In a recent investigation an attempt was made to discover, by this empirical method, a set of mental tests which would aid in the selection of efficient workers in a specific field. Thirty workers who were already employed under fairly comparable conditions of work were taken as subjects in a preliminary search for tests of value. These thirty people were each put through a series of "association tests," of the familiar laboratory form, naming opposites, naming colors and forms, completing mutilated passages, following hard directions, giving responses bearing specified relations to stimulus words, cancellation and number checking, etc. While these tests were in progress, during a period of several days, the thirty workers were rated by three supervisors who were familiar with their work at the actual task, and who had for some time been observing their performance with a view to making subsequent judgments. Each supervisor arranged the thirty workers in an order of merit, according to his or her impression of their relative efficiency. The judgments of these three supervisors were then averaged and each worker assigned a final position on the basis of these averages. This was believed to be as accurate a measure of actual ability as could be secured under the complex conditions of work.
The results of these ratings were then compared with the results of the mental tests. Some of the tests were found not to correlate with the ratings for actual working efficiency. Three tests showed definite and positive correlations, as follows: _Color-Naming_ (thirty-seven per cent), _Hard Directions_ (forty per cent), _Completion_ (thirty-three per cent). When results from these three tests were combined, the records correlated with the ratings by a coefficient of fifty-five per cent. These three tests were then accepted as having value in the selection of good operators, and search was continued for further tests which might also yield positive correlations. This investigation is again an illustration of the purely empirical method.
These four procedures in the search for useful vocational tests, in the absence of complete vocational psychographs, are quite generally recognized to be but tentative expedients of an explorative character. Individual workers have not always clearly recognized the principles involved in their work, but have proceeded as best they could under the special circumstances. Each method has its own defects and advantages. The miniature model has the advantage of concreteness and apparent relevance, but, as Münsterberg points out, "a reduced copy of an external apparatus may arouse ideas, feelings and volitions which have little in common with the processes of actual life." This writer is inclined to believe, on the basis of his experiments so far, that "experiments with small models of the actual industrial mechanism are hardly appropriate for investigations in the field of economic psychology. The essential point for the psychological experiment is not the external similarity of the apparatus, but exclusively the inner similarity of the mental attitude. The more the external mechanism with which or on which the action is carried out becomes schematized, the more the action itself will appear in its true character."
