Influence of peer group norms on aggression in early adolescence

The present study builds on previous research that has established group influences on individual aggressive behavior. It is hypothesized that group norms regarding aggression influence individual aggression, and that this influence is mediated by social status. Participants were 647 Chilean 5th and 6th graders. Children were followed over a one-year period. Peer nominations on aggression, social preference and peer perceived popularity were collected. Social networks were derived through Social Cognitive Mapping. Two important features were novel in this study. Following previous findings on group members' perceptions, peer nominations were calculated following two different procedures that were compared: As perceived by group affiliates (i.e., reported only by fellow group members), and as perceived by all classmates. Also, considering children's social migration and group stability, the longitudinal design allowed introducing a new framework that considered prospective (characteristics of the departing or time 1 group) and attractive (characteristics of the final or time 2 group) group influences. Results showed that group affiliates' reports were more sensitive to assess individual variation and group influences on individual aggression. Hierarchical Linear Modeling showed that both individual aggression and popularity positively predicted later individual aggression. Group norms on aggression and popularity mediated the effects of popularity and aggression (respectively) on later individual aggression. Children who kept stable group affiliations were influenced by both departing and final group characteristics (prospective and attractive influences), but children who changed their affiliations were affected only by later group characteristics (attractive influence). Implications of these results and methodological considerations are presented in the discussion.