Does the variance of personality traits change across the lifespan? A meta-analytic review of longitudinal studies.

Although personality traits are relatively stable compared to other constructs, comprehensive meta-analyses have shown that the mean-levels and rank-orders of personality traits change throughout the lifespan. In contrast, relatively little is known about whether and how the variance of personality traits develops with age. Examining changes in personality trait variance is, however, critical to contextualize knowledge on mean-level changes, to identify disruptive life phases, to evaluate the changes in predictive utility of personality traits, and to advance personality development theories. The present meta-analysis thus integrated research from 362 longitudinal studies (Ntotal = 398,124) to identify changes in personality trait variance across time and age. We found remarkable stability of personality variance for all traits, indicating that, at the population level, people neither get more different nor more alike across the lifespan. The only deviations from this pattern were variance increases in neuroticism during late childhood and early adolescence (5 to 14 years) and variance decreases in extraversion during middle and late adulthood (45 to 80 years). Notably, though, effect sizes differed substantially across studies and measures. Our results provide novel insights into the lifespan development of personality traits that can be used to advance theoretical frameworks and inform practical applications. Furthermore, by providing benchmark values for the comparison of effect size estimates of future studies (https://personalityresearch.shinyapps.io/VarianceChange/), we aim to facilitate more systematic and cumulative research on variance changes in psychological traits.