Classical Texts in Psychology
Christopher D. Green
York University, Toronto, Ontario
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Psychology and Industrial Efficiency
Hugo Münsterberg (1913)
CHAPTER 14: THE ADJUSTMENT OF TECHNICAL TO PSYCHICAL CONDITIONS
TEACHING and learning represent only the preliminary problem. The fundamental question remains, after all, how the work is to be done by those who have learned it in accordance with the customs of the economic surroundings and who are accordingly already educated and trained for it. What can be done to eliminate everything which diminishes and decreases efficiency, and what remains to be done to reinforce it. Such influences are evidently exerted by the external technical conditions, by variations of the activity itself, and by the play of the psychical motives and counter-motives. It must seem as if only this last factor would belong in the realm of psychology, but the technical conditions, of which the machine itself is the most important part, and the bodily movements also have manifold relations to the psychical life. Only as far as these relations prevail has the psychologist any reason to study the problem. The purely physical and economic factors of technique do not interest him at all, but when a technical arrangement makes a psychophysical [p. 159] achievement more difficult or more easy, it belongs in the sphere of the psychologist, and just this aspect of the work may become of greatest importance for the total result. In all three of these directions, that is, with reference to the technical, to the physiological, and to the purely psychical, the scientific management movement has prepared the way. The engineers of scientific management recognized, at least, that no part of the industrial process is indifferent; even the apparently most trivial activity, the slightest movement of arm or hand or leg, became the object of their exact measurement. The stopwatch which measures every movement in fractions of a second has become the symbol of this new economic period. As long as special psychological experiments in the service of industrial psychology are still so exceptional, it may, indeed, be acknowledged that the practical experiments in the service of scientific management have come nearest to the solution of these special psychotechnical problems.
To proceed from without toward the centre, we may begin our review with the physical technique of the working conditions and its relations to the mind. The history of technique shows on every page this practical adjustment of external labor conditions to the psychophysical necessities [p. 160] and psychophysical demands. No machine with which a human being is to work can survive in the struggle for technical existence, unless it is to a certain degree adapted to the human nerve and muscle system and to man's possibilities of perception, of attention, of memory, of feeling, and of will. Industrial technique with its restless improvements has always been subordinated to this postulate. Every change which made it possible for the workingman to secure equal effects with smaller effort or to secure greater or better effects with equal effort counted as an economic gain, which was welcome to the market. For instance, throughout the history of industry we find the fundamental tendency to transpose all activities from the great muscles to the small muscles. Any activity which is performed with the robust muscles of the shoulder when it can be done with the lower arm, or labor which is demanded from the muscles of the lower arm when it can just as well be carried out by the fingers, certainly involves a waste of psychophysical energy. A stronger psychophysical excitement is necessary in order to secure the innervation of the big muscles in the central nervous system. This difference in the stimulation of the various muscle groups has been of significant consequence for the differentiation of work throughout the development of mankind. [p. 161] Labor with the large muscles has, for these psychophysical reasons, never been easily combined with the subtler training of the finer muscles. Hence a social organization which obliged the men to give their energy to war and the hunt, both, in primitive life, functions of the strongest muscles, made it necessary for the domestic activities, which are essentially functions of the small muscles, to be carried out by women. The whole history of the machine demonstrates this economic tendency to make activities dependent upon those muscles which presuppose the smallest psychophysical effort. It is not only the smaller effort which gives economic advantage to the stimulation of the smaller muscles, but the no less important circumstance that the psychophysical after-effect of their central excitement exerts less inhibition than the after-effect of the brain excitement for the big muscles.
But we must not overlook another feature in the development of technique. The machines have been constantly transformed in the direction which made it possible to secure the greatest help from the natural coördination of bodily movements. The physiological organization and the psychophysical conditions of the nervous system make it necessary that the movement impulses flow over into motor side channels and thus [p. 162] produce accessory effects without any special effort. If a machine is so constructed that these natural accessory movements must be artificially and intentionally suppressed, it means, on the one side, a waste of available psychophysical energy, and on the other side it demands a useless effort in order to secure this inhibition. The industrial development has moved toward both the fructification of those side impulses and the avoidance of these inhibitions. It has adjusted itself practically to the natural psychical conditions. Ultimately it is this tendency which shaped the technical apparatus for the economic work until the muscle movements could become rhythmical. The rhythmical activity necessarily involves a psychophysical saving and this saving has been instinctively secured throughout the history of civilization. All rhythm contains a repetition of movement without making a real repetition of the psychophysical impulse necessary. In the rhythmical activity a large part of the first excitement still serves for the second, and the second for the third. Inhibitions fall away and the mere after-effect of each stimulus secures a great saving for the new impulse. The history of the machine even indicates that the newer technical development not only found the far-reaching division of labor already in the workshops of [p. 163] earlier centuries, but a no less far-reaching rhythmization [sic] of the labor in fine adaptation to the needs of the psychophysical organism, long before the appearance of the machines. The beginnings of the machine period frequently showed nothing but an imitation of the rhythmical movements of man. To be sure, the later improvements of the machine have frequently destroyed that original rhythm of man's movement, as the movement itself, especially in the electric machines, has become so quick that the subjective rhythmical experience has been lost. Moreover, the rhythmical horizontal and vertical movements were for physical reasons usually replaced by uniform circular movements. But even the most highly developed machine demands human activity, for instance, for the supplying with material; and this again has opened new possibilities for the adjustment of technical mechanism to the economic demand for rhythmical muscle activity. The growth of technical devices has thus been constantly under the control of psychological demands, in spite of the absence of systematic psychological investigations. But the decisive factor was, indeed, that these psychological motives always remained in the subconsciousness of civilization. The improvements were consciously referred to the machine as such, however much the [p. 164] practical success was really influenced by the degree of its adjustment to the mental conditions of the workingmen. The new movements of scientific management and of experimental psychology aim toward bringing this adaptation consciously into the foreground and toward testing and studying systematically what technical variations can best suit the psychophysical status of man.
Those who are familiar with the achievements of scientific management remember that by no means only the complicated procedures on a high level are in question. The successes are often the most surprising where the technique is old, and where it might have been imagined that the experiences of many centuries would have secured through mere common sense the most effective performance. The best-known case is perhaps that of the masons, which one of the leaders of the scientific management movement has studied in all its details. The movements of the builders and the tools which they use were examined with scientific exactitude and slowly reshaped under the point of view of psychology and physiology. The total result was that after the new method 30 masons completed without greater fatigue what after the old methods it would have taken 100 masons to do, and that the total expense [p. 165] for the building was reduced to less than a half in spite of the steady increase of the wages of the laborers. For this purpose it was necessary that exact measurements be made of the height at which the bricks were lying and of the height of the wall on which they must be laid, and of the number of bricks which should be carried to the masons at once. He studied how the trowel should be shaped and how the mortar should be used and how the bricks should be carried to the bricklayers. In short, everything which usually is left to tradition, to caprice, and to an economy which looks out only for the most immediate saving, was on the basis of experiments of many years replaced by entirely new means and tools, where nothing was left to arbitrariness. Yet these changes did not demand any invention or physically or economically new ideas, but merely a more careful adaptation of the apparatus to the psychological energies of the masons. The new arrangement permitted a better organization of the necessary bodily movements, fatigue was diminished, the accessory movements were better fructified, fewer inhibitions were necessary, a better playing together of the psychical energies was secured.
The students of scientific management stepped still lower in the scale of economic activity. There [p. 166] is no more ordinary productive function than shoveling. Yet in great establishments the shoveling of coal or of dirt may represent an economically very important factor. It seems that up to the days of scientific management, no one really looked carefully into the technical conditions under which the greatest possible economic effect might be reached. Now the act of shoveling was approached with the carefulness with which a scholar turns to any subtle process in his laboratory. The brilliant originator of the scientific management movement, who carried out these investigations in the great Bethlehem Steel Works, where hundreds of laborers had to shovel heavy iron ore or light ashes, found that the usual chance methods involve an absurd economic waste. The burden was sometimes 90 heavy that rapid fatigue developed and the movements became too slow, or the lifted mass was so light that the larger part of the laborer's energies remained unused. In either case the final result of the day's work must be anti-economic. He therefore tested with carefully graded experiments what weight ensured the most favorable achievement by a strong healthy workingman. The aim was to find the weight which would secure with well-arranged pauses the maximum product in one day without over-fatigue. As soon as this weight was determined, [p. 167] a special set of shovels had to be constructed for every particular kind of material. The laborers were now obliged to operate with 10 different kinds of shovels, each of such a size that the burden always remained an average of 21 pounds for any kind of material. The following step was an exact determination of the most favorable rapidity and the most perfect movement of shoveling, the best distribution of pauses, and so on, and the final outcome was that only 140 men were needed where on the basis of the old plan about 500 laborers had been engaged. The average workingman who had previously shoveled 16 tons of material, now managed 59 tons without greater fatigue. The wages were raised by two thirds and the expenses for shoveling a ton of material were decreased one half. This calculation of expenses included, of course, a consideration of the increased cost for tools and for the salaries of the scientific managers.
Whoever visits factories in which the new system has been introduced by real specialists must be surprised, indeed, by the great effects which often result from the better psychophysical adaptation of the simplest and apparently most indifferent tools and means. As far as the complicated machines are concerned, we are accustomed to a steady improvement by the efforts of the [p. 168] technicians and we notice it rather little if the changes in them are introduced for psychological instead of the usual physical reasons. But the fact that even the least complicated and most indifferent devices can undergo most influential improvements, as soon as they are seriously studied from a psychological point of view, remains really a source for surprise. Sometimes no more is needed than a change in the windows or in the electric lamps, by which the light can fall on the work in a psychologically satisfactory way; sometimes long series of experiments have to be made with a simple hammer or knife or table. Often everything must be arranged against the wishes of the workingmen, who feel any deviation from the accustomed conditions as a disturbance which is to be regarded with suspicion. In one concern I heard that the scientific manager became convinced that all the working-chairs for the women were too low and that the laborers therefore had to hold their arms in a psychophysically unfavorable position during the handling of the apparatus. All were strongly opposed to the introduction of higher chairs. The result was that the manager arranged for the chairs to be raised a few millimeters every evening, without the knowledge of the working-women, as soon as the factory was empty. After a few weeks the chairs had reached [p. 169] the right height without those engaged in the work having noticed it at all. The outcome was a decided increase of efficiency.
But the most rational scheme will after all be to prepare for such arrangements of tools and apparatus by systematic experiments in the psychological laboratory. The subtlety of such investigations will lead far beyond the point which is accessible to the attempts of scientific management. Exact experiments on attention, for instance, will have to determine how the various parts of the apparatus are to be distributed best in space if the laborer must keep watch for disturbances at various places. Only the laboratory experiment can find the most favorable speed of the machine or can select the muscles to which the mind can send the most effective impulses. The construction of the machine must then be adapted to such results. In the Harvard laboratory, for instance, a practical question led us to examine which fingers would allow the quickest alternation of key movements. If any two of the ten fingers perform for ten seconds the quickest possible alternation of motion, as in a trill, the experiment can demonstrate exactly the differences between the various combinations of fingers and the individual fluctuations for these differences. With an electrical [p. 170] registration of the movements of the alternating fingers we studied in hundredths of a second the time for the motions of two hands and of fingers of the same hand, in order to adjust the keys of a certain machine to the most favorable impulses.
We approach this group of problems from another side when we test the relations of various kinds of machines to various mental types. Psychologists have studied, for example, the various styles of typewriting machines. From a purely commercial point of view the merits of one or another machine are praised as if they were advantageous for every possible human being. The fact is that such advantages for one may be disadvantages for another on account of differences in the mental disposition. One man may write more quickly on one, another on another machine. As every one knows, the chief difference is that of the keyboard and that of the visible or invisible writing. Machines like the Remington machine work with a shift key; that is, a special key must be pressed when capital letters are to be written. Other machines like the Oliver even demand double shifting, one key for the capital letters, and one for the figures, and so on. On the other hand, machines like the Smith Premier have no shift key, but a double keyboard. [p. 171] It is evident that both the shift-key arrangement and the double keyboard have their particular psychological advantages.
The single alphabet demands much less from the optical memory, and the corresponding motor inner attitude of consciousness is adjusted to a smaller number of possibilities. But the pressure on the shift key, which goes with the single alphabet, is not only a time-wasting ad; from the psychological point of view it is first of all a very strong interruption of the uniform chain of impulses. If the capital and small letters are written for a minute alternatingly with the greatest possible speed, the experiment shows that the number of letters for the machine with the double alphabet is about three times greater than for the machine with simple alphabet and shift key. Both systems accordingly have their psychological advantages and disadvantages. Human beings of distinct visual ideational type or of highly developed motor type will prefer the double alphabet, provided, of course, that the touch system of writing is learned, and this will be especially true if their inner attitude is easily disturbed by interruptions. But those who have a feebly developed optical mental centre and who have small ability for the development of complex motor habits will be more efficient on the machines [p. 172] with the single alphabet, especially if their nervous system is little molested by interruptions and thus undisturbed by the intrusion of the shift key act.
In a similar way the visibility of the writing will be for certain individuals the most valuable condition for quick writing, while for others, who depend less upon visual support, it may mean rather a distraction and an interference with the speediest work. The visible writing attracts the involuntary attention, and thus forces consciousness to stick to that which has been written instead of being concentrated on that which is to be produced by the next writing movements. The operator himself is not aware of this hindrance. On the contrary, the public will always be inclined to prefer the typewriters with visible writing, because by a natural confusion the feeling arises that the production of the letter is somewhat facilitated, when the eye is coöperating, just as in writing with a pen we follow the lines of the written letter. But the situation lies differently in the two cases. When we are writing with a pen, the letter grows under our eyes, while in the machine writing we do not see any part of the letter until the whole movement which produces the single letter is finished. By such a misleading analogy many a man is led to prefer the [p. 173] typewriter with visible writing, while he would probably secure a greater speed with a machine which does not tempt him to attend the completed letters, while his entire attention ought to belong to the following letters.
These last observations point to another psychological aspect of the machine and of the whole technical work, namely, their relations to the impressions of the senses. The so-called dynamogenic experiments of the psychological laboratory have demonstrated what a manifold influence flows from the sense-impressions to the will-impulses. If the muscle contraction of a man's fist is measured, the experiment shows that the strongest possible pressure may be very different when the visual field appears in different colors, or tones of different pitch or different noises are stimulating the ear, and so on. As yet no systematic experiments exist by which such results can be brought into relation to the sense-stimuli which reach the laborer during his technical work. The psychophysical effect of colors and noises has not been fructified at all for industrial purposes. The mere subjective judgment of the workingman himself cannot be acknowledged as reliable in such questions. The laborer, for instance, usually believes that a noise to which he has become accustomed does not disturb him in his work, [p. 174] while experimental results point strongly to the contrary. In a similar way the effect of colored windows may appear indifferent to the workmen, and yet may have considerable influence on his efficiency. Numberless performances in the factory are reactions on certain optical or acoustical or tactual signals. Both the engineer and the workman are satisfied if such a signal is clearly perceivable. The psychological laboratory experiment, however, shows that the whole psychophysical effect depends upon the character of the signal; a more intense light, a quicker change, a higher tone, a larger held of light, a louder noise, or a harder touch may produce a very different kind of reaction.
With a careful time-measurement of the motions, it can often be ;directly traced how purely technical processes in the machine itself influence and control the whole psychical system of impulses in the man. I observed, in a factory, for instance, the work at a machine which performed most of its functions automatically. It had to hammer fine grooves into small metal plates. A young laborer stood before every such machine, took from a pile, alternately from the right and from the left, the little plates to be serrated, placed them in the machine, turned a lever to bring the hammer into motion, and then removed [p. 175] the serrated plates. The speed of the work was dependent upon the operative, as he determined by his lever movement the instant at which the automatic serrating hammer should be released. The man's activity demanded 9 independent movements. I found that those who worked the most quickly were able to carry out this labor for hours at a uniform rapidity of 4 to 4½ seconds for those 9 movements. But the time-measurement showed that even these fastest workers were relatively slow in the first 5 movements which they made while the machine stood quiet, and that they reached an astonishing quickness of movement in the 4 last actions during which at the same time the serrating hammer in bewildering rapidity was beating on the plate with sharp loud cracks. The hammer reinforced the energy of the young laborers to an effectiveness which could never have been attained by mere voluntary effort.
Often the simplicity or complication of the stimulus may be decisive in importance, and this also holds true where the most elementary reactions are involved, for instance, the mere act of counting which enters into many industrial functions. Experiments carried on in my laboratory  have shown that the time needed to count a certain number of units becomes longer [p. 176] as soon as the units themselves become more complicated. Their inner manifoldness exerts a retarding influence on the eye as it moves from one figure to another. A certain psychical inhibition arises; the mind is held back by the complexity of the impression and cannot proceed quickly enough to the next. Psychologically no less important is the demand that the external technical conditions so far as they influence consciousness, should remain as far as possible the same, if the same psychical effect is desired, because then only can a perfectly firm connection between stimulus and movement be formed. In technical life this demand is much sinned against. A typical case is that of the signals for which the engineer on the locomotive has to watch. In the daytime the movable arms of the semaphore indicate by their horizontal, oblique, or vertical position whether the tracks are clear. At night-time, on the other hand, the same information reaches him by the different colors of the signal lanterns. From a psychical point of view it is probable that the safety of the service would be increased if an unchangeable connection between signal and movement were formed. It would be sufficient for that purpose if the color signals at night were given up and were replaced by horizontal, oblique, or vertical lines of white light or [p. 177] rows of points. Successful experiments of this kind have been carried on by psychologists in the service of this railroad problem.
The interest in all these problems of large concerns, in transportation and factory work and complex industries, ought not to make us overlook the fact that on principle the same problems can be found in the simplest industrial establishment. Even the housewife or the cook destroys economic values if daily she has to spend useless minutes or hours on account of arrangements in the household which are badly adjusted to the psychological conditions. She sacrifices her energy in vain and she wastes her means where she herself is under the illusion of especial economy. Scientific management would perhaps be nowhere so wholesome as in kitchen and pantry, in laundry and cellar, just because here the saving would be multiplied millionfold and the final sum of energy saved and of feeling values gained would be enormous, even if it could not be calculated with the exactitude with which the savings of a factory budget can be proven. The profusion of small attractive devices which automatically perform the economic household labor and disburden the human workers must not hide the fact that the chief activities are still little adjusted to the psychophysical conditions. The situation [p. 178] is similar to that of the masons, whose function has also been performed for thousands of years, and yet which did not find a real adaptation to the psychical factors until a systematic time-measuring study was introduced. A manufacturer who sells an improved pan or mixing-spoon or broom expects success if he brings to the market something the merits of which are evident and make the housewife anticipate a decrease of work or a simplification of work, but the development of scientific management has shown clearly that the most important improvements are just those which are deduced from scientific researches, without at first giving satisfaction to the laborers themselves, until a new habit has been formed.
Perhaps the most frequent technical activity of this simple kind is sewing by hand, which is still entirely left to the traditions of common sense, and yet which is evidently dependent upon the interplay of many psychical factors which demand a subtle adaptation to the psychical conditions. To approach, at least, this held of human labor a careful investigation of the psychophysics of sewing has been started in my laboratory. The sewing work is done, with the left hand supported, and the right hand connected with a system of levers which make a graphic record of every movement on the smoked surface of a revolving [p. 179] drum. For instance, we begin with simple over and over stitches, measuring the time and the character of the right hand movements for 50 stitches under a variety of technical conditions. The first variation refers to the length of the thread. The thread itself, fixed at the needle's eye, varied between 3 feet and 6 inches in length. Other changes refer to the voluntary speed, to the number of stitches, to fatigue, to external stimuli, to attention, to methods of training, and so on, but the chief interest remains centred on the psychical factors. We are still too much at the beginning already to foresee whether it will be possible to draw from these psychophysical experiments helpful conclusions. The four young women engaged in this laboratory research will later extend it to the psychological conditions of work with the various types of sewing-machines.