Infants begin to show an interest in each other at a very young age. At 6 months old they demonstrate an interest in other infants by looking, reaching, touching, smiling, and vocalizing. By 3 or 4 years of age friendships begin to develop. Relationships with peers become increasingly important. Membership in a peer group is central to a child’s happiness by middle childhood.
By providing models of behavior, dress, and language the peer group serves as a socializing function. It is a continuing source of both reinforcement for appropriate behavior and punishment for deviant behavior. The peer group serves as an objective measure against which children can evaluate their own traits and abilities. Children learn to share and cooperate develop social skills, and regulate aggression in peer groups.
Even in children as young as 3 years old physical attractiveness is a major factor in peer acceptance. Unattractive children often get negative traits attributed to them. The peer group also values academic success and athletic ability. The children who are popular are usually energetic, happy, cooperative, sensitive, and thoughtful. They have social skills that lead to positive social outcomes and help the goals of their peers. They are able to be assertive and aggressive when the situation calls for it. These children usually have authoritative parents.
Children with low peer acceptance are more like to have mental health problems. Neglected children who are shy and withdrawn, as well as rejected children who typically exhibit aggressive and inappropriate behavior and who are likely to start fights are often excluded from the peer group. Children who are abused at home tend to be viewed as aggressive and uncooperative and therefore unpopular with their classmates. Rejection by peers is linked to unhappiness, alienation, and poor achievement, and in middle childhood with delinquency and dropping out of school.
Source: The World of Psychology 4th Edition