Personality Change in Middle Adulthood: With Focus on Differential Susceptibility.

Little attention has been paid to middle adulthood in research on personality stability and change. In addition, previous research on individual differences in personality change has not fully explained its variability. This study focused on the differential susceptibility model, which suggests that individual susceptibility interacts with environmental factors and produces variability in outcomes, and investigated individual differences in personality change with a middle adult sample. A total of 1051 Japanese middle adults (M = 41.61 years; SD = 5.31; range 30-50 years; 534 females) participated in this two-wave short-term longitudinal study. Latent change score model analyses revealed substantial mean-level declines in Agreeableness and Honesty-Humility. Moreover, the results showed that the influences of some life events on personality change are moderated for better and for worse by individual susceptibility to one's environment. These findings suggest that the trends of personality development may differ between Western and non-Western countries and that differential susceptibility model may play an important role in deriving individual differences in personality stability and change.