By nature, people are social creatures—it is evolutionarily adaptive that, during all periods of life, interaction with others occurs. From infancy to adulthood, however, the way in which the interaction takes place, as well as with whom, changes. During infancy, interactions occur primarily with parents and family members. During childhood the frequency of interactions with same-age peers increases, though parental support is still important. Adolescence marks the increased centrality of interactions with peers and the emergence of romantic relationships. Both of these events forecast the progression into adulthood, during which individuals become autonomous from parents and often begin families of their own.
The developing person is affected by multiple socializing forces, including biological, parental, peer, and cultural factors. The results of these forces include one's views of the self and others, one's personality, and one's behaviors (e.g., aggression) when interacting with others. Moreover, these socializing forces and the complex array of outcomes show both normative trends and interindividual variability across development.
Biological and familial factors are important socializing agents in infancy, while peer relationships become more important in childhood and adolescence. This is not meant to imply, however, that other socializing agents play no role during certain periods of development. Similarly, the focus in this article on particular topics during only one period of development should not be taken to mean that these topics are not salient aspects of social development during other periods.
Infancy and Preschool: An Emphasis on Biology and Parenting
Even before a child is born, much has occurred in terms of social development. Genetic and prenatal biological factors play a large, persistent role in determining later social behavior. After birth, parents and other family members are the key socializing agents of the preschooler's development.
By studying monozygotic (i.e., identical) and dizygotic (i.e., fraternal) twins, as well as adopted siblings, behavioral geneticists have concluded that genetic factors account for 40 to 70 percent of the variability in certain characteristics. Sandra Scarr described how genes contribute directly to children's characteristics and indirectly influence social development through three processes: passive effects, in which children's genes are related to the parenting of their biological parents; evocative effects, by which children elicit certain types of behaviors from others; and active effects, through which children seek out environments that best fit their genetic makeups.
Although it is clear that genetic makeup plays a crucial role in social development, it is less certain exactly what biological mechanisms account for this influence. Certainly, many innate factors affecting social behavior are common to nearly all infants. For instance, infants will cry when distressed, and they actively attend to and seek attention from caregivers. Infants have differences, however, in their genetic makeups, and researchers have searched for ways in which these differences are expressed. Perhaps the most widely studied aspect is temperament, which consists of several components related to emotional reactivity and regulation. Infants described as having "difficult temperament" are those who are fussy, become upset easily, and are not easily soothed. Other infants are considered inhibited—they are timid and fearful, become easily upset by intense stimuli, and are also not easily soothed. Infants with "easy temperaments" are outgoing and respond positively to social stimuli (i.e., do not show excessive fear), and are easily soothed when they do become upset. Temperament is rather stable across time and exerts powerful eliciting effects on parents' and other family members' behaviors toward the child across development.
Parenting practices also play a crucial role in infants' social development. Certain parenting practices, such as feeding and protecting, are necessary for the infant's survival and are performed by nearly all parents. Parents vary considerably, however, in the degree to which they are permissive, are warm or rejecting, and are consistent in the form of discipline they apply. Many of these factors are incorporated into Diana Baumrind's three typologies of parenting: authoritative parenting, in which parents are warm and responsive to the child, yet place limits on the child's behavior; authoritarian parenting, in which parents place strict limits on the child's behavior, with violation of these limits harshly punished, and in which there is little parental warmth; and permissive parenting, in which parents are warm and nurturing without placing limits on the child's behavior. There is ample evidence that authoritative parenting is associated with positive social development, whereas authoritarian and permissive parenting are associated with negative development (e.g., conflictual relationships).
These parenting styles are influential throughout development, but may be especially important in the formation of attachment security in infancy. According to John Bowlby, nearly all infants form an attachment bond to their caregivers, and this bond is evolutionarily adaptive in promoting a balance between exploring the world and seeking safety with the caregiver. Mary Ainsworth demonstrated that there are important differences in infants' attachment styles, depending on the history of caregiver availability and responsiveness. Secure attachment is related to a history of warm and consistent parenting, avoidant attachment to parental negativity and rejection, and resistant attachment to inconsistent parenting. These attachment styles influence social behavior not only with parents, but also with siblings and peers. Securely attached children are the most socially competent with others, while avoidant toddlers are hostile and aggressive, and resistant toddlers are socially inhibited in their interactions with others.
These early influences likely exert influence on later social behavior through the formation of social cognitions, or mental representations of the social world. Albert Bandura described three classes of social cognitions that guide social behavior: self-efficacy is the perception of one's ability to enact a behavior (e.g., "how well am I able to maintain a conversation with a peer?"); outcome expectations are the expected consequences if one enacts a behavior (e.g., "if I converse with this boy will he want to be my friend?"); and outcome values are the values placed on the expected outcomes (e.g., "do I want him as my friend?"). The behaviors of parents and other family members shape these early social cognitions, which are further shaped by interactions with peers in childhood.
Childhood and Early Adolescence: An Emphasis on Peers
Children spend much of their time with similar-age peers. Meaningful interactions between peers begin in infancy—infants direct and respond to each other's smiles and vocalizations. As preschoolers age, their interactions with peers become increasingly complex, progressing from solitary play to onlooking (child watches others but does not join), parallel play (child plays beside but not with others), associative play (child plays with others), and cooperative play (child plays with others using coordinated roles). As children age they engage in more of the latter forms of play, though the former types of play are not entirely abandoned. Moreover, the topics of play change during childhood, from constructive play (e.g., block building) to dramatic play to games with formal rules.
This increased complexity of play is paralleled by increased complexity of social behavior. This, as well as the increased time spent with peers, has led psychologists to focus much of their attention on the peer relations of children and adolescents. Topics of study include children's acceptance or rejection by the larger peer group, friendships, and aggressive and prosocial behaviors toward others. Researchers have also examined gender differences in each of these aspects of development.
The terms "popularity" and "rejection" are used to describe the degree to which children are liked or disliked by their peers. Certain types of behavior are consistently related to group acceptance throughout childhood. Popular children, who are liked by many of their peers and disliked by few, tend to be sociable, often do well in school, and are generally not aggressive. Rejected children, on the other hand, who are disliked by many of their peers and liked by few, are often aggressive or withdrawn, have poor social skills, and do not do well in school. Despite these generalizations about popular and rejected children, however, these groups are heterogeneous (i.e., children in these groups vary in their characteristics and/or behaviors). Some children are rejected because their aggressive, disruptive behavior is annoying to peers, while other children are rejected because they are timid and socially anxious. Children may be popular by behaving prosocially, being academically competent, and being leaders, while other popular children are aggressive or delinquent, but are seen as "cool" by their peers. Importantly, behaviors that are valued or devalued by peers are dependent upon group norms, which are influenced by surrounding societal and cultural values.
Whereas friendships of younger children center around concrete reciprocities (e.g., sharing toys) and those of older children emphasize self-disclosure and loyalty, friendships at all ages are based on mutual liking, reciprocity of positive behavior, and seeking the other's presence. Both having friends and the qualities of friendships are predictors of later development. For instance, having friends during childhood predicts having romantic relationships in adolescence and feelings of self-worth in adulthood, having supportive friendships predicts academic achievement during school transitions, and having protective friends can reduce peer victimization. It must be remembered that friendships are defined by two members, and the characteristics that make a child a desirable friend to one peer may not make that child desirable to another. Children tend to have friends who are similar to them in demographic characteristics (e.g., age, race, gender), academic abilities (e.g., intelligence, school achievement), and social behavior (e.g., aggression, attachment styles). Not only do children tend to form friendships with those who are similar, but friends also tend to influence each other such that they become more similar over time.
The frequency of aggressive behavior remains fairly constant during childhood, but physical forms of aggression (such as hitting and pushing) displayed in younger children tend to be replaced with verbal aggression (such as teasing and threatening) among older children. Highly aggressive children are often rejected by their peers, and aggressive behavior is often associated with academic failure. Despite often being rejected by the larger peer group, however, aggressive children typically have as many friends as nonaggressive peers, most commonly with other aggressive children. These deviant friends reinforce the child's aggression, and, when combined with academic failure and the loss of socialization from mainstream peers, may lead to later delinquency and antisocial behavior. The experience of being the victim of peer aggression can lead to negative outcomes—both personal (e.g., depression, anxiety, low self-esteem) and interpersonal (e.g., rejection, few friends)—which in turn further perpetuate peer abuse. These consequences are not limited to the period during which the child is victimized; chronic victimization can lead to low self-esteem and depression that persists into adulthood.
The frequency of prosocial behavior, behavior meant to assist others, increases during childhood, then remains relatively constant during adolescence. Nancy Eisenberg and Richard Fabes suggested that acts of prosocial behavior are based upon the development of prosocial moral reasoning, which involves increasing concern for others and ability to understand their suffering. Across childhood, prosocial behavior is related to popularity, the presence of friendships, and high quality friendships.
It is important to keep in mind that differences exist between boys and girls. Boys tend to play differently and in larger groups than girls. Boys' friendships are marked by common activities whereas girls' are marked by intimacy. Boys are more aggressive than girls, and girls tend to use aggression that is more social (e.g., excluding someone from a group) than physical in nature. There is less evidence, however, that the causes and consequences of these social behaviors differ for boys and girls. For example, although aggression is more common in boys, the same cognitions that motivate aggressive behavior appear to operate for both genders, and behaving aggressively often leads to peer rejection for both boys and girls. Rather than focusing on the differences in boys' and girls' behavior in general, Eleanor Maccoby suggested that it may be more important to focus on how boys and girls interact among themselves and with each other. During childhood, interactions occur almost exclusively with same-sex peers when children are given a choice (e.g., on playgrounds). When required to interact, the power-assertive behavior typical in boys' groups results in boys dominating the interactions (e.g., playing with the more desirable toys). Girls in these interactions, who are accustomed to the supportive style typical in girls' groups, find this style aversive and the boys unresponsive to change. When possible, the girls will discontinue interaction or seek proximity to an adult whose presence can reduce the boys' dominating style.
Adolescence and Adulthood: Completing the Cycle
Whereas opposite-sex interactions are infrequent in childhood, they increase during adolescence. Much of this increase is due to the emergence of romantic attraction, which is a product of both biology (i.e., pubertal maturation) and societal standards. Adolescent dating can be both a positive and negative socializing influence—it can be a source of intimacy, expanded social competency, and heightened self-esteem and peer status, but it can also be a source of jealousy, abuse, and damage to self-esteem. Adolescent romantic relationships are based upon many of the same principles as children's friendships (such as mutual liking, positive behavior, and proximity seeking), but physical attractiveness also becomes important in the selection of romantic partners. Although the rule that opposites attract may sometimes apply, adolescent romantic relationships (like childhood friendships) are typically characterized by similarity in race, academic achievement, activities, attitudes, and physical attractiveness.
In adolescence there is also an increasing desire for autonomy—of separating from parents and becoming an independent adult. This desire may lead to heightened family conflict (e.g., arguments about time spent with peers) and defiant behaviors (e.g., affiliation with antisocial peers and engagement in delinquent activities). These manifestations of autonomy striving have resulted in the frequent use of the term "adolescent storm" in referring to this age. The intensity of this storm, however, is heavily influenced by parenting styles (e.g., authoritative parenting is associated with less problematic autonomy development), family characteristics (e.g., single-parent and divorced families may impede autonomy or intensify conflict), peer relations (e.g., dating and involvement with peers are frequent sources of conflict), cultural values (e.g., the importance placed on autonomy and deference to parents affect the occurrence and expression of conflict), and generational differences (e.g., differences between parents and children in beliefs about appropriate behavior may be a frequent source of conflict). Healthy individuation involves a gradual shifting of balance between autonomy and connectedness with parents—of gaining independence while maintaining quality relationships with parents.
The importance of romantic relationships and individuation during adolescence is congruent with events common in adulthood—marriage and beginning one's own family. The characteristics of these relationships are based upon previous social learning. Adults often interact within their romantic relationships in a manner similar to how their parents interacted with each other, because as children they observed these interactions. Direct experiences with parents and peers also affect these relationships. For example, securely attached children are more likely to be securely attached with their spouses in adulthood, and childhood friendships based on intimacy and trust are likely to foster these types of relationships with later romantic partners. These past experiences also influence parenting behavior. Thus, the familial environment in which a child is raised is to some extent replicated in the environment these adults provide for their children, though relations with peers and romantic partners modify this continuity.
Limitations, Controversies, and Future Directions
Despite all that is known about social development in the home and the peer context, there is still much to be learned about the bidirectional influences across these two contexts. The works of Ross Parke and Gary Ladd have illuminated some of the linkages from the home to the peer group. For instance, it is known that secure attachment is associated with peer acceptance and quality friendships, while insecure (avoidant or resistant) attachment is related to rejection, having fewer friends, and involvement in aggression (either as the aggressor or victim). Social development in the home appears to contribute to social outcomes with peers through the development of social competence (or incompetence). The impact of the peer context on social behavior in the home, however, is less well known. Previous studies have too often been concurrent (i.e., examining factors in the home and peer group at the same time), preventing the elucidation of temporal primacy (i.e., did home factors precede behavior and status in the peer group, or vice versa?). Researchers have recognized this limitation, and future longitudinal research will likely provide answers to this ambiguity.
Judith Harris challenged the notion that parent-child interactions affect social development outside of the home context. Based upon the premise that socialization in dyads (e.g., parent-child, child-friend) does not generalize beyond that dyad, Harris proposed that the primary source of socialization is the peer group. According to Harris, parents' influence is limited to the selection of the child's peer group (e.g., attending a particular school, affiliating more or less with one's racial or ethnic group). As might be expected, this proposition has elicited a great deal of controversy, and has been criticized by some developmental researchers; perhaps it has also prompted researchers to more carefully consider threats to their assumptions of socializing influences.
The beginning of the twenty-first century is an exciting time for social development researchers— much has been learned and it is likely that the rate of learning will rapidly accelerate in the future. As knowledge of human genetics increases, the focus on how much behavior is affected by genes is likely to shift to how behavior is affected by genes. Additionally, although much has been learned about biological, familial, and peer socializing influences during infancy, childhood, and adolescence, long-term studies considering multiple contexts are needed to examine the interactive effects of these influences on social development.
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