The relationship between three types of aggression and peer relations in elementary school children

Previous studies have repeatedly found that aggression causes various internalizing and externalizing problems. Despite the robust relationship, exactly how aggression causes these problems remains unclear, although it is plausible to postulate that this occurs both directly and indirectly (via other behavioural factors). One possible indirect factor might be the aggravation of peer relations. The poor peer relations of aggressive children could make them isolated psychologically or physically from peers, which in turn might result in depressive or disruptive problems. This study examined the relationships between three types of aggression and peer relations in Japanese elementary school children. The three aggression types comprised reactive-expressive (i.e., verbal and physical aggression), reactive-inexpressive (e.g., hostility), and proactive-relational aggression (i.e., aggression that can break human relationships, for instance, by circulating malicious rumours). Participants were 1581 children in grades 4 to 6 (752 boys and 829 girls), all of whom completed the Proactive-Reactive Aggression Questionnaire for Children to measure three types of aggression and the Peer Relation Questionnaire to measure peer relations (mutual understanding, self-disclosure, and similarity of taste) and number of friends. Hierarchical regression analyses of the data showed that higher scores of relational aggression were significantly associated with higher scores of all of the peer relations and the number of friends, and that higher scores of inexpressive aggression were significantly associated with lower scores of all except for self-disclosure in the peer relations. These findings suggest that among the three types of aggression, relational aggression leads to the best friendship in both dyadic relations and the number of friends, whereas inexpressive aggression to the poorest friendship. The implications of these findings with respect to internalizing and externalizing problem behaviours for aggressive children are discussed.