Researchers have long assumed that complex thinking is determined by both situational factors and stable, trait-based differences. However, although situational influences on complexity have been discussed at length in the literature, there is still no comprehensive integration of evidence regarding the theorized trait component of cognitive complexity. To fill this gap, we evaluate the degree that cognitive complexity is attributable to trait variance. Specifically, we review two domains of evidence pertaining to (a) the generalizability of individuals' complex thinking across domains and the temporal stability of individuals' complex thinking and (b) the relationship of complex thinking with conceptually related traits. Cumulatively, the literature suggests that persons' cognitive complexity at any point in time results partially from a stable and generalizable trait component that accounts for a small-to-moderate amount of variance. It further suggests that cognitively complex persons are characterized by chronic trait-based differences in motivation and ability to think complexly.
Keywords: cognitive complexity; individual differences; integrative complexity; social cognition.