Structural and Inter-individual Differentiation in Personality 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 association between trait domains, facets and nuances, 2) the correlations between trait domains, and 3) inter-individual differences at all trait levels. We used three large cross-sectional samples (Ns > 3,000) covering 16 to 90 years of age, and 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 facet rank-ordering within trait domains, suggesting relatively stable trait domain compositions across age. Age-associated differences in the facet loadings were unsystematic and differed in direction across the three measures used. Extraversion-Openness correlations increased across age for all three measures, whereas an increase in Extraversion-Agreeableness and decrease in absolute Neuroticism-Extraversion correlations only replicated across the five-dimensional models. Inter-individual differences in personality varied most at the item or nuance level. In summary, personality differentiation is particularly evident at the lowest level and some trait domain correlations, but studies into this topic need to account for the heterogeneity of personality taxonomies and measures.