An apparently simpler problem in ascertaining the relationship between significant variables in the work situation is illustrated by an inquiry into the relation between intensity of illumination on the one hand, and output, accidents, and employee morale on the other, which has been made under the auspices of a committee of the National Research Council, and is soon to be published. This relation is not so clear cut as earlier experiments had seemed to indicate, since personal and social factors as well as physical aspects of the environment have had to be controlled before effects of lighting on industrial behavior could be unambiguously ascertained.

The variety and complexity of the factors which come within the scope of the industrial psychologist's inquiry are seen at a glance in the accompanying partial list of variables, in which managers and workers are chiefly interested.

Each aspect of significant industrial behavior listed in column A, such as proportion of spoiled work, rate of advancement in salary or in responsibility, or degree of satisfaction in the job, has actually been measured or quite conceivably can be measured. The factors conditioning behavior, of which many are listed in column B, must also be measured, and their relationship ascertained to the behavior items in column A.

This is not the whole picture. Even when each of the humanly and industrially significant effects mentioned in the first column of the table is thoroughly understood in its relation to each of the causes listed in the second column, it still will be necessary to determine interrelationships. Quantity and quality of goods produced, for example, are determined in part, not only by the ability of the workers, their training, supervision, incentives, feelings of security, and other conditions listed in the second column; they are affected also by regularity of attendance, health, number and severity of accidents, and other variables appearing in column A. The task, then, is neither easy nor simple.

It does not follow, however, that the problem that faces the industrial psychologist is utterly baffling, and that the methods of science must, therefore, be put aside in favor of shrewd, unaided common sense, or that intuitive, impressionistic executive judgments based on conference and pooled "experience" are superior to precise records, measurement, and controlled experiment. True, the answer in its entirety is not going to be found in this generation, or the next. But already we know that, taking the problem bit by bit, exploring minutely the relations of one of its variables to a few of the others, the findings are often of immediate practical value. They are also steps in advance for the science of industrial psychology.

Unexpected By-products of Industrial Research. Current industrial investigations of the Western Electric Company in their great manufacturing plant at Hawthorne, a suburb of Chicago, are in point. The story is told in the Personnel Journal for February, 1930, by G. A. Pennock, M. L. Putnam, and Elton Mayo. These studies were initiated nearly four years ago, when a small group of women relay assemblers were separated from the other employees in this department, and a series of observations and experiments was begun for the purpose of accurately determining individual variations in output and the relationship of these ups and downs to conditions of work - particularly to such factors as method of payment, length of working day and working week, nutrition, sleep, length and distribution of rest periods, and the like.

The procedure required that conditions be maintained as nearly constant as possible for a period of weeks, followed by the introduction of a single change, such as provision for a light lunch at the time of the mid-morning rest pause. After a while another change was introduced, such as shortening or lengthening the working day. All this time, each worker's output was automatically recorded minute by minute. There was no pressure to speed up, no driving by the supervisor. But the workers were encouraged to tell how they felt, to comment on what they liked and disliked about the situation, and also to mention anything that happened outside of working hours which might be useful in accounting for their fluctuations in working efficiency.

The outcome has been astonishing. Workers' earnings and satisfactions improved far beyond expectation, and in some degree quite independently of the changes made in physical working conditions. While information of real value regarding optimal number, length, and distribution of rest periods, mid-morning lunches, and similar variables was secured, the management attaches far greater importance to what this experiment has revealed regarding the characteristics of effective supervision. Indeed, a systematic effort is now being made, through a program of employee interviewing and a new type of supervisory training, to extend throughout the works to all the 40,000 employees some of the benefits that were first brought clearly to light in this modest experiment. Here, as in many scientific researches, the unexpected by-products have far exceeded in value the direct returns, important as those have been.

Gradually industry is realizing the great potentialities of such experiments as these. Management is carrying over into the realm of human behavior the same scientific ideals that it has long demanded of the chemist, the metallurgist, and the engineer. In so doing, it has taken steps toward the development of a well-rounded industrial psychology.

Relation of Industrial Psychology to Allied Fields. The aims of industrial psychology have a great deal in common with those of the mental hygiene movement on the one hand, and of scientific management on the other. When a psychiatrist approaches the personnel problems of a vast mercantile organization, he is not only plunged at once into those familiar problems of emotional maladjustment with which the physician of the mind has largely been preoccupied; he also faces many practical details of supervisory training and executive organization, not to mention the whole range of practices and techniques designed to select employees for particular duties and to adjust them to occupations in which their natural abilities and predilections find the greatest opportunity.

The expert in scientific management also, faced with the necessity of securing maximum output at minimum cost in order that the enterprise may prosper and continue to furnish steady employment, realizes that morale is essential, that excessive labor turnover is inordinately expensive, that industrial accidents due to worry and other preoccupations are an avoidable waste, and that the highest productivity can be obtained only with a vocationally well-adjusted personnel.