Differentiation of cognitive abilities and the Medical College Admission Test

Cognitive Ability Differentiation (CAD) theory proposes greater differentiation of narrow cognitive abilities occurs at a high level of g, the general factor of ability. CAD also proposes that g is a stronger determinant of cognitive performance in low-g versus high-g individuals, but that narrow cognitive abilities are stronger determinants of performance in high- versus low-g individuals. We assessed whether CAD occurs in Medical College Admission Test (MCAT) scores using data from over 4800 medical school applicants. In support of CAD, our results provided consistent evidence that the MCAT's measures of narrow cognitive abilities were more differentiated in high- versus low-g individuals. Also consistent with CAD, g was a stronger predictor of a cognitive performance criterion, GPA, in low- versus high-g individuals. Contrary to CAD, however, the MCAT's measures of narrow abilities were not stronger predictors of GPA in high- versus low-g individuals. Implications of these results for future CAD research and for medical schools' use of the MCAT are discussed.