It is quite probable that further advance in this direction will come, not from the elaboration or invention of more tests, but by the selection of a very few tests, and the examination of the final limits of practice with respect to them. The problem will then be the selection of sets of tests in which initial performance shows high correlation with ultimate capacity in the tests themselves, or else the laborious and undramatic, but perhaps preferable, alternative of continuing every test until the practice limit is reached by the individual. In the latter case it would be well to learn more about the nature and range of these limits than we know at present. In so far as particular tasks are actually found to call for highly specialized aptitudes, for the detection of which tests are sought, there will be the further problem of correlating these various tests with the particular aptnesses or fitnesses toward the detection of which diagnosis is directed. There will also be the problem of the alignment of the various types of work along the general intelligence scales, as rapidly as these are extended and elaborated. In so far as this method is followed, the task of selecting from candidates those best fitted for the accomplishment of special types of work will be easily handled. Vocational selection will readily find methods suited to its purposes. But vocational guidance, as distinguished from vocational selection, must for some time to come depend largely on the determination of interests, incentives, satisfactions, emotional values and preferences, and the discovery and direction of these through general channels of information and through the methods of industrial and pre-vocational education. This is a hard and an arduous program. It calls for strenuous work on the part of investigators, patience and faithfulness on the part of observers, and wide cooperation of investigators with each other. From the immediately practical point of view it also offers an inviting opportunity to those foundations and individuals who are interested in supporting the further development of "the arts of social control over human nature." FOOTNOTES: [16] For explanation of the technique and meaning of correlation see the footnote on p. 45. CHAPTER XII CONCLUSION