|Birth to 12 months
- By 7 months, infants can discriminate between male and female voices.
- By 9 months, infants can make visual discriminations of pictures of males and females.
- By 1 year, infants show intermodal coordination of information regarding gender (e.g., match voice with appearance).
|12 to 24 months (1 to 2 years)
- Males show more aggressive behavior and greater assertiveness than females from an early age. The difference decreases over age, except for relational aggression. These differences are found across many cultures and across ages.
- Beginning around 2 years, children begin to show preferences for same-sex toys. Boys show a tendency to avoid playing with "girls' toys" such as dolls, while girls do not show a consistent avoidance of other-sex toys.
|24 to 36 months (2 to 3 years)
- By 26 months, children show knowledge of gender differences in adult possessions, roles, physical appearance, and abstract characteristics (e.g., soft, cruel).
- By 30 months, children understand the category labels boy and girl. They apply gender labels to adults before using them for children. By 36 months, most children understand gender identity (i.e., they can consistently label their own sex), but they rely on hairstyle and clothing cues.
- By 2½ to 3 years, children show knowledge of gender stereotypes regarding objects, activities, and children's toys. Children increasingly play with same-sex toys.
- Both boys and girls have increasing positive contact with same-sex peers and begin to show same-sex peer preferences.
|Preschool years (3 to 5 years)
- Children show increasing gender differences in toy preferences and play activities.
- By 3 years, most children understand gender stability (i.e., that one's gender is stable over time).
- Children show increasing stereotypes regarding children's toys, activities, colors, traits, and play preferences. Stereotypes increase rapidly and are well-established by 5 years, and are stronger for boys than for girls.
- By 2 to 4 years, there is some evidence of children distinguishing between male and female traits, behavior, and emotions, especially along power/fearfulness dimension (e.g., "boys are strong, fast, and they hit"; "girls cry, need help, and are fearful") and negative/positive evaluation (males as negative; females as positive).
- Preference for same-sex peers and sex-segregation in play groups increases. This preference is found across cultures and even in nonhuman primates.
- Same-sex positive bias develops by age 5. (Girls may develop this positive bias earlier, by age 3.)
- Same-sex peers are expected to prefer to play together.
- Stereotyped differences in personality/social characteristics begin to develop, especially in aggressive and helping behaviors.
- The late preschool years are a period of high rigidity in gender beliefs and behavior.
|Early elementary school (6 to 7 years)
- Rigidity in gender-stereotyped beliefs regarding activities, occupations, traits, sports, and school tasks is very high during kindergarten.
- Segregation into same-sex play groups remains high and continues until early adolescence.
- Gender-stereotyped preferences remain high or increase, though preferences are higher for some areas than others. When stereotyped preferences show declines, the decreases are seen only in girls.
- Stable or increasing gender differences are seen in such things as television show preferences (boys view more cartoons and action-adventure shows), sports participation, chores, hobbies, and outdoor/indoor play.
- By entry into school, children have extensive knowledge of gender-related activities, which they use to make inferences about novel tasks, activities, and toys.
- There is a strong negative reaction to cross-gender behavior, especially when it involves cross-gender appearance.
|Elementary school (7 to 9 years)
- By 7 years, most children show full understanding of gender constancy (i.e., that gender remains the same despite changes in appearances or clothing).
- By 8 to 9 years, children consistently use genital cues to determine gender. Until now, most children have relied on appearance cues (e.g., hair, dress).
- By first grade, there is evidence of gender-stereotyped patterns of self-concept (e.g., "math is important for boys but not for girls"). These patterns increase across the elementary school years. Self-perceptions (e.g., self-reports of qualities such as kind, gentle, persistent) also become increasingly gender stereotyped.
- Gender stereotypes remain very rigid until 7 to 8 years of age. After this, knowledge of gender stereotypes continues to increase, but stereotype rigidity gradually decreases (i.e., children's gender concepts start to become more flexible). Girls show more and earlier stereotype flexibility than boys.
- Children begin to understand the cultural relativity of gender norms.
- Acceptance of cross-gender behavior and appearance increases during middle elementary school years.
|Early adolescence (9 to 11 years)
- By 10 years, there is increasing awareness of different cultural values given to traditionally male versus female roles, attributes, etc.
- Flexibility of gender stereotypes increases, at least up to early adolescence. Girls show greater flexibility in stereotyped preferences than do boys.
- There is increasing awareness by both boys and girls of the male-favored status, and girls begin to report dissatisfaction with female status.
- Differences are found or increase in some spatial skills, emotional expressiveness, emotional perceptions, and self-esteem.
|Adolescence (11 years and older)
- Changes in stereotype flexibility during adolescence are unclear. There is some evidence for increasing flexibility as cognitive development progresses, but conflicting evidence due to increasing pressure toward gender intensification.
- Reactions to cross-gender behavior and appearance become more negative, reversing the trend seen during the later elementary school years.
- Gender intensification increases, especially in girls (e.g., increasing time spent in interpersonal activities, personal care, and doing chores; decreasing time spent in sports activities). High levels of sex-typed activities and interests are seen across contexts for both girls and boys.
- Differences emerge or increase in problem solving, physical skills and performance, and incidence of depression.