A sample of 9173 noninstitutionalized youth who took the 1980 Armed Services Vocational Aptitude Battery (ASVAB) was divided into five ability levels. Analysis supports the assertion that cognitive abilities are less correlated in higher ability groups and implies that greater classification effects can be associated with more intelligent groups.…

These authors cite their own study of the relationship between traditional measures of intelligence and Piagetian measures of cognitive development in support of Glass and Stephens' contention that there are important qualitative differences. They question Humphreys' and Parsons' conclusions on both substantive and factor theoretical grounds. (CTM)