Beginning in late infancy, all children display aggression from time to time.

As early as the preschool years, some children show abnormally high rates of hostility, assaulting others verbally and physically with little or no provocation.

Emergence of Aggression  In the second half of the first year, infants develop the cognitive capacity to identify sources of anger and frustration and the motor skills to lash out at them.

By the second year, two general types of aggression emerge:  proactive (or instrumental) aggression  reactive (or hostile) aggression

Proactive and reactive aggression come in three forms.  Physical aggression  Verbal aggression  Relational aggression

Aggression in Early and Middle Childhood  Between ages 3 and 6, physical aggression decreases, whereas verbal aggression increases.

Aggression in Early and Middle Childhood cont.  Proactive aggression declines  Reactive aggression in verbal and relational forms tends to rise

By age 17 months, boys are considerably more physically aggressive than girls—a difference found throughout childhood in many cultures.

Biological factors and temperamental traits on which boys and girls differ contribute to this difference.

Gender-role conformity is also a factor.

Although girls have a reputation for being verbally and relationally more aggressive than boys, sex differences in most studies are small.

Girls concentrate most of their aggressive acts in the relational category; boys inflict harm in more variable ways and, therefore, display considerably higher overall rates of aggression than girls.

 Girls more often use indirect relational tactics that disrupt intimate bonds especially important to girls.  Whereas physical attacks are usually brief, acts of indirect relational aggression may extend for hours, weeks, or even months.

Aggression and Delinquency in Adolescence  Most young people decline in teacher- and peer-reported aggression in adolescence, but delinquent acts rise in the teenage years.  Although North American youth crime has declined since the mid-1990s, U.S. and Canadian 12- to 17-year-olds account for a substantial proportion of police arrests.  Most teenagers admit to having committed some sort of offense—usually a minor crime, such as petty stealing or disorderly conduct.

 Delinquency rises over the early teenage years, remains high in middle adolescence, and then declines.

For most adolescents, a brush with the law does not forecast long-term antisocial behavior.

Stability of Aggression  Children high in either physical or relational aggression relative to their agemates tend to remain so over time.

In a study of boys from age 6 to 15 in Canada, New Zealand, and the United States, researchers identified four main patterns of change.  Kindergarten boys high in physical aggression were especially likely to move to high-level adolescent aggression, becoming involved in violent delinquency.  Kindergarten boys who were moderately physically aggressive usually declined in aggression over time.  Boys who rarely physically aggressed in early childhood typically remained nonaggressive.  A small number of boys high in oppositional behavior (such as disobedience and inconsiderateness) but not in physical aggression were prone to less violent forms of adolescent delinquency (such as theft).

Girls who consistently engage in disruptive, disobedient behavior in childhood are also more likely to have continuing conduct problems.

Aggressive behavior that emerges in childhood is far more likely to translate into long-term adjustment difficulties than aggression that first appears in adolescence.

The Family as Training Ground for Aggressive Behavior  Parenting behaviors that undermine moral internalization and self-control are also related to aggression

Anger and punishment quickly create a conflict-ridden family atmosphere and an “out-of-control” child.

Preschool siblings with critical, punitive parents are more aggressive toward one another, and conflict spreads to peer relationships, contributing to poor impulse control and antisocial behavior by the early school years.

Helping Children and Parents Control Aggression  Coaching, Modeling, and Reinforcing Alternative Behaviors  Parent training programs based on social learning theory have been devised to interrupt destructive family interaction.

For the child, teaching nonaggressive ways of resolving conflict is helpful.  Sessions in which children model and role- play cooperation and sharing and see that these behaviors lead to rewarding social outcomes reduce aggression and increase positive social behavior.  Many aggressive children also need help with language delays and deficits that interfere with development of self-control.