Although the heritability of general intelligence has been the subject of much study and can be considered to be well established, the heritability of specific factors in intellectual functioning has not as yet been the object of such intense scientific inquiry.

The recent work of Nichols (1965), utilizing a large sample of twins from the National Merit Scholarship testing program and employing a battery of tests measuring achievement in five different academic areas, is an excellent pioneering study. Nichols used a composite score derived from the five subtests, presuming this to be a measure of general ability, and he found that MZ twins were much more alike than DZ twins with respect to the composite score; about 70% of the variance in the composite could be attributed to heredity. The novel result of his investigation is his discovery that the specific subject areas also have significant heritability components. When the influence of the composite general ability upon subtests was removed statistically, the residual subtest scores also showed considerable heritability.

A limitation of Nichols' findings is that the subtests do not offer any potential theoretical link to basic factors in mental functioning. Such measures, however, may be provided by the fundamental factor analytic explorations of Guilford and his associates during the past twenty years. Since our own interest has been in the area of creative thinking and esthetic judgment, we have restricted ourselves in the present investigation to the use of tests in those areas whose factorial classification has been studied previously.