This replication and extension of Mõttus and Rozgonjuk (2019) compared the extents of age-related information captured by different levels of the personality trait hierarchy (domains, facets and nuances, indexed by individual items) in several samples (N = 51,524) of different age ranges and cultural backgrounds, and tested with different instruments. Across samples and measures, lower trait hierarchy levels (especially nuances) tended to contain substantially more age-sensitive information than higher levels; most of the unique age-sensitive information was in nuances. Besides showing the need for more nuanced personality (development) research, the findings suggest ways of testing novel hypotheses that rely on systematic between-trait variance in age differences.

Rationale: Personality traits change in both mean levels and variance from childhood through mid-adolescence, but the mechanisms underlying these developmental trends remain unknown. We tested the possible roles of social pressure and self-regulation. Methods: The Common-Language California Child Q-Set was used to measure youths’ mean-level personality, social expectations for youths’ behavior from multiple perspectives (parents, teachers, peers) and the self-regulatory requirements for achieving the desired trait levels. Results: There were consistent expectations for youths’ traits, regardless of who described the expectations or whether these pertained to children or adolescents. Mean trait levels were moderately commensurate with social expectations, but age differences in the means did not follow these expectations. Traits with strong expectations showed more pronounced individual differences and increased even more in variance with age. In contrast, traits’ self-regulation requirements did not predict their developmental trends. Implications: Strong social expectations may contribute to the development of individual differences.