in response to the electrical stimulus a circuit through the -time-measuring apparatus was broken by the release of a delicate spring -which had been held in place up to the instant of reaction by the -weight of the frog. A Hipp chronoscope, controlled by a Cattell falling -screen, served as a time-measuring mechanism. Three intensities of -stimulus were used: (1) A current from one Mesco dry cell, (2) from two -cells, and (3) from four cells. - -Of the reactions whose time was measured there are three series. Series -I is constituted by the recorded reaction-times in response to a -one-cell stimulus, Series II, those in response to a two-cell stimulus, -and Series III, those in response to a four-cell stimulus. The number -of reactions, range and mode of each series are as follows: - - Number of reactions Range Mode - Series I 193 161-798^{σ} 235^{σ} - Series II 288 41-647 235 - Series III 256 61-178 105 - -The distribution of the 481 reaction-times of Series I and II is shown -by Figure 1; that of the 256 reaction-times of Series III, by Figure -2. For both of these distribution polygons the reaction-times were -arranged in ten^{σ} classes, beginning with the class 41-50^{σ}[178] in -the case of the combined Series I and II and with the class 61-70^{σ} -in the case of Series III. - -Series I exhibits a primary mode at 235^{σ}. There are no reflex -reactions in this series, unless it be maintained that the reflex -reactions of the frog may have a reaction-time of over 160^{σ}, -but there are a number of delayed reactions, some of which have -reaction-times as long as 798^{σ}. This intensity of stimulation -(one cell) may be said to call forth prompt reactions, which we may -provisionally call instinctive, and delayed reactions, which have all -the appearances of voluntary acts. There are no reactions which come -within the range commonly considered as the reflex range of the frog -(20-60^{σ}), and there are relatively few delayed reactions: almost all -centre about the mode 235^{σ}. - -[Illustration: FIG. 1, LOWER. FIG. 2, UPPER.] - -Series II, in contrast with Series I, exhibits a secondary -mode at 65^{σ} in addition to the primary mode at 235^{σ}. The -stimulus-intensity of this series (roughly twice as great as that for -Series I) induces a variety of short reaction, which did not appear in -the case of the one-cell stimulus, and at the same time fewer delayed -reactions. The range of the reaction-times for the two series is about -the same, but the lower limits are markedly different. - -Observation of the subjects during the experiments revealed two methods -of reaction to the two-cell stimulus: a locomotor reaction (jump) -which at once removed the animal from the source of stimulation, -and a twitch of the hind legs which was instantly followed by the -above-mentioned locomotor reaction. The leg reactions constitute the -reflex group of Fig. 1, the usual prompt locomotor reactions, the -instinctive group, and the slow locomotor reactions, the delayed or -voluntary group. - -It is to be noted that the instinctive reaction-time mode is the same -for the two intensities of stimulation. This apparently indicates -that change in intensity of stimulation causes a change in the type -of reaction, not merely a gradual change in the position of the -mode. For example, the modal reaction-time of 235^{σ} given by a -one-cell stimulus did not shift to 200^{σ} or lower, as might have -been expected, but instead there appeared a new type of reaction. The -average reaction-times for the two series indicate a decrease in time -with increase in intensity of stimulation, but they give no indication -of the really important difference in the two series of reactions. The -great importance of the distribution of the data, in addition to the -common statistical quantities, is manifest. - -Series III, whose reactions occurred in response to a very strong -stimulus, differs in several important respects from the other series. -Its range is much narrower, only 117^{σ}. Delayed reactions are -lacking, and so also, curiously enough, are the reflex reactions of -Series II. Instead of either or both of the modes of Series II, there -appears in Series III an intermediate mode at 105^{σ}. - -Our interpretation of these facts is facilitated by results of -observation of the reacting subject. The leg reflex which frequently -occurred in response to the two-cell stimulus never appeared in -response to the four-cell stimulus. This in part explains the lack -of the short reaction-time mode of Series II; it does not, however, -account for the lack of delayed reactions. The latter fact may be -referred to the intensity of the stimulus. Another difficulty in -interpretation appears in connection with the intermediate mode, -105^{σ}. Is this to be considered an instinctive mode, as were those -at 235^{σ}, or a reflex mode? Where is the line between reflex -and instinctive action to be drawn? These results very clearly -indicate that no line can be drawn, except quite arbitrarily. Reflex -reaction-time, in the case of the frog, is continuous with instinctive, -yet for any given situation the reflex, instinctive, and delayed -(voluntary?) modes are likely to appear, as, for example, in the case -of the data of this paper. Our conclusion must be, therefore, that -although types of reaction are indicated by reaction-time results, -the mode for a given type varies too much in position with different -conditions to make it possible to say that a particular reaction-time -is that of a certain type. - -We may safely say, then, that for any given subject, the muscle -contraction-time, nerve transmission-time, and simple sensory -reaction-time to the constant stimulus in question being known, we -should be able safely to interpret reaction-time records in terms of -reaction types. For reflex, instinctive, and voluntary are terms which -designate modes of reaction, albeit not isolated classes, for they -intergrade. - -Whether there are more types of reaction than are indicated by the -data of this report does not concern us at present, for the practical -as well as the theoretical bearings of our conclusions depend upon the -existence of types, and not upon their number. - - -REACTION-TIME AS AN INDICATION OF CONSCIOUSNESS - -Hesitation in reaction is commonly accepted as an important sign of -volitional consciousness in man; consequently delayed reactions in -lower animals are supposed to be indicative of psychic processes. -Granting this much, reaction-time may be used as a sign of -consciousness. It cannot be denied that the longer the reaction-time -of a given animal the greater the probability that the reaction is -conditioned by mental processes. Such a statement, it is true, has a -basis neither better nor worse than that of most of our inferences -concerning the nature of the actions of our fellow beings. As I have -already attempted to show in a discussion of criteria of consciousness -in animal psychology,[179] there is no one criterion of consciousness -which can be used alone satisfactorily, but instead there are numerous -signs of mind each of which has value according to the number and -variety of our observations concerning its occurrence in connection -with states of consciousness. The more of such signs we discover -and learn to evaluate properly in relation to consciousness in its -different grades and to one another, the safer will be our inferences -concerning the existence of mental processes in animals. - -Reaction-time is presented in this paper as an additional sign of -mind. Like all other signs it is of value only if used as one of a -series of indications of mental life. For if we attempt to judge of -consciousness by reference to reaction-time alone, we may be seriously -misled, whereas if we use it in connection with docility, variability, -neural specialization, and other recognizedly valuable signs, we may -be greatly aided in our inference. As in juristic procedure judgment -is not based upon one bit of evidence nor even upon the evidence of -a single witness, but upon evidence accumulated from all available -sources, so in our attempts to judge of the existence of consciousness, -it matters not whether the being be human or infra-human, we should -make use of all phenomena which are recognized as signs of mind. The -chief task of comparative psychology at present is the discovery and -evaluation of signs of mind. - -Reaction-time data, however, furnish another sign, or, as I prefer -to call it in this case, measure of the intensity of consciousness; -for variability of the time of reaction as well as its duration is -significant. Reflex reaction-time is relatively constant, instinctive -varies considerably, and the variability of voluntary reaction-time is -extremely large. Degree of variability of reaction-time may be used -as an indication of consciousness in the same way that variability in -the form of reaction is used. The higher the power of consciousness -the greater the variety in form of reaction and the variability of the -reaction-time. - -Reaction-time studies, as well as introspection and the investigation -of animal behavior, indicate the importance of three activity concepts: -automatism, instinct, and will. The automatic act is quick and -relatively constant in form as well as reaction-time, while all signs -lead us to infer that consciousness, when it accompanies the act, is a -sequent phenomenon and not a condition of the act. The instinctive act -is both slower and more variable in form and time than the automatic: -consciousness is indicated as an accompaniment, and apparently it is -at times a condition of the act. The will-act is extremely variable, -unique in form, and almost without limits of reaction-time, for the -conscious organism may react to the present situation in a fifth of a -second, a day, or a year. Will is experience in action: it is our name -for individually acquired control, and voluntary action is above all -consciously conditioned activity. - -Reaction-time, with respect to its two aspects of duration and -variability, may be used as a sign or criterion of consciousness, for -in accordance with the nature of these two sets of facts we classify -acts as reflex, instinctive, or voluntary. - -FOOTNOTES: - -[Footnote 175: Sanderson: Journal of Physiology, vol. 18, p. 147. -Tigerstedt: Archiv f. Physiologie, p. 111, 1895. Boruttau: Archiv f. -Physiologie, p. 454, 1892.] - -[Footnote 176: ς = thousandths of a second.] - -[Footnote 177: Yerkes: Harvard Psychological Studies, vol. I, p. 609, -1903.] - -[Footnote 178: The last four classes of Fig. 1 are 100^{ς} classes, -401-500, 501-600, 601-700, 701-800.] - -[Footnote 179: Yerkes: Journal of Philosophy, Psychology, and -Scientific Method, vol. 2, p. 143.] - - - - -THE MENTAL LIFE OF THE DOMESTIC PIGEON - -AN EXPERIMENTAL STUDY OF CERTAIN EMOTIONAL AND ASSOCIATIVE PROCESSES - -BY JOHN E. ROUSE - - -I. INTRODUCTION - -Naturalists have observed the habits of pigeons, and physiologists -since Flourens have subjected them to numerous experiments, but so -far they seem to have received little psychological study. As a -contribution to this interesting field the present paper reports an -investigation of certain emotional and associative processes of the -domestic pigeon. Since the literature of the subject is meagre, I shall -state at the beginning a few related facts which I have gathered from -various sources; then I shall discuss in detail the problems, methods, -and results of my several experiments. - -The brain of the pigeon is well developed, although the hemispheres -are unconvoluted. When they are removed, the animal retains unaltered -its reflex and vital activities, but ceases for a time at least to -show evidence of mental life, for example, memory and will.[180] In -the normal animal sight and hearing are acute, and touch seems keen, -although the claws are not used for grasping and eating, as in the case -of more intelligent birds, especially, parrots. There is considerable -sensitiveness to temperature changes. Taste, and probably smell, appear -to be deficient.[181] The "sense of support" is marked, even in the -young.[182] - -Since the pigeon seems to dream and also to miss its absent mate, some -observers believe that imagery is present. There is certainly local -memory, and also capacity to observe. Various intelligent acts have -been reported.[183] The remarkable homing habits of the carrier pigeon -have received no satisfactory explanation. While Cyon[184] suggests the -stimulation of the nasal organs by air currents, Thauzièr[185] holds -to the electrical theory; they agree, however, that certain higher -psychical processes are probably involved. - -Graber's[186] tests indicate that pigeons have no color-preference. -Beebe's[187] statement concerning birds in general is peculiarly true -of pigeons: "There are few species which do not show the emotions of -love and sympathy, and ... one will sometimes pine and die of grief at -the loss of its mate." After referring to their patient care of the -young, he adds: "Indeed, sympathy is the keynote in the development -of the higher mental faculties." These birds communicate, but their -language consists of comparatively few sounds. As in many other birds, -the play-instinct is highly developed. - - -II. PROBLEMS AND METHODS - -My study of the pigeon's _emotional life_ had for its object certain -respiratory "expressions." These were investigated by means of a -pneumographic tracing, secured while the animal was comfortably -fastened in a shallow nest, partially open below. A small box was -placed over the bird, and apparatus was so arranged that the time -of giving various stimuli was recorded automatically on the smoked -paper of the kymograph drum, below the breathing-curve. A third line -indicated rate of drum movement. Although some interesting results -were obtained, the chief significance of the research consists in its -demonstration of the fact that this method of studying animal mind is -valuable. - -In the study of _association_ I sought to determine the sense-data -which the process involves, its method of formation (with due regard -to social conditions), its rapidity, permanence, and modifiability, -and also its probable degree of complexity. Material contributing to -the subject was secured by observing the behavior of the animal when -seeking to obtain food by overcoming such obstacles as labyrinths with -wire passages, and latches, when the food was left in view, or by -finding it when out of sight. In the latter case it was placed in a box -occupying a customary place in a group of exactly similar boxes, or -else in a box of color or form unlike the other members of the group -and variously arranged, from time to time, with respect to them. When -the animals were learning the labyrinth habits, various stimulations -were given them; later the character of some of these was altered, and -the resulting changes in behavior were noted. After the habits had -been thoroughly learned, the birds were given a rest for some weeks, -and then tested again under the old conditions. A few trials were -arranged with special reference to the study of imitation; the animals -here were tested as to their ability to execute simple but unfamiliar -acts, after having only seen them performed by an animal previously -trained. Throughout the associational tests the animals very seldom -received food in their cages; but as they were tested daily and allowed -to satisfy their hunger completely at the last test, they were never -in a state of "utter hunger"--a condition which most experimenters -think best to avoid. A series of tests, given at the conclusion of the -investigation, indicated that the odor of the food had not assisted the -animals in reaching it. - -In the two series of experiments (emotion and association) thirty-five -animals in all were used. They were confined in large cages in a fairly -well lighted and ventilated room, and were fed wheat, cracked corn, -and occasionally fruit, and kept well supplied with fresh water and -sand. They generally remained in a healthy condition throughout the -tests, especially during the winter. To exclude, as far as possible, -the disturbing influence of fear, they were usually handled only -after the room had been darkened. As the noise made by the curtains -was objectionable, the birds were tested with the room illuminated by -incandescent lamps; the light was turned off before the birds were -placed in position for the trials, and again before they were removed -from the apparatus to the cages. It is generally agreed that an -experimenter should be out of sight when giving a test. I am convinced -that it is important to avoid being seen by the animals at any time. -This involves great inconvenience, especially when one employs the -pneumographic method, but better results are thus obtained. - -For practical suggestions as to apparatus and methods I am -greatly indebted to Dr. Robert MacDougall, at the beginning of my -investigation, and to Dr. Robert M. Yerkes, throughout. I also owe -much to the researches of Zoneff and Meumann,[188] Thorndike,[189] -Mills,[190] Small,[191] and Kinnaman.[192] Porter's[193] interesting -study of sparrows was made almost simultaneously with the investigation -here reported. Fewer animals were used by him, but in some instances -more tests were given. - - -III. INVESTIGATION OF EMOTION[194] - -1. _Respiration in general._ The normal breathing-curve in pigeons -is quite similar in contour to that of the human subject, although -the rhythm is more rapid and the pauses are less pronounced. When -acoustical, visual, olfactory, or tactual stimuli are given, various -modifications appear, for example, quickening, deepening, and minor -irregularities. It was noticed that meaningless stimuli (pistol-shots) -quickly lose their disturbing influence, whereas the breathing remains -sensitive to those of a significant character, such as the noises -made by other birds. It was also found that a stimulus which no -longer affects the breathing will sometimes occasion disturbance if -accompanied by a second stimulus of another order, although of a weak -intensity (summation). - -2. _Respiratory reactions to light._ As the easy control of conditions -makes vision an excellent field in which to work, light reactions were -investigated in detail. Two distinct series of tests were given. One -sought to determine the relation between quality of light and reaction; -the other, between intensity of light and reaction. Four colors of one -intensity and three intensities of one color, respectively, were used. -In the first series four stimuli, one for each of the colors, red, -yellow, green, and blue, were given daily; in the second series five -daily stimuli were given, of the same intensity for any one day, and -one minute apart; this made it possible to observe also the effect of -repetition. Each stimulus was given at the beginning of a respiration -and continued two seconds. When the tracings were studied, various -modifications were noted, but special attention was paid to alterations -in rate of breathing. In the case of both sets of trials an immediate -quickening usually occurred after stimulation, and occasionally -shallowing[195] and minor irregularities of contour. - -In the first set of tests ten animals were used for twenty-five days. -Average results indicated that red and yellow are less stimulating -than green and blue. To secure data that would assist in the -interpretation of these results, an investigation was made of the -animals' color-preference. This was done by recording, at thirty-minute -intervals, the position of the birds when confined, singly, in a -box one half of which was illuminated (from the side) by light of -one color, and one half by light of different color but of the same -intensity. A water screen excluded the heat rays. After nine records -had been taken the colored glasses were interchanged, and the animal's -position relatively to the two colors was observed as before. This was -repeated with the other colors until each of the four had been used -with each of the other three. There were far more choices of green and -blue than of red and yellow, though none of the colors was avoided. -It seemed a question of _degree of liking_, rather than of liking or -disliking. As stated, Graber's experiments indicated that pigeons have -no color-preference, but his results are probably untrustworthy, since -he tested several animals at once and apparently was not careful to -change the colored glasses regularly. Putting together our two sets of -data (the latter stated first) we have the following comparison: - - R Y G B - Color choices of } - 5 animals } 72 129 167 172 - - Breathing-rise of} - 10 animals } 9.94% 10.39% 10.41% 12.11% - -Although the proportions do not hold, there is a direct correspondence -between the two series of responses; hence it would seem that -_increased respiratory activity is an expression of agreeable feeling_ -in pigeons, and this especially since the breathing, when varying at -all in amplitude, usually became shallower, and also showed certain -minor irregularities of contour, as often occurs in human respiration -during moderate stimulation of a pleasant character.[196] - -In the second series of respiratory tests four animals were used -for fifteen days. Average results showed nothing as to the relation -between intensity of stimulus and amount of quickening, since the three -intensities used, 1, 2, and 4, produced reactions, respectively, as -follows: 6.6%, 4.3%, and 6.4%. This may have been because the three -intensities were employed each on different days. When the reactions -are averaged according to daily succession, without regard to the -intensities of the stimuli, we get the following results: first -reaction, 8.0% rise in rate; second, 3.7%; third, 4.1%; fourth, 5.7%; -and fifth, 6.9%. We should have expected the second daily response to -be less vigorous than the first, since the animals were perhaps better -prepared for the second stimulation. That the reactions increased -thereafter was probably due, partially to summation, and partially -to the fact that the short illuminations occasioned mental action -(_perception_ of interior of box, increased _desire_ to escape, -etc.) which involved heightened, rather than depressed, breathing -activity, and thus worked directly against the dulling tendency of -repetition.[197] - - -IV. INVESTIGATION OF ASSOCIATION - -1. _Labyrinth experiments._ Four labyrinths in all were used (L, M, H, -O). Each was constructed by attaching moveable wire partitions in a -wooden box, covered with chicken wire. The pigeon was admitted through -a small entrance compartment which was fastened at one end of the box, -and which communicated with it by means of a lifting door, operated by -pulling a cord from behind the observation curtain. Food was placed -within the maze, and usually at the opposite end. Before beginning the -tests the bird was allowed to become thoroughly familiar with the box -without the partitions. After a few trials it learned to go to the food -immediately upon entering the box. The partitions were then put into -position, and the bird was tested as to the time required (except in -the case of labyrinth O) and as to the method employed in reaching the -food. The time was measured by means of a stop-watch, and the bird's -horizontal movements were recorded on a small plot of the labyrinth; -other general observations were added. - - -A. _Habits in Labyrinth L_ - -[Illustration: FIG. 1. Labyrinth L. BB, box 6 in. high; E, entrance; -F, feeding-place; a, b, c, and d, moveable partitions 6 in. apart; NN, -edge of pigeon cage; D, observation screen. The lamps which illuminated -the room hung directly above the apparatus.] - -In this labyrinth (Fig. 1) six animals were tested once daily for -thirty days, and five of these again after two and six weeks, -respectively. On entering the labyrinth with the partitions in place -the first time, a bird started on its usual direct course toward the -food-box; running against the first partition it made vigorous efforts -to push through, flying at the wire and often clinging to it for a -short time; some of these random movements eventually brought it to -the left of the compartment, and thence, through the opening, into -the second compartment, and so on through the others, until finally -it reached the food by a series of fortunate accidents.[198] The same -general reaction was shown in case of the next few tests, except that -fewer and fewer useless movements were made, and that the right ones -were carried out with greater and greater precision. Later the animal -had no difficulty in reaching the food; it did not run against the -partitions, enter the blind alley, nor display such general signs of -uncertainty as pausing and looking about. The process of learning in -this case was obviously one of "trial and error," or the selection -of useful movements. From the mass of random movements constituting -the reaction to the unfamiliar environment, only those which enabled -the bird to reach the food were retained and improved; the others -gradually disappeared until finally the path taken became the shortest -one possible, and was entered upon and pursued without hesitation by -each animal as soon as it was allowed to enter the labyrinth. The time -required for the tests is given in Table I. - -It will be seen at a glance that the absolute time required for -reaching the food varied for the individuals (see especially the -results given by different birds in the case of test 1), but that the -several periods for any one bird were relatively similar to those -for another; and also that the time was long at first, but rapidly -shortened from test to test, thus showing a steady advance in the -learning process. Various lapses occurred (for example, A, 8; C, 13; E, -10) after the habit had been fairly well fixed. - -In tests 18-22 the time-shortening was due principally to quickening of -movements which had already become well defined. The great importance -of visual data is brought out by the abrupt lengthening of the periods -in the case of tests 23-25, and 26-30, where the light intensities -were decreased. The lengthening was roughly proportional to the change -of illumination. In the relative darkness the birds had to re-acquire -the habits. The same mistakes were made as at first (running against -partitions, and into the blind alley), yet here, as before, there was -a ready adjustment. That the food was out of sight, or at least very -much less visible, probably made no difference, since it was found -that the birds would readily go to the old place after both food and -food-box had been removed. In order to exclude the light entirely -without making their movements invisible to me, I blindfolded the birds -by means of a thin black hood, comfortably adjusted over their eyes and -top of head; as a result, none was able to make the course in twenty -minutes. The first turn, however, was usually made naturally, perhaps -because associated with certain non-visual sense-data (sound of the -lifting door, and perhaps tactual impressions of the close entrance -compartment, etc.). Rats[199] seem far less dependent upon visual data -than do pigeons. The great permanence of the pigeons' habits is shown -by comparing the periods for tests 31-3, given after two and six weeks -of rest, respectively, with those for tests 18-22. - - -TABLE I. TIME REQUIRED TO REACH FOOD IN LABYRINTH L - - _Animals_ - - _Trials_, A B C D E F _Average_ - 1 daily. - ' " ' " ' " ' " ' " ' " ' " - { 1) 28:50 :59 42:20 49:04 22:13 4:04 24:35 - { 2) 7:22 :22 25:47 10:17 :48 2:02 7:46 - { 3) 1:18 :12 8:29 12:35 :12 1:41 4:05 - { 4) :32 :21 10:51 1:26 :19 :52 2:24 - { 5) :24 :28 2:36 2:18 :12 1:33 1:15 - { 6) :25 :26 1:10 :55 :12 1:50 :50 - { 7) :15 :24 :28 :32 :15 2:09 :41 - { 8) 1:05 :23 :33 1:19 :17 1:46 :54 - 1 { 9) :16 :24 :57 :58 :10 :26 :32 - {10) :24 :32 1:15 :51 2:12 :31 :58 - {11) :12 :21 1:40 :30 :17 :54 :39 - {12) :16 :32 :49 1:34 :22 1:18 :49 - {13) :13 :18 2:30 :18 :10 :42 :42 - {14) :29 :32 :27 :31 :25 :36 :30 - {15) 1:00 :24 :30 :31 :12 :35 :32 - {16) :19 :52 1:10 :22 :17 :24 :34 - {17) :14 :14 :31 :39 :13 :57 :28 - - {18) :13 :09 :29 :13 :16 :29 :18 - {19) :10 :10 :36 :26 :07 :14 :17 - 2 { 20) :11 :15 :34 :17 :07 :10 :16 - {21) :13 :14 :34 :16 :09 :21 :18 - {22) :09 :16 :26 :14 :08 :11 :14 - - {23) :12 :42 1:29 :39 5:53 :13 1:31 - {24) :20 :17 1:31 :33 :15 :13 :31 - 3 { 25) :15 :24 :40 :28 :19 :20 :24 - - {26) 1:21 16:29 1:22 13:54 3:51 1:36 6:26 - {27) 3:36 4:45 :44 1:03 1:09 2:59 2:23 - 4 { 28) :51 1:24 :46 1:04 :56 1:09 1:02 - {29) :51 :41 1:10 :40 2:17 :11 :58 - {30) 2:04 :18 :41 :14 :07 :19 :37 - - 5 { 31) :08 :33 :25 :07 :07 :16 - 6 { 32) :09 :15 :20 :08 :31 :17 - -1: With 18-candle-power illumination of the room. - -2: Same illumination; tests given after the animals had heard four -other pigeons pecking in the labyrinth. - -3: With 2-candle-power illumination, other conditions the same. - -4: With a slight illumination through single curtain, other conditions -the same. - -5: After two weeks' rest, conditions as in 2. - -6: After six weeks' rest, conditions as before. - -Let us now notice the gradual progress of learning in three important -parts of the maze, as shown in Fig. 2. It will be seen that in the -beginning the animals started upon their usual course and pressed -against the first partition (stage 1), but that later they touched -it less and less (stages 2 and 3), and that finally they avoided it -entirely (stage 4). The adjustment here was fairly simple: the sound -made by the opening of the entrance door, and the glimpse thus given -of the labyrinth, gradually came to be conditions of the movements of -turning to the left, on emerging from the entrance, and passing along -the compartment toward the opening, where impressions, mostly visual, -in the same manner determined the movements of turning to the right and -entering compartment 2. - -The blind alley was naturally a decided obstacle. The pigeons -learned to avoid this compartment by going around it only after many -unsuccessful attempts to go through it. During the first test the -animals entered it many times (stage 1); on emerging they returned to -the second or the first compartment, only to encounter the pen again -when they re-advanced toward the food; finally, on reëmerging from the -annoying enclosure, perhaps for the eighth or tenth time, they might -happen to turn to the right instead of going forward as usual toward -the entrance of the box, and thus make their way along the new passage -and reach the food. For the next few tests they usually entered the -blind alley, but less frequently, and they remained for shorter periods -(stages 2-4). Later they merely entered (stage 5); and still later they -passed very near the opening without entering, or only paused a moment -before it (stage 6); and finally they passed it without the slightest -hesitation, walking briskly, but with well-directed movements, midway -between the partitions (stages 7-8). The act of turning seemed to be an -especially important factor in this habit. We notice that it was a turn -to the right (most probably accidental) which first enabled the animals -to get beyond the opening of the blind alley; that this same act was -repeated in each successive trial until, by the gradual shortening of -the loop forming the path taken by the animals in passing into, and -from, the labyrinth it was finally reduced to a mere pause (stage 6); -and that this later disappeared entirely, leaving only the left turn, -which instead was now conditioned by the visual data at that part of -the labyrinth and carried the animal past the entrance of the blind -alley. - -[Illustration: FIG. 2. Stages in learning Labyrinth L. The curves -indicate the pigeon's horizontal movements. Pauses are represented by -heavy dots.] - -The animals did not come in contact with the second partition until -they had almost learned to pass the opening of the blind alley (see -stage 6). This was probably because the turn to the left which was -made on approaching _x_ was associated with visual data derived from -points farther along the course (_y_), and when the animals reached -_z_, compartment 2, these same data were received and were sufficient -to occasion the turn to the left there also, thus bringing the birds -against the partition. The adjustment was made principally on the basis -of new sense-data arising from running against the wire, looking at it -more closely, etc. For a few trials the birds made the turn at _x_ too -quickly, and thus failed to reach the third compartment. One of my most -intelligent subjects made this mistake in the third test, and again in -the sixth and seventh, and retained the act almost unchanged through -the tenth, eleventh, twelfth, thirteenth, fourteenth, sixteenth, -seventeenth, twentieth, and twenty-first tests, so strong was the -tendency to continue a movement once begun, though it was really -disadvantageous.[200] - -[Illustration: FIG 3. Labyrinth M. E, entrance; F, food-box; height of -large box and width of passages the same as in Labyrinth L.] - -After reaching the food and satisfying their hunger, the animals -often returned to the maze passages, seeking an exit; but they never -"explored" passages or showed other evidence of "free curiosity" -and "desire to know all their new surroundings," as Small reports -concerning rats.[201] - - -B. _Habits in Labyrinth M_ - -Five of the animals previously used were next tested twice daily, -forenoon and afternoon, for five days, in a larger, more complicated -maze. It had two blind alleys, and the food-box was near the centre -(see Fig. 3). The animals' general behavior was similar to that before -observed. The periods are given in Table II. - - -TABLE II. TIME REQUIRED TO REACH FOOD IN LABYRINTH M - - _Animals_ - _Trials_, A B C E F _Average_ - 2 daily. ' " ' " ' " ' " ' " ' " - (1) 16:25 2:55 6:33 3:26 4:11 6:42 - (2) :55 4:10 2:24 3:36 :23 2:18 - (3) 1:12 :55 8:27 9:06 2:07 4:21 - (4) :48 :44 2:31 :34 1:04 1:08 - (5) :27 :16 :14 :16 :14 :17 - (6) :18 :32 :25 :15 :27 :23 - (7) :14 :11 :31 :44 :30 :26 - (8) :12 :16 :57 :16 :48 :30 - (9) :12 :18 :23 :16 :16 :17 - (10) :10 :19 :16 :15 :28 :18 - -Although this maze was much more difficult, it will be seen that -the animals learned the route to the food far more readily than -before. The first period in this series was only about one fourth as -long as the first period in the other, and the course was mastered -sooner (by the fifth trial instead of by the ninth). There was less -pressing against the wire than before, and unsuccessful movements were -sooner discontinued. This improvement was probably due entirely to -experience gained in dealing with the first maze. Thorndike speaks of -the gradually increasing ability of animals to deal with successive -contrivances.[202] The average results given in Tables I and II are -plotted in Fig. 4, next page. - - -C. _Habits in Labyrinth H_ - -Since hearing is an important sense in pigeons, we should expect -them to be capable of useful acoustical associations. Several things -occurred in the course of the two preceding experiments which seemed to -indicate that this is true; for example, although I could move about, -rather noisily, in the darkened room, without apparently disturbing any -of the birds, some few showed signs of fright (moving about restlessly) -on hearing the low, grating noises made by lifting the hanging door of -the cage, sounds which had always preceded the handling of the subjects -before experimentation, and which had probably become signs to them of -being taken. - -[Illustration: FIG. 4. Learning-curves: A, in Labyrinth L; B, in -Labyrinth M. Divisions of ordinates indicate minutes; of abscissas, -successive daily trials. The rise on curve A for tests 23 and 26 was -due to diminution of illumination of room.] - -To investigate this kind of association I constructed a labyrinth (see -Fig. 5) in connection with which sounds could be utilized as one form -of sense-data. The passages were so arranged that along the route -leading to the food there were three blind alleys, which the animals -would surely enter before mastering the course. In another part of the -room were placed, very close to each other, two electric gongs of the -same size, but of different material. One was of metal and gave a clear -ringing sound; the other was of wood and gave a low rattling noise. - -When an animal was learning the route (as in the other two mazes) I -sounded the gongs, the metallic, as the bird approached and entered -the blind alleys, by openings _M_, _O_, and _R_, and the wooden, -as it emerged from them and proceeded along the proper course, and -occasionally after it had reached the food. The ringing sound was also -given after the animal passed _P_ and was approaching _Q_. When the -new route was fairly well learned, I changed the order of the sound -stimuli, ringing one gong at the places where the other had previously -been sounded, and compared the records thus obtained with those -obtained when the sounds were given in the original order. As an animal -is liable to become confused by the sounds, or else quickly accustomed -to them, I thought it best to give only a few trials, one trial with -the usual order of sound stimulations, the next immediately following -with the reversed order, and so on till four pairs of records had been -secured, the series of trials being completed in a single day. Four -animals were thus tested. The periods of the various trials are shown -in Table III. - - -TABLE III. SOUND ASSOCIATION, LABYRINTH H - -_Time required to reach food under different sound conditions_ - - I - _Order of gongs the same as when_ - _course was being learned._ - - _Animals_ - _Trials_ A B E G - " " " " - (1) 13 19 24 17 - (2) 16 12 13 16 - (3) 10 16 20 14 - (4) 12 19 10 12 - - Total, 51 66 67 59 " - 243 - - II - _Order of gongs reversed._ - - _Animals_ - _Trials_ A B E G - " " " " - (1) 14 16 18 27 - (2) 37 17 16 27 - (3) 14 19 26 11 - (4) 27 22 21 14 - - Total, 92 74 81 79 " - 326 - -In the case of thirteen of the sixteen tests given with reversed -acoustical conditions (see column II) the periods were longer than the -corresponding ones given alternately with them for comparison, and -there was an average time-lengthening of 5.2 seconds per trial, or -34.2%. The following is a short description of the animals' reactions -to the changed conditions. It corresponds to the time-values expressed -in column II of the table. - -Bird A: test 1, animal undisturbed; test 2, drew back from _S_, turned -to the left and went toward _R_, but later returned and passed _S_ -without pausing; test 3, paused at _O_ for a short interval, but did -not enter the blind alley; test 4, paused at _O_ again, later drew -back from _S_, turned to the left and entered blind alley 3; it soon -escaped, and this time passed _S_ without being disturbed, although it -paused at _T_ and _U_. - -Bird B: tests 1 and 2, animal apparently undisturbed; test 3, a few -slight pauses at openings; test 4, drew back from _S_, entered blind -alley 3, but soon escaped and passed _S_ without hesitation. - -Bird E: test 1, undisturbed; tests 2 and 4, paused at openings; test -3, turned back from _S_, entered blind alley 3, and paused at several -places later when passing toward F. - -Bird G: test 1, many pauses; test 2, turned from _S_ and entered blind -alley 3; test 3, undisturbed; test 4, drew back from _S_, went toward -_R_, but did not enter the blind alley. - -As the animals gave little attention to the wooden gong, but were -always sensitive to the metallic one, their observed movements probably -must be accounted for chiefly on the basis of certain visual and -organic sense-data _now with_, and _now without_, the ringing sound. -The data governing the start (as already noticed) were probably -sufficient for the avoidance of the first blind alley when the gongs -were reversed. In case of the other two, however, the birds had come -to depend upon acoustical data, and when these were lacking as they -approached the openings _O_ and _Q_, the left turn could not readily -be initiated, hence certain hesitations and misdirections of movement -frequently occurred. Experience with the blind alley in the first -experiment assisted the animals in dealing with the second blind alley -here, but mistakes were made. Visual data usually were sufficient to -produce the proper turn at _Q_, but when the ringing sound was given -just afterwards, it sometimes occasioned the left turn, thus bringing -the animals toward the opening of the blind alley. While the tests -given were not such as would indicate how far pigeons can discriminate -sounds, they certainly show that these birds are capable of useful -sound associations, although visual ones are evidently of greater -importance to them. - - -D. _Habits in Labyrinth O_ - -I next made tests in which tactual and electrical sense-data could also -be utilized. In one of the passages of a simple labyrinth was placed a -board 8 in. square and 3/4 in. thick, over which were stretched copper -wires which formed a series of interrupted electrical circuits. By -closing a key a bird could be stimulated whenever it stepped upon the -wire surface. A second key was connected with a metallic gong. When an -animal on its way through the maze first stepped upon the wire surface, -electrical and acoustical stimuli were given; later it was allowed -to walk across the board without being thus stimulated; afterward -acoustical stimuli were given it at various parts of the maze. - -[Illustration: FIG. 5. Labyrinth H. For study of acoustical -association. Passages 6 in. wide, as before.] - -Eight animals were used. All were found quite sensitive to the -electrical shocks, and when next tested they avoided the board, -especially if the gong sounded as they approached. Some would show -signs of uneasiness anywhere in the maze on hearing the gong. When -the board was so placed that they had to pass over it in reaching the -food, _when once on it_ they moved very leisurely, often lingering; -and if they stepped upon the wire surface in the darkened maze, they -showed no evidence of being frightened. Evidently no association had -been formed between the peculiar tactual stimulus of touching the -wires and the electrical shocks which had at first been given. But the -tactual stimulus may have been below the threshold. Yerkes[203] saw -evidence of association of this kind in the frog; this animal, however, -is probably much more sensitive to tactual stimulation received from -surfaces over which it passes than is the pigeon. - -The results of these four experiments indicate that the pigeon easily -acquires complicated labyrinth habits; that these remain fixed for some -weeks at least; that acoustical, visual, and certain organic data are -the most important sensory factors; and that the process of learning -is one of "trial and error," in which the animal comes to form such a -close connection between the sense-data of the interior of the box and -those other sense-data arising from movements involved in reaching the -food, that when the box impressions are again encountered the other -sense-data are revived and readily condition the proper movements. -How much memory of eating was involved in these tests cannot be told; -but it was certainly not an essential part of the mental act.[204] -Proper guidance throughout the course was the main thing, and this was -determined by definite sense-data. That recognition, discrimination, -and perhaps choice were to some extent present seems likely from the -animal's hesitating movements at certain critical points. Thus it is -highly probable that when the bird approached a blind alley which it -had always entered before (see Fig. 2, stage 6), two alternatives -were recognized, to enter, as before, or not to do so, as was usual -thereafter, and that the pause had for its mental correlate a state -closely bordering upon what in us would be deliberation. - -2. _Release experiments._ Under this heading are included certain cage -experiments in which some act, such as touching a lever, pecking, or -stepping upon a platform, resulted in the opening of the door, and thus -enabled the animal to escape and secure the food lying in view without. -The animal was admitted to the cage through an entrance compartment as -in the case of the maze trials. Before being tested it was allowed to -become familiar with the cage and to reach the food directly by passing -out through the open door. When first in the cage the animals did not -seem to notice the release apparatus, and hence they probably did not -begin learning the method of escape until later when they entered the -cage and found the door closed, and the ordinary exit thus obstructed. - - -A. _Latch Tests_ - -The cage here employed was an 18-inch cubical box. The top was of -chicken wire and the bottom and three sides of heavy boards; the fourth -side was formed by narrow vertical bars and a wire door which opened -inwardly and was held by a latch working on the outer surface of the -bars. At first a long wooden latch was used, which the animals raised -when reaching out for food. As this seemed an unnatural act, downward -pressure was substituted by attaching to the latch, now made smaller -and of brass, a string which ran over a pulley above the door and down -into the cage. As nooses did not seem adapted to the birds, the end of -the string was attached to a wooden lever which worked on the inner -surface of the bars, about three inches from the floor. Eight animals -were tested four times daily (twice in the forenoon and twice in the -afternoon) for ten days. The time required to escape and the animals' -behavior were recorded as in the case of the labyrinth tests. - -[Illustration: FIG. 6. Curve of learning to operate latch, plotted from -last column of Table IV. Each vertical division indicates 30 sec. The -horizontal divisions represent successive days.] - -When they first entered the box (singly as in the other experiments) -and found the usual exit closed they made various attempts to push -through between the bars, springing and often flying about with great -force and persistency. In course of their random movements they touched -the bar and opened the door and thus escaped. Later the unnecessary -movements were mostly dropped and the necessary ones became highly -specialized. The first association was established between the box -impressions received on entering and the movements involved in -approaching the front of the box and depressing the lever; later a -connection was formed between the sensations of touching the lever, of -hearing the sound of the opening door, of feeling the jar, etc., and -the movements of turning away from the lever and passing out. The sight -of the opening door seemed to be of less service to the birds than the -sound and jar. Each animal soon came to touch the bar at the point of -least resistance, and usually with considerable precision. The time -required by the several birds is shown in Table IV, next page. The -daily average results are plotted in Fig. 6, above. - - -TABLE IV. TIME REQUIRED TO ESCAPE FROM CAGE BY USING LATCH - - _Animals_ - _Trials,_ _Daily_ - _4 daily._ A B C E F G H I _Av._ _Average_ - ' " ' " ' " ' " ' " ' " ' " ' " ' " ' " - (1) :03 :06 3:20 :08 :03 1:10 4:30 :23 1:13 - (2) :05 1:10 :59 1:50 2:00 :10 2:46 1:00 1:00 - (3) 5:28 :29 1:04 :21 :29 :52 2:33 4:05 1:55 - (4) :31 1:45 3:52 :14 :06 :23 2:40 2:30 1:30 (1:25) - (5) :15 :10 2:25 :03 :10 :07 :31 :50 :34 - (6) :17 2:00 5:03 :03 :05 :15 :39 :10 1:04 - (7) :08 :20 :36 :31 :03 :11 :30 :46 :23 - (8) :03 :54 :47 :28 :03 :55 :06 :47 :30 (:38) - (9) 1:12 :34 :39 :17 :03 :04 :21 :20 :26 - (10) :02 :19 :28 :07 :01 :03 :20 :47 :16 - (11) :02 :51 :09 :14 :03 :02 1:46 :47 :29 - (12) :02 :15 :24 :12 :02 :02 1:17 :27 :20 (:23) - (13) :03 :19 :22 :07 :06 :04 :48 :11 :15 - (14) :02 :15 :22 :09 :02 :02 :20 :19 :11 - (15) :08 :06 :12 :05 :02 :02 :03 :06 :06 - (16) :03 :18 :44 :10 :02 :03 :02 :21 :13 (:11) - (17) :02 :17 :41 :03 :07 :07 :11 :06 :12 - (18) :02 :42 :26 :05 :01 :03 :31 :15 :16 - (19) :04 :13 :48 :04 :01 :02 :15 :14 :13 - (20) :04 :32 :35 :04 :01 :02 :08 :22 :15 (:14) - (21) :03 :13 :10 :13 :09 :01 1:10 :16 :17 - (22) :03 :05 :10 :11 :03 :02 :39 :26 :12 - (23) :02 :07 :17 :05 :03 :15 :20 :26 :12 - (24) :02 :14 :04 :02 :01 :02 :09 1:03 :12 (:12) - (25) :01 :03 :05 :04 :01 :02 :31 :24 :09 - (26) :02 :04 :08 :01 :01 :05 1:34 :33 :19 - (27) :02 :03 :03 :03 :10 :05 :15 :39 :10 - (28) :02 :04 :03 :01 :06 :05 :23 :51 :12 (:12) - (29) :02 :04 :10 :03 :02 :06 :23 :21 :09 - (30) :01 :03 :03 :02 :11 :02 :09 1:08 :12 - (31) :21 :03 :11 :03 :01 :03 :28 :11 :10 - (32) :03 :02 :04 :02 :01 :03 :11 :42 :09 (:10) - (33) :02 :02 :03 :10 :01 :03 :18 :17 :07 - (34) :02 :02 :03 :02 :01 :03 :11 :11 :04 - (35) :01 :02 :03 :02 :01 :02 :18 :09 :05 - (36) :01 :03 :03 :03 :03 :02 :04 :10 :04 (:05) - (37) :01 :02 :07 :02 :04 :01 :11 :09 :05 - (38) :01 :02 :02 :02 :02 :01 :08 :03 :03 - (39) :02 :04 :11 :01 :02 :02 :14 :08 :06 - (40) :01 :02 :03 :01 :01 :03 :10 :03 :03 (:04) - -The periods here were similar to those given in the maze tests--the -time was long at first, then it shortened very rapidly for a few -trials, then more slowly but still constantly, until the act became -thoroughly familiar. The process was one of "trial and error" -throughout. As before, various lapses occurred, even although the -animals were as persistent as usual in their efforts to escape. When -the lever was moved to the side or back of the box, none of the animals -could escape. In general, pigeons show less ingenuity in dealing with -latches than do sparrows, according to Porter's[205] observations, -although in some other tests they are equally apt. - - -B. _Pecking Tests_ - -The preceding series of trials proved the animals' ability to utilize -certain touching or clawing movements, at first accidental, in making -an escape, and showed that these could become highly specialized. -Desiring to carry out similar tests in the case of pecking movements, -which are quite as natural to pigeons, I arranged a contrivance by -means of which the act of pecking at corn-grains fastened to a small -piece of cardboard (placed just outside the cage, but within easy reach -through an opening in the wire) would open the cage-door by making a -delicate electrical contact. Four animals were tested. - -On entering the cage they endeavored to escape as before; failing in -this they began pecking about until they found the corn-grains and -made the contact which opened the door and allowed them to escape to -the food without. Three of the animals made their escape in this way -several times; but the habit seemed to be one that could not be readily -learned, as the successive periods showed little shortening. - -Thinking that the pecking of things at a definite place perhaps -complicated the matter, I removed the electrical apparatus and arranged -to open the door myself by pulling a string whenever the pigeon pecked -anywhere upon entering the box. Preliminary experiments with Bird J -indicated some ability to profit by this kind of experience. As the act -of pecking could be used to advantage in a series of imitation trials, -this animal only was allowed to learn to escape by actually pecking; -the others were reserved for the imitation tests next to be reported. - - -C. _Imitation Tests_ - -In the experiments already reported the animals were used individually -and usually out of sight of the others, although in the same room -and within hearing of them. When efforts were made in some of the -experiments to test the animals in a separate room, signs of fear and -discontent were often noticed, and it was necessary to return to the -first room to continue the tests. Some instances were noticed in which -a pigeon would do what it saw another doing. For example, one of my -subjects would not eat one day, being ill apparently; but when I put -two others into the compartment with it, and they began eating the food -lying about, it also began pecking. Its act could not have been due -to its only then happening to see the corn, for it had before looked -toward the food when this was thrown to it. - -Desiring to test, under definite conditions, the imitative ability of -these animals, I arranged trials in which birds were allowed to see a -useful, but simple act performed by another bird, and then were given -an opportunity to execute the act themselves. Using the animal which -I had trained for the purpose, I allowed its series of acts (entrance -to box, pecking, release, and food-eating without) to be observed by -another animal, confined in a small wire compartment (similar to the -entrance compartment before used) attached to the side of the large -cage. Care was taken to see that the confined bird was observing, or at -least was looking toward the acting one; in case of doubt, the trial -was repeated. Later the trained animal was replaced by the observing -one, and the latter's reaction was noted. Five animals, in all, were -tested, and each was given two opportunities to escape after having -seen the trained animal perform the act ten successive times. None of -them, however, showed any signs of trying to escape by repeating the -movements so often performed by the bird familiar with the act, but -each rushed against the sides of the cage and tried to push through at -various places, just as the trained bird had done when first learning -the habit. - -As the act, or series of acts, was rather too complex to be easily -observed and utilized by the other pigeons, I arranged two much simpler -tests. In one case the leading bird was taught to open the cage-door -by stepping upon a platform (the lowering of which made an electrical -contact); in the other, to avoid a blind alley, enter a short passage, -and ascend a wooden plane (inclined at an angle of thirty degrees) -which led into another box containing food. In these tests it was more -difficult for the series of acts to be viewed, but the animals, singly -as before, were placed at a point of vantage and apparently saw the -movements of the other animals. - -Of the five birds tested in the platform experiment, four utterly -failed to escape in the two trials given. The fifth, in its second -test, went to the platform promptly and thus made its escape, but the -success may have been accidental, or due to the animal's experience of -seeing and approaching the platform in its first test. In the labyrinth -experiment only one bird (second test) avoided the blind alley and went -directly up the inclined plane to the food; this success was probably -due to experience in the first test. There was certainly no evidence -that the animals had grasped the nature of the problem; nothing to -indicate that the performance of the trained animal had supplied data -for the guidance of future conduct, that is, for the conditioning -of the necessary movements, in this case those of pecking, stepping -upon a platform, or avoiding a blind alley and ascending an inclined -plane.[206] - -These results are similar to those which other experimenters have -secured in the case of chicks, cats, dogs, monkeys,[207] and also -rats.[208] Although the method I employed is doubtless open to the -criticism of being artificial,[209] some value at least should be -attached to the results; if so it would seem probable that imitation in -pigeons is not above the "instinctive" stage, and that learning depends -entirely upon first hand experience, upon really doing the thing, and -not upon merely seeing it done. - -3. _Position, Color and Form Tests._ The apparatus used in these -experiments consisted of small boxes, six inches in height, and open -at the top. Sometimes they were exactly similar, and sometimes they -differed in color or in form. They were moveably attached, six inches -apart, to a board which was placed in a large wire-covered box, having -an entrance compartment as in the case of the mazes and cages. Food -was placed in one of the small boxes, and the pigeons were allowed to -find it twice; later each bird was tested as to its ability to return -to the food by depending upon the position of the box in the group, -or upon its color or its form. Tests were given in series of six, and -the box which was first approached was recorded as the animal's choice -for that test. If it made a wrong selection, it was allowed to look -about until it found the box containing the food, but in no case was it -permitted to satisfy its hunger until the last test of the series. The -animal apparently did not see the food until it approached the box, and -subsequent tests demonstrated that it was not guided by odor. - - -A. _Position Tests_ - -In this series of trials I used at first six, later nine food-boxes, -four inches square and covered with dark gray paper. The board to -which the several receptacles were fastened was shifted at irregular -intervals to various oblique angles; this was done to prevent the -animal from being assisted by the position of the food-box in the -larger box rather than in the group of similar boxes. After a bird -had been tested sufficiently for one position it was then used, for a -week or so, in some other experiment, and thus given an opportunity -to forget, to some extent at least, the old experience before being -taught to find the food in a box placed elsewhere in the group. For -the positions 2, 3, and 4, in the group of six similar boxes, eight -animals were each given thirty tests in series of six, as stated above. -For the positions 5, 6, and 7, in the group of nine similar boxes, the -experiments were shortened. Six animals were given twenty-four trials -each, two animals for each of the three positions. - -The animals quickly learned the position of the food-box and passed to -it promptly when released from the entrance compartment. Changing the -position of the board to which the food-boxes were attached did not -affect the animals' ability to reach the food readily. They usually -selected the proper box as before, although frequently they went around -the end of the board and approached the food from the opposite side. -The general distribution of choices in the case of positions 2, 3, and -4 is given in Table V; the rate of learning, in Table VI. - -With a single exception (Bird B, box 3) the box containing the food -was far more often chosen than any one of the empty boxes, and usually -more often than all of them combined, the average right choices being: -position 2, 62%; position 3, 57.7%; position 4, 53.3%. It will be seen -that the animals were more successful in finding the food in the second -position than in either the third or the fourth, that is, positions -nearer the end were more easily located. But what is of greater -interest to us is the rate of learning to go to the right box. This -is indicated by the increasing number of right choices from series to -series. (Table VI.) That the increase was small was due to the fact -that the animals learned so quickly in the first series of six tests -that little improvement could be made thereafter; what they could -learn they acquired early in the experiment. There is some evidence -of improvement after the first series in the case of box 4, a more -difficult position, and the average for all three boxes shows a slight -improvement from series 1 to series 5, although a falling-off is seen -in the last series: 26, 27, 27, 31, 28. The same general features -appear in the case of the incomplete tests (positions 5, 6, and 7). For -each box there were, on the average, 26 right choices in the possible -48. There were more right choices in the case of box 7 than in the case -of either box 6 or box 5, box 7 being nearer one end (box 9). There was -little evidence of learning after the first series of trials. - - -TABLE V. ASSOCIATION OF POSITION: GENERAL DISTRIBUTION OF CHOICES - - _Choices of boxes 1 to 6 when food was placed in boxes 2, 3, and 4_ - - _Food in box 2_ _Food in box 3_ _Food in box 4_ - _Boxes_ _Boxes_ _Boxes_ - _Animals_ 1, 2, 3, 4, 5, 6. 1, 2, 3, 4, 5, 6. 1, 2, 3, 4, 5, 6. - (B) 1 18 4 6 1 0 1 1 8 7 8 5 0 0 2 21 4 3 - (C) 2 20 6 1 1 0 0 9 19 2 0 0 0 7 2 15 6 0 - (E) 4 18 2 3 2 1 0 6 18 3 3 0 2 6 2 15 3 2 - (F) 5 20 1 2 2 0 1 6 18 3 2 0 0 2 5 14 8 1 - (G) 0 18 5 2 2 0 0 3 13 5 7 2 0 0 3 17 9 1 - (H) 0 22 4 3 1 0 1 0 18 4 6 1 0 4 8 15 3 0 - (I) 4 18 3 1 3 1 0 1 23 6 0 0 0 6 7 15 2 0 - (J) 1 17 7 5 0 0 3 0 21 3 2 1 1 4 3 16 6 0 - - Total, 17 151 32 26 12 2 6 26 138 33 28 9 3 29 32 128 41 7 - - -TABLE VI. ASSOCIATION OF POSITION: DISTRIBUTION OF RIGHT CHOICES - - _Choices from series 1 to series 5 in the case of boxes 2, 3, and 4_ - - _Box 2_ _Box 3_ _Box 4_ - _Series_ _Series_ _Series_ - _Animals_ 1, 2, 3, 4, 5. 1, 2, 3, 4, 5. 1, 2, 3, 4, 5. - (B) 4 4 5 2 3 2 2 1 1 2 4 4 4 5 4 - (C) 5 4 2 5 4 4 4 4 4 3 3 3 2 2 5 - (E) 3 4 4 3 4 4 4 2 5 3 3 2 2 4 4 - (F) 5 4 3 5 3 5 3 3 4 3 0 2 4 4 4 - (G) 3 4 4 3 4 2 2 4 2 3 3 3 2 4 5 - (H) 4 4 4 5 4 4 3 4 5 2 3 3 4 3 2 - (I) 1 4 3 5 5 4 4 5 6 4 2 1 3 4 5 - (J) 4 5 4 3 1 3 4 6 4 4 3 3 3 4 3 - - Total, 29 33 29 31 29 28 26 29 31 24 21 21 24 30 32 - Average for the three boxes, 26, 27, 27, 31, 28. - -The method of learning in these position tests was the same as -that noticed in previous experiments, namely, building upon chance -successes. When first admitted to the large box containing the row -of small ones at the farther end, the animal accidentally found the -receptacle containing the food, and later associated the movements -involved in reaching that position with various sense-impressions of -the box, especially those experienced upon entering--certain tactual -impressions of the small entrance compartment, sound of the lifting -door and sight given of the interior of the large box. - -While the results clearly indicate that pigeons readily learn the -position of objects, nothing is proved as to "counting." Some -experimenters speak of similar trials as "number-tests," just as -they do of "form-tests," but this is probably going too far. To -investigate counting in animals, experiments should be arranged which -minimize spatial responses. These tests certainly show that pigeons -can discriminate positions readily, especially toward the ends of the -group, but little more is certainly indicated. Porter[210] says: "If -we do not find in birds the power to count, we have in their nice -sense for the location of a member of a series ... something of that -preliminary number-sense which Ribot describes as belonging to children -and savages." - - -B. _Color Tests_ - -To investigate the animals' ability to utilize colors[211] in finding -their food, I employed the same apparatus as before, except that -six boxes were used throughout and each was covered with paper of a -different color: red, yellow, green, blue (Bradley's standards, except -red, _RO_ being substituted), gray, and black. The boxes covered with -black and gray paper were employed merely to complete the group of -six. The same method as before was employed, except that the board to -which the boxes were attached was left stationary at the end of the -large box, and also that the position of all six boxes was changed -irregularly for each test. - -The general behavior of the animals at the beginning of these tests -was quite similar to that shown in the preceding experiment; but it -was soon evident that colors occasioned them far more difficulty than -positions. The general distribution of choices is given in Table VII. -It will be seen that the proper box was usually chosen more often -than any one of the empty ones, but never oftener than the other five -combined, as occurred in the position tests; also that in the case -of each color there were instances in which another color was as -often, or more often selected. Yet it is clear that colors may serve -as valuable sense-data for these animals. In the first series of six -tests (see Table VIII) there were few right choices or none, but in -each succeeding series the number increased. The learning process was -evidently of the same type as before observed (selection, in this case -gradual, of chance but useful movements), and involved visual data -largely. - - -TABLE VII. COLOR ASSOCIATION. GENERAL DISTRIBUTION OF CHOICES - - _Choices of all 6 boxes when food was placed in red, yellow, green, - or blue boxes_ - - _Food in Red Box_ _Food in Yellow Box_ - _Animals_ R, Y, G, B, B'k. G'y. R, Y, G, B, B'k, G'y. - (B) 12 6 7 3 2 0 2 12 6 7 0 3 - (C) 15 8 1 4 2 0 3 12 1 6 3 5 - (E) 11 8 5 3 3 0 3 10 5 3 5 4 - (F) 7 5 9 6 2 1 6 6 5 6 3 4 - (G) 9 1 7 5 3 5 5 11 6 3 2 3 - (H) 13 3 5 3 3 3 5 9 6 3 3 4 - (I) 11 5 2 4 6 2 4 10 5 4 3 4 - (J) 10 0 6 8 4 2 5 10 3 3 5 4 - - Total, 88 36 42 36 25 13 33 80 37 35 24 31 - - _Food in Green Box_ _Food in Blue Box_ - _Animals_ R, Y, G, B, B'k, G'y. R, Y, G, B, B'k, G'y. - (B) 4 5 12 4 5 0 1 3 5 10 6 5 - (C) 3 4 14 5 1 3 3 1 2 13 2 9 - (E) 1 9 7 11 0 2 3 5 5 10 3 4 - (F) 0 8 9 6 0 7 0 3 6 11 5 5 - (G) 2 5 16 2 4 1 5 5 4 5 4 7 - (H) 1 3 15 5 6 0 7 5 5 6 4 3 - (I) 0 4 15 6 2 3 5 5 3 9 5 3 - (J) 4 1 12 9 1 3 6 4 4 7 5 4 - - Total, 15 39 100 48 19 19 30 31 34 71 34 40 - - -TABLE VIII. COLOR ASSOCIATION. DISTRIBUTION OF RIGHT CHOICES - - _Choices from series 1 to series 5 in the case of red, yellow, green, - and blue boxes_ - - _Red Box_ _Yellow Box_ _Green Box_ - _Animals_ 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, - (B) 0 1 2 4 5 1 2 3 2 4 1 2 2 4 3 - (C) 2 2 4 3 4 1 2 3 3 3 3 2 3 4 2 - (E) 2 1 2 3 3 1 0 3 2 4 0 1 1 1 4 - (F) 0 1 1 2 3 0 2 2 1 1 0 1 2 3 3 - (G) 0 2 3 2 2 2 2 1 3 3 2 4 3 3 4 - (H) 1 1 3 4 4 0 2 2 2 3 2 3 4 3 3 - (I) 1 2 3 3 2 1 2 2 3 2 1 3 3 3 5 - (J) 1 2 2 2 3 1 2 1 2 4 1 1 3 3 4 - - Total, 7 12 20 23 26 7 14 17 18 24 10 17 21 24 28 - - _Blue Box_ - 1, 2, 3, 4, 5, - 1 3 1 2 3 - 3 2 2 3 3 - 0 1 3 2 4 - 1 1 2 4 3 - 1 1 0 0 3 - 0 1 2 2 1 - 0 2 2 3 2 - 1 2 1 1 2 - - 7 13 13 17 21 - -There is no evidence that the color-preference of the animals assisted -them in choosing correctly, in fact, they were rather less successful -in dealing with those colors for which they had previously shown -decided preference,[212] since the whole number of right choices was -less in the case of the green and blue boxes (85) than in the case of -the red and yellow ones (92), and since there was a relative diminution -in the rate of learning toward the last in case of the former -boxes.[213] - -To test the animals' ability to discriminate shades of colors in -finding their food, two birds were used, with four boxes, each covered -with a different shade of red paper, and two with the boxes covered -with green paper. The brightness of the different shades was not -measured, but to the eye it seemed to be equal in each of the cases. -The food was placed in the box having the most nearly saturated color, -and twenty-four trials in series of six, as before, were given each -bird. The results were quite similar to those secured with different -colors. With the red shades there were twenty-two choices of the best -saturated shade to eight, ten, and eight, respectively, of the other -three; and with green, twenty-one to nine, ten, and eight. The 43 -correct choices were distributed from series 1 to series 4 as follows: -7, 11, 12, and 13, which shows learning as before. The relatively large -number of right choices was probably due, partially to the fact that -fewer alternative choices were possible since only four boxes were -used, instead of six, and partially to the fact that the box containing -the food may have been slightly brighter than the others. - -Throughout these trials the position-element was a decidedly disturbing -factor. When the animals were first learning to choose a box of a -definite color, some would show a marked tendency to approach a -receptacle occupying a certain position, and would persist in this from -series to series. Others at first showed no special preference for -certain positions, but, after happening to make a correct choice, they -would return to that same place the next time, and thus miss the right -box which had been changed for the new test. - - -C. _Form Tests._ - -In this experiment the six food-boxes were each of different form: -triangular, square, oblong, hexagonal, circular, and elliptical. They -were of the same capacity, and were covered with light-brown paper. As -in the preceding experiment, the birds were tested for only four of the -boxes, and were given thirty trials each. Six animals were used, and as -they were not the same as those previously employed, the square box -(which had always been used before) had no advantage over the others -in attracting the birds at the beginning of the trials. The tests were -given as in the preceding experiment, except that it did not seem -necessary to change the position of each of the six forms before giving -each test; it was thought sufficient to move the food-box, and, if a -wrong choice had been made in the preceding test, also the box wrongly -chosen. The results are shown in Tables IX and X. - - -TABLE IX. FORM ASSOCIATION. GENERAL DISTRIBUTION OF CHOICES - - _Choices of all 6 boxes when food was placed in Tri., Sq., Hex., - or Cyl. boxes_ - - _Food in Tri._ _Food in Sq._ - _Animals_ Tri. Sq. Ob. Hx. Cyl. El. Tri. Sq. Ob. Hx. Cyl. El. - (U) 8 6 5 5 2 4 5 9 6 1 6 3 - (V) 9 2 3 6 7 3 5 8 5 2 5 5 - (W) 8 7 3 4 5 3 5 8 5 3 3 6 - (X) 11 5 2 5 3 4 5 8 3 6 3 5 - (Y) 11 4 5 4 2 4 4 9 5 6 3 3 - (Z) 8 3 7 4 4 4 6 11 7 3 1 2 - - Total, 55 27 25 28 23 22 30 53 31 21 21 24 - - _Food in Hex._ _Food in Cyl._ - _Animals_ Tri. Sq. Ob. Hx. Cyl. El. Tri. Sq. Ob. Hx. Cyl. El. - (U) 5 5 3 11 3 3 6 5 3 5 8 3 - (V) 4 4 5 8 5 4 6 6 3 4 7 4 - (W) 3 5 3 10 7 2 4 3 4 3 10 6 - (X) 4 5 4 7 6 4 2 5 4 4 9 6 - (Y) 3 4 2 8 6 7 3 2 5 6 9 5 - (Z) 5 4 2 11 3 5 3 5 4 4 9 5 - - Total, 24 27 19 55 30 25 24 26 23 26 52 29 - - -TABLE X. FORM ASSOCIATION. DISTRIBUTION OF RIGHT CHOICES - - _Choices from series 1 to 5 in the case of Tri., Sq., Hex., - and Cyl. boxes_ - - _Food in Tri._ _Food in Sq._ _Food in Hex._ _Food in Cyl._ - _Animals_ 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, - (U) 2 0 2 1 3 1 2 2 2 2 2 1 2 3 3 1 1 2 1 3 - (V) 1 1 2 3 2 2 1 1 2 2 0 1 2 3 2 1 2 2 1 1 - (W) 1 2 1 2 2 2 1 2 1 2 1 2 2 2 3 1 2 2 3 2 - (X) 1 2 3 3 2 0 2 2 3 1 1 2 2 1 1 1 1 2 3 2 - (Y) 1 2 3 2 3 2 2 2 3 2 1 1 2 1 3 0 2 2 2 3 - (Z) 1 2 2 2 1 0 2 3 3 2 1 2 2 4 2 1 2 3 1 2 - - Total, 7 9 13 13 13 7 10 12 13 11 6 9 12 14 14 5 10 13 11 13 - -It will be seen that each animal chose the right box oftener than any -other one box, but not oftener than all of them; also that there was a -small increase in the number of right choices from series to series. No -one of the four forms seemed better discriminated than the others if -we may judge from the practical equality of right choices made in each -case (55, 53, 55, 52) or from the similar increase in number of right -choices from series to series; the hexagonal and cylindrical boxes -received fewer choices in the first series than did the triangular -and square, but this was exactly counterbalanced in the last series. -The triangular box was more often confused with hexagonal and square, -and the square with triangular and oblong, than with the others. For -the hexagonal box the cylindrical was more frequently mistaken than -were the other forms, especially the oblong; and with the cylindrical -the elliptical was more frequently confused than were the others, -especially the oblong. In this series of tests nothing new as regards -general behavior or method of learning was observed. - - -TABLE XI. POSITION, COLOR AND FORM ASSOCIATION - - _Total Right - Choices_[214] _Right choices from series 1 to series 5_[215] - 1 2 3 4 5 - _Position_ 57.9% 54.2% 55.6% 56.9% 63.2% 59.0% - _Color_ 35.3% 16.2% 29.7% 37.0% 42.7% 51.6% - _Form_ 29.8% 17.4% 26.4% 34.7% 35.3% 35.3% - -If we compare the results obtained in these three experiments (see -Table XI and Fig. 7), we shall see that the pigeons were governed much -more by the position of the food-box than by either its color or its -form, and that color was better associated than form. Position was a -most important factor throughout, as was observed also by Porter[216] -in the case of the English sparrow. Porter[217] also found that his -sparrows could associate color better than form. In the position-tests -the pigeons showed very little improvement from series to series (see -table); almost all that the animals could learn was acquired at the -beginning. The more difficult color- and form-trials, however, showed -almost constant improvement, although we should have expected this to -be greater in the latter case than it was. When judged entirely by the -actual number of right choices in a given kind of tests, some of the -birds made a very poor showing; but from the standpoint of increasing -number of right choices they appeared in a wholly different light. - -Thus, for example, bird F (Table VII) made only 33 right choices in a -possible 120, yet their arrangement is significant, being, from series -1 to series 5, respectively, 1, 5, 7, 10, 10. It is probable that there -would have been still greater improvement had the tests been continued; -perhaps the animal would have become as proficient in finding its food -by depending upon the color of the receptacle usually containing it, as -by relying upon the position of the box in the group. - -[Illustration: FIG. 7. Position, Color, and Form Association. If -line S represent tests of a given kind, P, C, and F would represent, -respectively, the number of correct choices of position, color, and -form. The rate of learning in each case is shown by the corresponding -curves to the right, where vertical divisions each indicate 20%, and -horizontal divisions the successive series in which the tests were -given.] - - -V. SUMMARY - -1. Respiration in pigeons is sensitive to various stimuli, and since -its alterations of rate, amplitude, etc., can be easily recorded -pneumo-graphically without frightening the animals, it may well serve -as a process through which to study their mental life. - -2. By repetition meaningless stimuli, for example, pistol-shots, -quickly lose their disturbing influence; whereas the breathing remains -sensitive to those of a significant character, such as the noises made -by other birds. - -3. Reaction to light of moderate intensity consists principally in an -immediate quickening, the amount varying with the color; since a direct -correspondence was found between color-preference and breathing-rate, -it would seem that here agreeable feeling involves increased breathing -activity. - -4. Visual, acoustical, probably tactual, and certainly organic data, -are the principal sensory factors of the associations of pigeons. - -5. The animals readily form useful associations by a method of "trial -and error," or the selection of successful movements which were at -first accidental. - -6. Apparently a pigeon does not learn by merely seeing a new act -performed by another pigeon; yet there are instances of simple -("instinctive") imitation, and "trial and error" learning is not -wholly independent of social conditions, since it proceeds much more -satisfactorily if the animal is trained at least within hearing -distance of other pigeons. - -7. When a habit is being formed, the "period" required for the first -test is usually very long, but learning proceeds quite rapidly during -the next few trials; later it is more gradual, but it continues till -the act becomes thoroughly familiar. - -8. Associations are fairly permanent, and some remain practically -unaltered for at least six weeks. Modification is easily accomplished, -however, on the basis of new experience. - -9. Pigeons differ widely both as to the ease with which they acquire -associations and also as to their permanence. Difference in activity -seems the chief reason for this. - -10. While these birds seem mentally inferior to English sparrows and -to various mammals which have been tested in a similar manner, they -are capable of numerous ready adjustments. They discover circuitous -labyrinth passages, they learn to manipulate latch apparatus when -adapted to their natural habits and conveniently placed, and they -easily reach their food by depending upon the position, color, or -form of the box containing it. But the process is apparently simple -association throughout. There is no evidence of higher mental -activity--no looking the situation over and acting accordingly, no -"reasoning" in the proper sense of the word, but only blind movements, -some of which are retained and become highly specialized, merely -because successful. - -FOOTNOTES: - -[Footnote 180: D. Ferrier: The Functions of the Brain, p. 111, London, -1886.] - -[Footnote 181: A. Hill: Can Birds Smell? Nature, vol. 71, pp. 318, 319, -1905.] - -[Footnote 182: W. Mills: The Nature and Development of Animal -Intelligence, pp. 248, 250, New York, 1898.] - -[Footnote 183: Hachet-Souplet: Examen Psychologique des Animaux, pp. -33-38, Paris, 1900. See also Riverside Natural History, vol. 4, pp. -240, 241, Cambridge, 1888.] - -[Footnote 184: Orientation chez le pigeon-voyageur, Revue Scientifique, -vol. 13, pp. 352-359, 1900.] - -[Footnote 185: Orientation du pigeon-voyageur, Revue Scientifique, vol. -2, pp. 417-420, 453-457. 1904.] - -[Footnote 186: Grundlinien zur Erforschung des Helligkeits- und -Farbensinnes der Tiere, p. 102, Prague, 1888.] - -[Footnote 187: Some Notes on the Psychology of Birds, Seventh Annual -Report of the New York Zoölogical Society, p. 154, 1902.] - -[Footnote 188: Ueber die Begleiterscheinungen psychischer Vorgänge in -Athem und Puls, Philosophische Studien, vol. 18, pp. 7-14, 1901.] - -[Footnote 189: Animal Intelligence, pp. 8-12, 31-36, 51-55, New York, -1898.] - -[Footnote 190: Nature of Animal Intelligence and Methods of -Investigating It, Psychological Review, vol. 10, pp. 262-274, 1897.] - -[Footnote 191: An Experimental Study of the Mental Processes of the -Rat, American Journal of Psychology, vol. 11, pp. 135-164; vol. 12, pp. -206-210, 1900-1901.] - -[Footnote 192: Mental Life of Rhesus Monkeys in Captivity, American -Journal of Psychology, vol. 13, pp. 97-148, 180-210, 1902.] - -[Footnote 193: A Preliminary Study of the Psychology of the English -Sparrow, American Journal of Psychology, vol. 15, pp. 313-346, 1904.] - -[Footnote 194: For a more complete report of this special part III, -see the writer's paper, Respiration and Emotion in Pigeons, Journal of -Comparative Neurology and Psychology, vol. 15, pp. 494-513, 1905.] - -[Footnote 195: If shallowing accompanies quickening, the respiratory -activity may be no greater than before; but since depth alterations -were seldom observed in these trials after the first day of -experimentation, the rise in rate may be taken as a fair measure of the -influence of the stimulus.] - -[Footnote 196: P. Zoneff und E. Meumann: _op. cit._, pp. 57, 58.] - -[Footnote 197: R. MacDougall: The Physical Characteristics of -Attention, Psychological Review, vol. 3, pp. 162, 176, 177, 1896.] - -[Footnote 198: Thorndike: _op. cit._, pp. 13-15.] - -[Footnote 199: Small: _op. cit._, vol. 12, pp. 236, 237.] - -[Footnote 200: Small (_op. cit._, vol. 11, p. 146) states that in -his rats "the persistence of useless motor habits is striking" and -"explainable by the supposition that the movements are touched off -automatically."] - -[Footnote 201: _Op. cit._, vol. 12, p. 214.] - -[Footnote 202: _Op. cit._, p. 28.] - -[Footnote 203: The Instincts, Habits and Reactions of the Frog, Harvard -Psychological Studies, vol. 1, pp. 591-593, 1903.] - -[Footnote 204: Small: _op. cit._, vol. 12, pp. 230, 231.] - -[Footnote 205: _Op. cit._, pp. 318, 319.] - -[Footnote 206: C. L. Morgan: Animal Behaviour, pp. 179-193, London, -1900; Animal Life, and Intelligence, p. 453, Boston, 1891.] - -[Footnote 207: Thorndike: _op. cit._, pp. 54, 56, 57, 60, 61; The -Mental Life of the Monkeys, Psychological Review, Monograph Supplement, -vol. 3, pp. 318, 319, 1901. Kinnaman: _op. cit._, pp. 198-200.] - -[Footnote 208: Small: _op. cit._, vol. II, p. 160.] - -[Footnote 209: W. Mills: Nature of Animal Intelligence and Methods of -Investigating It, Psychological Review, vol. 10, pp. 262-274, 1897.] - -[Footnote 210: _Op. cit._, p. 335. See also C. L. Morgan: Introduction -to Comparative Psychology, p. 232, London, 1900.] - -[Footnote 211: Cornish states (Animals at Work and Play, p. 30) that -hunters near the Caspian are able to decoy partridges by use of -brilliant colors.] - -[Footnote 212: See the writer's paper, Respiration and Emotion in -Pigeons, _op. cit._, p. 502.] - -[Footnote 213: One of Porter's sparrows was less successful with -yellow and red than with blue and green. He says: "This may be partly -explained from the fact that she was more afraid of these." _Op. cit._, -pp. 338, 339. See also E. L. Thorndike: Instinctive Reactions of Young -Chicks, Psychological Review, vol. 6, pp. 283-284, 1899.] - -[Footnote 214: Tables V, VII, and IX.] - -[Footnote 215: Tables VI, VIII, and X.] - -[Footnote 216: _Op. cit._, p. 338.] - -[Footnote 217: From the tables (_op. cit._, pp. 330-339) it seems that -the right choices for position, color, and form, were respectively, -40%, 58% and 20%. The comparatively small number of correct position -choices was probably due to his using ten boxes instead of six, as in -the other two series. My results given in Table XI were secured under -almost exactly comparable conditions. Compare results of Kinnaman in -case of the Rhesus monkey, _op. cit._, pp. 130, 131, 134, 141, and 177.] - - - - -REACTIONS OF THE CRAYFISH - -BY J. CARLETON BELL - - -The crayfish has long been the typical Crustacean for anatomical -and physiological investigations, but it is only recently that its -reactions to sensory stimuli have been made the object of experimental -study. The purpose of this paper is to describe the reactions of the -animal to certain sensory stimuli under experimental conditions, and to -estimate the relative importance of these stimuli in the life of the -organism. - - -I. REACTIONS TO VISUAL STIMULI - -Huxley[218] states that crayfish avoid direct sunlight, hiding under -stones during the day, and becoming active in the evening. On the other -hand, they are attracted like moths to fires lighted on the bank at -night, and may be scooped out by hand. Abbott,[219] giving an account -of the burrowing crayfish, _Cambarus diogenes_, states that it is very -difficult to observe the animals at work, since all their digging is -done at night. It would seem from the account of Miss Hoppin, quoted -by Garman,[220] that the blind crayfish, _Cambarus pellucidus_, is not -altogether insensitive to light, for, reporting on the fauna of the -caves of Missouri, she says that the crayfish are all found near the -entrance to the cave, where there is considerable light. In the dark -recesses there are only little white fishes. Blind fish and crayfish -are also taken from the wells in the neighborhood, where the crayfish -are found only in wells that are rather shallow and light; the fish, on -the other hand, are only obtained from deep, dark wells. - -According to the above accounts it would appear that the crayfish is -negatively phototactic to direct sunlight or diffuse daylight, but -positively phototactic to a light at night, and moreover, that light -may influence the behavior of the animal even when the eyes have ceased -to function. - -The directive influence of light upon the movements of the crayfish has -never been experimentally studied to my knowledge. Dearborn[221] thinks -that light has no effect upon the animals. Yerkes[222] and Towle[223] -have shown that Daphnia move toward the light. Bethe[224] finds that -Carcinus is negatively phototactic, and also shows a tendency to -hunt out corners. When the eyes are varnished with lampblack, the -phototaxis disappears, but the tendency to seek out corners still -remains. Bethe says that he has observed the same phenomenon in the -crayfish. Keeble and Gamble[225] discovered that _Hippolyte varians_ -responds positively to light under all conditions, and Palæmon is just -as markedly negative. _Macromysis_, however, reacted now positively now -negatively, depending on the background. A black (absorbing) background -called forth a positive response, while a white (scattering) background -produced a negative reaction. Spaulding,[226] in studying the habits of -the Hermit Crab (_Eupagurus_), found that it is strikingly positively -phototactic. When animals are placed in an aquarium, one half of which -is shaded, none of them are ever noticed inside of the dark line. -Herrick[227] notes that lobsters are nocturnal, and avoid the light -when placed in a tank, and Bateson[228] says that prawns and shrimps -lie hidden during the day, and are active only at night. Parker,[229] -in a study of Copepods, finds that the females have a strong positive -phototaxis for light of a low intensity, while males show a weak -negative phototaxis. To light of over 100-candle power at a distance of -10 cm. or to direct sunlight the female Copepods are negative, while -the reaction of the males does not seem to be altered. - -In his work on _Carcinus_, Bethe obtained retraction of the eye-stalks -by suddenly throwing a strong light on the eye by means of a mirror. -"Usually the eyes were quickly drawn in and protruded again, sometimes -several times in rapid succession, like a man blinking under a sudden, -strong light." When a dark object, the size of the hand, was moved just -over the water, the eyes were seldom retracted, but the antennules were -usually drawn in. Lemoine[230] observed that in Astacus retraction -was due to touch alone, and that no light, however strong, was able -to bring about such a reaction. Gulland[231] takes just the opposite -view with reference to Astacus, stating that there are no setæ of any -sort on the eye-stalk, and therefore it is insensitive to touch, but is -withdrawn only because the animal sees the object by which the stimulus -is given. If a curved needle is used, and the stimulus is applied -from behind, no retraction follows. Dearborn,[232] however, working -with Cambarus, agrees with Lemoine in saying, "Withdrawal of the -ophthalmites into their sockets occurs only on contact with some hard -object,--not from any light-stimulus of an ordinary sort." I may say in -passing that in none of the following experiments on Cambarus was there -ever a sign of retraction due to stimulation by light, the retraction -always taking place in response to a touch-stimulus. - -Lyon,[233] in his study of compensatory movements of the eye-stalks, -found that when the eyes were painted with lampblack, the crayfish -showed a reduction of about 10% in the compensatory movements when -rotated in vertical planes, but the compensation remained the same for -rotation about the dorsi-ventral axis. On rotation in the dark the -compensatory movement of the eyes was found to be from 5° to 8° less -than in the light. - - -EXPERIMENTAL - -In the investigations to be described, 58 crayfish of the species -_Cambarus affinis_ were made use of, and for identification the animals -were marked on the back with white enamel paint, the males receiving -the even numbers from 2 to 64, the females the odd numbers from 1 to 51. - - -1. _Reactions to White Light_ - -The questions proposed for investigation were, (_a_) How does the -crayfish react to diffuse daylight; (_b_) to reflected sunlight; (_c_) -to direct sunlight; (_d_) to artificial light of different intensities? -(_e_) What is the influence of previous conditions of exposure to light -upon the reactions of the animal? (_f_) Do changes of temperature -affect the reactions? - -A wooden box, 80 cm. long, 25 cm. wide, and 20 cm. high, painted black -on the inside, and constructed so as to hold water, was covered with -a heavy black cloth to exclude the light from above. The front end of -the box was of glass, thus admitting the light from the end. In all -the experiments except those with direct sunlight, this glass end was -covered with black cardboard in which a hole 10 cm. long and 5 cm. high -had been so cut that the light was admitted at the middle of the bottom -of the glass. The direct sunlight was admitted through the whole of -the glass end. At the rear of the box a piece of black cardboard was -so arranged that an aperture was afforded for observing the animals -without admitting any appreciable amount of light, and this aperture -could be readily closed by a slide when not in use. - -The method of experimentation was to place the animal in the box about -20 cm. from the glass end, and observe whether it went toward or away -from the source of light. The animals were experimented on in two -groups of five each, and one hundred observations were made on the -individuals of each group with each intensity of light, that is, twenty -observations on each animal. In order to check the influence of the -orientation of the animal at the time of exposure to the stimulus, the -following four positions for placing the animal were chosen: (1) Head -toward the light; (2) Head away from the light; (3) At right angles -to the light with right side toward it; (4) At right angles with the -left side toward the light. Thus five observations were made on each -animal of each group in each position, exposed to each of the different -intensities of light. - -Seven different intensities of light were employed, and the results -have been arranged in eight sets, as follows: I. Diffuse daylight in -dry box, _i. e._, the animals were taken out of their ordinary medium, -water, and were exposed to the stimulus of diffuse daylight in the air. -The reactions under these conditions, however, were so slow and so -unsatisfactory that the test was abandoned after the first group, and -thus the second group has nothing to show for itself under this head. -The remaining seven sets of observations were made on animals placed -in 10 cm. of water at 15° C. II. Diffuse daylight. III. Reflected -sunlight. The box was placed near a window on a clear day, and the -sunlight was thrown in horizontally by means of a mirror. IV. Direct -sunlight. On a clear day the box was placed in such a position that -the sun shone in directly and illuminated the front half of it. V. -9-candle-power incandescent electric light. This lamp was marked 16 -c., but it had been used a great deal, and on being tested with a -Lummer-Brodhun photometer showed only 9 c. VI. An incandescent electric -light of about 50 c. This lamp was marked 100 c., but had been used -considerably and was slightly smoked. Unfortunately it was broken -before there was any opportunity to test it. Judging from the fact -that another 100 c. lamp of the same manufacture, in slightly better -condition, measured 64 c., the estimate of 50 c. seemed a safe one. -VII. The incandescent electric light alluded to above, which measured -64 c. VIII. An arc light which varied in intensity from 150 c. to 250 c. - -In intensities V and VI the lamp was placed 5 cm. from the glass end -of the box to allow the interposition of a heat-screen consisting -of an alum solution in a flat glass jar 5 cm. thick. Reckoned in -candle-metres, therefore, the intensity of the illumination at the -surface of the animal in V was 144 c. m., and that in VI was about 800 -c. m. In VII two heat-screens were used, and between these was placed a -lens of considerable but not accurately determined curvature, so that -it is impossible to express the intensity in candle-metres. In VIII the -light was so variable that such an expression would mean nothing. - -Unfortunately it was impossible to keep the two groups constant -throughout the whole series, owing to the death of two individuals in -each group during the experimentation. Group 1 was composed of nos. -1, 3, 4, 8, and 9, of which 1 and 8 were replaced by nos. 13 and 42 -respectively. Group 2 was begun with nos. 23, 27, 32, 34, and 38, and -the vacancies caused by the death of 23 and 32 were filled by nos. 21 -and 36. The following table exhibits the reactions to the different -intensities of light, + indicating an orientation toward the source -of light, - an orientation away from the light, and ± an indifferent -orientation, which usually means no movement at all. - - -TABLE I. SUMMARY OF REACTIONS TO WHITE LIGHT - - Group 1 Group 2 Totals - + - ± + - ± + - ± - I. 23 48 29 23 48 29 - II. 49 47 4 19 81 68 128 4 - III. 40 60 30 70 70 130 - IV. 47 52 1 36 64 83 116 1 - V. 51 49 30 70 81 119 - VI. 39 61 39 61 78 122 - VII. 28 72 28 71 1 56 143 1 - VIII. 35 63 2 37 60 3 72 123 5 - - 312 452 36 219 477 4 = 531 929 40 = 1500 - -The following table gives the average time required for orientation -for each group. The time of each animal in seconds was noted with a -stop-watch from the instant the animal was placed in the box until -a definite orientation was assumed with reference to the light. If -no orientation followed within three minutes, the result was called -indifferent. - - -TABLE II. AVERAGE TIME OF ORIENTATION - - Intensities - I II III IV V VI VII VIII Ave. - Group 1 (144) 52 11 4-1/2 9 8-1/2 11 19 16-1/2 - Group 2 9 3 4 4 5 4 5 5 - -Inspection of these tables shows that when the animals were taken -from the water and placed in diffuse daylight in the air (I), their -movements were so sluggish that in twenty-nine cases out of one hundred -there was no orientation within the three-minute limit. Moreover, -in the seventy-one cases where there was definite orientation the -average time was over two minutes (144 seconds). While, therefore, the -conditions were quite different from the normal environment of the -animal, it is interesting to note that of the cases where orientation -did take place the negative reactions were more than twice as many as -the positive. In II, where the animals were under the same conditions -of diffuse daylight but in the water, a wide variation in the reactions -of the two groups is noted. In group 1 they are about equally divided -between positive and negative, while in group 2 there is the largest -proportion of negative reactions in the whole series. It will be -observed that the time for group 1 is extremely long compared with the -other averages, and this doubtless indicates a general sluggishness -and lack of sensitiveness to stimuli in the animals, which might to -some extent account for the difference in reaction. If we consider the -totals of both groups for each intensity, we are led to conclude that -there is no appreciable difference in the reactions of crayfish to -diffuse daylight, to sunlight, or to artificial light within the limits -here employed. A slight exception to this is found in VII, where the 64 -c. lamp with the lens caused a somewhat more uniform negative reaction. -The action of direct sunlight in IV is rather remarkable in that with -the lowest proportion of negative reactions in the whole series we -also observe the shortest time-average, indicating that the animals -are the liveliest and most sensitive. This would seem to indicate that -while the animals are in general somewhat negatively phototactic to -all light-stimuli of moderate intensity the action of direct sunlight -tends to reduce the negative phototaxis to a minimum. If we consider -the totals of the two groups separately we observe that group 1 has -only 57% of negative reactions while group 2 shows 68%. This is rather -in accordance with what we would expect from the general time-average, -which is over three times as much for group 1 as for group 2. But -although we may in a general way connect rapidity of orientation with -a large percentage of negative reactions, it will not do to carry it -to individual cases, for it was observed that no. 27 showed 83% of its -reactions negative, yet its total time-average was 10 sec., the highest -in its group. - -In general, then, we conclude that the crayfish is negatively -phototactic in the proportion of about two to one. This apparently -contradicts the statement made by Huxley that crayfish "are attracted -like moths to fires lighted on the bank at night." For surely if this -were the case some such tendency would have been observed in these -experiments. On the other hand, there is no such marked and definite -response to light as in the case of Daphnia or Hippolyte or Palæmon or -the Hermit Crab. The action of the stimulus is by no means mechanical -and constant, but there is wide variation in individuals. - -As was mentioned in the description of the method of experimentation, -four different positions for placing the animal were chosen with the -idea that the initial position of the animal with respect to the -light might have some influence on the direction of its movement. To -determine what this influence might be, a careful record was kept of -the orientation with reference to each one of these positions, and the -following table gives a summary of these observations. In the table -position I is where the animal is placed with its head toward the -light; position II, with head away from the light; position III, at -right angles to the light with the right side toward it; position IV, -at right angles with left side to light. - - -TABLE III. INFLUENCE OF POSITION ON LIGHT REACTIONS - - Position I Position II Position III Position IV Totals - + - ± + - ± + - ± + - ± + - ± - - Group 1 85 108 7 61 135 4 74 114 12 92 95 13 312 452 36 - Group 2 39 133 3 48 126 1 57 118 75 100 219 477 4 - - 124 241 10 109 261 5 131 232 12 167 195 13 531 929 40 - -Since the animals have been shown to be somewhat negatively -phototactic, we should expect that position II, with the head away from -the light, would show the largest number of negative reactions, and -this is what we find if we take the sum of both groups. But by the same -course of reasoning we should expect position I, with head toward the -light, to yield the smallest number of negative reactions, a condition -which prevails neither in the sum nor in either of the groups. On -the whole we can only say that difference of position seems to have -remarkably little influence on the orientation of the animals. - -In his work on the eye of the crayfish, Parker[234] called attention to -the migration of the pigment in the retinular cells under the influence -of light. The question now arose, what influence, if any, does this -pigment migration exert upon the reactions of the crayfish to light? -The time required for pigment migration in the eye of the crayfish has -never been determined to my knowledge, but from the work of Parker[235] -on Palæmonetes it was thought that confinement in the dark for about an -hour would be sufficient to bring about a retraction of the pigment. -Accordingly, group 1 was kept in the dark for one hour, group 2 for -one hour and a half, before experimentation. A further test was made -to observe the effects of pigment expansion, both groups having been -exposed for one hour and a half to the rays of a 32 c. incandescent -electric light at a distance of 40 cm. The apparatus used in the -reaction-tests was the box described above, with the 64 c. light as a -stimulus. As to the method of observation, each group was placed in -the centre of the box at right angles to the horizontal rays of light, -and the position of each animal was accurately noted at intervals of -one minute for one hour. In reporting the results, all the observations -of animals in the half of the box nearest the light are denominated -positive, those in the half farthest from the light negative. The -results are given in Table IV, where line I indicates the reactions -after confinement in the dark, line II those after exposure to the -light. - - -TABLE IV. INFLUENCE OF PREVIOUS CONDITIONS UPON REACTIONS TO LIGHT - - Group 1 Nos. 13 3 4 9 42 Totals - + - + - + - + - + - + - - I 54 6 60 5 55 48 12 60 167 133 - II 59 1 60 60 9 51 55 5 183 117 - - Group 2 Nos. 21 27 31 36 38 Totals - + - + - + - + - + - + - - I 5 55 5 55 7 53 10 50 4 56 31 269 - II 38 22 60 13 47 45 15 16 44 116 184 - -Let it be said at once that these results do not offer an altogether -satisfactory basis for an answer to the question proposed above. Some -of the animals would take up a position during the first ten minutes -and remain in it for the rest of the hour. Whether the position taken -was due solely to the light, or was owing to thigmotactic influences, -or whether it depended on the way in which the animal was released, -are questions which cannot be answered, and for this reason the -conclusions to be drawn from the table are tentative. If we examine -the table we find that the totals of both groups agree in manifesting -a decrease in negative results for line II, after exposure to the -light, as compared with line I, after confinement in the dark. This is -what we would expect from negatively phototactic animals. When taken -from the dark the pigment is retracted, and the sensitive retinal -substance is exposed to the direct action of a rather strong light. The -negative tendency of the animal we should expect to find accentuated. -The decrease in negative reactions is especially marked with group 2, -which was shown above to be much the livelier of the two, and all the -individuals except no. 27 share in the change. In group 1 the decrease -is not so striking, and is observed to be due to two individuals -solely. Inexplicable is the preponderance of positive over negative -reactions in the results for group 1. - -All of the experiments thus far described were carried out in water at -approximately 15° C. The question naturally arises, what will be the -result of raising or lowering the temperature upon the reactions of the -animals to light? Unfortunately the experiments anent this question -are fragmentary and incomplete, but the results will be given for what -they are worth. The same apparatus and the same intensity of light (64 -c.) were used as in the preceding paragraph. The results, presented -in Table V, are arranged in three sets, as follows: The line marked I -represents the results obtained from group 1 at a temperature of 5° C. -The animals were placed in the box one at a time, as in Table I, and -their orientation noted. They were set at right angles to the rays of -light, five times with the right and five with the left side toward -the source of the stimulus. No observations were made upon group 2 -at 5° C., and those on group 1 are so few as to have a questionable -value. Line II gives the reactions of both groups of animals in water -at 25° C., and in this set the animals were placed in all four of the -positions indicated for Table III. Line III presents the reactions of -the animals in water at 25° C. by the method outlined for Table IV, _i. -e._, each group of animals was placed in the centre of the box, and -observed at intervals of one minute. To obviate the objection of the -animals remaining in one spot, they were reset every ten minutes in the -middle of the box, at right angles to the entering rays. - - -TABLE V. REACTIONS TO LIGHT AT DIFFERENT TEMPERATURES - - Group 1 Nos. 13 33 4 42 9 Totals - + - + - + - + - + - + - - I 7 3 4 6 2 8 2 8 8 2 23 27 - II 16 4 14 6 11 9 9 11 13 4(±3) 63 34(±3) - III 19 41 13 47 39 21 17 43 27 33 115 185 - - Group 2 Nos. 21 27 31 36 38 Totals - + - + - + - + - + - + - - II 12 8 5 15 12 8 15 5 13 7 57 43 - III 12 48 12 48 31 29 42 18 44 16 141 159 - -Judging from lines II and III we may say that there is a tendency -toward a decrease of the negative phototaxis with an increase in -temperature. It is true that group 1 in line III maintains the average, -62% negative reactions, but the others are much lower than this, line -II even going over to positive phototaxis in both groups. In line III -the animals of both groups were extremely active during the first -ten minutes, rushing about from one end of the box to the other, -pushing each other back and forth, and in general exhibiting great -restlessness. Some of the animals when first put into the water reacted -with a sort of cramp reflex, which was followed in a few seconds by -intense activity. After the first ten minutes the animals began to -grow more quiet, and in twenty or thirty minutes they had become quite -sluggish, scarcely moving out of the position in which they were reset. -During the period of restlessness the males showed marked sexual -activity, rushing up to the females, pushing them about, seizing them, -and trying to turn them over in spite of their vigorous resistance. -One of the males, no. 36, did succeed in turning a female on her back -twice, although she struggled violently to escape,--a thing which the -female never does in the ordinary sexual act. The rise in temperature, -therefore, seemed to stimulate the males to sexual activity, but not -the females. - - -2. _Reactions to Colored Light_ - -No observations have ever been made, so far as I know, on the reactions -of the crayfish to colored light. Lyon, in his work on compensatory -eye-movements, found that rotation in blue light gave a compensatory -movement only slightly less than that in white light, while in red -light the compensation was only a little larger than in darkness. In -some animals the interposition of an opaque object between the eye and -the source of light caused an elevation of the eye 1° or 2° toward the -vertical. Red glass acted like an opaque object, blue glass produced -no effect, _i. e._, blue light had the same effect as white light. To -observe whether the same thing applied to movement reactions was the -object of the following experiments. - -_a. Reactions to Horizontal Colored Light._ The same apparatus was used -as in the previous experiments, viz., the dark box with light from -the 64 c. lamp entering horizontally at the end. Across half of this -end were placed pieces of colored glass of a saturated blue, green, -yellow, and red. The colored light obtained by this means was not -spectrally pure, but it was the nearest to it that could be obtained. -A more serious objection is that the intensities were not the same, -the red and the yellow being very appreciably brighter than the blue -and the green. In addition to observations with these colors, a piece -of black cardboard was introduced in the same position as the glass, -thus cutting off the light from that half of the box. This, to preserve -the uniformity of the series, is denominated black. The animals were -placed in the centre of the box, on the line separating the white from -the colored light, and were observed at intervals of one minute for -forty minutes, the position of each animal being accurately noted. At -the end of every ten minutes the animals were reset at the centre of -the box. The following table gives a summary of the results for each -individual. Here again it was impossible to keep the groups constant -owing to the death of individuals during the progress of the experiment. - - -TABLE VI. REACTIONS TO HORIZONTAL COLORED LIGHT - - Group 1 Group 2 - Animals 13 37 41 42 44 33 4 9 43 46 Sum 21 27 31 36 38 52 Sum Sum - Total - Blue 12 9 21 30 18 90 23 2 24 13 37 99 189 - White 28 31 19 10 22 110 17 38 16 27 3 101 211 - - Green 15 9 23 36 17 100 12 19 3 28 40 102 202 - White 25 31 17 4 23 100 28 21 37 12 98 198 - - Yellow 20 10 31 28 19 108 17 11 28 37 35 128 236 - White 20 30 9 12 21 92 23 29 12 3 5 72 164 - - Red 26 9 32 20 17 104 2 30 16 29 36 113 217 - White 14 31 8 20 23 96 38 10 24 11 4 87 183 - - Black 24 27 12 27 26 116 15 18 26 25 5 89 205 - White 16 13 28 13 14 84 25 22 14 15 35 111 195 - -In this table the colored lights are arranged in the order of the -spectrum from blue to red. On the hypothesis that blue light has -practically the same effect upon animal reactions as white light, -while red is about the same as darkness, we might expect that the -reactions would be about equally divided between the blue and the -white, and that there would be a gradually increasing difference in -number as we go down the table, reaching the maximum with the last -pair, black-white. This, we see, however, is not quite the case. In -both groups the white has a slightly larger number of reactions than -the blue, while the pair green-white shows numbers more nearly equal. -In the sum totals the yellow shows a greater preponderance over the -white than any other color, and the black and white are very nearly -equal. Group 1, it is true, shows a fairly regular ascending scale in -reactions to the colored lights with the exception of the red, and the -same might be said of group 2 if it were not for the very low number -of reactions to the black and the exceptionally high showing of the -yellow. On the whole, however, the differences are so small and the -individual variations are so large that we can only conclude that for -these conditions colored light has little or no effect on the reactions -of the animals. - -In the foregoing experiment the light came from a broad spiral coil -inside the bulb of the lamp, and the distance from it to the edge of -the glass was so small compared with the length of the box that there -was no sharp dividing-line between the colored light and the white, -but rather a wedge-shaped block of lessening saturation of the color, -and this wedge, having the point toward the light, took up the whole -of the box at the extreme farther end. Thus the imaginary central line -dividing the white light from the colored departed farther and farther -from the reality as the rear of the box was approached. To obviate -this difficulty and to get a check on the previous work, the following -series of experiments was undertaken. - -_b. Reactions to Vertical Colored Light._ The same box was used as in -the previous experiments, but the end was closed with a black cloth, -and an electric light marked 32 c. but measuring only 22 c. was hung -exactly over the middle of the box, 40 cm. from the bottom. By means -of wires it was arranged that a plate of colored glass could be swung -in such a manner that all of one half the box (the whole of one end) -was illuminated with the desired color, while the other half was either -left white or illuminated with another color. In this way there was a -fairly sharp dividing-line between the two colors. The animals were -observed at intervals of one minute for 40 minutes, and reset at the -middle on the dividing-line every ten minutes as before. Table VII -gives the results of the observations. - -In this set of experiments it was possible to keep the groups intact -except that in group 1 no. 13 had to be replaced by no. 46. If now we -conceive the colors arranged in the order of the spectrum with black -at one end and white at the other, and consider the black a lower -stimulus than the white, we have the ascending series black, red, -yellow, green, blue, white. Now since the animals have already been -shown to be somewhat negatively phototactic, we should expect them to -prefer a color of lower stimulus to one of higher. Turning to the sum -totals in the table we find that the first color of each pair (which -is always the lower stimulus) has the larger number of reactions in -every case but one, the first pair of red-blue. As was stated above, -it was impossible to secure colored light of the same intensity by -means of the glass at our disposal, and in the present case the red -was considerably brighter than the blue. Owing to the fact already -mentioned that different intensities of white light seem to have no -effect on the reactions it was thought that these differences in the -intensities of the colored lights might be overlooked. Since the only -thing that could be thought of to account for the anomalous behavior to -the red-blue was this difference in intensity, another experiment was -undertaken with the same animals under slightly different conditions. A -glass aquarium about 40 cm. long by 20 cm. wide was covered with black -cardboard and black cloth in such a manner that light could enter only -through a space 5 cm. wide at the bottom of each end. Each of these -ends was covered, the one with blue, the other with red glass, and 15 -cm. from each end was placed an electric light marked 32 c. Later, -however, it was found that one of these lamps measured 30 c. and the -other 22 c. The red light was found to be much more intense to the -eye than the blue, so the former was damped down with tissue paper -until the two appeared to have the same intensity. The second pair of -red-blue in Table VII gives the results of the observations under these -conditions, and these are found to be in harmony with the rest of the -table, _i. e._,[236] the color giving the lower stimulus has the higher -number of reactions. - - -TABLE VII. REACTIONS TO VERTICAL COLORED LIGHT - - Group 1 Group 2 Group 3 Sum - Animal - no. 13 37 41 43 44 Sum 21 27 36 38 52 Sum 54 56 58 60 62 Sum Total - - Blue 17 22 14 25 29 107 11 21 26 27 26 111 26 32 26 28 10 122 340 - White 23 18 26 15 11 93 29 19 14 13 14 89 14 8 14 12 30 78 260 - - Green 17 26 11 21 29 104 21 27 30 7 26 111 29 31 26 10 9 105 320 - White 23 14 29 19 11 96 19 13 10 33 14 89 11 9 14 30 31 95 280 - - Yellow 25 21 12 20 35 103 12 20 34 25 29 120 19 20 9 28 22 98 321 - White 15 19 28 20 15 97 28 20 6 15 11 80 21 20 31 12 18 102 279 - - Red 37 33 23 22 28 143 21 30 30 33 22 136 32 37 26 33 28 156 435 - White 3 7 17 18 12 57 19 10 10 7 18 64 8 3 14 7 12 44 165 - - Black 23 20 1 28 34 106 9 12 25 40 32 112 25 32 18 34 16 125 343 - White 17 20 39 12 6 94 31 28 15 14 88 15 8 22 6 24 75 257 - - Black 20 15 13 27 37 112 16 11 16 27 24 94 36 40 18 29 29 152 358 - Red 20 25 27 13 3 88 24 29 24 13 16 106 4 22 11 11 48 242 - - Black 20 25 26 20 32 123 22 15 39 40 32 148 33 22 34 34 11 134 405 - [236] - Blue 20 15 14 20 8 77 18 25 1 8 52 7 18 6 6 29 66 195 - - Red 25 17 28 18 8 96 3 15 21 28 20 87 21 13 15 14 28 91 274 - Blue 15 23 12 22 32 104 37 25 19 12 20 113 19 27 25 26 12 109 316 - - Red 21 27 22 10 36 116 13 40 24 21 28 126 22 25 18 21 16 102 344 - [237] - Blue 19 13 18 30 4 84 27 16 19 12 74 18 15 22 19 24 98 256 - -The most striking feature of the table is the marked predominance of -the red over the white. Here the red reaches 73% of the total number -of reactions, and inspection shows that this predominance is uniform -not only through the groups but even for the individuals. The constancy -of this reaction and the fact that it is so much more frequent than -the one to the black as compared with the white, would lead one to -expect that the red would have the higher percentage in the combination -black-red. Such, however, is not found to be the case, although it -does happen with one group. If the arrangement of our color-scale in -accordance with increasing intensity of stimulus were correct, we -should expect a gradually increasing predominance in reactions to -colored light over those to white in the first five pairs. Instead of -this we find that green and yellow stand nearest to the white, blue and -black come next and are almost equal, while red is very much higher -than any. In the pairs black-red and black-blue the red holds its -predominance over the blue at about the same rate as in the second pair -of the direct comparison, red-blue. The wide individual variations, -however, in all these reactions to colored light, except perhaps in -the case of red-white, indicate that there is nothing very regular, -stereotyped, or mechanical about them. The most that can be said is -that in a general way the red end of the spectrum furnishes a less -intense stimulus to negative reaction than the blue. - -A tendency to habit formation was noticed during the course of these -experiments, and it is possible that this may have influenced the -results somewhat. Many individuals apparently formed a habit of going -to a certain corner as soon as they were reset at the centre. The -positions in which they were set were varied and they were headed in -different directions, but within a minute after they were released in -the middle of the box they would be found in their favorite corner. -This was especially the case with no. 38 in Table VI, and I think -accounts in some measure for the persistent avoidance of the white. -In no case did this continue throughout the whole series, but would -sometimes be noted for two or three days at a time in the case of an -individual. What were the controlling factors in this habit formation, -the means by which orientation and recognition were effected, I was -unable to determine. - - -3. _Reactions to Objects_ - -In no case did an animal give any sign of perceiving stationary objects -in its path or of avoiding them in any way that could be referred to a -visual stimulus. When the animal approached an obstruction there was -no hesitation in the movement until the object was touched. Usually -even when the antenna had touched the object the animal did not stop, -but continued until the contact of the chelæ or even of the rostrum -made further movement in that direction impossible. - -With moving objects the case was quite different. Here the condition -and disposition of the individual animal seemed to be the deciding -factors. Often when the animals were trying to climb out of a shallow -pan in which they were kept in the experimenting-room, raising a -finger or holding out a pencil would be sufficient to make them stop -or even start back into the pan. Nor was this response occasioned by -any change in the intensity of light, such as that caused by a shadow -falling on the animal, for they would react to a movement made on the -opposite side of them from the window. In fact, no. 56, the most active -in response to moving objects, seemed to react more vigorously to a -motion made on the opposite side than when it was made between him -and the light. Whenever a person came near the aquarium he and one or -two others would take an attitude of defence, and would "face about" -to correspond to any movement the person made toward one side or the -other. When in the pan mentioned above, any movement of a person within -two or three yards of him usually called forth a reaction on his part, -and if the pan were placed on the table and the person moved slowly -round it, the animal turned with the person, making a complete circuit -of the pan. - -Reaction to a smaller moving object, however, was not so marked. A -black object, 20×8×8 cm., was suspended above the middle of the pan -so that if set swinging it would just pass over the top. When it was -pulled to one side the animal responded slightly, but after the first -swing he seemed to pay no more attention to it. When the operator -stepped out from behind the screen, the animal was as keen in its -response as before. The experiment was now tried of allowing the object -to approach from one direction while the operator moved to a position -at right angles to its line of movement. Without hesitation the animal -moved so as to keep fronting the operator, without paying any attention -to the movement of the smaller object, although this was much nearer. - -These observations on the reactions of the crayfish to stationary and -moving objects are in line with the conclusions of Plateau[238] and -Exner[239] drawn from observations on other Arthropods. It is Exner's -belief that the compound eye is a visual apparatus which is almost -worthless for detecting the _forms_ of objects, especially if these -objects are stationary, but that it may furnish a very keen perception -of _moving_ objects. - - -II. EXPERIMENTS WITH SOUNDS - -Hensen[240] stated that Palæmon and Mysis reacted to sounds made by -striking a thin, resonant board floating on the surface of the water, -or by tapping the walls of the aquarium or of the room. Beer[241] -repeated Hensen's experiments, but denied that the Crustacea reacted to -sounds, and claimed that their movements were due to visual and tactual -stimuli. Prentiss[242] confirmed Beer's results on Palæmonetes, and -noted that the reactions were only slightly diminished by the removal -of the otocysts, but that removal of the antennæ and antennules caused -their almost complete cessation. More extended experiments were made -on the fiddler crab, _Gelasimus pugilator_, which is on land a good -deal of the time, and Prentiss's conclusions are: "(1) The reactions -formerly attributed to sound-stimuli are nothing more than tactile -reflexes. (2) The otocyst has little or no part in calling forth these -reactions. (3) There is no direct evidence to prove that decapod -Crustacea hear, and until such evidence has been obtained, we are not -warranted in ascribing to the otocyst a true auditory function." - -The experiments performed on the crayfish in this connection -all resulted negatively and go to confirm Beer's and Prentiss's -conclusions. Rapping upon a board floating in the water, and tapping -the sides of the aquarium did not cause the slightest apparent reaction -in the animals under observation, even though the vibration of the -water could be plainly perceived by the sense of touch in the hand. -When a rather large electric bell was sounded just over the surface -of the water some reactions were observed which were evidently due -to the movements of the hammer, but there was nothing which could be -referred to the sound-stimuli. If the bell was held against the sides -of the aquarium, or in the water near the animals, the vibration could -be plainly felt by the fingers, yet no reactions on the part of the -crayfish were observed. A metal snapper making a crack like a small -pistol-shot was tried both in and out of the water but with no success -in producing a reaction. A large hand tuning-fork, when held with its -base pressed firmly against the glass walls of the aquarium, gave a -deep rich tone of great volume, or when lightly touched to the glass -produced a shrill, piercing, penetrating sound which was extremely -sharp and disagreeable. Here again the vibrations of the water were -quite perceptible to the hand at a distance of 10 cm., yet in neither -case was there a sign of a reaction. Finally two electric tuning-forks, -one of 256, the other of 512 vibrations per second, were tried on the -animals taken one by one, and especial attention was given to the -regular movement of the little thread-like appendages which keep up the -current of water to the gills, with the idea that perhaps their rate of -movement might be affected. In no case was there the slightest movement -that could be referred to vibration, although here again the tactile -stimulus was very perceptible to the finger. None of these experiments, -then, give any indication that the crayfish reacts to vibratory stimuli -which to the human ear produce sound. - - -III. ROTATION EXPERIMENTS - -It has been found that the higher vertebrates, on being rotated on a -turn-table, exhibit all the symptoms which accompany the sensation -of dizziness in man. The question arises, to what degree and in what -manner do invertebrates respond to rotation? Schaefer,[243] the first -to take up this question, denied on rather meagre observations that -Crustacea respond in any way to rotation on the turn-table. Kreidl[244] -showed that this statement was altogether too sweeping, that Palæmon -reacts very definitely to rotation by running in the opposite -direction. Bunting[245] tried the crayfish, but all the rotation -experiments resulted negatively, so she was led to confirm Schaefer's -statement so far as the crayfish is concerned. Bethe[246] found that -Carcinus behaved in a very definite manner on being rotated, that -during the rotation the animals ran in the opposite direction to that -in which they were turned, and as soon as the motion ceased they began -running in the other direction. Finally Lyon,[247] while agreeing with -Bunting that adult crayfish do not react to rotation, discovered that -young animals two or three centimetres long react very prettily to the -movement, going in a direction opposite to the turn. To confirm and if -possible extend these observations on the crayfish was the purpose of -the following experiments. - -It was soon found that a great deal depended on the method of -experimentation. None of the experimenters mentioned above gives any -detailed description of the manner in which the experiments were -carried out. One is left uncertain whether the animals were placed on -the periphery of the turn-table or over the centre, whether in the -former case they were set with their heads toward the centre or away -from it, or placed at right angles to a radius, or whether they were -merely set down in any chance fashion and whirled about. The same -indefiniteness exists in most of the accounts as to how fast they were -turned, and whether the experiments were performed in the air or in the -water. Finally it is not stated whether the rotation was always in the -same direction, or whether its direction was alternated. - -The turn-table used in the following experiments was one that had to -be turned by hand, so that it was impossible to regulate the speed -accurately. The crank, however, was not attached directly to the -rotating board, but was connected with it by means of a gearing so -that one turn of the crank produced about ten turns of the table. This -gearing gave a steadying effect to the motion so that the speed could -be kept tolerably constant. A circular pan, about 15 cm. in diameter at -the bottom with the sides slightly sloping outward, was set so that its -centre coincided with the axis of the rotating table. It was in this -pan that all the experiments were tried. Through various preliminary -experiments to determine the most favorable speed, it was found that a -rotation rate of over one turn of the table per second produced such a -strong centrifugal force that unless the animals were set exactly over -the centre they were swept off against the side of the pan in such a -manner that it was difficult to decide whether the rotation as such had -any effect upon their movements. It was finally decided that the best -results were obtained from a rate of approximately one rotation in two -seconds. - -It soon became evident that when the larger and more sluggish crayfish -were merely dropped in the pan and rotated there was no particular -reaction. This was true whether the animals rotated were in the air or -in the water. The smaller and more active crayfish, however, showed a -decided tendency to run either with or against the direction of the -rotation, especially when the experiments were carried on in the water. -In no case was there any tendency to go in the opposite direction when -the rotation ceased, except in so far as the animals were carried along -by the water. To get a quantitative expression for these tendencies a -more delicate method of experimentation was resorted to. If there was -a tendency on the part of the active animal to move either with or -against the rotation, such a tendency might also be supposed to exist -in the sluggish animal, only in the latter the inertia was sufficiently -strong to prevent its appearance. If, however, the animals should be -set radially to the periphery of the pan, the tendency to go with or -against the rotation would be exhibited in the direction in which they -turned out of the radial position. For it was found that no animal -would remain in that position for any great length of time. Two groups -of animals were used for these experiments, five animals in each group, -and the first group was selected from the smallest and most active -animals, the second from the largest and most sluggish. Each animal -was set in two positions, position I, with the head toward the centre, -position II, with the head away from the centre. Each animal was given -ten trials in each position, and the number of times it turned in a -direction _with_ the rotation is set down in the + column, the number -of times it turned _against_ the rotation is indicated in the - column. -In general from 5 to 15 turns were necessary for the orientation of -the animal, though sometimes the number ran up to 30 or 40. Each trial -was made in the opposite direction to the preceding one, in order to -avoid the formation of any habit in turning. All these experiments were -carried out in water, the depth of which in the pan was about 4 cm. In -order that there should be no difference between the velocity of the -water and that of the pan, the table was rotated a few times before -the animal was put in. As a check a series of experiments of 5 in each -position was performed in the air on the more active group. - -The following table shows the results of these experiments in rotation: - - -TABLE VIII. REACTIONS TO ROTATION - - In Water In Air - Sum - I II Sum I II Sum Total - Group 1 + - + - + - + - + - + - + - - 44 5 5 10 5 15 1 4 5 1 9 6 24 - 49 2 8 4 6 6 14 5 1 4 1 9 7 23 - 56 3 7 8 2 11 9 5 3 2 8 2 19 11 - 62 4 6 10 14 6 2 3 2 3 4 6 18 12 - 64 2 8 9 1 11 9 1 4 1 4 2 8 13 17 - Sum 16 34 31 19 47 53 9 16 7 18 16 34 63 87 - Group 2 - 21 5 5 3 7 8 12 - 27 2 8 5 5 7 13 - 36 7 3 8 2 15 5 - 37 2 8 3 7 5 15 - 54 5 5 6 4 11 9 - Sum 21 29 25 25 46 54 46 54 - Sum Total 37 63 56 44 93 107 9 16 7 18 16 34 109 141 - -Examination of the table reveals great individual variation. Some -animals, as nos. 44, 49, and 37, turn rather constantly against the -direction of the rotation, while others, as nos. 56 and 36, are almost -as constant in their movement with the rotation. On the whole we -observe that for each group, and for Group 1 in both water and air, -there is a slightly greater tendency to go against the rotation than -with it. This tendency, strange to say, comes out much more clearly in -the air than in the water. It is evident, however, from the variation -exhibited that there is nothing very stereotyped or mechanical about -the reaction. Mention should be made of the fact that usually (though -not always) the animals not only oriented themselves with reference -to the rotation, but moved forward in that direction as long as the -rotation continued. - - -IV. GEOTAXIS, BAROTAXIS, AND TURNING - -(1) _Geotaxis._ So far as my knowledge extends, no experimental work -has been done to determine the geotaxis of decapod Crustacea. Most -of the vertebrates are positively geotactic, while a great many of -the invertebrates, particularly unicellular organisms, larvæ of moths -and butterflies, slugs, etc., are negatively geotactic. Parker[248] -found that in the case of the Copepod, _Labidocera æstiva_, the -females exhibited strong, the males weak, negative geotaxis. In the -investigation of the geotaxis of the crayfish, two sets of experiments -were undertaken. In the first the method of procedure was as follows: - -On a level table before a window a board was so arranged that it could -be set at an inclination of 5°, 10°, 15°, 20°, and 25° either toward -or away from the window. Starting, let us say, with the inclination -toward the window, each one of a group of five animals was placed on -the board with the right side to the window five times. The board was -then inclined the same amount away from the window and the process was -repeated. The same procedure was carried out with the animals set with -the left side to the window. The following table gives the results of -this set of experiments. - - -TABLE IX. GEOTAXIS IN FRONT OF WINDOW - - 10 12 14 16 18 Totals - + - ± + - ± + - ± + - ± + - ± + - ± - 5° 14 5 1 11 7 2 11 9 13 7 8 10 2 57 38 5 - 10° 13 7 12 7 1 13 6 1 16 4 14 6 68 30 2 - 15° 17 3 14 6 16 3 1 17 3 9 11 73 26 1 - 20° 12 8 17 3 18 1 1 19 1 14 6 80 19 1 - 25° 18 2 19 1 19 1 17 3 16 4 89 11 - -From this table it appears that the crayfish is positively geotactic, -and that the positive geotaxis increases regularly with the increase -in inclination. As a check on these results another set of experiments -was undertaken with different animals under different conditions. The -board was placed on a level table in the centre of a darkened room, -and the operator stood behind a screen so as to be quite hidden from -the animals. In order to observe the orientation a 2 c. incandescent -electric light was suspended directly above the spot where the animals -were set, at a distance of 60 cm. above the board. Each animal of a -group of five was set five times in each of four positions, viz., head -down the incline, head up the incline, and at right angles to it with -first the right and then the left side down the slope. The results were -as follows: - - -TABLE X. GEOTAXIS IN DARKENED ROOM - - 41 46 48 51 64 Totals - + - ± + - ± + - ± + - ± + - ± + - ± - 5° 12 4 4 13 4 3 8 10 2 14 5 1 11 7 2 58 30 12 - 10° 14 5 1 13 6 1 11 8 1 13 6 1 14 3 3 65 28 7 - 15° 16 4 15 5 13 7 11 6 3 14 2 4 69 24 7 - 20° 16 4 19 1 16 4 20 17 2 1 88 11 1 - -It will be observed that Tables IX and X agree quite well in the main, -and we may conclude that the crayfish is positively geotactic and that -the positive reactions vary from 58% at 5° to 89% at 25°. - -(2) _Barotaxis._ Verworn[249] uses the term barotaxis in an inclusive -sense to cover all pressure phenomena that can be classed under the -sub-heads of thigmotaxis, rheotaxis, and geotaxis. It seems preferable -to me to employ the term in a more restricted sense of reaction to -pressure other than the pull of gravity, the flow of a current, or -the contact with bodies. The following experiment with the crayfish -furnishes us, I think, with a case in point. - -A glass aquarium, 54 cm. long and 28 cm. wide, was so inclined that -the water was 20 cm. deep in one end and 8 cm. deep in the other. A -board was so anchored that one end rested on the bottom at the shallow -end of the aquarium while the other end projected slightly out of and -above the deepest water. The board was about 45 cm. long, so that its -slope was very gradual. Nine animals were placed in this aquarium and -observed for three successive days. If we denote the bottom of the -deep end of the aquarium by A, the shallow end under the board by B, -the shallow end on top of the board by C, and the end of the board at -the surface of the water by D, the results of the observations were as -follows: On the first day 1 animal was found at D, 6 at C, and 2 at B. -On the second day 5 were at C, 3 at B, and 1 at A. On the third day 1 -was at D, 4 at C, and 4 at B. Totals, 2 at D, 15 at C, 9 at B, and 1 at -A. - -While these observations were too few to base very positive statements -on, the striking fact that only one animal was found at A, the deep -end of the aquarium, whereas 15 were noted on top of the board at C, -indicates strongly that the animals avoid the deeper water. That the -animals were found _on top_ of the board, not under it, indicates -that the observation is not to be referred to thigmotaxis, although -the latter is doubtless very strong, as we shall see later. It should -be observed that the negative barotaxis works against and overcomes -the marked positive geotaxis which, as we have just seen, the animals -exhibit in the air. Under the influence of the positive geotaxis, -we should expect to find the greater number of the animals at A,--a -condition which is speedily realized if we let the water run out -of the aquarium. We conclude, therefore, that at certain pressures -(specifically at the pressure exerted by water at a depth of 20 cm.) -the crayfish is negatively barotactic. - -(3) _Turning._ In the experiments with light it was observed that very -seldom do the animals, when placed upon a surface, move off at once -in a straight line, but usually they first turn through an angle of -90° or more and then start off straight. This came out strongly in the -work on geotaxis, where oftentimes, when the animal was set with the -head up the incline, the reactions would be preponderantly positive, -whereas when set with the head down the incline the reactions were on -the whole negative. In other words, when headed up the incline the -animal would go down, and when headed down he would more often go up. -Some experiments were tried under various conditions to determine how -general this tendency is. The table presents the results in condensed -form. - - -TABLE XI. EXPERIMENTS IN TURNING - - Nos. 10 12 14 16 18 Sum 7 9 15 17 25 Sum - I III - 90°- 8 5 6 8 10 37 2 4 7 5 5 23 - 90° 4 6 7 2 2 21 3 1 4 - 90°+ 8 9 7 10 8 42 5 5 3 5 5 23 - II IV - 90°- 2 1 2 2 7 9 3 1 2 15 - 90° 1 1 2 4 3 5 3 3 1 16 - 90°+ 7 9 7 10 6 39 12 1 9 11 11 44 - - Nos. 41 43 46 48 64 Sum Sum - V Totals - 90°- 9 11 12 14 2 48 130 - 90° 2 1 2 1 3 9 54 - 90°+ 9 8 6 5 15 43 191 - -In this table the first line indicates the number of times each animal -turned less than 90° when starting off from the position in which it -was set, the second line the number of times the amount of turn was -practically 90°, and the third more than 90°. The five parts of the -table mark the different conditions; in Part I twenty observations were -made on each animal placed on a level board before the window, and set -now with the right now with the left side toward the window. In Parts -II and III the animals were set with the head turned now toward now -away from the window. In Parts IV and V the animals were placed on a -level board in the middle of a darkened room with a 2 c. light about -three feet above them. This was to exclude any possible directive -influence of light. In all cases the operator was concealed by a -screen. In Parts I and V twenty observations were made on each animal, -in II and III ten, and in IV fifteen. - -Rarely the animal would turn completely round and start off in the -direction originally set, but usually the turn was between 90° and -180°. When once the animal began to move off, it would ordinarily keep -to an approximately straight line. How seldom this was observed when -the animals were first set down may be judged from the fact that out of -a total of 375 observations in only 18 did the animals move straight -ahead from their original position. From the table we observe that in -over 65% of the cases (a proportion of almost two to one) the animals -turned through 90° or more before starting off. At present the writer -has no explanation to offer for this phenomenon. - - -V. THIGMOTAXIS AND TOUCH REACTIONS - -(1) _Thigmotaxis._ Experiment has shown that there are some animals -which tend to avoid contact with objects as much as possible, and -on the other hand there are animals that seek to get as much of the -surface of their bodies as possible in contact with objects. The former -are spoken of as negatively, the latter as positively thigmotactic. -Does the crayfish show any tendency in the one way or the other, and -if so is it positively or negatively thigmotactic? In a large glass -aquarium, 80 cm. long and 40 cm. wide, was a thin wooden box, 22 cm. -long and 16 cm. wide, set in one corner 4 cm. from the glass walls. -At the bottom of the box was an opening where the crayfish could -enter. The following table shows the disposition of the animals for -27 different days, on which one examination was made each day. Line I -indicates the number of times each animal was found against the walls -of the aquarium, line II in the 4 cm. space between the box and the -walls of the aquarium, line III inside the box against its sides, and -line IV resting freely in the middle of the aquarium or in the middle -of the box. - - -TABLE XII. THIGMOTAXIS REACTIONS - - Animal 4 5 9 13 21 27 29 31 33 35 36 37 38 39 41 42 43 44 45 46 47 48 - - I 4 9 2 10 4 17 16 6 6 10 3 2 11 9 3 2 1 9 1 15 - II 5 2 13 18 9 5 2 4 5 22 1 14 11 3 6 11 1 9 4 7 - III 2 1 2 5 1 9 3 2 3 11 2 24 7 1 4 14 9 1 5 - IV 1 11 2 1 2 4 4 1 2 - - - Animal 49 51 52 54 56 58 60 62 64 Sum - Totals - I 6 11 3 1 2 4 7 10 12 195 - II 8 3 7 5 8 1 3 2 1 190 - III 1 16 9 5 10 3 2 2 154 - IV 1 1 2 1 33 - 572 - -In order to appreciate the significance of the figures in this table it -is necessary to consider the amount of lateral surface with which it -was possible to come in contact in each case. In IV of course it was -zero, in III it was 76 cm. with four corners in close proximity, in II -it was only 38 cm. and one corner, but the space was so narrow that -there was practically a contact-surface on both sides, and in I there -was 212 cm. of lateral surface with three corners. I mention corners -in this connection because they were almost invariably occupied. If -we examine the table with these facts in mind, we find, (1) that the -number of animals resting freely without contact with any lateral -surface is very small, only about 6% of the whole; (2) that the number -of animals found in the narrow space between the box and the walls -of the aquarium is very large in proportion to the length of the -space: indeed the animals were frequently found wedged into this space -three or four deep; (3) that the number of animals found in the box -was probably due largely to the fact that they found in it a greater -lateral contact-surface, particularly in the corners, than was possible -outside. - -Two or three minor considerations are of interest. The animals were -frequently observed "on edge" about half out of the water, that is, -with the ventral surface of the body pressed against the vertical -surface against which they were resting. This was also observed where -the water was so deep that none of the members could touch the bottom. -It was perhaps on account of the quality of the surface affording a -rougher contact that so large a number of the animals were found in -contact with the wooden box rather than the smooth, slippery surface -of the glass. In the centre of the aquarium a wooden stopper 2 cm. in -diameter projected about 15 cm. above the surface of the water. Very -often a crayfish would be found almost at the top of this stopper, -completely out of the water. This tendency to climb was frequently -observed in the light-reaction experiments, where the animals would -climb up on any piece of wood that chanced to be left in the box. It -reminds one of the tree-climbing crabs of the West and East Indies. -Along the creeks of Ohio I have frequently seen crayfish that had -climbed up on logs or sticks that projected some feet out of the water. - -In the table we see decided evidences of "habit" in the sense of an -animal returning to the same place which it had occupied. No. 5 has -almost half the observations in the open, nos. 21, 37, and 39 showed a -decided preference for the space between the box and the aquarium wall, -while nos. 38, 44, and 52 were more frequently found on the inside of -the box. This recurrence to a particular position also came out in the -light-reaction work, where an individual would return to the same spot -in the box for days at a time as soon as released. - -From the above considerations we conclude that the crayfish is strongly -positively thigmotactic and that this thigmotaxis probably plays a most -important part in the life of the animal. - -(2) _Touch Reactions._ Lemoine[250] investigated the reactions of -crayfish to touch-stimuli and found that the plates of the telson, the -sternal portions of the thorax, the abdominal pleopods, the chelæ, and -particularly the antennæ toward their points are especially sensitive, -but that nowhere, even on the back of the carapace, is a touch-stimulus -altogether devoid of reaction. Gulland[251] found that a needle could -be inserted between the tufts of setæ on the chelæ without causing any -reaction, but as soon as one of the hairs was touched, the chelæ closed -with a snap. Considering the setæ as the organs of touch, he claimed to -have found that the eyes, eye-stalks, and carapace (which he says have -no setæ) are impervious to tactile impressions. This claim of Gulland's -is strangely at variance with the facts. In no case have I been able -to bring about retraction of the eye-stalk by visual stimulation, but -a very light touch-stimulus on the eye itself or on the eye-stalk -or a stronger stimulus on some portion of the head will cause the -eye to be drawn in. It is true that after repeated stimulation the -eye is retracted no longer, and with a heavy bristle one can make a -perceptible indentation in the corneal surface without the eye being -withdrawn. - -The antennæ, from their anatomical structure, their position, and -the manner in which they are carried, are generally considered the -special organs of touch. Nevertheless, as far as the reactions of the -animal are concerned, a stimulation of the antennæ by touch produces -a less decided response than almost any other portion of the body. -If the stimulus is very light no reaction at all is observed in most -cases, and if stronger the antennæ are moved away, but that is all. A -stimulation of the edge of the telson produces a more decided reaction. -Either the animal folds it under the abdomen at once or faces about -like a flash in an attitude of defence; frequently both reactions -occur. While the response to stimulation of the chelæ was decided, -that to touch on the first chelipedes was quicker and more accurate. -The mouth-parts are also very sensitive to touch. I cannot agree with -Gulland's assertions as to the insensitiveness of the carapace, for I -have been able to find no place upon it where a light-stimulation would -not produce a reaction. In this connection a curious phenomenon is -characteristic of the animal. If the carapace or the front portion of -the abdomen be lightly stroked with a solid object such as a pencil, -the animal will slowly turn toward the stimulus on its antero-posterior -axis. If, now, a like stimulus be applied on the other side, the animal -will roll back through the normal position to a like inclination -toward the stimulus on the other side. If the alternation be kept up -and the change made quickly, a continuous and curious rolling movement -is maintained, the animal growing more and more excited until it -scampers off with a kind of cramp-like motion. With some animals this -rolling reflex is more marked than with others, but in no case is it -altogether lacking. Some animals have been known to roll so far over -that they topple over on their backs. Dr. Yerkes informs me that he has -observed the same phenomenon in a less degree with turtles when the -edge of their shell is stimulated by scratching. The movement seems -to be caused by the reflex stimulation of the extensor muscles on the -opposite side of the body from the part stimulated. The thrust of the -legs thereby brought about raises that side of the body and thus causes -a rotation to some extent about the antero-posterior axis. But how was -this connection between the stimulation of one side of the body and -the contraction of the extensor muscles of the other side established? -I have no doubt that it is intimately connected with the positive -thigmotaxis described above. These animals live under loose stones for -the most part, and thus the carapace gets a great deal of stimulation. -If the animal is stimulated on one side, a contraction of the extensor -muscles of the opposite side tends to roll the animal toward the source -of the stimulus, and hence to increase the contact. In the race-history -of the animal this has doubtless been advantageous in enabling it to -escape the dangers of its habitat. - - * * * * * - -In a succeeding paper the writer hopes to discuss the reactions of -the crayfish to chemical stimuli. In conclusion he desires to make -acknowledgment to Dr. Robert M. Yerkes of the Harvard Psychological -Laboratory for kindly suggestions and helpful criticism throughout the -course of the investigation. - - -SUMMARY - -(1) Crayfish are somewhat negatively phototactic, going away from -rather than toward the source of light in the ratio of 62% to 38%. The -different intensities employed in this investigation produced very -little difference in the reactions. The average reaction-time was much -less for the group of animals which showed the highest percentage -of negative reactions, indicating a greater general sensitiveness. -Variations of the position in which the animals were set affected the -results very slightly. - -(2) Previous confinement in the dark tended to increase slightly the -number of negative reactions, and previous exposure to strong light -tended to decrease the number, but the results were not constant. An -increase in temperature tended to decrease the number of negative -reactions to light, but here again the results were somewhat -conflicting. - -(3) Reactions to horizontal colored light showed a tendency to go to -the colored light rather than to the white in the following order: -Blue 47%, green 50.5%, black (or the absence of light) 51%, red 54%, -yellow 59%. In the case of vertical colored light the comparison with -the white resulted somewhat differently, as follows: Green 53%, yellow -53.5%, blue 57%, black 57%, red 72.5%. In the latter experiments the -animals showed a marked and constant preference for the red. - -(4) The animals showed no signs of reaction to static objects from -visual stimulation, i. e., there is no evidence of visual perception -of form in the case of stationary objects. Moving objects, especially -large ones, are plainly perceived and definitely reacted to. - -(5) There were no reactions whatever caused by those vibrations which -to the human ear produce sound. So far as these experiments go, the -animals cannot be said to hear. - -(6) In rotation experiments individual animals were rather constant in -moving either with or against the direction of the rotation, but no -definite tendency for all animals was observed. - -(7) The pull of gravity was followed with constantly increasing -frequency from 58% at 5° to 89% at 25°. Therefore we conclude that -the animals are positively geotactic. They are negatively barotactic, -avoiding the pressure of water at the depth of 20 cm., and this is -sufficient to overcome their positive geotaxis. When placed upon a -level surface the animals show a peculiar tendency to turn through a -greater or less angle before starting out in a straight line. In only -18 out of 375 observations, or 5%, did the animals start straight, in -30% they turned through an angle of less than 90°, and in 65% they -turned through an angle of 90° or more. - -(8) The crayfish is positively thigmotactic in a marked degree, as is -indicated by the fact that in only 33 out of 572 observations, or less -than 6%, were the animals found resting in the open, while in 190, or -33%, they were found in a narrow opening between two vertical surfaces. - -(9) The animal is sensitive to touch over the whole surface of the -body, but especially on the chelæ and chelipedes, the mouth-parts, the -ventral surface of the abdomen, and the edge of the telson. If one side -of the carapace or of the dorsal surface of the abdomen be stimulated, -the extensors of the legs on the opposite side are contracted, and -the animal turns on its antero-posterior axis toward the source of -the stimulus. If opposite sides be stimulated alternately, a peculiar -rolling motion is set up. - -FOOTNOTES: - -[Footnote 218: An Introduction to the Study of Zoölogy, illustrated by -the Crayfish, Internat. Sci. Ser., 1880.] - -[Footnote 219: How the Burrowing Crayfish works, Inland Monthly, -Columbus, Ohio, vol. 1, pp. 31, 32, 1885.] - -[Footnote 220: Cave Animals from Southwestern Missouri, Bull. Mus. -Comp. Zoöl. Harv. Univ., vol. 17, pp. 225-239, 1889.] - -[Footnote 221: Notes on the Individual Psychophysiology of the -Crayfish, Amer. Jour. of Physiol., vol. 3, pp. 404-433, 1900.] - -[Footnote 222: Reactions of Entomostraca to Stimulation by Light, II, -Reactions of Daphnia and Cypris, Amer. Jour. of Physiol. vol. 4, pp. -405-422, 1900; Reactions of Daphnia pulex to Light and Heat, Mark -Anniversary Volume, pp. 359-377, 1903.] - -[Footnote 223: Heliotropism of Cypridopsis, Amer. Jour. of Physiol., -vol. 3, pp. 345-365, 1900.] - -[Footnote 224: Das Nervensystem von Carcinus mænas, I, Arch. f. mikros. -Anat., vol. 50, pp. 460-547, 589-640, 1897.] - -[Footnote 225: The Color Physiology of Higher Crustacea, Phil. Trans., -London, Series B, vol. 196, pp. 295-388, 1904.] - -[Footnote 226: An Establishment of Association in Hermit Crabs -(_Eupagurus longicarpus_), Jour. Comp. Neur. and Psych., vol. 14, pp. -49-61, 1904.] - -[Footnote 227: The American Lobster; A Study of its Habits and -Development, Bull. U. S. Fish Comm., vol. 15, pp. 1-252, 1895.] - -[Footnote 228: Notes on the Senses and Habits of some Crustacea, Jour. -Marine Biol. Assoc'n., Plymouth, N. S., vol. 1, pp. 211-214, 1889.] - -[Footnote 229: The Reactions of Copepods to Various Stimuli, Bull. U. -S. Fish Comm., vol. 21, pp. 103-123, 1902.] - -[Footnote 230: Recherches pour servir à l'histoire des systèmes -nerveux, musculaire, et glandulaire de l'écrevisse, Ann. des Sci. Nat., -Series 5, vol. 9, pp. 99-280; vol. 10, pp. 5-54, 1868.] - -[Footnote 231: The Sense of Touch in Astacus, Proc. Roy. Physiol. Soc., -Edinburgh, vol. 9, pp. 151-179, 1886.] - -[Footnote 232: _Loc. cit._] - -[Footnote 233: Contribution to the Comparative Physiology of -Compensatory Movements, Amer. Jour. of Physiol., vol. 3, pp. 86-114, -1899.] - -[Footnote 234: The Retina and Optic Ganglia in Decapods, especially -in Astacus fluviatilis Mitth. Zool. Stat. Neapel., vol. 12, pp. 1-73, -1895.] - -[Footnote 235: Photomechanical Changes in the Retinal Pigment Cells of -Palæmonetes, etc., Bull. Mus. Comp. Zoöl. Harv. Univ., vol. 30, pp. -273-300, 1897.] - -[Footnote 236: No. 46 substituted.] - -[Footnote 237: The second pair of red-blue gives the results of an -experiment under somewhat different conditions as described above.] - -[Footnote 238: Recherches expérimentales sur la vision chez les -Arthropodes, Mém. Corronnés de l'Acad. Roy. des Sci. etc. de Belgique, -vol. 43, pp. 1-91, 1889.] - -[Footnote 239: Die Physiologie der facettirten Augen von Krebsen und -Insekten, 1891.] - -[Footnote 240: Studien über das Gehörorgan der Dekapoden, Zeitsch. f. -wiss. Zool., vol. 13, pp. 319-412, 1863.] - -[Footnote 241: Vergleichend-physiologische Studien zur -Statocysten-function, I. Ueber den angeblichen Gehörsinn und das -angebliche Gehörorgan der Crustaceen, Arch. f. d. ges. Physiol., vol. -73, pp. 1-49, 1898; Idem. II. Versuche an Crustaceen, Arch. f. d. ges. -Physiol., vol. 74, pp. 364-382, 1899.] - -[Footnote 242: The Otocyst of Decapod Crustacea, Bull. Mus. Comp. Zoöl. -Harv. Univ., vol. 36, pp. 165-251, 1901. (Contributions, no. 123.)] - -[Footnote 243: Das Verhalten wirbelloser Thiere auf der Drehscheibe, -Zeitsch. f. Psych. und Physiol. d. Sinnesorgane, vol. 3, pp. 185-192, -1892.] - -[Footnote 244: Weitere Beiträge zur Physiologie des Ohrenlabyrinthes, -II. Mittheilung, Versuche an Krebsen, Sitzungsb. Kais. Akad. Wiss., -Wien., vol. 102 (Part. 3), pp. 149-174, 1893.] - -[Footnote 245: Ueber die Bedeutung der Otolithenorgane für die -geotropischen Functionen von Astacus fluviatilis, Arch. f. d. ges. -Physiol., vol. 54, pp. 531-537, 1893.] - -[Footnote 246: Das Nervensystem von Carcinus mænas, I. Arch. f. mikros. -Anat., vol. 50, pp. 460-547, 589-640, 1897.] - -[Footnote 247: Contribution to the Comparative Physiology of -Compensatory Movements, Amer. Jour. of Physiol., vol. 3, pp. 86-114, -1899.] - -[Footnote 248: The Reactions of Copepods to Various Stimuli, Bull. U. -S. Fish Comm., vol. 21, pp. 103-123, 1902.] - -[Footnote 249: General Physiology, English translation by Frederic S. -Lee, 1899.] - -[Footnote 250: Recherches pour servir à l'histoire des systèmes -nerveux, musculaire, et glandulaire de l'écrevisse, Ann. des Sci. Nat., -series 5, vol. 9, pp. 99-280; vol. 10, pp. 5-54, 1868.] - -[Footnote 251: The Sense of Touch in Astacus, Proc. Roy. Physiol. Soc. -Edinburgh, vol. 9, pp. 151-179, 1886.] - - - PRINTED AT THE RIVERSIDE PRESS - H. O. HOUGHTON & CO. - CAMBRIDGE, MASS., U. S. A. - - * * * * * - +----------------------------------------------------------------+ - | | - | Transcriber notes: | - | | - | Please note, _underscore_ indicates italics, equals sign around| - | the word indicates bold. | - | Fixed various punctuation. | - | P.47. 'to +5.93' may be 'to +:+5.93', however leaving it. | - | P.142. The Standard for F calculation should be 110.40 total, | - | not 122.40, with the average 3.94, not 4.35. Corrected table. | - | P.47. 'for eyes at 0' added a degree like the others. | - | P.272. 'abcab, cabe', changed 'cabe' to 'cabc 'as there is no | - | 'e' and it looks to be 'c'. | - | P.143. The Standards for Active M. Total calculation should | - | be 65.40, not 59.40, with the average 4.67, not 4.24. | - | The average for Total Passive M. should be 71.00 not 72.00. | - | Corrected table. | - | P.144. The Standards for F. Total calculation should be 120.11,| - | not 117.04, with the average 4.45, not 4.33. The average for | - | M. should be 4.19 not 4.20. Corrected table. | - | P.145. Correct the net results on table IV. | - | First table: | - | Raised or lowered #25 2.1 to 2.7. #27 8.9 to 8.7. #28 3.5 to 4.| - | Totals: 131 total is 132. 48.1 total is 47.9. 270 to 271.1. | - | Net lowered 221.9 change to 223.2. | - | Average lowering of each color judgment, 221.9/756 = .293 | - | change to: 223.2/756 = .295 | - | % of judgments of color not affected, 131/756 = 17+ is | - | 132/756 = 17+. | - | | - | Second table: | - | Raised or lowered, #8 36.3 is 36.4. #14 3.72 is 37.2. | - | Total Raised 829.7 is 749.8, Net lowered 820.9 is 741. | - | Average lowering of each tone judgment, 1.08+ is .98+ | - | | - | P.146. Table V. 2nd.--Lowered #18 8.2 is 8.6, change the | - | total to 20.4. | - | Net lowered change from 581.3 to 560.9 | - | | - | P.147. | - |1st table: The Net + raised should be 640.5, not 649.5; with | - | the 'Average raising of each tone judgment,' being 1.69, not | - | 1.71. Changed in table. | - |2nd table: -3.3 Net result lowered in #11 moved to | - | #12 and is now +3.3. No figures affected. | - | | - | P.149. Table VII. 1st table. | - | #15 Net result + 1 should be - 1. Moved. This does not affect | - | negative figures. | - | However, the + figure total is 197.5, not 186.5. | - | Making the net raised 182.3. | - | Averaging raising of each tone judgment, .45 is .48+ | - | | - | P.150. Table VIII. | - | 1st table. #16. 1 Raised is 1 Lowered. Moved. #21 Raised 2.2 | - | is 3.2, changed. | - | Total Net Result needs to be changed from 11. to 12. | - | Total Raised net result needs to be changed from 211.7 | - | to 221.9, making Net raised = 209.9. | - | Average raising of each tone judgment, .52 is .55+ | - | | - | P.151. Table IX. | - | 2nd table. #13. raised 41.6 is 41.8. Changed. | - | Total for Net Result Raised 130.0 is 150.2. . | - | Net raised Grand total is 88.8. | - | Average raising of each active touch judgment, .17+ is .22+ | - | | - | P.152. Table X. | - | 1st table. #4 Net result raised, 4.3 is 4.6 = Total 57. | - | Net lowered is 54.4. | - | | - | P.153. Table XI. First table. No. of colour 10-17 illegible. | - | corrected. | - | Points raised total & net raised 282.2 is 292.2. | - | Average raising of each color judgment, .72- is .75-. | - | | - | 2nd. table. #2. Net Result - 13 changed to 11. | - | Total Net Result - 56 is 54. | - | Net raised, 104 is 106. | - | Avererage .26+ is .27+. | - | | - | P.154. Table XII. | - | First table. Total of column Raised, 226 change to 22 | - | Total of column Lowered, 100 change to 101 | - | | - | P.313. 'obseved' changed to observed. | - | Table I. Obs B row, 13.9 sec., taken out sec. | - | | - | P.400. (b) 'irrevelant' changed to 'irrelevant'. | - | Footnote 128: 'Wahrscheinlichkeitseechnung' changed to | - | 'Wahrscheinlichkeitsrechnung' | - | P.463. moved 0 & 0 up one column in L. row of table from the | - | percentage line | - | P.499. Table. 23 Huggins. c. N. 98 first column '+55' changed | - | to +'5.5'. | - | P.550. Added closing quotation at: is markedly thinner." | - | P.551. 'under expermental' changed to 'under experimental'. | - | Footnote 141. 'Woods Holl' changed to 'Woods Hole'. | - | P.583. 'thoughout' changed to 'throughout'. | - | P.594. Fig. 4. 'The rise curve' changed to 'The rise on curve'.| - | P.606. 'mimimize' changed to 'minimize'. | - | P.638. Table XI. No. II, first row, 90deg: the minus was added.| - | Note: Carat followed by { } indicates superscription. | - | | - +----------------------------------------------------------------+ - -*** END OF THE PROJECT GUTENBERG EBOOK HARVARD PSYCHOLOGICAL STUDIES, -VOLUME II *** - -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the -United States without permission and without paying copyright -royalties. Special rules, set forth in the General Terms of Use part -of this license, apply to copying and distributing Project -Gutenberg-tm electronic works to protect the PROJECT GUTENBERG-tm -concept and trademark. 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