Yoona Lee, Xiaodong Liu, Malcolm W. Watson

This longitudinal study investigated the timing effect of bullying on developmental trajectories of externalizing behaviors from middle childhood to adolescence. We focused on the relation of (a) only an early experience of bullying (i.e., desisters) to subsequent externalizing behaviors in adolescence and (b) only a late experience of bullying (i.e., late-onsetters) to the concurrent externalizing behaviors in adolescence. Their trajectories of externalizing behaviors were compared with the persisters and to the non-experience group. Individual growth curve modeling was conducted using 440 child-mother dyads from the Springfield Child Development Project, a community-representative, longitudinal study over a 6-year period that included four time interviews. We modeled the changes in child aggression and delinquency from 7 to 19 years of age as a function of bully status group. Results indicated that the levels of aggression and delinquency for the desisters decreased over time (with the cessation of bullying in adolescence) and were significantly lower than those of the persisters and similar to those of the non-involved group at the end of the trajectory (cessation effect). For the late-onsetters, the level of delinquency increased over time (with the onset of bullying behaviors in adolescence) and were significantly higher than those of the non-involved group and similar to those of the persisters at the end of the trajectory (onset effect). The aggression for the late-onsetters, however, did not support the onset effect. This study implies that we need to pay more attention to intervening for late-onset.