Personality differentiation by cognitive ability: An application of the moderated factor model

The personality differentiation hypothesis holds that at higher levels of intellectual ability, personality structure is more differentiated. We tested differentiation at the primary and global factor levels in the US standardisation sample of the 16PF5 (n = 10,261; 5124 male; mean age = 32.69 years (SD = 12.83 years). We used a novel combined item response theory and moderated factor model approach that overcomes many of the limitations of previous tests. We found moderation of latent factor variances in five of the fifteen primary personality traits of the 16PF. At the domain level, we found no evidence of personality differentiation in Extraversion, Self-Control, or Independence. We found evidence of moderated factor loadings consistent with the personality differentiation for Anxiety, and moderated factor loadings consistent with anti-differentiation for Tough-Mindedness. As differentiation was restricted to a few personality factors with small effect sizes, we conclude that there is only very limited support for the personality differentiation hypothesis.