Reactive and regulative temperament and non-suicidal self-injury in Flemish adolescents: The intervening role of identity formation

• We combined temperament and identity theories to investigate their influence on NSSI.
• 14.2% of the 528 high school students reported engaging in NSSI.
• Effortful control moderated the pathway between Behavioral Inhibition System and NSSI.
• Identity synthesis mediated the pathway between Behavioral Inhibition System and NSSI.

In the present study, we combined temperamental and identity models to investigate the influence of these two constructs on the vulnerability to non-suicidal self-injury (NSSI). We assessed NSSI, reactive [behavior inhibition system (BIS)/behavior activation system (BAS)] and regulatory temperament [effortful control (EC)], and identity synthesis and confusion using self-report questionnaires in 528 high school students (Mean age = 15 years, SD = 1.84, 50.4% female). The lifetime prevalence of NSSI was 14.2%. Our findings suggested that the association between BIS and NSSI was moderated by EC, such that higher levels of BIS and lower levels of EC predicted higher lifetime NSSI. Also, the association between BIS and NSSI was partially mediated by identity synthesis. The findings of the current study indicate that interventions that stabilize BIS reactivity, enhance EC, and promote identity synthesis may have important meaningful implications in the clinical management of NSSI.