Combined effects of traditional and cyberbullying victimization on adolescent non-suicidal self-injury: The buffering role of family and peer support.

Traditional bullying victimization and cyberbullying victimization are well-documented risk factors for adolescents' non-suicidal self-injury (NSSI). However, less is known about their potential nonlinear effects, as well as the extent to which family and peer support may buffer these risks and whether such protective effects vary by gender. To address these gaps, the present longitudinal study followed 1917 Chinese adolescents (58.8% males; Mage ± SD = 13.46 ± 0.81) across two measurement waves. Polynomial regression and response surface analysis were employed to examine how the congruence and incongruence between traditional and cyberbullying victimization jointly predicted NSSI. The results indicated that adolescents experiencing high and congruent levels of both traditional and cyberbullying victimization were at the greatest risk for subsequent NSSI. In addition, a significant incongruence effect also emerged, with higher NSSI levels observed when cyberbullying victimization exceeded traditional victimization compared to the reverse. Moderated response surface analyses further indicated that both family and peer support buffered the adverse effects of victimization. Moreover, analyses of gender differences showed that these protective effects were stronger among females than among males. These findings highlight the complex combined impact of offline and online victimization and underscore the critical protective role of family and peer support, particularly for female adolescents.