Decline of Extraversion in Japan: A Cross-Temporal Meta-Analysis

Extraversion is a fundamental personality trait that explains individual differences in behavior, cognition, and attitudes. Changes in extraversion suggest shifts in various related constructs, including self-esteem, and the number of friendships. While previous studies have reported an increasing trend in extraversion in countries such as the United States and China, temporal changes in extraversion in Japan remain unexplored. Therefore, this study examines temporal changes in extraversion in Japan using a cross-temporal meta-analysis. We collected a total of 75 data points (48 studies, n = 48,905) conducted between 2010 and 2021 that reported average extraversion scores using the Japanese version of the Ten Item Personality Inventory (TIPI-J). To assess the influence of survey year on extraversion, hierarchical multiple regression analyses were conducted, controlling for the average age and gender composition. Findings revealed a significant decline in extraversion scores over time and a significant decline in both men and women. These findings enhance our understanding of personality shifts in Japan.