Individuals within a given culture hold expectations and beliefs about the behaviors characteristic of males and females called gender stereotypes. The process by which children acquire the characteristics and behaviors prescribed for males and females is called gender-role development.

1. Gender stereotypes versus actual sex differences
   
   1. The stereotypes: what are they?
      Although some differences in gender stereotypes are seen across cultures, many cross-cultural similarities exist. Men are often described in terms of instrumental characteristics such as assertiveness and independence, whereas women are described in terms of expressive characteristics associated with emotions and interactions with people.
   2. Children's knowledge of gender stereotypes
      Eighteen-month-old infants show evidence of gender-role stereotypes, and knowledge continues to develop as children get older, when they begin to recognize that gender stereotypes are flexible. Later in adolescence, gender stereotypes increase somewhat, a phenomena described as gender intensification.
   3. What sex differences actually exist?
      Males and females are more alike than different; greater variability exists within the sexes than between them. Sex differences in physical attributes appear very early in life. Early studies suggested that girls are more skilled than boys in verbal ability, but a recent meta-analysis detected no sex differences in verbal skills. Overall sex differences in math skills also failed to appear in a recent meta-analytical study. The cognitive skill in which sex differences still appear is mental rotation and spatial perception, where males outperform females. Males are more aggressive than females, particularly preschoolers. This difference decreases through the college years. Under some circumstances, for example, when attempts to harm another include indirect or relational aggression, girls are found to be more aggressive than boys. To some degree, girls show a heightened sensitivity to emotions compared with boys. However, this may be due to socialization factors in that girls feel more comfortable expressing their emotions than boys. Differences in self-esteem between boys and girls, even in adolescence, is small. However, girls show a sharp rise in rates of depression compared to boys in adolescence.
   4. Sex differences in perspective
      Research suggests that the behaviors of males and females are more alike than different. Many sex differences that we perceive exist only in terms of gender stereotypes.
      
      
2. Theories of gender-role development
   
   1. Biological theories
      Biological theories focus on the interactions between behavior and chromosomal and hormonal influences. During initial sexual differentiation of the fetus, the XY configuration of chromosomes leads to the growth of the testes and the secretion of male hormones called androgens. The lack of a Y chromosome (XX pair) leads to the growth of female physical structures.
      The androgens also influence the organization of the structure of some areas of the central nervous system, which in turn may affect sex-typed behaviors such as aggression. However, whether levels of androgens and aggression are causally linked remains uncertain.
      
      

      Atypical Development: Hormonal Disorders in Children Both genetic males and females may be exposed to hormonal influences not typical for their sex. For example, the overproduction of adrenal steroids, a condition called congenital adrenal hyperplasia (CAH), may contribute to masculinization of genitalia in individuals who are genetically female and greater likelihood of rough-and-tumble play behavior than in females who do not have this condition. For individuals genetically male, a failure to be sensitive to androgens, a condition called androgen insensitivity syndrome (AI), may cause female-appearing genitalia and greater interest in female gender stereotypes. Although these studies suggest a role for biological factors in gender-stereotypic behavior, socialization practices may also account for some of the findings.

      
      Some investigators suggest that sex differences in visual-spatial skills result from differences in lateralization of the brain. According to this view, the later maturity in males produces greater brain lateralization than in females, who mature earlier and more quickly. Sex differences in visual-spatial skills may also result from differences in the play experiences of boys and girls; boys appear more likely to play with toys that encourage visual-spatial skills.
   2. Social learning theory
      According to social learning theory, behavioral differences between the sexes result primarily from differential reinforcement and punishment of sex-typed behavior and imitation or modeling of these behaviors. Social learning theory has also incorporated the importance of attention, recognition, and motivation in explaining how sex roles are learned through modeling. Children are more likely to attend to, imitate, and display sex-typical behavior than sex-atypical behavior.
      Cross-cultural studies show that differences between males and females are more exaggerated in some cultures than in others and, in fact, are among the least pronounced in American children. The fact that there are cultural differences in behaviors and interests between boys and girls suggests that biology cannot entirely explain gender-role development.
   3. Cognitive-developmental theories
      Cognitive-developmental theories focus on the ways in which children understand gender roles in general and themselves as males or females in particular.
      In Kohlberg's theory, gender development emerges as a result of cognitive development. An important cognitive milestone is gender identity, the knowledge that one is male or female, which emerges at about two to three years. At about age four, the child develops gender stability, the knowledge that gender does not change over time. The understanding that biological sex is not determined by external factors such as clothing, behaviors, or desires is called gender constancy and occurs at about seven years.
      Gender schema theory stresses the importance of gender identity and intrinsic motivations to display sex-typical behavior. Once children acquire gender identity, they actively construct gender schemas to organize information relevant to sex typing and their social world. Young children often distort information to conform to their beliefs about gender and may remember information discordant with those beliefs less effectively.
      Cognitive-developmental theories have been useful in explaining how children think about gender and particularly in explaining children's distortion of information that is inconsistent with gender stereotypes. Children differ considerably in their acquisition of gender schematic behavior, perhaps in part as a result of the importance of gender to the community around them.
      
      
3. The socialization of gender roles
   Gender roles are assumed to be taught to children by others in their social environment, first parents and other family members and then peers and other people in their school experiences.
   1. The influence of parents
      Parents provide their children with gender-role information in subtle ways, such as through sex-differentiated toys, and in more direct ways, such as by playing more aggressively with their sons than with their daughters. Parents also communicate gender-role information by delivering direct reinforcement for sex-typical behavior in their children and punishing sex-atypical behavior. However, the impact of parental factors on gender role development may be limited.
      Studies of gender-role development in nontraditional families (for example, single-parent families and families with working mothers) suggest that children's conceptions of gender roles in traditional and nontraditional families may differ. Children of employed mothers, for example, are more likely to have flexible conceptions of gender roles. Daughters of working mothers have higher achievement motivation and are more likely to display a blend of female-typed and male-typed personality traits. Children in families in which fathers play less stereotyped roles acquire less knowledge of gender stereotypes; adolescent girls appear to show some of the greatest benefits of growing up in homes with nontraditional fathers.
   2. The influence of peers
      The peer group also has a major influence on children's gender-role development. Toddlers' play behavior differs as a function of whether a partner is male or female. In preschool and kindergarten, children consistently reward boys for sex-typical behavior but punish them for sex-atypical behavior. Girls are rewarded by their peers for sex-typical behavior but are not punished for sex-atypical behavior.
      Some children exhibit cross-gender behavior, that is, show characteristics more typical of the other sex. Children's negative attitude toward cross-gender behavior, particularly in boys, increases with age. Cross-gender boys are more likely than cross-gender girls to become social isolates over time.
      Sex segregation, the clustering of individuals in same-sex groups, enhances the peer group's influence on sex-typed behavior by fostering different social interactions in boys (aggressive play) and girls (cooperative play). Sex segregation becomes less pronounced by adolescence as children begin to engage in heterosexual interactions.
      
      

      Controversy: Is Gender Identity Disorder Really a Disorder? According to the DSM-IV, gender identity disorder occurs when children express a strong desire to be members of the opposite sex or claim to be unhappy as a boy or a girl. Controversy exists as to whether this is a true psychiatric disorder or if the problem lies in society's intolerance for behaviors that violate gender boundaries.

      
      In adolescence, behaviors other than sex-typed behaviors, such as politeness and leadership abilities, become important determinants of popularity. Adolescents are also more likely to tolerate sex-atypical personality characteristics.
   3. The influence of teachers and schools
      Teachers display attitudes that reflect gender-role stereotypes. For example, teachers are likely to see males as more skilled in mathematics and females as more skilled in language, even though sex differences in these abilities are minimal or nonexistent. Teachers are also more likely to dispense disapproval to boys than to girls, and are more likely to call upon boys than girls in the classroom.
      
      

      Research Applied to Education: Promoting Gender Equity in the Classroom Teachers can take a number of steps to promote gender equity in the classroom. These steps include reinforcing cooperative cross-sex play, offering lessons that challenge common gender stereotypes, and providing girls with more opportunities to participate in the classroom.

      
      Like parents and teachers, students also view some subjects as masculine and others as feminine. Math, for example, is seen as masculine by children of many cultures. Girls perceive themselves as less competent in math and are less willing to take math courses than are boys, despite the fact that girls do as well as boys on classroom and standardized math tests.
      Girls are more self-critical of their academic work than are boys. Boys are more likely to overestimate their academic competence than are girls.
      
      
4. Alternative conceptualizations of gender
   
   1. Androgyny
      Early theorists viewed sex-atypical behavior as undesirable. Recent views of gender-role development recognize that individuals who exhibit androgyny are more adaptive than traditional masculine or feminine individuals. Androgynous people exhibit high levels of masculine and feminine personality characteristics, whereas people who have few masculine or feminine characteristics are defined as undifferentiated. Psychological androgyny is associated with psychological health and popularity with peers.
      What factors determine whether someone becomes androgynous is unclear. Parental characteristics may play a role, but few studies have examined this possibility. Androgyny may emerge during adolescence as children develop the ability to conceptualize gender roles in more complex, abstract terms rather than through modeling.
   2. The relational approach
      Some theorists maintain that males and females develop in unique and different ways. For example, females may be more concerned than males about establishing and maintaining relationships with others. Thus, rather than emphasizing the blending of male and female traits, the relational approach stresses the differences that can be valued and embraced.