Modeling Intraindividual Change in Personality Traits: Findings From the Normative Aging Study

To advance an intraindividual life-span approach to the issue of stability and change, we studied personality trait trajectories in adulthood. Growth curves for extraversion and neuroticism were estimated for over 1600 men (initially aged 43-91) in the Normative Aging Study, who were followed over 12 years. We found significant individual differences in intraindividual change for both traits, as well as different trajectories for extraversion and neuroticism. The overall extraversion trajectory was best defined by a linear model, but neuroticism was characterized by quadratic decline with age. We then considered several variables as predictors of individual differences around these overall trajectories. Birth cohort, marriage or remarriage, death of spouse, and memory complaints were all significant predictors, explaining variability in both level and rate of personality trait change. These findings suggest that there is a good deal of variability in personality trajectories, and that some of this variability can be explained by birth cohort as well as by age-graded life events.