Structural and Inter-individual Differentiation in Personality Traits Across the Adult Lifespan

The concept of differentiation describes increasing or decreasing similarities between inter-individual differences on psychological constructs, reflecting processes of specialization or adaptation. In this study, we studied age-differentiation in personality traits in (1) the trait domain and facet loadings, (2) the correlations between trait domains, and (3) trait domain, facet, and item (residual) variances. We used three large cross-sectional samples (Ns > 3000) covering 16–90 years of age with broad measures of the Big Five, Five-Factor, and HEXACO models. We examined age effects on the model parameters using local structural equation modeling. We found a high stability of the trait domain loadings, suggesting relatively stable trait domain compositions across age. Extraversion-Openness correlations increased across age for all three measures, whereas an increase in the Extraversion-Agreeableness and decrease in the absolute Neuroticism-Extraversion correlations only replicated across the five-dimensional models. Inter-individual differences in personality were similar across age in the trait domains and facets but differed substantially for item residuals. In summary, the structure and individual differences in broad personality traits is relatively stable across the adult lifespan, with most age-differences only affecting the item level.