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)


IT was in a large city which I was visiting for the first time. I went to see the hypnotic experiments of a friend, a physician for nervous diseases. He invited me to witness the treatment of a lady who had been deeply hypnotised by him for a local nervous disturbance. Her mind seemed normal in every respect. She was a woman of wealth and social position. When she was in hypnotic sleep, he suggested to her to return in the afternoon when she would find us both, and, as soon as he took out his watch, to declare her willingness to make a last will in which I should become the only heir to all her property. She had never seen me before and I was introduced to her under a fictitious, indifferent name. When she left the office after awakening from her hypnotic sleep, she did not take any notice of me at all. At the appointed hour she returned, apparently not knowing herself why she came. She found in the parlour, besides her physician and me, three or four others who [p. 176] wanted to watch the development of the experiment. She was not embarrassed. She said that she had passed the house by chance and that she thought it would be nice to show her doctor how much better she felt and to ask whether there was any objection to her going to the theatre. I then began a conversation with her about the opera. We talked for perhaps ten minutes on music and the drama, exactly as if we had met at any dinner party, and there was nothing in the least strange in her ideas or in her expression of them.

Suddenly my friend asked how late it was and, as arranged, took his watch out of his pocket. There was a moment of hesitation. The lady spoke the next few words in a stammering way; but then she rushed on and told us that she had not expected to find such a company, but that her real purpose in coming was to report to me that she had selected me as her heir and that now she wanted accordingly to make her last will. Up to this moment her action has been a mechanical carrying out of the post-hypnotic suggestion, but the really interesting part was now to begin. I told her that there must be a mistake, as she could [p. 177] not have seen me before, and I mentioned a fictitious city in which I claimed to live. At once she replied that she had just spent the last winter in that city, and that she had met me there daily on the street, and that from the first she had planned to leave me all that she owned. I insisted that at least she had never spoken to me. Yes, in that same city she had met me repeatedly in society. I represented to her the unnaturalness of leaving her wealth to a stranger instead of to her children. At once she replied that she had thought it out for years, that it would be a blessing for the children not to be burdened with riches, while she knew that I would use them in a philanthropic way. The others took part in the conversation, scores of arguments were brought up to discourage her from this fantastic plan. For each one she had a long-considered excellent rejoinder.

Finally, I told her directly that, as she knew, she had been hypnotised that morning and that this whole idea of the last will had been planted in her head by the witnessed suggestion of her physician. With a charming smile she replied that she knew all that perfectly well, but that she did not [p. 178] contradict and resist this proposition of the doctor simply because it by chance coincided entirely with her own cherished plans, which had been perfectly firm in her mind for a year. She would have written to me some day soon if I had not come to town. She went on that she was unwilling to hear any further doubts of her sincerity and that she was ready to take an oath that she had made up her mind in favour of such a testament long before she was hypnotised. To put an end to all this, she insisted that paper be brought to her, and then she wrote a codicil which left all her property to the fictitious man from the fictitious town. The doctors present had to sign as witnesses. I put the paper into my pocket, switched the conversation over to the theatre again, and, after a few minutes, she had evidently forgotten the whole episode. She treated me again as a complete stranger; and when I asked whether she happened to know the city before mentioned, I was told that she had once passed through it on the train. When she left the house, she had clearly not the slightest remembrance of that document in my pocket, which we others then burned together.

[p. 179] If I had been present as an uninformed stranger during that afternoon visit, I should have been so completely misled that I could not have thought of any additional inquiry or any further argument to test the validity of the testimony. Everything seemed to harmonise with the one plan which had been put into her mind. All her memories became falsified, all her tastes and emotions were turned upside down, all her life experiences were mingled with and supplemented by untrammelled imagination, coupled with the strongest feeling of certainty and sincerity, and yet everything was moulded by her own mind, with the exception of that one decision which had been urged upon her from the outside.

If a suggestion planted in a consciousness would remain there isolated, it would be easy to detect it. It would be in such manifold contradiction with all the normal reminiscences and habitual arguments that every court, for instance, would quickly recognise the strange thought as an intruder. But just this is the uncanny power of suggestion, that it at once infects all the neighbouring ideas and emotions and [p. 180] forces the whole mental life Of the personality under the unnatural influence. Of course, life does not often make such effective experiments, and the danger seems small that judges or jurymen should ever be deceived by such an elaborate performance of a witness. Few persons only can be hypnotised to the degree that a post-hypnotic suggestion becomes so powerful. But it cannot be emphasised too strongly that the extreme abnormal changes in mental life go over by the smallest steps into the perfectly normal and habitual behaviour. The grotesque destructiveness of such a hypnotic revolution shows only an exaggerated form of the dangerous working of suggestion which leads in a sliding scale down to the little bits of strange influences with their unreasonable reasoning, as when we read in the cars the unhypnotic suggestions of "cook with gas" or "read the Sun" or " wear rubber heels."

The psychologist does not need, indeed, the hypnotic state to demonstrate experimentally how every suggestion contaminates the most sincere memory. A picture of a farmer's room was shown to about forty persons, children and adults. Each [p. 181] one examined it individually and was then asked to give a report from the fresh memory image in reply to detailed questions. The picture had plenty of detail which could easily be grasped. The questions were partly indifferent and objective. How many persons are in the room? Does the room have windows? What is the man doing? There were persons and windows and the man was eating his soup. But other questions, referring to objects not present in the picture, could pass through different stages of suggestiveness. Is there a stove in the room? is [sic] not so intense a suggestion as the express question, did you see the stove in the room? There was no stove in the picture. Are there houses to be seen through the windows of the room? Does a lamp hang from the ceiling? The result showed that the replies to these suggestive questions were correct only in fifty-nine per cent, of all cases. Hundreds of times objects were invented in accordance with the suggestion of the question and this immediately after the direct observation of the picture, and without any personal interest in the falsified result.

The experiments show that the resistance for [p. 182] the young people is much weaker than for the grown-ups, for the girls weaker than for the boys, but they all were under perfect conditions of emotional calmness. Such conditions are not to be found on the witness stand under the excitement of the solemn court procedure; there the resistance of the adult persons may sink to the low level of that of the boys and girls. Above all, the experiments show that at all ages the positive effect of the suggestion works itself out in minute and concrete detail. As soon as the subject has answered that there is a stove in the room, he is at once ready to reply by a positive statement to the further question, where is the stove standing? The one says on the left, the other on the right; one in the corner, and one against the middle of the wall, each simply following the path of least resistance in his own imagination. The experiments allowed a complete gradation of the suggestive power of the various questions. The gown of the farmer's wife was red. It was sufficient to ask whether the gown was blue or green to eliminate for many the red entirely from memory. And with the suggestiveness of the question the [p. 183] readiness to elaborate their own inventions steadily increased. Experiments of this kind have been carded on with almost identical results in different nations with persons of different ages and professions with most varied material, and every time the power of a suggestive question to break down the true memory appears alarming. But whoever has studied these protocols of the psychological laboratories cannot help feeling that many cross-examinations in court are only continuations of the interesting tests carried on to demonstrate that there is nothing more suggestive for some persons than a skillful question. Their influence may set in long before the lawyer of the other side rejects a too clumsy suggestion as an unallowed "leading question."

Of course, the illusory effect of a suggestion need not wait till the labour of the memory sets in. Our perceptions themselves may be distorted through suggestive influences. Experimental psychology can demonstrate it and at the same time test it in a thousand forms. Of course, such little psychological laboratory experiments seem petty and far removed from the reality of life experience, [p. 184] as they can offer nothing but a dry schematic pattern. Yet this is a complete misunderstanding. Not the weakness of the experiments but their strength lies in their schematic character. All the experimental sciences teach us to understand the world by bringing its manifoldness to the simplest formula. The physicist too does not wait till the lightning breaks through the clouds; he does not need the thunder storm. The small electrical machine on his laboratory table can teach him in a much more instructive way what factors determine the electric discharge. The artificial schematisation shows the connections between cause and effect alone. Thus we do not need in the laboratory the erratic play of emotions and prejudices which suggestions and persuasions may stir up in the chaos of practical life. We recognise the essential features just as well in the slight changes of perceptive judgment with the tiny material of our workshop.

If I have, for instance, on the one side of my table thirty little squares of grey paper and on the other side the same number of the same material, and I ask the subject to decide without [p. 185] counting on which of the two sides there are more of the grey squares, I can easily arrange that he sees more on whichever side I want him to. I find, perhaps, that his judgment depends upon the grouping, that those thirty pieces suggest different numbers according as they lie in regular lines or in irregular disorder; according as they are shut off in small groups or grouped in one circle; surrounded by a frame, or accentuated by a few ink spots, or brightened by a light background, -- in short, that very various side factors suggest an erroneous judgment as to the number of the perceived things. And yet such harmless experimental tests unveil all the factors with which, for instance, political parties before election awake misleading suggestions as to the relative strength of the party vote. A little bit of bright colour on my laboratory table gives me all the moral effect on my subjects which the most wonderful torchlight processions and brass bands can have on the suggestive voter.

Or take a still more striking experiment. We have a series of cardboard boxes of different sizes, from a width of a few inches to several feet, and [p. 186] we make them all exactly equal in weight, filling the smallest, perhaps, with iron and the largest with straw. All are to have the same handle, and if one after the other is lifted with closed eyes, all of course appear of equal heaviness. But now the subject is to lift them, one after the other, with open eyes, and the impression of weight will at once be controlled by the suggestion given by the size. The small box appears now several times heavier than the large one, and no effort to overcome the suggestion can rule out the illusion. It may be a long way from the overestimation of the weight of a little cardboard box to the falsifying overestimation of a piece of evidence by the jury of a murder case, but it is a straight way without demarcation lines. If the twelve jurymen were grouped according to their suggestibility, from the most stubborn to the most easily influenced, they would stand probably in the same order as if they were tested for errors in the judgment of our boxes of cardboard. Yes, we might simplify our test still more. Sometimes I found it sufficient to show to my subjects various pairs of circles drawn on paper; they had to decide which of the [p. 187] pairs was the larger. The pairs were always of the same size, but in their centres various figures were printed; the suggestible person is easily inclined to call the circle with the figure 79 larger than the circle which contains merely the figure 32, just as there may be men who think the prettier girl to be the cleverer, or the richer fellow the more brilliant.

What does the psychologist really understand by a suggestion? Let us be sure from the first that it certainly means nothing abnormal or pathological. The illustrations have indicated sufficiently that abnormal disturbance and ordinary normal life can meet here. My lady with the over-generous last will had certainly left the realm of normality; the voter who is imposed on by the big parade, or the customer who is carried away by the bargain prices of the great removal sale, is also under the influence of suggestion and may yet be otherwise quite a normal person. Suggestion is, moreover, no symptom of weakness, and it would be absurd to believe that life might be wholesomer and better if it could move on without the aid of influences of suggestion. On the contrary, [p. 188] life would be dreary and commonplace, without enthusiasm and without convictions, if all suggestions evaporated. Education and art, politics and religion, rely on the power of suggestion, for a suggestion is after all any idea which takes hold of our consciousness in such a way that it inhibits and excludes the opposite ideas.

But in what sense is there any meaning in speaking of opposite ideas? Our consciousness has room for ally combination of thoughts, and each idea seems to go peacefully together with any other idea. We can think black and white and summer and winter and man and woman quietly together. When the psychologist speaks of opposite ideas, he means something very different. He calls opposite such ideas as involve mutually exclusive attitudes. I can think of man and of woman, but I cannot take the attitude towards a person of taking him for a man and at the same time the attitude of taking him for a woman. I can think of summer and winter, but I must believe that the season is either winter or summer, not both, and must act accordingly. The whole antagonism thus lies in our own activities, and, [p. 189] if we say that one idea excludes the opposite, we really mean that the idea which demands one attitude excludes another idea which demands an opposite attitude. In ordinary life, in states free from suggestion, no idea has any prerogative. Each has fair play. When a new idea comes to our mind, perhaps from hearing it from a friend, perhaps from reading it, perhaps from our own imagination, it may fall into a conflict of attitudes with some other idea present and, above all, with some associations and memories which awake; then begins a fair fight in which either the newcomer or the old idea may win; both together cannot last, as we cannot live through opposite actions at the same time: we cannot turn to the right and to the left, we cannot close the hand and open it, we cannot speak and be silent.

Wrong ideas and inappropriate propositions enter our consciousness through many doors all the time, but they are at once eliminated through the influence of the opposite ideas which a faithful memory and a sound reasoning provide. That which is connected most firmly with the remainder of our experience will survive. Each of the rivalling [p. 190] ideas is thus backed by its own connections and stands on its own merits. Whenever this is changed, and an idea, it may he the new intruder or the old incumbent, gets an unfair chance so that all its opposing ideas are weakened and perhaps even suppressed from the start, then we call it a suggestion. All our prejudices and all our convictions work as such suggestions. They do not give to the idea of opposite attitude the opportunity for a test. That may work for the good or for the bad. The moral idea and the vicious desire may be equally strengthened through such suggestive energy which eliminates the opposite from the start. We call the readiness to receive such suggestions from other persons suggestibility. The degree of suggestibility changes from man to man and changes in every individual from mood to mood, from hour to hour. Hypnotism, finally, is an artificially increased state of suggestibility. Yet there are nowhere sharp demarcation lines. Even the most stubborn mind is open to certain suggestions and even the most deeply hypnotised mind has still the power to resist certain ideas which would be opposed by the deepest [p. 191] maxims of his life. Emotion certainly increases suggestibility with everybody; so does fatigue and nervous exhaustion.

There is nothing mysterious in all this, and the psychologist is not unable to understand it all as product of the brain mechanism. He knows to-day that each idea is composed of sensations which accompany nervous excitement in many sensorial brain cells and these are stimulated by the sense organs. But he knows further that this excitement does not stop in those sensory cells. The process which starts from the sense organs does not find in those sensory brain centres an end station, but runs on into motor paths which lead, finally, to the muscular system. Those central brain stations thus serve for the transmission of the incoming sensory stimuli into outgoing motor impulses. All this is endlessly complex. Millions of paths lead to the brain and millions of paths lead out again, and the cortex of the brain is the great automatic switch-board for all those tracks. Yet all this alone would be no explanation. It would make us only understand that any sensory idea, a word which we hear, a thing which we see, [p. 192] would necessarily lead over into an action. But plenty of facts speak now in favour of the following view.

Firstly, those motor paths in the brain are so related to each other that whenever excitement goes on in the one, the track which would lead to the opposite action becomes blocked. When the impulse runs into those nerves which, for instance, open the hand, the brain closes those channels of motor discharge which would lead us to clench the fist. Secondly, the ideas which accompany the sensory brain processes become vivid only when the channels of discharge are open; they remain unvivid, that is, they become inhibited and suppressed when those channels of discharge are closed. A suggestion would thus be an idea whose sensory brain accompaniment keeps the channels of motor discharge wide open, so that the paths which would lead to the opposite action are, on the whole, closed; and because the channels of discharge are closed, all the ideas which might lead to such opposite action are eliminated from the first. If the words, "This is a garden," spoken to me here in my library, came as a suggestion, [p. 193] they would not exclude any activity of mine. I might carry on a conversation on politics, might read a book, and might remember correctly all that happened to me before, but everything must remain in harmony with my attitude towards this room as a garden. The wish to take a book from the shelf on the wall would be indeed inhibited and the books themselves would become correspondingly invisible, while I should believe I saw the flowers in the garden, which I should feel ready to pick. Of course, to take my library shelves for flower bushes because someone tells me this is a garden demands an extreme degree of suggestibility, and, where it is reached, we should certainly speak of an hypnotic state. To take in an anxious mood at twilight the trunk of a willow tree for a burglar requires much less suggestibility; and to believe the latest news of the yellow journal only because it is shouted in big headlines, in spite of the fact that a hundred earlier experiences ought to suppress belief, a still smaller degree of suggestibility is sufficient.

If, therefore, no mystery and no disease is involved, if suggestion rests on an opening and [p. 194] closing of motor channels which goes on automatically and to a high degree independent of conscious will, if everyone is open to suggestions and yet suggestions are able to turn white into black and black into white, it seems indeed astonishing that the work of justice is carried out in the courts without ever consulting the psychologist and asking him for all the aid which the modern study of suggestion can offer. There is no one participant in the drama of the court who might not change the plot by the operation of suggestions in his mind: the defendant may have worked under suggestion at the time of his criminal deed, the witnesses may be influenced during their observation of the deed or may labour under suggestion on the witness stand and, even if their observation and recollection is correct, their narration may still be tainted by the strange spell; but is the lawyer or the judge, above all, is the juryman less open to a disturbance of the normal ideational rivalry ?

To be sure, popular imagination runs often enough into the suspicion that a crime was performed under hypnotic influence; but just this is on the whole more a motive for dime novels than [p. 195] for legal consideration. All the probabilities are against it. For the purpose of justice it is far more important to keep in mind that hypnotism is only the strongest degree of suggestibility and that the weaker states of openness for suggestion are the real hotbeds of criminal impulses. We know to-day, for instance, that alcohol poisoning can produce with many persons a state of suggestibility in which complete imitations of post-hypnotic suggestions become possible. The order to do a certain foolish act at an appointed hour in the sober state will be carried out when the order has been given in an impressive way while the wine was still paralysing the inhibitory centres. In the same way emotion changes the man; during a panic the suggestibility is reinforced to a degree where all resistances seem to be broken down, and to be a member of a crowd is always sufficient to weaken the counter action. But there are many persons whose unusual suggestibility makes them constantly liable to chance influences, even in normal social life. They are enthusiastic for the last arguments they hear, and the next speaker who says the opposite convinces them just as fully. [p. 196] The psychological experiment can measure the degree of this constitutional weakness with exactitude, and to leave this nervous disposition altogether out of account in judging the criminal act is in principle not different from punishing the insane like a normal man.

Still more important than the influence of suggestion on the crime is that on the report of the witness. The distortion may begin with the mere perception of the circumstances. Whenever the court becomes doubtful as to whether the witness really observed the facts correctly, we hear some speculative generality as to the probability of a reliable judgment. Here again the first thing ought to be to find the personal equation and to determine by the means of science to what degree the perceptive consciousness of the observer remains independent of intruding suggestions. The suggestible witness may have heard distinct words where the objective witness heard only a noise. Much may depend upon that for the trial. Words distinguished by the unsuggestible mind would count for much; those distinguished by the suggestible one for almost nothing. But to say which [p. 197] is which, it ought not to be sufficient to rely on hearsay and anecdotes, with all the means of the laboratory experts at disposal to determine the exact degree of suggestibility, just as experts would decide whether a bullet can have taken the one way or the other through the body.

Where the perception was fairly correct, the recollection may be entirely distorted by suggestive side influences. We have spoken of the experiments which prove the powerful influence of suggestive questions. No doubt the whole situation of the court-room reinforces the suggestibility of every witness. In much-discussed cases current rumours, and especially the newspapers, have their full share in distorting the real recollections. Everything becomes unintentionally shaped and moulded. The imaginative idea which fits a prejudice, a theory, a suspicion, meets at first the opposition of memory, but slowly it wins in power, and as soon as the suggestibility is increased, the play of ideas under equal conditions ends, and the opposing idea is annihilated. Easy tests could quickly unveil this changed frame of mind and, if such a hall hypnotic state of suggestibility: has [p. 198] set in, it is no wiser to keep the witness on the stand than if he had emptied a bottle of whiskey in the meantime. And even if the memory itself is correct, the narration may be dictated by suggestive influences and the reported story itself may work backwards with auto-suggestive influence on the memory. There are not a few who finally believe their hunting stories after they have told them repeatedly.

Is it necessary to say that the most suggestible man in court and the one whose suggestibility is most dangerous may be neither the criminal nor the witness, but the juryman? His task demands freedom from suggestion more than almost any other quality. He has to weigh the value of conflicting evidence. Here again psychological experiment can show how easy it is to interfere with the unhampered play of rival ideas when the mind is suggestible. The lawyer who knows his average juryman instinctively makes the richest use of all the psychological factors which bring the arguments of the one side fully into the focus of interest and suppress and inhibit the effectiveness of the opposite idea. But here again there may be a [p. 199] degree of suggestibility which simply interferes with the purpose of justice and only psychological experiment can bring such deficiency to light. The judgment of a jury becomes a caricature, if not the evidence, but insignificant and accidental circumstances determine the attitude of the suggestible juror.

Of course public opinion with its crowd of instincts is for the most part just such a suggestible arbiter. I heard at the centre of politics that after the Spanish War, when the nation was delighted with the navy and all kinds of scandals seemed to bring evidence against the army, Congress would never have voted so much to the army had not West Point in that year won the football match over Annapolis, and thus swung round the suggestible public opinion from navy to army. But, to be sure, when the Court of public opinion begins to weigh the evidence, it is no longer law, but politics, and it might not be wise to ask how far there is suggestion in politics too, inasmuch as we might be checked too soon by the counter question: Is there anything in politics which is not suggestion?