The serial effect of bullying victimization and aggression outcome expectancies on within-person changes in proactive aggression among adolescents across one year.

The mechanisms of within-person changes in proactive aggression among senior high school students remain unclear. A Victimization-Expectancy Model of Proactive Aggression (VEMPA), inspired by ideas of the General Aggression Model (GAM) and Social Learning Theory (SLT), was developed to address this issue. Specifically, we conducted a longitudinal study to examine how bullying victimization has an effect on within-person changes in proactive aggression through positive aggression outcome expectancies (positive AOE) in 641 senior high school students (43.1% girls, Mage = 16.76 years, SD = 0.68) across one year. A Random Intercept Cross-Lagged Panel Model (RI-CLPM) analysis indicated that positive AOE at Time 2 mediated the effect of bullying victimization at Time 1 on proactive aggression at Time 3 at the within-person level, after controlling for reactive aggression. These results partially support the VEMPA, which provides an effective theoretical framework for understanding the mechanisms of within-person changes in proactive aggression among senior high school students. These findings have implications for developing targeted interventions for proactive aggression.