sensitive to internal cues and women more sensitive to external social cues. In response to stress, men may be more likely to show a “fight or flight” response and women a “tend and befriend” response. Men's self-concepts may be organized more in terms of the independent characteristics emphasized by individualistic cultures, and women's self-concepts may be organized more in terms of the interdependent characteristics emphasized by collectivist cultures. Women's relatedness to others is conceived more in terms of personal, one-on-one relationships, and men's relatedness is conceived more in terms of social groups and social hierarchy.
Boys and girls show a number of robust behavioral differences. Boys' social lives are more hierarchical and group-centered, and boys engage in more competitive, aggressive, and rough-and-tumble play. Girls' social lives are more one-on-one, and girls engage in more reciprocal, verbal, and negotiated kinds of play. Boys fantasize more about heroic individual achievements, and girls fantasize more about family and reciprocal social roles. All these childhood sex differences contribute to the sex segregation commonly observed in children's friendship and playgroups. This segregation begins at around age three, grows stronger through middle childhood, and does not wane until opposite-sex romantic and sexual attractions emerge in preadolescence.
Accordingly, in this chapter, I use the term sex differences, for the goal here is to contrast two biological groups: males and females. My use of sex differences implies nothing about the causes of these differences. In the next chapter, I will use the terms masculinity and femininity to refer to individual differences within each sex in how male-typical or female-typical individuals are.