FOR many years now educationists have been experimenting in the application of psychology to the problem of discovering and measuring mental capacity or “general intelligence.” At first they made little progress and met with much hostility, but in recent years their successes have been so great and the acceptance of psychological tests as a measure of intelligence has become so general that it has become necessary for psychologists to warn enthusiastic educationists that as yet such tests are far from in-fallible and must not be used as the sole basis for important decisions. 1 Among the most valuable contributions to industrial progress made by the “Scientific Management” school in America was the emphasis which they put 26upon the necessity for scientific selection of the most efficient workers for each kind of work. In the oft-quoted case of Pig Iron Handling at the Bethlehem Steel Works, 1 Taylor’s first step was to select the right kind of worker, and although his insistence on employing only first-class men which necessitated the dismissal of seven out of eight of the men who had previously done the work would be impossible if scientific selection became general, the results of his experiment showed the gains in efficiency which such selection helped to make possible. From the scientific point of view the value of this experiment and the equally familiar one carried out by Thompson at a Bicycle Ball Factory 2 is seriously diminished by the introduction of several changes at the same time, so that it is impossible to judge how much of the saving in time and effort which resulted in this second case from shorter hours, the introduction of rest periods, better methods of work and selection of the workers who had a low reaction coefficient, was due to such selection 27and how much to the other changes. The investigation into the practice of “Scientific Management” shops carried out by Hoxie 1 showed that these did not justify the claims made—that workers were “scientifically” selected, and it has remained for the Industrial Psychologists to devise means whereby the enormous waste of efficiency which results from wrong choice of occupation and the employment of workers who might be highly efficient at some other work in an occupation for which they are not fitted 2 may be avoided. The extent of such waste at present is far greater than is popularly imagined. It has been estimated that in the United States alone “it would be possible to increase the national wealth by $70,000,000,000 each year by properly fitting every man, woman and child to the kind of work each could best perform.” 3 Instead of attempting to do this, however, at present boys and girls are guided in their choice of a profession by untrust-worthy advertisements, by suggestion, imitation, 28desire for immediate material gain, or purely accidental circumstances, 1 taking the first opening which presents itself, and the boy who might have been a highly efficient engineer becomes an unsatisfactory and dissatisfied clerk, while the boy who might have become an efficient clerk and done the work in half the time is condemned by chance to waste his talent as a plumber’s apprentice. 2 Moreover, it has been found that “in so far as a man does work for which he is naturally most fit, he works easily and with relatively little fatigue, since he moves along the lines of least resistance,” 3 and on the elimination of unnecessary fatigue depends the future of industry. 4 The enormous waste of the present chaotic selection of workers lies in its disregard for individual differences. “For each individual,” Dr. Myers has said, “there is one occupation more suitable than any other, and in every occupation some succeed better than others owing to wide mental and physical 29differences.” 1 It has been found that tests for speed in feeding machines correlate highly and positively with known fitness of the subjects for a slow-running or a fast-running machine in the factory, and that a worker who is below the average on a slow-running machine may be considerably above the average on a fast-running machine. 2 The economy which would result from finding for which type of machines a worker was fitted and employing him on that type is obvious. In the course of an investigation into the Tin Box Industry undertaken on behalf of the National Institute of Industrial Psychology 3 it was found that workers engaged in soldering boxes, some of which were round and others angular in form, found greater difficulty in one type of work than in the other, and the data obtained proved that some found greater difficulty in doing one type and others in doing the other type. By arranging that those workers who naturally moved their hands more easily in circles should be employed on round tins, and those who found it easier to move along straight 30lines should be employed on angular tins, much unnecessary fatigue was eliminated and greater satisfaction was obtained from their work. Another way in which vocational selection can eliminate waste is by lessening the avoidable labour turnover. Dr. Myers has estimated that in the case of factories where women are employed the rate of labour turnover is usually from 50 per cent to 300 per cent 1 —that is to say, in order to keep a staff of 100 workers, from 50 to 300 workers have to be engaged each year. A high rate of labour turnover is due largely to unsatisfactory conditions and unsuitability of workers.