Belief in a just world mediates the relation between early life environmental unpredictability and poor cyber defending behavior in adolescence: Evidence from a longitudinal study

Cyber defending behavior is an effective prosocial behavior in combating cyberbullying, and thus identifying its related factors is critical. This longitudinal study aims to examine how early life environmental unpredictability will be associated with cyber defending behavior in adolescence through the mediating effect of belief in a just world. During three waves (T1: January 2023; T2: August 2023; T3: February 2024), a total of 2,053 Chinese adolescents completed the questionnaires of early life environmental unpredictability and cyber defending behavior, as well as the two-dimension scale of belief in a just world at 3-time points. The cross-lagged model analysis showed that being exposed to unpredictable early life environments predicted less cyber defending behavior later among adolescents. General belief in a just world, rather than personal belief in a just world, mediated the longitudinal relation between early life environmental unpredictability and cyber defending behavior. In addition, engaging in cyber defending behavior could predicted higher general and personal belief in a just world later. Compared to boys, the relation between early life environmental unpredictability and less cyber defending behavior was more robust for girls. These findings highlight the importance of early life environments with low unpredictability in shaping adolescent cyber prosocial behavior for interventions against cyberbullying.