more complex speech overall at 3.5 years old. preschoolers (3–6 years old) self-concept self-concept refers to the set of attributes, abilities, attitudes, and values that one identifies as defining who he or she is. although some initial milestones occur before this period that support self-concept, including basic self awareness (i.e., the ability to recognize themselves in a mirror) and self-labeling of their gender, this period involves several advances in this domain. by 42 months, children are able to describe their likes and dislikes, suggesting a developing awareness of what elicits positive and negative emotions in themselves. by 5 years old, children demonstrate agreement with their mothers' ratings of their behavior on basic behavioral indicators of personality. gender identity during the preschool period, children are deepening their gender identity and integrating gender socialization information into their self-concept. preschoolers learn gender stereotypes quickly and definitively, ranging from toy preferences, clothes, jobs, and behaviors. these stereotypes are initially held firmly, such that 3 to 4-year-olds will often state that violations are not possible and that they would not want to be friends with a child who violates their stereotypes. children acquire gender stereotypic behaviors early in the preschool period through social learning, then organize these behaviors into beliefs about themselves, forming a basic gender identity. by the end of the preschool period, children acquire gender constancy, an understanding of the biological basis of sex and its consistency over time. understanding others younger preschool aged children demonstrate the basics of theory of mind, or the ability to take the perspective of others. however, this skill is constrained by children's limited understanding of how thoughts and beliefs, even when false, influence behavior. this is demonstrated in the following scenario: danny puts his toy on the shelf, then leaves the room. his friend sally comes in, plays with the toy, and puts it in the cabinet. when asked where danny will look for his toy, a young preschool aged child will state that he will look in the cabinet, therefore not recognizing danny's current false belief about the toy's location. between 4 and 6 years, children's capacity to understand false beliefs, and subsequently their accuracy in perspective taking, becomes strengthened. social interactions play can have an important role in social emotional development, allowing opportunities to engage in practice cooperation, negotiation, and conflict resolution skills. play is often cited as a central building block to children's development, so much so that the united nations commission on human rights has declared it to be a human right of all children. the complexity and diversity of play increases immensely in the preschool years, most notably with the onset of cooperative play, where children work toward a common goal, and socio-dramatic play (a type of cooperative play), where children act out make believe scenes. socio-dramatic play is rooted in the child's real-life experiences, falling into three categories: family scenes (e.g., "playing house" with assigned mommy and daddy roles), character scenes (e.g., being a superhero, or a princess), and functional scenes (e.g., playing doctor). cooperative play and socio-dramatic play both bring about increased social interactions, as compared to solitary play and parallel play, where children play similarly next to each other without significant interaction (e.g., two children building their own towers). it is here where play becomes intertwined with social emotional development. the characteristics of socio-dramatic play allow children to practice cooperation, negotiation, and conflict resolution skills, as well as engage in role-playing that promotes perspective taking. as such, socio-dramatic play has been associated with all of these social emotional skills in children. middle childhood (7–12 years old) self-concept between 8–11 years old, children begin to use self-evaluations and competencies to define their sense of self. this derives from the recently developed ability to make social comparisons. at 6 years old, these social comparisons may be to a specific individual; however, this becomes more complex in the coming years, allowing children to compare themselves and their performance to multiple individuals to arrive at a general conclusion. school aged children also show the ability to simultaneously hold differentiated self-evaluations across domains (e.g., having good physical appearance, but poor school performance). gender identity in middle childhood, boys and girls form peer groups segregated by gender, which may act to perpetuate previously learned gender stereotypes. deriving from the ability to make social comparisons, school aged children begin to integrate attributions about how gender typical they are into their gender identity. at this age, children's ability to make more global self-evaluations also allows them to recognize contentedness or dissonance with their gender assignment. children's gender identity on these two dimensions is significantly correlated with their self-esteem, such that children with higher levels of typicality and contentedness report having higher self-esteem and worth. emotion vocabulary by 3 years old, children have acquired a basic vocabulary for labeling simple emotional experiences, using words such as "scared," "happy," and "mad." however, the emotional vocabulary of children grows much more rapidly during middle childhood, doubling every two years in this period before slowing down dramatically in adolescence. at the end of the preschool period, most children reliably comprehend the meaning of around 40 emotion words; by the time they are 11 years old, most children see a sevenfold increase to understanding almost 300 emotion words. furthermore, a shift in the processing of positive and negative words in the course of development occurs: while young children (aged 5 and 6) have shown a better performance for positive words, this preference disappeared with increasing age (i.e., positivity bias in emotion term processing). display rules emotional display rules are culturally bound norms that dictate when, how, and with whom individuals can express emotions. accordingly, the ability to enact display rules relies on children's capacity for emotional expression and emotion regulation. socialization toward these display rules begins in infancy, and children show some capacity in the preschool period. however, children's use of display rules and understanding of their value become increasingly complex in elementary school. as children age from 1st to 7th grade, they are less likely to outwardly express anger or sadness. children also report using display rules to control their emotional expressions more with teachers than with peers, and more than peers than with parents. there is some evidence to suggest that this emotional masking also increases with age throughout the school age period, at least with teachers. display rules also inform how children choose to express emotions; as children move from the preschool period to middle childhood, they become more likely to use verbal communication to express negative emotions than nonverbal behaviors, such as crying or hitting. finally, at around 9 years old, bolstered by increased perspective taking skills, display rules are recognized as important to maintaining social harmony and relationships rather than simply a means to avoid punishment. emotion regulation upon school entry, children's emotion regulation repertoire becomes increasingly diverse as previously relied upon methods (e.g., seeking support from parents, moving away/avoiding an emotionally activating stimuli) become less effective. in middle childhood, children implement more complex distraction techniques, cognitive appraisal strategies (e.g., choosing to focus on the positive), and problem solving methods. at 10 years old, children's emotion regulation involves a balance of problem-focused coping and emotion-focused coping strategies. problem-focused coping represents a change driven strategy, focused on attempting to eliminate the source of stress through proactive action (e.g., if a child feels worried about a test, choosing to study to regulate that worry). in contrast, emotion-focused coping is acceptance based and can be more effective when the stressor can not be easily changed or removed (e.g., if a child is disappointed about their grade on the test, using strategies to reduce disappointment in the moment: "this will help me know what to study for the final"). and although diversification of emotion regulation strategy use occurs at this age, school aged children continue to strengthen their use of previous regulation strategies as well. notably, school age children continue to seek out regulation support, but not just from their parents, but increasingly from teachers and peers in this period. children also show a developmental progression in differentiation of whom to go to for emotional support given then specific situations. thus on the whole, by the beginning of adolescence, children have become more skilled emotion regulators. adolescence (13–18 years old) identity development as adolescents navigate an increasingly diverse social world, their self-concept shifts to create and accommodate an organized understanding of how situational factors may influence their behavior (e.g., how and why behavior is different with friends as compared to with parents). with this added complexity, a fundamental task of adolescence is considered forming a unified, coherent identity, inclusive of traits, values, and goals. erik erikson theorized that adolescence is characterized by a period of exploration and commitments. the combination of these two traits resulted in four identity statuses: identity achievement: a status characterized by a past period of exploration, and subsequent commitment to values and goals moratorium: a status characterized by continued active exploration, without commitment foreclosure: a status characterized by strong commitment to a prescribed identity (e.g., by teachers, parents), without a previous period of self exploration diffusion: a status characterized by both a lack of exploration and a lack of commitment past research suggests that over the course of high school, the distribution of identity statuses changes, such that many adolescents begin high school in a diffusion status, but many adolescents reach identity achievement status at the end of high school. this general pattern is echoed in specific studies of minority group ethnic identity development, where youth initially have an unexplored ethnic identity, then enter a moratorium phase, followed by ethnic identity achievement. in general, identity achievement and moratorium statuses appear to be associated with positive psychological adjustment, including higher self-esteem, goal-oriented behavior, self-efficacy, and openness. friendships adolescence is a time in which peer relationships become increasingly important and frequent. in this period, adolescents reliably spend approximately twice as much time with their peers than with their parents. at the same time, there is a developmental shift occurring in the quality and nature of friendships in this period. adolescents' friendships are characterized by increased emotional support, intimacy, closeness, and loyalty. this is contrasted to friendships in early childhood, which is built upon time spent in joint activities, and middle childhood, which is defined by reciprocity and helping behavior. close friendships in adolescence can act as a buffer against the negative impacts of stressors, provide a foundation for intimacy and conflict resolution necessary in romantic relationships, and promote empathy for others. peer acceptance peer acceptance is both related to children's prior social emotional development and predictive of later developments in this domain. sociometric status identifies five classifications of peer acceptance in children based on two dimensions: social liking and social impact/visibility: popular, average, rejected, neglected, and controversial. these patterns of acceptance can become self-perpetuating throughout childhood and adolescence, as rejected children are excluded from peer interactions that promote relationship skills, such as perspective taking and conflict resolution. peer groups during adolescence, children increasingly form peer groups, often with a common interest or values (e.g., "skaters," "jocks"), that are somewhat insular in nature (e.g., "cliques" or "crowds"). theoretically, peer groups have been hypothesized to serve as an intermediary support source as adolescents exert independence from their family. this is supported by data that indicates that the importance of peer group membership to youth increases in early adolescence, followed by a decline in later adolescence. peers and peer groups at this age become important socialization agents, contributing to adolescents' sense of identity, behavior, and values. peer groups, whether intentionally or unintentionally, exert peer pressure and operant learning principles to shape behavior through reinforcement, resulting in members of peer groups become increasingly similar over time. many adolescents report the effects of peer influence on many aspects of their behavior, including academic engagement, risk-taking, and family involvement; however, the direction of this influence varied dependent on the peer group the adolescent was affiliated with. emotion dynamics the literature suggests systematic changes in emotion dynamics throughout childhood and adolescence such as in the intensity of specific emotions they experience, and in the variability, instability, inertia, and differentiation of emotions, and whether and how emotions augment or blunt each other over time. from early to late adolescence positive and negative emotions tend to