The base-rate and longer-term relevance of year-to-year change in personality traits

Abstract

Personality traits are assumed to change slowly and incrementally. Recent intervention studies apparently challenge this assumption, showing that personality traits can also change quickly and substantially. However, how frequently do such quick changes manifest in the general population? This study sought to determine (1) a base rate of year-to-year changes in the general population and (2) the extent to which these shifts are related to longer-term change patterns. We examined year-to-year change in Big Five traits with nationally representative data from 7005 German participants, annually tracked for up to six years. Year-to-year patterns exhibited stability and change (e.g., ≥ 1 SD year-to-year change in ≈ 20%). Across participants, year-to-year trait score increases and decreases occurred in equal proportions, suggesting that in a given sample, year-to-year changes in different directions average out. Within participants, however, in all domains but agreeableness, year-to-year changes reliably propagated to longer-term trajectories. While much of the year-to-year change faded away in subsequent years, lasting shifts in individuals' trait levels remained, particularly upon pronounced year-to-year decreases. Overall, (pronounced) year-to-year changes were relatively common, largely reversible, and yet predictive of individuals' longer-term trajectories. We discuss how the results bridge set-point assumptions with assumptions of incremental trait change.