Personality change in adolescence: Results from a Japanese sample

We examined developmental trends in personality traits during adolescence by using data from the secondary school affiliated with the University of Tokyo (N = 3656; range 12-18; 1832 female), collected from 1981 to 2010. Hierarchical linear modeling analyses revealed cumulative mean-level changes in personality averaging approximately 1 SD across adolescence. Scales related to Neuroticism showed linear increases, and those related to Extraversion showed distinct developmental patterns: General Activity and Rhathymia did not change, while Ascendance and Social Extroversion declined. Additionally, we found significant gender and birth cohort effects on personality. Although the intercepts differed according to both factors, the trajectories were different only for the birth cohort. These findings suggest that personality development trajectories differ according to the sociocultural context.