Secular Trends and Personality: Perspectives From Longitudinal and Cross-Cultural Studies-Commentary on Trzesniewski & Donnellan (2010).

According to cross-temporal meta-analyses (Twenge, 2000, 2001), social trends over the last decades have powerfully influenced the personality profiles of children and students, with effects accounting for 20% of the variance of Neuroticism and Extraversion. However, Trzesniewski and Donnellan (2010, this issue), who examined a large and representative U.S. high-school student sample, found little evidence of secular trends. In this commentary, I emphasize the distinction between cohort and period effects and review findings from longitudinal and cross-cultural studies on the role of social trends and other cultural influences on personality traits. Analyses of adult personality scores from the Baltimore Longitudinal Study of Aging provide little support for powerful secular effects on Neuroticism and Extraversion; evidence supports a secular trend of declining trust, along with additional small effects on other facets of personality. Analyses of personality scores from around the world suggest that social and cultural differences account for about 5% of the variance on major dimensions of personality. The integration of findings from multiple perspectives provides useful insights into the role of the environment on personality traits.