Traits and Adaptations: A Theoretical Examination and New Empirical Evidence

We investigated the distinction between traits (also labelled basic tendencies or dispositions) and (characteristic) adaptations, two related features of the personality system postulated to influence how personality manifests throughout the lifespan. Traits are alleged to be universal, causal, and enduring entities that exist across cultures and through evolutionary time, whereas learned adaptations are acquired through sustained interaction with cultural, physical, and social environments. Although this distinction is central to several personality theories, they provide few measurable criteria to distinguish between traits and adaptations. Moreover, little research has endeavoured to operationalize it, let alone test it empirically. Drawing on insights from four frameworks—the Five-Factor Theory, Cybernetic Big Five Theory, Disposition–Adaptation–Environment Model, and New Big Five—we attempted to investigate the distinction both theoretically and empirically. Using various experimental rating conditions, we first scored 240 questionnaire items in their degrees of definitionally reflecting traits and/or adaptations. Next, we correlated these definitional ratings with the items' estimates of rank-order stability, consensual validity, and heritability—criteria often associated with personality traits. We found some evidence that items rated as more trait-like and less adaptation-like correspond to higher cross-rater agreement and stability but not heritability. These associations survived controlling for items' retest reliability, social desirability, and variance. The theoretical and empirical implications of these findings are discussed. © 2020 European Association of Personality Psychology