But our original three questions are at present answered with very unequal reliability. With respect to the relation between early success or failure in elementary school subjects and success or failure in handling more advanced subject matter, the evidence is clear and definite.
On the question as to the permanence of interests and the relation between interest and ability, the evidence is far from adequate for vocational purposes. While the conclusion suggested is positive in Thorndike's study, the investigator recognizes that the results require confirmation or refutation at the hands of more reliable and verifiable information. It has appeared fairly certain that interest, as reflected in choice of college subjects, bears no relation to ability to undertake the work of at least two definite branches of professional training.
On the third question, concerning the relation between general or particular academic aptitude or inclination and general or particular proficiency in later domestic, industrial, commercial, professional or civic activities, the data, although consistent, are far from complete. Here, then, as in so many other aspects of vocational psychology, we find an inviting field of research and an abundance of interesting problems.
[13] _Educational Review_, September, 1914.
Without attempting to distinguish between the different detailed occupations, either on the basis of materials dealt with, the social or individual purposes realized, or the special qualifications demanded, we can still divide vocations broadly into five general types, depending on the degree to which they are likely to call for complete and normal psychological equipment. Such a classification is of little service in the concrete guidance of individuals, since the general types include work of the most diverse sorts; but it may be useful in suggesting the various types of qualities that are of vital importance in determining aptitude for any work at all, and may in this way aid in outlining the work of further investigation.
1. In the first place there are many useful and remunerative types of labor which can be performed by a domesticated animal or an imbecile, when working under constant or close supervision. Hauling loads, mowing grass, felling timber, sawing wood, digging holes, breaking stone, weaving doormats, and the simple types of work commonly performed in institutions for the mentally deficient are instances. The detection of individuals thus poorly equipped, their congregation and segregation under supervision, and their useful employment, are at once psychologically easy and economically desirable, as has already been indicated in detail in Chapter III.