The power of many small sex differences in cognition, personality, and interests

Abstract It has repeatedly been shown that most psychological sex differences are small, with largely overlapping distributions. This study examined whether multiple small sex differences—across cognitive performance, personality traits, and interests—can collectively distinguish between males and females and predict real-life outcomes. Participants (N F = 1465, N M = 1302, 35–45 years old) completed online tests and questionnaires that assessed cognitive performance, personality, and interest in people and in things. Results showed sex differences across 13 tasks and questionnaires in the expected directions. Importantly, when combined, these measures correctly predicted whether an individual was male or female in 80% of cases and accounted for a substantial share of the variance in the real-life outcome of occupational gender segregation. These findings demonstrate how multiple small individual differences can collectively yield substantial predictive power, offering new insight into the underpinnings of gender differences in society.