Experimental psychology and its bearing upon culture

Preface

THE aim of the present volume is to give an untechnical account of certain groups of experiments in psychology and to show something of their significance. As to the particular experiments that are of most interest and importance in this field, of course opinions would differ. Every one who works in psychology soon finds himself attracted in special directions, and on the whole it is perhaps well for a writer to respect this element of personal affinity. - But in preparing the book, I have aimed to present, as best I could within somewhat narrow limits, the character and value of the laboratory psychology, especially as bearing upon our moral and philosophical interests. In this way the book is planned to occupy a different field from that already so well covered by the excellent works of Titchener, Sanford, and Scripture.

Considerable attention has thus been given to the interpretation of the experimental results, —to their more immediate scientific meaning, as well as to what they suggest for life and for speculation. But first and foremost the purpose has been to get the experiments themselves clearly before the reader, so that the main features of the research work might Vv vi Preface be seen concretely. Many of the experiments thus described are already familiar to students of psychology, but a number appear here for the first time.

It would be difficult, if not impossible, to tell in detail of my obligation to others. I cannot forbear to mention, however, the Council and members of the Philosophical Union of the University of California, who some years ago invited me to speak to them upon the character and import of psychological experiments, and to whose interest and encouragement the present volume largely owes its existence. I am also particularly grateful to my friend, Professor Bakewell, who has kindly read the book in proof, and has given me throughout most helpful advice. In preparing the chapters dealing with the psychology of A%sthetics I have received great benefit from the criticism of my friend, Mr. Frederic C. Torrey, and I am indebted to my colleague, Dr. Montague, for similar aid in regard to certain problems of Space. For the photographs required in many of the illustrations I must thank Mr. Brand, the former Assistant in the Laboratory, and Mr. Dunlap, the present Assistant. There is a more general indebtedness to my honored teacher, Professor Wundt of Leipzig, who introduced me to the experimental work. But I owe most of all to my teacher and friend, Professor Howison, to whom I should have been glad to dedicate affectionately this book were I not so fully conscious of its shortcomings.

Contents

CHAPTER PAGE

I. Historical Introduction . : : ; A : I II. The General Character of Psychological Experiments 17 III. The Possibility of Mental Measurements ES rep nie &

IV. The Evidence for Unconscious Ideas . : Mem OG V. Further Considerations as to the Unconscious ee oe VI. Illusions and their Significance. ; : as

Chapter I Historical Introduction

ONLy within a few years has it been generally known that experiments on the mind were being attempted. Doubtless the whole subject has still for some an air of novelty and perhaps almost of faddishness, as if it had sprung into life but yesterday and would pass away to-morrow. But the fact is, that like so many things that suddenly catch the public eye, the days of its growth have been long and quiet, and the suddenness is not of its appearance but only of noising its fame abroad. For just as Darwinism was germinating in the days of Heraclitus, so we can now discover the premonitions of what is often called the ‘‘ New Psychology”’ at least as early as Aristotle. He performed experiments in psychology, and ever since his time traces of such work can be found. The modern turn, then, is not in discovering the possibility of psychological experiments, but in becoming distinctly conscious of their value, —in utilizing them, therefore, to a greater extent and in developing something like a critical procedure in carrying them out.

To understand the motives that have led to the laboratory work in psychology one must recall that for centuries the peculiar and solitary method of

B I

The roots of the

“ New Psychology.”

Reasons for its growth.

Difficulties of introspection.

getting at the facts of mind was supposed to be that of self-observation, or of introspection, as it is more frequently called. Whether we recognize the method by name or not, it certainly is one with which all are familiar. You can probably tell, for instance, whether the thought of territorial expansion beyond the seas meets your approval, or whether you view it with mingled consent and distrust, or perhaps with unmixed regret. This direct acquaintance with the state of our minds which all of us to some extent possess, is the essence of introspection, and, as I have said, was for centuries the only recognized mode of collecting the data of psychology. The psychologist turned his mental gaze inward, and reported as best he could what he there observed. The objects of this science were supposed to be noted by some inner sense, in contrast with our eyes and ears, with which we observe external objects, the materials for the familiar natural sciences.

Now it can be pretty clearly shown that self-observation must always be the fundamental method of psychology; it permits the initial step and furnishes us with all the really first-hand knowledge of the mental world that we possess. But for all that, one must not fail to recognize the historical fact that psychology, as long as it relied solely on this method, was at a striking disadvantage compared with the natural sciences generally. In the first place, the posture of introspection is cramped and unnatural. We are practical beings and, if we are healthy, life has trained us to be interested in things beyond ourselves. The habit of self-observation, if not a morbid trait, as in Amiel or Marie Bashkirtseff, is at least artificial, and tends to throw the whole mental train off the track. Try, for instance, to be deeply interested in what some one is saying to you, and at the same time to scrutinize and report to yourself how it feels to be deeply interested. Many of our most important mental states positively refuse to be gazed at in this way; they elude our direct scrutiny, and the best we can do is— paradoxical as it sounds — to recall how they looked when we were not looking at them.! Compared with those sciences whose materials are absolutely indifferent to any amount of weighing and grinding and heating and examination, one can well understand how the progress of psychology was inevitably slow and, to some extent, disappointing. Moreover, there is something peculiarly private and incommunicable in every fact of mind. We cannot, as a mineralogist may, hand around our particular speci-

1 This fugitive character of many of our mental states has often been pointed to in proof of the impossibility of introspection. The truth of course is, that only by means of introspection do we know that our mental processes are changeable and elusive. It is curious that when critics like Maudsley, at least in his earlier writings, make such short work of self-observation as a psychological method, they do not see that most of the facts they bring forth as evidence of its fundamental inadequacy are obtained only by this very self-observation. They trust their own introspection in its report that the mental life is always in flux, that attention to our mental processes alters their character, etc., and then argue that this discredits the whole procedure ; whereas these very results show that the method, within certain limits, is the readiest and most reliable we have.

Such criticisms also invariably dwell on those mental processes (the emotions, for instance) that are most liable to interruption if we attend to them, and cannot well be repeated at will, and leave out of account the many processes, such as perceptions and judgments and certain memory-images, that can be repeated and observed with great security.

Desire for “ objective” methods.

Influence of British empiricism.

Bacon to Hume.

Berkeley's psychology of space, men of judgment or volition, and ask others to verify the results of our examination of it. The results of self-observation consequently seem to be personal and “subjective,” and lacking in that universality which is the pride of chemistry and of physics. It was to be expected, then, that there would be a longing for some mode of investigation wider in its application and more fruitful than self-observation, and that in due time there would be an organized revolt in favor of “ objective” methods, among which the experimental procedure was to have an important place.

The present-day experimental study of mind is but the latest development of that scientific movement of which Francis Bacon was chief spokesman. Bacon led to Hobbes, with whom there began the strong. empirical movement in psychology in the seventeenth and eighteenth centuries, to which our present methods of investigating the mind owe so much. The English were the first to become interested in psychology for its own sake. On the continent it had always been a secondary matter, a mere appendage to metaphysics; whereas the English, in Locke and Berkeley and Hume, almost reversed the order and made metaphysics a subordinate chapter of psychology. At any rate, the facts of our everyday mental life at last came to their own, and in the writers just mentioned some of the chief problems of the experimental work began to be mapped out. Berkeley’s remarkable ‘ Essay toward a New Theory of Vision” shows a distinctly modern attitude toward psychology, which at that day it would indeed be difficult to parallel. He states the particular question, how we are able to discern by sight the size and distance and shape of objects ; and after a masterly array of facts and arguments, comes to his well-known conclusion that none of these aspects of things is given us by vision alone and of itself, but only by vision in conjunction with our sense of touch. Not until we are able to translate our impressions of sight into terms of touch and muscular movement, does our vision come to mean for us anything spatial. If history had been as silent in regard to the life and time of Berkeley as it is about the personality of Shakespeare, not only his theory but also the manner in which he supports it might have given excellent grounds for some clever critic to claim that the good bishop had merely lent his name to the production of some shy disciple of Helmholtz or of Wundt. So far as I am aware, Berkeley gives the first instance of a problem of psychology being thus disentangled and honored with a special and purely psychological treatise.

As if to furnish the experimental verification which Berkeley himself recognized was needed for his theory, there soon appeared the first of a series of contributions by various physicians in the “ Philosophical Transactions of the Royal Society of London,” giving the results of experiments on persons operated upon for congenital cataract. The most celebrated case was that reported by Cheselden in 1728, and this was followed by others from Home, Ware, Wardrop, and many besides. If Berkeley’s theory were correct, then a person gaining his sight sud-

Surgeons’ experiments to test his view.

Place of the English associationists.

denly, as these patients for the most part did, ought not to be able to discern the shape or distance or direction of objects by sight alone, but only by sight working in combination with touch. A number of tests were accordingly made, the detailed discussion of which will come more appropriately in a later chapter. Here it is sufficient to say that the results have generally been considered as strongly.in favor of Berkeley’s theory; but this interpretation is, I think, open to question, and needs a careful review. The interesting fact in the present connection, however, is not whether the evidence he offered is adequate or inadequate, but that Berkeley and a large body of men recognized in this practical way that there were important psychological problems which were to be decided, not by the traditional introspective method, but by external and experimental means.

We may pass by the later English development in Hartley, James Mill, John Stuart Mill, and Spencer. It is of great importance for the history of psychology in general, but not for the growth of the experimental side. These men were system-makers, interested most of all in working out what seemed to them to be the one great explanatory principle in psychology, —the principle of association. It is well that there are such men, who feel that the subordinate questions of a subject are to be answered by learning the common secret of the whole. But experimental psychology is indebted perhaps more to those whose interests run to the opposite pole,—who feel that the search for the secret of the whole may be deferred until we know more about the subordinate parts of that whole. Wisdom is doubtless justified of both kinds of children. But it is easy to see that when the English psychological activity turned more and more to buttressing up a system, the atmosphere there grew less stimulating for the other kind of work. Germany, on the other hand, was running exactly the opposite course. The Germans, after their long line of philosophers from Leibnitz to Hegel, were at last coming to the point which England and France had reached long before,—were losing faith in philosophy altogether, and were preparing to attack the problems of mind from the other side.

But in Germany, as in England, the interest in the experimental study of consciousness was not developed entirely from within the ranks of the psychologists themselves. Goethe, for instance, was among the early experimenters in psychology. He made an interesting study of the influence of color upon the emotions, by observing the landscape through glasses now of one color and now of another, and noting the contrasting moods induced by the different hues.1 And some experiments which bear a much closer connection with the direct historical development came indeed from the astronomers, brought about, of course, not by any special interest in psychology, but by the practical needs of their observatory work.

According to the older method of determining the time when a star reached its meridian, the observer watched the passage of the star through the field of his telescope, and at the same time listened

The Germans weary of metaphysics.

Goethe's experiments with color.

Psychological experiments by astronomers.

Determination of ‘“personal equation,”

Influence of the physiologists.

8 Experimental Psychology x.

to the beats of a clock near at hand. As the critical moment approached, he had now to perform the somewhat difficult task of noting at what instant in the series of pendulum beats the passage of the star across the meridian (marked by a hair-line in the field of the telescope) actually occurred. To do this accurately he must tell not merely at which beat of the clock this transit took place, but since the transit usually occurs somewhere between two beats, he must determine the more exact fraction of a beat which had elapsed when the star reached the meridian. This was the “eye and ear” method, now discarded, by many astronomers, for the chronograph with its electric recorders. The astronomer Bessel noticed as early as 1822 that when different persons observed the very same fact, there were discrepancies which could be accounted for only by the different make-up of the observers themselves. And experiments were accordingly instituted to determine what has since come to be known as “personal equation.” All this was a psychological matter, and the experiments that gave some light on the question were psychological experiments, even though carried on from an interest primarily in quite a different field. Out of these has grown an important group of laboratory investigations in what is called reaction-time, of which more will be said in a later chapter.

But the work which had a more direct influence in developing systematic experimentation in psychology came from the physiologists, especially from those who were interested in the sense-organs. Any one who will turn the pages of the particular volumes of

Hermann’s “ Hand-book” that are devoted to the subject, will see how many experiments were early carried on to discover primarily the function of the sense-organs, but which in so doing laid bare much of the psychology of our sense-perception. Probably few besides professional students appreciate the fact that much of Helmholtz’s labors lay on the psychological side of the border between physiology and psychology, and that he may be claimed for either science. His great works on “ Physiological Optics” and on “Sensations of Tone” are stores of psychological material gathered in, for the most part, through Helmholtz’s own genius for devising and carrying out experiments in this field. And there were many other pioneers in the same region. Vierordt, for example, more than half a century ago, made an experimental study of our sense of time— a field of investigation since then diligently worked in the modern laboratories. And almost with apologies, one ought to mention the phrenologists, Galland Spurzheim. Unscientific as the‘whole spirit of these men was, their curious system undoubtedly did much to stimulate those later experiments regarding the connection between brain and consciousness, that led to the brilliant discoveries in the “localization” of mental function, with which the names of Broca, Goltz, Ferrier, and many others are connected.!

1 The more physiological aspects of psychology are considered at some length in the chapter on “The Connection of Mind and Body.” There is an excellent sketch of the growth of this neural work by Dr. Henry Smith Williams in an article entitled “The Century’s

Progress in Experimental Psychology,” in Harper's Magazine for September, 1899, Vol. 99, p. 512.

Helmholtz’s psychological work.

Phrenology and modern brain localization.

The immediate parentage of experimental psychology.

E, H. Weber.

Character of his experiments.

When we try to trace out, however, not so much the various distant sources, but the immediate parentage of experimental psychology, one must name first of all Ernst Heinrich Weber. With him there begins what we might call an unbroken experimental tradition. Up to Weber’s time (his jforuzt is well along in the second and third quarters of the nineteenth century), and even with many who outlived him, psychological experiments were carried on sporadically and without much appreciation of their true significance. Weber, however, aroused an interest not only in his results, but even more in the experimental method by which his results were obtained. He made men recognize experimentation as a mode of procedure for psychology, —a recognition which since his time has gradually become clearer until now it is no longer open to doubt. So that the historical importance of Weber’s experiments quite overshadows their intrinsic interest. But his contributions so enter into the after-life of the subject, and in telling of his successors one must so often refer to Weber’s Law, that it will perhaps be well to go somewhat into detail at this point, even at the risk of seeming prolix.

In these experiments the more immediate purpose was to determine the relative sensitiveness of different parts of the skin, probably with some appreciation of the value of such tests for the physician. In certain nervous diseases, for instance, the symptoms are in part a lowering or heightening of the sense of touch, and the character and extent of the disease are indicated by comparing the sensitiveness of the

Historical Introduction II patient with that of a normal person. Weber arrived at a table of this normal sensitiveness and its variations for different parts of the body, experimenting with compass points and with weights.

But more important, judged by the amount of discussion they set going, were his experiments on our power of comparing different weights on the skin.

His tests here led him to discover an interesting bit of relativity. He placed a standard weight of 32 drachms on his hand and found that an addition of about 10 drachms made the weight sensibly heavier. But when he used, instead, a standard weight of 32 ounces (eight times heavier than the former standard) the same absolute addition of 10 drachms was no longer detected, but he must make the same relative addition, namely 10 ounces, before the weight was noticeably increased. Stated as a general proposition, applicable not only to weights and pressures, but to all our perceptions, this becomes the famous formula known as Weber’s Law, that our power of detecting His law differences between sensations does not depend on oN eaiaxae the absolute amount of difference in the stimuli, but on its relative amount. And although some might believe that it did not require experiments to show so obvious a truth, yet later researches have demonstrated that it is by no means so obvious after all, and that there are considerable stretches of our mental life where, if the law does hold good, something at least interferes with its clear manifestation.

One of the most important results of Weber’s Fechner and experiments, however, was their effect upon Fech- wanes ner, a German scientist of philosophical bent. He Law, entered with zeal upon the investigation of the problem which Weber’s studies had raised, and for years his daily programme included an hour or more of careful and accumulated tests of the validity of Weber’s Law, by an elaborate method (and for his day, somewhat elaborate apparatus) largely of Fechner’s own devising. Finding that the results he obtained by his thousands of experiments in lifting weights were approximately what the law would require, he recast Weber’s statement into a mathematical formula which, in spite of its impressive logarithmic appearance, is in all probability not so near the actual truth as is Weber’s own simpler expression. Having satisfied the mathematical impulses within him, Fechner next fell to work to point out the philosophical consequences which his formula might imply. The result of his own and Weber’s experiments seemed to him to indicate a peculiar interrelation of brain and mind —that the mind is, in some respects, more sluggish than the brain, and that as we increase the activity of the brain, the activity of the mind increases at a much slower pace. Or, to express his view more exactly and technically, our sensations vary in intensity as the logarithm of the brain-action which corresponds to them.! Because

1 With Fechner the law took the mathematical form: — = log?

Y g F where ¥ represents the intensity of the sensation, 8 the amount of the stimulus, 4 the threshold intensity, and 4 a constant to be determined experimentally for each of the senses. See his Hlemente der Psychophysth, 2d ed., Vol. II, p. 13.

It might be added that the essential point of Fechner’s modification

Fechner believed that his modification of Weber’s Law expressed a fundamental relation between the world of matter and the world of mind, his formula is known as the Psycho-physical Law, and experiments in this line, or even merely in verification of Weber’s Law, are often grouped together under the term “ psycho-physics.”

But whatever we may think of Fechner’s interpretation of his results, his robust faith in experiment and his feeling of the bearing of such work on the fascinating problem of mind and brain did much to accelerate the movement which Weber had inaugurated. With his work is directly connected that of Miiller at Gottingen, whose correspondence with Fechner over their common interests has made an attractive little book. At Miiller’s laboratory one may still see Fechner’s contrivances for his weight of Weber’s Law is often attributed to Weber himself, even by careful writers. The statement of the law, that for the sensation to increase in arithmetical progression the stimulus must increase in geometrical progression, is in the spirit of Fechner rather than of Weber. Weber himself apparently never went into the question of the mathematical relation between stimulus and sensation, and merely expressed the fact that in making comparisons we note the re/ative differences of things, and not their aédsolute differences. (See his De Pulsu, Resorptione, Auditu, et Tactu, Lips., 1834, p. 173; and also his Ueber die Lehre vom Tastsinne und Gemeingefiihle, 1851, p. 105.) And even to this day the facts seem to give no especial warrant for the logarithmic interpretation. If the least perceptible difference may be psychologically a variable, — in other words, since it is perhaps ever increasing as the sensation itself increases, — what is to prevent our believing that stimulus and sensation increase from threshold to acme in practically parallel courses, rather than that the sensation increases at a slower rate than the stimulus, as is so often stated in the text-books as the obvious meaning of the psycho-physical experiments ?

G. E, Miiller,

Wundt and the work at Leipzig.

experiments, and actually still in use, as I know, not far in the past. Other things that he used are treasured at the Leipzig laboratory, in what the assistants there humorously call the “reliquary” of the establishment.

It is, in fact, at Leipzig that one next finds the main line of the experimental tradition. It was there that the first special laboratory for psychology was established by Professor Wundt,—a man who has for many years maintained a preéminent place among those interested in this line of research. Like so many others who have contributed to the development of this side of psychology, Wundt began as a physiologist, although even in his early writings one can detect an interest beyond the material processes involved. But the philosophical and psychological strain in the man’s nature became manifest when in 1874 he published the first edition of his celebrated ‘“ Physiological Psychology,” subsequently many times rewritten until it now consists of some twelve hundred pages and more. In this work Wundt has gathered together the scattered mass of psychological material, in large part from the experiments of the physiologists, and has added the rich results of his own experiments and of the band of workers whom he has had associated with him for many years. In 1879 he induced the University of Leipzig to set aside for him a small space for psychological experiments, and from this modest beginning has come his present laboratory of most impressive size and equipment. Wundt’s laboratory, moreover, is the parent stock from which a host of others of like kind have either directly or indirectly had their origin. The layman can get an impression of its activity from the fact that the Phzlosophische Studien, the official organ of the laboratory, has just closed its career after completing twenty solid volumes. Wundt himself has shown an astonishing power of stimulating the work and at the same time rendering it cautious and critical, and he will certainly always be counted one of the great figures in the history of modern psychology.

This historical sketch ought not to close without some mention of the name of Lotze, whose ‘ Medicinische Psychologie” (1852) is an important forerunner of all our present physiological psychologies. The main current of the experimental stream came less directly through him than through Weber and Fechner; but he was aman incomparably larger than either of them, and must certainly be acknowledged as one of the great forces in developing the work, — his mind was so rich and frank and judicial in regard to the larger problems of the subject, and at the same time so appreciative of the details and bearing of minute scientific research. It would be well if all could preserve the fine balance and interplay of exact observation and large ideas which Lotze always showed. If one were to attempt to trace the intellectual ancestry of Lotze and to account for his philosophical breadth along with the sincere sympathy for the newer methods, this would undoubtedly lead us back through Herbart, with his attempt to found a mechanical and mathematical psychology, to

The importance of Lotze.

Leibnitz’s spirit in the new work,

Leibnitz to whom no human interest ever seems to have been foreign, ranging as his mind did through metaphysics, mathematics, law, and theology, as well as through the minutize of practical concerns, whether of diplomacy or of calculating machines or of the shaping of optical lenses. May the experimental work in psychology always be worthy of its great progenitors !

CHATTER: if

THE GENERAL CHARACTER OF PSYCHOLOGICAL EXPERIMENTS

THE more striking influences that established the experimental method in psychology have been indicated in barest outline. The present chapter will be occupied in showing some of the important characteristics of psychological experiments, and first of all their relation to physiological investigations.

Why was it that the experimental mode of investigating the mind came, in the first instance, chiefly from among the physiologists rather than from those upon whom psychology had a more immediate claim ? The explanation itself is, I believe, a psychological one. The physiologists would perhaps say, as indeed many of them have said, that it is because they themselves have the only true method of getting at the mental life scientifically ; that the only sure avenue to the mind is through the nervous system, and that the professional psychologists who until recently have always tried to get at the facts in some other way were of course doomed to failure. One can expertment, some have said, only on the nervous system, and the older introspective method to which the psychologists clung, naturally excluded the experimental procedure. For this reason experimentation had to begin outside the ranks of the psychologists.

Cc 17

The relation of psychological to physiological experiments,