Classics in the History of Psychology

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Christopher D. Green
York University, Toronto, Ontario

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Psychology and Industrial Efficiency

Hugo Münsterberg (1913)


IT is perhaps not without interest to turn into a by-path at this point of our road. All the illustrations which we have picked out so far have referred to strictly economic conditions. But we ought not to forget that these economic problems of commerce and industry are everywhere in contact with legal interests as well. In order to indicate the manifoldness of problems accessible to the experimental method, we may discuss our last question, the question of packing and of labels, in this legal relation too. All the packings, covers, labels, trademarks, and names by which the manufacturer tries to stimulate the attention, the imagination, and the suggestibility of the customer may easily draw a large part of their psychological effectiveness from without, as soon as they imitate the appearance of articles which are well introduced and favored in the market. If the public is familiar with and favorably inclined toward an article on account of its inner values or on account of its being much advertised, [p. 283] a similar name or a similar packing may offer efficient help to a rival article. The law of course protects the label and the deceiving imitation can be prosecuted. But no law can determine by general conceptions the exact point at which the similarity becomes legally unallowable. This creates a situation which has given rise to endless difficulties in practical life.

If everything were forbidden which by its similarity to an accredited article might lead to a possible confusion in the mind of the quite careless and inattentive customer, any article once in the market would have a monopoly in its line. As soon as a typewriter or an automobile or a pencil or a mineral water existed, no second kind could have access to the market, as with a high degree of carelessness one economic rival may be taken for another, even if the new typewriter or the new pencil has a new form and color and name. On the other side, the purchaser could never have a feeling of security if imitations were considered as still legally justifiable when the difference is so small that it needs an intense mental effort and careful examination of details to notice it.

The result is that the jurisdiction fluctuates between these two extremes in a most alarming way, and this seems to hold true in all countries. In [p. 284] theory: "There is substantial agreement that infringement occurs when the marks, names, labels, or packings of one trader resemble those of another sufficiently to make it probable that ordinary purchasers, exercising no more care than such persons usually do in purchasing the article in question, will be deceived." But it depends upon the trade experts and the judges to give meaning to such a statement in the particular case, as the amount of care which purchasers usually exercise can be understood very differently. Sometimes the customer is expected to proceed with an attention which is most subtly adjusted to the finest differences, and sometimes it is taken for granted that he is unable to notice even strong variations. It is clear that this uncertainty which disturbs the whole trade cannot be eliminated as long as the psychological background has not been systematically studied. Mere talking about the attention of the customer, and his ability to decide and select, and of his observations and his habits in the spirit of popular common-sense psychology, can never secure exact standards and definite demarcation lines. The question is important not only where imitations of morally doubtful character are in the market. Even the most honest manufacturer is in a certain sense obliged to imitate his predecessors, [p. 285] as they have directed the taste and habits of the public in particular directions, and as the product of his company would suffer unnecessarily if he were to disregard this psychical attitude of the prospective customers. The economic legal situation accordingly suggests the question whether it would not be possible to devise methods for an exact measurement of the permissible similarity, and this demand for exactitude naturally points to the methods of the psychological experiment. E.ĚS. Rogers, Esq., of Chicago, who has thoroughly discussed the legal aspect of the problem,[53] first turned my attention to the psychological difficulty involved.

When I approached the question in the Harvard psychological laboratory, it was clear to me that the degree of attention and carefulness which the court may presuppose on the part of the customer can never be determined by the psychologist and his experimental methods. It would be meaningless, if we tried to discover by experiments a particular degree of similarity which every one ought to recognize or a particular degree of attention which would be sufficient for protection against fraud. Such degrees must always remain dependent upon arbitrary decision. They are not settled by natural conditions, but [p. 286] are entirely dependent upon social agreement. A decision outside of the realm of psychology must fix upon a particular degree in the scale of various similarity values as the limit which is not to be passed. The aim of the psychologist can be only to construct such a scale by which decisions may be made comparable and by which standards may become possible. The experiment cannot deduce from the study of mental phenomena what degrees of similarity ought to be still admissible, but it may be able to develop methods by which different degrees of similarity can be discriminated and by which a certain similarity value once selected can always be found again with objective certainty. After many fruitless efforts I settled on the following form of experiments, which I hope may bring us nearer to the attainment of the purpose.

A group of objects is observed for a definite time and after a definite interval another group of objects is offered for comparison. This second group is identical with the first in all but one of the objects, and this is replaced by a Similar one. The question is how often this substitution will be noticed by the observers. I may give in detail a characterization of the set of experiments in which we are at present engaged. We are working with picture postal cards, using many hundred [p. 287] cards of different kinds, but for each one we have one or several similar cards. As postal cards are generally manufactured in sets, it is not difficult to purchase pairs of pictures with any degree of similarity. Two cards with Christmas trees, or two with Easter eggs, or two with football players, or two with forest landscapes, and so on, may differ all the way from a slight variation of color or a hardly noticeable change in the position of details to variations which keep the same motive or the same general arrangement, but after all make the card strikingly different. The first step is to determine for each pair the degree of similarity, on a percentage basis. To overcome mere arbitrariness, we ask thirty to forty educated persons to express the similarity value, calling identical postal cards 100 per cent and two postal cards as different as a colored flower piece and a black picture of a. street scene 0. The average value of these judgments is then considered as expressing the objective degree of similarity between the two pictures of a pair. After securing such standard values, we carry on the experiments in the following form. Six different postal cards, for instance, are seen on a black background through the opening of a shutter which is closed after 5 seconds. The six may be made up of a landscape, a building, a head, a genre scene, and [p. 288] so forth. After 20 seconds the same group of postal cards is shown once more, except that one is replaced by a similar one, instead of one church another church building, or instead of a vase with roses a vase with pinks. If the substituted picture has the average similarity value of 80 per cent and we make the experiment with;l0 persons, the substitution may be discovered by 7 persons and remain unnoticed by 3. We can now easily vary every one of the factors involved. If instead of 6 cards, we take 10, it may be that only 4 out of 10 persons, instead of 7, will discover the substitution, while if we take 4 cards instead of 6, perhaps 9 persons out of 10 will recognize the difference under these otherwise equal conditions. Only an especially careless observer will overlook it. But instead of changing the number of objects, we may change the periods of exposure. If we show the 6 cards only for 2 seconds instead of 5 seconds, the number of those who recognize the difference may sink from 7 to 5 or 4, and if we make the time considerably longer, we shall of course reach a point where all 10 will recognize the substitution. The same holds true of the shortening or lengthening of the time-interval between the two presentations. The third variable factor is the similarity itself. If instead of one church, not another church, but a theatre or a skyscraper is [p. 289] shown, that is, if the similarity value of 80 per cent sinks down to a similarity of 60 per cent or 50 per cent, the number of those who recognize the substitution will again become larger; if, on the other hand, the substituted card shows the same church, only from a slightly different angle, bringing the similarity value up to90 per cent or 95 per cent, the number of observers who recognize the substitution may sink to 2 or 3. To make the experiments reliable, it is also necessary frequently to mix in cases in which no substitution at all is introduced.

If these experiments are varied sufficiently and a large mass of material brought together, we must be able to secure definite formulæ. We may find that if the critical card appears among 6 cards, is shown for 5 seconds, and the group is again exposed after 20 seconds, 80 per cent of the subjects will recognize the substitution of a similar card, if the degree of similarity is 30 per cent, but only 60 per cent will recognize it if the degree of similarity is 70 per cent, and only 30 per cent will recognize it if the degree of similarity is 90 per cent. These are entirely fictitious figures and are only to indicate the principle. If such an exact formula were definitely discovered, we should still be unable to say from mere psychological reasoning what similarity value is legally permissible. If [p. 290] the rules against infringement are interpreted in a very rigorous spirit, it may seem desirable to prohibit imitations which are as little similar as those postal cards which were graded as 40 per cent in our similarity scale, and if the interpretation is a loose one, it may appear permissible to have imitations on the market which are as strongly similar as our postal cards graded at 80 per cent in our similarity scale. All this would have to be left to the lawmakers and to the judges. But what we would have gained is this. We could say: if our object exposed for 5 seconds in a group of 6 other objects is replaced after an interval of 20 seconds by an imitation and this change is recognized by 8 persons among 10, the degree of similarity is 30 per cent and if it is recognized by 3 out of 10 subjects, the degree of similarity is 90 per cent. In short, from any percentage of subjects who under these conditions discovered the substitution, we could determine the degree of similarity, independent of any individual arbitrariness. If such methods were accepted by the trade and the courts, it would only be necessary to agree on the percentage of similarity which ought to be permitted, and all uncertainty would disappear. There would be no wrangling of opposing interests; it would be possible to find out whether the permitted limit were overstepped or [p. 291] not with an exactitude similar to that with which the weight or the chemical constitution of a trade commodity is examined. Certainly the experiment establishes here conditions which are very different from those of practical life. The customer who wants to buy a particular picture postal card which he saw once before and to whom the salesman offers a similar one, suggesting that it is the same, is facing only one card and not a group of six. But in practical life the card which he has seen was not observed with the definite intention of keeping the memory picture in mind, and months may have passed since it was seen. The memory picture which the customer has in, his consciousness when he seeks the particular card is much weakened by this circumstance too. We secure this weakening artificially by the arrangement of the experiment in placing the card in a group of six or ten and exposing them for a few seconds only. The force of attention and the corresponding memory-value are by this distribution diminished in a definite degree in the case of every single card.

The investigation must include a careful study of the size of the groups, of the time-relations, of the percentage of correct answers, all under the point of view of greatest fitness for practical application. In the Harvard laboratory the research [p. 292] has been carried on partly with such picture material, partly with word material, and partly with concrete objects.[54] Whatever the details of the outcome may be, we hope that the work will lead to results which may, indeed, make such a psychotechnical use possible. Its principles and formulae might easily be adjusted to any marketable material. As a matter of course, if in future the courts were ever to accept such psychological, experimental methods, it would be intolerable dilettantism if such experiments were carried on by lawyers and district attorneys. It is as true of this economic legal question as of many other legal psychological problems that its introduction into the courtroom can become desirable only when psychological experts are engaged and called in the same way as chemical or medical experts are invited to the court. On the other hand, there is surely not the slightest desire on the part of psychologists to be dragged into humiliating performances like those which not only handwriting experts, but even psychiatric specialists have had to undergo repeatedly in sensational court trials. The day for the expert activity in the courtroom will come for the psychologist only when the country has attached the expert to the court and has eliminated the expert retained by the plaintiff or the defendant. But this general [p. 293] practical question as to the position of the psychologist in the courtroom and as to the need of a psychological laboratory in connection with the courts would lead us too far aside.


[53] E. S. Rogers: The Unwary Purchaser: A Study in the Psychology of Trade Mark Infringement. (Michigan Law Review, vol. 8, 1910.)

[54] The experiments are being conducted and will be published by Mr. G. A. Feingold.