There are theoretical reasons to hypothesise that men and women will display differences in personality traits. These hypotheses arise from biological and social models of personality: that men and women differ because of biologically/evolutionarily-based innate temperamental or hormonal differences; or that personality differences appear because men and women class themselves into gender roles (Feingold, 1994;Costa, Terracciano and McCrae, 2001). The main questions, therefore, have arisen around agreeableness (nurturance) and emotional expression (N), both of which are thought to be higher in women, and dominance (A and E), thought to be higher in men. In addition, differences might be expected between traditional or collectivist cultures (e.g., Pakistan or China), and individualistic cultures (e.g., Europe or the USA).
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The two meta-analyses of Feingold (1994) and Costa, Terracciano and McCrae (2001) collated findings of studies on personality traits from many different age groups and nations. The answer to the question ‘are there sex differences in personality traits?’ is: ‘yes,’ and these differences, while small-to-medium in effect size, are in line with expectations. The first of the meta-analyses reported that, across cultures (Canada, China, Finland, Germany, Poland and Russia), males score higher on assertiveness measures, whereas females score higher on anxiety, trust and tender-mindedness (Feingold, 1994). The second of the meta-analyses studied a much broader array of traits, and a wider range of cultures, including Africa, South America, and central and eastern Asia (Costa, Terracciano and McCrae, 2001). Costa and colleagues reported that women were higher in negative affect, submissiveness and nurturance; men were higher in dominance and were less concerned with feelings than with ideas.
Some cultures showed greater differences than others; contrary to expectation, individualistic cultures showed wider sex differences than collectivistic cultures. Overall, however, the two meta-analyses, covering hundreds of studies, show that there are consistent sex differences in personality - in emotional (N), agreeableness and dominance-related traits - both within and across cultures.
Curiously, gender differences in children seem to be different. Else-Questet al. (2006) conducted a meta-analysis of temperamental factors that are precursors of personality (see chapter 3). The largest gender difference was in effortful control, which may support later conscientiousness; girls scored higher. Boys were higher than girls in surgency (extraverted qualities including activity and high-intensity pleasure). Again, contrasting with the adult data, differences in negative emotionality were negligible. Developmental changes in gender differences in personality might reflect either sex differences in the maturation of the brain, or social forces (or some interaction of the two).