Classics in the History of Psychology

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Christopher D. Green
York University, Toronto, Ontario

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On the Witness Stand:
Essays on Psychology and Crime

Hugo Münsterberg (1908/1925)


THERE had been an automobile accident. Before the court one of the witnesses, who had sworn to tell "the whole truth, and nothing but the truth," declared that the entire road was dry and dusty; the other swore that it had rained and the road was muddy. The one said that the automobile was running very slowly; the other, that he had never seen an automobile rushing more rapidly. The first swore that there were only two or three people on the village road; the other, that a large number of men, women, and children were passing by. Both witnesses were highly respectable gentlemen, neither of whom had the slightest interest in changing the facts as he remembered them.

I find among my notes another case, where everything depended upon the time which had passed between a whistle signal from the street and the noise of an explosion. It was of the greatest importance for the court to know whether the time was long enough to walk a certain distance for [p. 16] which at least half a minute was needed. Of two unbiassed witnesses, one swore that the time was less than ten seconds; the other that it was more than one minute. Again, there was a case where it was essential to find out whether at a certain riot the number of guests in the hall was larger than the forty who had been invited to attend. There were witnesses who insisted that there could not have been more than twenty persons present, and others who were sure that they saw more than ne hundred. In a case of poisoning, some members of the family testified that the beverage had a disagreeable, sour taste, others, that it was tasteless, and others, that it was sweet. In some Bowery wrangle, one witness was quite certain that a rowdy had taken a beer-mug and kept it in his fist while he beat with it the skull of his comrade; while others saw that the two were separated by a long table, and that the assailant used the mug as a missile, throwing it a distance of six or eight feet. In another trial, one witness noticed at the sea-shore in moonlight a woman with a child, while another witness was not less sure that it was a man with a dog. And only recently passengers in a [p. 17] train which passed a courtyard were sure, and swore, that they had taken in at a glance the distinct picture of a man whipping a child; one swore that he had a clean-shaven face, a hat, and was standing, while another swore that he had a full beard, no hat, and was sitting on a bench. The other day two most reliable expert shorthand writers felt sure that they had heard the utterances which they wrote down, and yet the records differed widely in important points.

There is no need of heaping up such illustrations from actual cases, as everyone who remembers the last half-dozen murder trials of his city knows with what regularity these differences in reports of witnesses occur. We may abstract from all cases which demand technical knowledge; we want to speak here only of direct observations and of impressions which do not need any special acquaintance with the matter. Wherever real professional knowledge is needed, the door is, of course, open to every variety of opinion, and one famous expert may conscientiously contradict the other. No, we speak here only of those impressions for which every layman is prepared and [p. 18] where there can be no difference of opinion. We further abstract entirely from all cases of intentional deception; the witness who lies offers no psychological interest for the student of illusions. And we exclude all questions of mental disease. Thus there remain the unintentional mistakes of the sound mind, -- and the psychologist must ask at once, Are they all of the same order? Is it inasmuch as the contradictory evidence has to be enough to label them simply as illusions memory. To make memory responsible is indeed the routine way. It is generally taken for granted that we all perceive our surroundings uniformly. In case there were only twenty men in the hall, no one could have seen one hundred, In case the road was muddy, no one can have seen in dusty. In case the man was shaved, no one can have seen the beard. If there is still disagreement, it must have crept in through the trickery of memory. The perception must be correct; its later reproduction may be false. But do we really all perceive the same thing, and does it have the same meaning to us in our immediated absorption of the surrounding world? Is the court sufficiently aware [p. 19] of the great differences between men's perceptions, and does the court take sufficient trouble to examine the capacities and habits with which the witness moves through the world which he believes he observes? Of course some kind of a "'common-sense" consideration has entered, consciously or unconsciously, into hundreds of judicial decisions, inasmuch as the contradictory evidence has to be sifted. The judges have on such occasions more of less boldly philosophised or psychologised on their own account; but to consult the psychological authorities was out of the question. Legal theorists have even proudly boasted of the fact that the judges always found their way without psychological advice, and yet the records of such cases, for instance, in railroad damages, quickly show that the psychological inspirations of the beach are often directly the opposite of demonstrable facts. To be sure, the judge may bolster up the case with preceding decisions, but even if the old decision was justified, is such an amateur psychologist prepared to decide whether the mental situation is really the same in the new case? Such judicial self-help was unavoidable as long as the [p. 20] psychology of earlier times was hazy and vague but all that has changed with the exact character of the new psychology.

The study of these powers no longer lies outside of the realm of science. The progress of experimental psychology makes it an absurd incongruity that the State should devote its fullest energy to the clearing up of all the physical happenings, but should never ask the psychological expert to determine the value of that factor which becomes most influential-the mind of the witness. The demand that the memory of the witness should be tested with the methods of modern psychology has been raised sometimes, but it seems necessary to add that the study of his perceptive judgment will have to find its way into the court-room, too.

Last winter I made, quite by the way, a little experiment with the students of my regular psychology course in Harvard. Several hundred young men, mostly between twenty and twenty-three, took part. It was a test of a very trivial sort. I asked them simply, without any theoretical introduction, at the beginning of an ordinary lecture, to write down careful answers to a number [p. 21] of questions referring to that which they would see or hear. I urged them to do it as conscientiously and carefully as possible, and the hundreds of answers which I received showed clearly that every one had done his best. I shall confine my report to the first hundred papers taken up at random. At first I showed them a large sheet of white cardboard on which fifty little black squares were pasted in irregular order. I exposed it for five seconds, and asked them how many black spots were on the sheet. The answers varied between twenty-five and two hundred. The answer, over one hundred, was more frequent than that of below fifty. Only three felt unable to give a definite reply. Then I showed a cardboard which contained only twenty such spots. This time the replies ran up to seventy and down to ten. We had here highly trained, careful observers, whose attention was concentrated on the material, and who had full time for quiet scrutiny. Yet in both cases there were some who believed that they saw seven or eight times more points than some others saw; and yet we should be disinclined to believe in the sincerity of two witnesses, of whom one felt sure [p. 21] that he saw two hundred persons in a hall in which the other found only twenty-five.

My next question referred to the perception of time. I asked the students to give the number of seconds which passed between two loud clicks. I separated the two clicks at first by ten seconds, and in a further experiment by three seconds. When the distance was ten, the answers varied between half a second and sixty seconds, a good number judging forty-five seconds as the right time. The one who called it half a second was a Chinese, while all those whose judgments ranged from one second to sixty seconds were average Americans. When the objective time was three seconds, the answers varied between half a second and fifteen seconds. I emphasise that these large fluctuations showed themselves in spite of the fact that the students knew beforehand that they were to estimate the time interval. The variations would probably have been still greater if the question had been put to them after hearing the sound without previous information; and yet a district attorney hopes for a reliable reply when he inquires of a witness, perhaps of a cabman, how [p. 23] much time passed by between a cry and the shooting in the cab.

In my third experiment I wanted to find out how rapidity is estimated. I had on the platform a large clock with a white dial over which one black pointer moved once around in five seconds. The end of the black pointer, which had the form of an arrow, moved over the edge of the dial with a velocity of ten centimeters in one second; that is, in one second the arrow moved through a space of about a finger's length. Now, I made this clock go for a whole minute, and asked the observers to watch carefully the rapidity of the arrow, and to describe, either in figures or by comparisons with moving objects, the speed with which that arrow moved along. Most men preferred comparisons with other objects. The list begins as follows: man walking slowly; accommodation-train; bicycle-rider; funeral cortège in a city street; trotting dog; faster than trot of man; electric car; express train; goldfish in water; fastest automobile speed; very slowly, like a snail; lively spider; and so on. Would it seem possible that university students, trained in observation, could watch a movement [p. 24] constantly through a whole minute, and yet disagree whether it moved as slowly as a snail or as rapidly as an express-train. And yet it is evident that the form of the experiment excluded every possible mistake of memory and excluded every suggestive influence. The observation was made deliberately and without haste. Those who judged in figures showed not less variation. The list begins: one revolution in two seconds; one revolution in forty-five seconds; three inches a second; twelve feet a second; thirty seconds to the hundred yards; seven miles an hour; fifteen miles an hour; forty miles an hour; and so on. In reality the arrow would have moved in an hour about a third of a mile. Not a few of the judgments, therefore, multiplied the speed by more than one hundred.

In my next test I asked the class to describe the sound they would hear and to say from what source it came. The sound which I produced was the tone of a large tuning-fork, which I struck with a little hammer below the desk, invisibly to the students. Among the hundred students whose papers I examined for this record were exactly [p. 25] two who recognised it as a tuning-fork tone. All the other judgments took it for a bell, or an organ-pipe, or a muffled gong, or a brazen instrument, or a horn, or a 'cello string, or a violin, and so on. Or they compared it with as different noises as the growl of a lion, a steam whistle, a fog-horn, a fly-wheel, a human song, and what not. The description, on the other hand, called it: soft, mellow, humming, deep, dull, solemn, resonant, penetrating, full, rumbling, clear, low; but then again, rough, sharp, whistling, and so on. Again I insist that every one knew beforehand that he was to observe the tone, which I announced by a signal. How much more would the judgments have differed if the tone had come in unexpectedly? -- a tone which even now appeared so soft to some and so rough to others -- like a bell to one and like a whistle to his neighbour.

I turn to a few experiments in which I showed several sheets of white cardboard, of which each contained a variety of dark and light ink-spots in a somewhat fantastic arrangement. Each of these cards was shown for two seconds, and it was suggested that these rough ink-drawings represented [p. 26] something in the outer world. Immediately after seeing one, the students were to write down what the drawing represented. In some cases the subjects remained sceptical and declared that those spots did not represent anything, but were merely blots of ink. In the larger number the suggestion was effective, and a definite object was recognised. The list of answers for one picture begins: soldiers in a valley; grapes; a palace; river-bank; Japanese landscape; foliage; rabbit; woodland scene; town with towers; rising storm; shore of lake; garden; flags; men in landscape; hair in curling-papers; china plate; war picture; country square; lake in a jungle; trees with stone wall; clouds; harvest scene; elephant; map; lake with castle in background; trees; and so on. The list of votes for the next picture, which had finer details, started with: spider; landscape; turtle; butterfly; woman's head; bunch of war-flags; ballet-dancers; crowd of people; cactus plant; skunk going down a log; centipede; boat on pond; crow's nest beetle; flower; island; and so forth. There are hardly any repetitions, with the exception that the vague term "landscape" occurs often. Of course, [p. 27] we know, since the days of Hamlet and Polonius, that a cloud can look like a camel and like a whale. And yet such an abundance of variations was hardly to be foreseen.

My next question did not refer to immediate perception, but to a memory image so vividly at every one's disposal that I assumed a right to substitute it directly for a perception. I asked my men to compare the apparent size of the full moon to that of some object held in the hand at arm's length. I explained the question carefully, and said that they were to describe an object just large enough, when seen at arm's length, to cover the whole full moon. My list of answers begins as follows: quarter of a dollar; fair-sized canteloupe; at the horizon, large dinner plate, overhead, dessert-plate; my watch; six inches in diameter; silver dollar; hundred times as large as my watch; man's head; fifty-cent piece; nine inches in diameter; grape-fruit; carriage-wheel; butter-plate; orange; ten feet; two inches; one-cent piece; school-room clock; a pea; soup-plate; fountain-pen; lemon-pie; palm of the hand; three feet in diameter: enough to show, again, the overwhelming [p. 28] manifoldness of the impressions received. To the surprise of my readers, perhaps, it may be added at once that the only man who was right was the one who compared it to a pea. It is most probable that the results would not have been different if I had asked the question on a moonlight night with the full moon overhead. The substitution of the memory image for the immediate perception can hardly have impaired the correctness of the judgments. If in any court the size of a distant object were to be given by witnesses, and one man declared it appeared as large as a pea at arm's distance, and the second as large as a lemon-pie and the third ten feet in diameter, it would hardly be fair to form an objective judgment till the psychologist had found out which mental factors were entering into that estimate.

There were many more experiments in the list; but as I want to avoid all technicality, I refer to only two more, which are somewhat related. First, I showed to the men some pairs of coloured paper squares, and they had ample time to write down which of the two appeared to them darker. At first it was a red and a blue; then a blue and a green; [p. 29] and finally a blue and a grey. My interest was engaged entirely with the last pair. The grey was objectively far lighter than the dark blue, and any one with an unbiassed mind who looked at those two squares of paper could have not the slightest doubt that the blue was darker. Yet about one-fifth of the men wrote that the grey was darker.

Now, let us keep this in mind in looking over the last experiment, which I want to report. I stood on the platform behind a low desk and begged the men to watch and to describe everything which I was going to do from one given signal to another. As soon as the signal was given, I lifted with my right hand a little revolving wheel with a colour-disk and made it run and change its color, and all the time, while I kept the little instrument at the height of my head, I turned my eyes eagerly toward it. While this was going on, up to the closing signal, I took with my left hand, at first, a pencil from my vest-pocket and wrote something at the desk; then I took my watch out and laid it on the table; then I took a silver cigarette-box from my pocket, opened it, took a cigarette out of it, closed it with a loud click, and [p. 30] returned it to my pocket; and then came the ending signal. The results showed that eighteen of the hundred had not noticed anything of all that I was doing with my left hand. Pencil and watch and cigarettes had simply not existed for them. The mere fact that I myself seemed to give all my attention to the colour-wheel had evidently inhibited in them the impressions of the other side. Yet I had made my movements of the left arm so ostentatiously, and I had beforehand so earnestly insisted that they ought to watch every single movement, that I hardly expected to make any one overlook the larger part of my actions. It showed that the medium, famous for her slate tricks, was right when she asserted that as soon as she succeeded in turning the attention of her client to the slate in her hand, he would not notice if an elephant should pass behind her through the room.

But the chief interest belongs to the surprising fact that of those eighteen men, fourteen were the same who, in the foregoing experiment, judged the light grey to be darker than the dark blue. That coincidence was, of course, not chance. In the case of the darkness experiment the mere idea [p. 31] of greyness gave to their suggestible minds the belief that the colourless grey must be darker than any colour. They evidently did not judge at all from the optical impression, but entirely from their conception of grey as darkness. The coincidence, therefore, proved clearly how very quickly a little experiment such as this with a piece of blue and grey paper, which can be performed in a few seconds, can pick out for us those minds which are probably unfit to report, whether an action has been performed in their presence or not. Whatever they expect to see they do see; and if the attention is turned in one direction, they are blind and deaf and idiotic in the other.

Enough of my class-room experiments. Might they not indeed work as a warning against the blind confidence in the observations of the average normal man, and might they not reinforce the demand for a more careful study of the individual differences between those on the witness stand? Of course, such study would be one-sided if the psychologist were only to emphasise the varieties of men and the differences by which one man's judgment and observation may be counted on to throw [p. 32] out an opposite report from that of another man. No, the psychologist in the court-room should certainly give not less attention to the analysis of those illusions which are common to all men and of which as yet common sense knows too little. The jurymen and the judge do not discriminate, whether the witness tells that he saw in late twilight a woman in a red gown or one in a blue gown. They are not expected to know that such a faint light would still allow the blue colour sensation to come in, while the red colour sensation would have disappeared.

They are not obliged to know what directions of sound are mixed up by all of us and what are discriminated they do not know, perhaps, that we can never be in doubt whether we heard on the country road a cry from the right or from the left, but we may be utterly unable to say whether we heard it from in front or from behind. They have no reason to know that the victim of a crime; nay have been utterly unable to perceive that he was stabbed with a pointed dagger; he may have felt it like a dull blow. We hear the witnesses talking about the taste of poisoned liquids, and there [p. 33] is probably no one in the jury-box who knows enough of physiological psychology to be aware that the same substance may taste quite differently on different parts of the tongue. We may hear quarrelling parties in a civil suit testify as to the size and length and form of a field as it appeared to them, and yet there is no one to remind the court that the same distance must appear quite differently under a hundred different conditions. The judge listens, perhaps, to a description of things which the witness has secretly seen through the keyhole of the door; he does not understand why all the judgments as to the size of objects and their place are probably erroneous under such circumstances. The witness may be sure of having felt something wet, and yet he may have felt only some smooth, cold metal. In short, every chapter and sub-chapter of sense psychology may help to clear up the chaos and the confusion which prevail in the observation of witnesses.

But, as we have insisted, it is never a question of pure sense perception. Associations, judgments, suggestions, penetrate into every one of our observations. We know from the drawings of [p. 34] children how they believe that they see all that they know really exists; and so do we ourselves believe that we perceive at least all that we expect. I remember some experiments in my laboratory where I showed printed words with an instantaneous illumination. Whenever I spoke a sentence before-hand, I was able to influence the seeing of the word. The printed word was courage: I said something about the university life, and the subject read the word as college. The printed word was Philistines: I, apparently without intention, had said something about colonial policy, and my subject read Philippines. In this way, of course, the fraudulent advertisement makes us overlook some essential element which may change the meaning of the offer entirely. Experimental psychology has at last cleared the ground, and to ignore this whole science and to be satisfied with the primitive psychology of common sense seems really out of order when crime and punishment are in question and the analysis of the mind of the witness might change the whole aspect of the case.

It is enough if we have to suffer from these mental varieties in our daily life; at least the [p. 35] court-room ought to come nearer to the truth, and ought to show the way. The other organs of society may then slowly follow. It may be that, ultimately, even the newspapers may learn then from the legal practice, and may take care that their witnesses be examined, too, as to their capacity of observation. Those experiments described from my class-room recommend at least mildness of judgment when we compare the newspaper reports with each other. Since I saw that my own students do not know whether a point moves with the slowness of a snail or with the rapidity of an express-train; whether a time interval is half a second or a whole minute; whether there are twenty-five points or two hundred; whether a tone comes from a whistle, a gong, or a violin; whether the moon is small as a pea or large as a man, -- I am not surprised any more when I read the reports of the papers.

I had occasion recently to make an address on peace in New York before a large gathering, to which there was an unexpected and somewhat spirited reply. The reporters sat immediately in front of the platform. One man wrote that the [p. 36] audience was so surprised by my speech that it received it in complete silence; another wrote that I was constantly interrupted by loud applause, and that at the end of my address the applause continued for minutes. The one wrote that during my opponent's speech I was constantly smiling; the other noticed that my face remained grave and without a smile. The one said that I grew purple-red from excitement; and the other found that I grew white like chalk. The one told us that my critic, while speaking, walked up and down the large stage; and the other, that he stood all the while at my side and patted me in a fatherly way on the shoulder. And Mr. Dooley finally heard that before I made my speech on peace I was introduced as the Professor from the Harvard War School -- but it may be that Mr. Dooley was not himself present.