title: Linear and nonlinear associations between general intelligence and personality in Project TALENT.
abstract: Research on the relations of personality traits to intelligence has primarily been concerned with linear associations. Yet, there are no a priori reasons why linear relations should be expected over nonlinear ones, which represent a much larger set of all possible associations. Using 2 techniques, quadratic and generalized additive models, we tested for linear and nonlinear associations of general intelligence (g) with 10 personality scales from Project TALENT (PT), a nationally representative sample of approximately 400,000 American high school students from 1960, divided into 4 grade samples (Flanagan et al., 1962). We departed from previous studies, including one with PT (Reeve, Meyer, & Bonaccio, 2006), by modeling latent quadratic effects directly, controlling the influence of the common factor in the personality scales, and assuming a direction of effect from g to personality. On the basis of the literature, we made 17 directional hypotheses for the linear and quadratic associations. Of these, 53% were supported in all 4 male grades and 58% in all 4 female grades. Quadratic associations explained substantive variance above and beyond linear effects (mean R² between 1.8% and 3.6%) for Sociability, Maturity, Vigor, and Leadership in males and Sociability, Maturity, and Tidiness in females; linear associations were predominant for other traits. We discuss how suited current theories of the personality-intelligence interface are to explain these associations, and how research on intellectually gifted samples may provide a unique way of understanding them. We conclude that nonlinear models can provide incremental detail regarding personality and intelligence associations.
authors.affiliation: Department of Psychology.
authors.forename: Jason T
authors.initials: JT
authors.lastname: Major
authors.affiliation: Department of Psychology.
authors.forename: Wendy
authors.initials: W
authors.lastname: Johnson
authors.affiliation: Department of Psychology.
authors.forename: Ian J
authors.initials: IJ
authors.lastname: Deary
mesh_terms: D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D007360:Intelligence; D007361:Intelligence Tests; D016014:Linear Models; D008297:Male; D010551:Personality; D010555:Personality Inventory; D012737:Sex Factors; D055815:Young Adult