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)


WHERE the avoidance of accidents is in question, the test of a special experimental method can seldom be made dependent upon a comparison with practical results, as we do not want to wait until the candidate has brought human life into danger. The ordinary way of reaching the goal must therefore be an indirect one in such cases. For the study of motormen the conditions are exceptionally favorable, as hundreds of thousands of accidents occur every year, but another practical example may be chosen from a field where it is, indeed, impossible to correlate the results with actual misfortunes, because the dangerous situations occur seldom; and nevertheless on account of their importance they demand most serious study. I refer to the ship service, where the officer on the bridge may bring thousands into danger by one single slip of his mind. I turn to this as a further concrete illustration in order to characterize at once the lengths to which such vocational studies may advance.

One of the largest ship companies had approached [p. 84] me -- long before the disaster of the Titanic occurred -- with the question whether it would not be possible to find psychological methods for the elimination of such ship officers as would not be able to face an unexpected suddenly occurring complication. The director of the company wrote to me that in his experience the real danger for the great ships lies in the mental dispositions of the officers. They all know exactly what is to be done in every situation, but there are too many who do not react in the appropriate way when an unexpected combination of factors suddenly confronts them, such as the quick approach of a ship in the fog. He claimed that two different types ought to be excluded. There are officers who know the requirements excellently, but who are almost paralyzed when the dangerous conditions suddenly threaten. Their ability for action is inhibited. In one moment they want to act under the stimulus of one impression, but before the impulse is realized, some other perhaps rather indifferent impression forces itself on their minds and suggests the counteraction, and in this way they vacillate and remain inactive until it is too late to give the right order or to press the right button. The other type feels only the necessity for rapid action, and under the pressure of greatest haste, without clear thought, they [p. 85] jump to the first decision which rushes to their minds. Without carefully considering the conditions really given, they explode in an action which they would never have chosen in a state of quiet deliberation. They react on any accidental circumstance, just as at a fire men sometimes carry out and save the most useless parts of their belongings. Of course, beside these two types, there is third type, the desirable one, the men who in the unexpected situation quickly review the totality of the factors in their relative importance and .with almost instinctive certainty immediately come to the same decision to which they would have arrived after quiet thought. The director of the company insisted that it would be of highest importance for the ship service to discriminate these three types of human beings, and to make sure that there stand on the bridge of the ship only men who do not belong to those two dangerous classes. He turned to me with this request, as he had heard of the work toward economic psychology in the Harvard laboratory.

As the problem interested me, I carried on a long series of experiments in order to construct artificial conditions under which the mental process of decision in a complicated situation, especially the rapidity, correctness, and constancy of the decision, could be made measurable. I started [p. 86] from the conviction that this complex act of decision must stand in definite relation to a number of simpler mental functions. If, for instance, it stood in a clear definite relation to the process of association, or discrimination, or suggestibility, or perception, or memory, and do on, it would be rather easy to foresee the behavior of the individual in the act of decision, as every one of those other simple mental functions could be tested by routine methods of the psychological laboratory. This consideration led me to propose ramified investigations concerning the psychology of decision in its relation to the elementary mental processes. These studies by students of the laboratory are not yet completed. But I soon saw that they would be unfit for the solution of my practical problem, as we recognized that these relations between the complex act of decision and the elementary- functions of the individual seem to have different form with different types of men.[12] If I was to approach the solution of the practical problem, accordingly, I had to reproduce in an experimental form the act of decision under complex conditions.

It seemed necessary to create a situation in which a number of quantitatively measurable factors were combined without any one of them forcing itself to consciousness as the most important. [p. 87] subject to be experimented on then has to decide as quickly as possible which of the factors is the relatively strongest one. As usual, here, too, I began with rather complicated material and only slowly did I simplify the apparatus until it finally took an entirely inconspicuous form. But this is surely the most desirable outcome for testing methods which are to be applied to large numbers of persons. Complicated instruments, for the handling of which special training is needed, are never so useful for practical purposes as the simple schemes which can be easily applied. The form of which I finally made use is the following. I work with 24 cards of the size of playing-cards. On the upper half of every one of these cards we have 4 rows of 12 capital letters, namely, A, E, O, and U in irregular repetition. On 4 cards, one of these vowels appears 21 times and each of the three others 9 times; on 8 cards, one appears 18 time and every one of the three others 10 times; on 8 cards, one appears 15 times and each of the others 11 times; and finally, on 4 cards one vowel appears 16 times, each of the three others 8 times, and besides them 8 different consonants are mixed in. The person to be tested has to distribute these 24 cards as quickly as possible in 4 piles, in such a way that in the first pile are placed all cards in which the letter A is most frequent, in the second [p. 88] those in which the letter E predominates, and so on. As a matter of course the result; must never, be secured by counting the letters. Any attempt to act against this prescription and secretly to begin counting would moreover delay the decision so long that the final result would be an unsatisfactory achievement anyhow. It would accordingly bring no advantage to the candidate.

We measure with a stopwatch in fifths of a second the time for the whole process from the subject's looking at the first card to his laying down of the last card, and, secondly, we record the number and the character of his mistakes, if cards are put into wrong piles. I have made the experiment with very many persons, and results show that those various mental traits which have been observed in the practical ship service come clearly to light under the conditions of this experiment. Some of the persons lose their heads entirely, and for many of them it is a painful activity for which they require a long time. Even if the number of mistakes is not considerable, they themselves have the feeling that they are not coming to a satisfactory decision, because their attention is pulled hither and thither so that they feel an inner mental paralysis. Some chance letters stand out and appear to them to be predominant, but in the next moment the attention is [p. 89] captured by some other letters which bring the suggestion that they are in the majority and that they present the most important factor. The outcome is that inner state of indecision which can become so fatal in practical life. Other subjects distribute the cards in piles at a relatively high speed, and they do it with the subjective feeling that they have indeed recognized at the first glance the predominant group of letters. The exact measurement of the results, however, shows that they commit many errors which would have been improbable after quiet consideration. Any small group of letters which catches their eye makes on them, under the pressure of their haste, such a strong impression that all the other letters are inhibited for the moment and the wrong decision is quickly made. Finally, we find a group of persons who carry out the experiment rather quickly and at the same time with few mistakes. It is characteristic of them to pass through it with the feeling that it is an agreeable and stimulating mental activity. In all cases the subjects feel them selves under the unified impression which results from all those 48 letters of the card together; and this is the reason why the qualitative manifoldness of a practical life situation can be compared with these intermingled, quantitatively determined groups of letters.

[p. 90] If I consider the general results of these experiments only with reference to the time-measurement, I should say that a person who completes the distribution of the cards in less than 80 seconds is quick in his decisions; from 80 to 150, moderately quick; from 150 to 250, slow and deliberate and rather too deliberate for situations which demand quick action; over 250 seconds, he would belong among those wavering persons who hesitate too long in a life situation which demands decision. The time which is needed for the mere distribution of the cards themselves plays a very small rôle compared with the time of the whole process, and can be neglected. In order to determine this, I asked all the subjects before they made the real experiment to distribute 24 other cards in 4 piles, on each of which one of the four letters, A, E, 0, and U was printed only once. Hence no comparison of various factors was involved in this form of distribution. The average time for this ordinary sorting was about 20 seconds. Only rather quick individuals carried it out in less than 18 and only very slow ones needed more than 25 seconds. This maximum variation of 10 seconds is evidently insignificant, as the variations in the experiment amount to more than 200 seconds. But it is very characteristic that the results of the two experiments do not move parallel. Some [p. 91] persons, who are able to sort the cards on which only one of the 4 letters is printed very quickly, ,are rather slow when they sort the cards with the 48 letters for which the essential factor is the act of comparison. In the first case the training in card-playing also seems to have a certain influence, but in the second case, our real experiment on decision, this influence does not seem to exist.

We have emphasized from the start that it is no less important to give consideration to the number of mistakes. A mere rapidity of distribution with many mistakes characterizes, as we saw, a mental system which is just as unfit for practical purposes as one which acts with too great slowness. But it would not have been sufficient simply to ask how many cards were put into wrong piles. The special arrangement of the cards with four different types of combinations was introduced for the purpose of discriminating among mistakes of unequal seriousness. When one letter appeared 21l times and the three others only 9 times, it was surely much easier to make the decision, than when the predominant letter appeared only 15 times and the other three each 11 times. The easier the right decision, the graver the mistake. Of course the valuation of these mistakes must be rather arbitrary. We decided to value as 4 every mistake in these cards on which the predominant [p. 92] letter appears 21 times; as 3, a mistake in the 18 letter cards; as 2, a mistake in the 16 letter cards; and as 1, a mistake in the most difficult ones, the 15 letter cards. If the mistakes are calculated on this basis and are added together, a sum below 5 may indicate a very safe and perfectly reliable ability for decision; 5 to 12, satisfactory; 12 to 20, uncertain; and over 20, very poor. In order to take account of both factors, time and mistakes, we multiply the sum of the calculated mistakes by the number of seconds. If the product of these two figures is less than 400, it may be taken as a sign of perfect reliability in making very quick, correct decisions, in complex life situations; 400 to 1000 indicates the limits between which the ability for such decisions may be considered as normal and very satisfactory; 1000 to 2000, not good but still adequate; 2000 to 3000, unreliable, and over 3000, practically absent. It is clear that the real proof of the value of this method cannot be offered. This is just the reason why we selected this illustration as an example of the particular difficulty. Wrong decisions, that is, cases in which the man on the bridge waits too long before he makes his decision and thus causes a collision of ships by his delay, or in which he rushes blindly to a decision which he himself would have condemned after quiet deliberation, are [p. 93] rare. It would be impossible to group such men together for the purpose of the experiment and to compare their results with those of model captains, the more as experience has shown that an officer may have a stainless record for many years and yet may finally make a wrong decision which shows his faulty disposition. The test of the method must therefore be a somewhat indirect one. My aim was to compare the results of the experiments with the experiences of the various individuals which they-themselves reported concerning their decisions in unexpected complicated situations, and moreover with the judgments of their friends whom I asked to describe what they would expect from the subjects under such conditions. The personal differences in these respects are extremely great, and are also evident in the midst of small groups of persons who may have great similarity in their education and training and in many other aspects of their lives.

Among the most advanced students of my research laboratory, for instance, all of whom have rather similar schooling and practically the same training in experimental work, the product of mistakes and seconds varied between 348 and 13,335. That smallest value occurred in a case in which the time was 116 seconds and the sum of the mistakes only 3, inasmuch as 3 cards of the most difficult [p. 94]group where the predominating letter occurred only 15 times were put in the wrong piles. The shortest time among my laboratory students was 58 seconds, but with this individual the sum of the mistakes, calculated on the basis of the valuation agreed upon, was 13. The largest figure mentioned resulted in a case in which the student needed 381 seconds and yet made mistakes the sum of which amounted to 35. It is characteristic that the person with the smallest product felt a distinct joy in the experiment, while the one with the largest passed through painful minutes which put him to real organic discomfort. If we arrange the men simply in the order of these products, of course we cannot recognize the various groups, as those who are quick but make mistakes and those who make few mistakes but act slowly may be represented by the same products. The coincidence of the results with the self-characterization is frequently quite surprising. Every one has at some time come into unexpected, suddenly arising situations and many have received in such moments a very vivid impression of their own mental reaction. They know quite well that they could not come to a decision quickly enough, or that they rushed hastily to a wrong decision, or that in just such instants a feeling of repose and security came over them and that with sure instinct they [p. 95] turned in the direction which they would have chosen after mature thought. The results of the experiments in sorting the cards confirmed this self-observation in such frequent cases that it may indeed be hoped that a more extended test of this method will prove its practical usefulness. It is clear that the held is a wide one, as these different types of mental dispositions must be of consequence not only in the ship service, but also to a certain degree in the railroad service and in many other industrial tasks.

We have emphasized from the start that as a matter of course such a tested function, while it is taken in its complex unity, is nevertheless not the only psychophysical disposition of significance. This is as true for the ship officer as it was for the motorman of the electric car. If we were to study all the mental dispositions necessary or desirable for the ship officer, we should find many other qualities which are accessible to the psychological investigation. The captain of the ship, for instance, is expected to recognize the direction of a vessel passing in the fog by the signals of the foghorn. But so far no one has given any attention to the psychological conditions of localization of sound, which were for a long while a much-studied problem of our psychological laboratories. We know how this localization is dependent upon [p. 96] the comparison of the two ears and what particular mistakes occur from the different sensibility of the two ears. Yet there are to-day men on the bridges of the ships who hear much better with one ear than with the other, but who still naïvely believe that, as they hear everything very distinctly with one ear, this normal ear is also sufficient for recognizing the direction of the sound. It is the same mistake which we frequently see among laborers whose vision has become defective in one of their eyes, or one of whose eyes is temporarily bandaged. They are convinced that the one good eye is sufficient for their industrial task, because they are able to recognize everything clearly and distinctly. They do not know that both the eyes together are necessary in order to produce that psychological combination by which the visual impression is projected into the right distance, and that in the factory they are always in danger of underestimating the distance of a wheel or some other part of the machine and of letting the hand slip between the wheels or knives. The results of experimental psychology will have to be introduced systematically into the study of the fitness of the personality from the lowest to the highest technical activity and from the simplest sensory function to the most complex mental achievement.


[12] The experiments are being conducted and will be published by Mr. J. W. Bridges.