How left-behind experience moderates the impact of impulsivity on non-suicidal self-injury among Chinese senior high school students: the mediating role of self-control.

Background: Prior research has identified a range of risk factors for and functions of non-suicidal self-injury (NSSI), of which two broad classes are most prominent: adverse early experiences and individual susceptibility. Much less is known, however, about how these two classes of factors operate together within an integrated mechanism. We therefore examined whether self-control mediates the relationship between impulsivity and NSSI in senior high school students, and whether an early left-behind experience moderates this mediated pathway. Methods: Questionnaires measuring impulsivity, self-control, and NSSI were administered to senior high school students in Guizhou Province, China. A total of 534 valid responses (Mage = 17.26 years, SD = 1.30; 57.62% girls) were analysed. Results: Impulsivity was positively associated with NSSI, and self-control significantly mediated this association, accounting for a substantial proportion of the indirect effect. Left-behind experience further moderated the mediation pathway: among students with a left-behind experience, the indirect effect of impulsivity on NSSI via self-control was significant, whereas the direct effect was not; among students without a left-behind experience, the opposite pattern was observed. Because the proposed model explained only a modest proportion of the variance in NSSI, these results are best regarded as identifying one theoretically grounded pathway to NSSI rather than as a complete account of how NSSI develops. Conclusion: Impulsivity is an important correlate of NSSI in senior high school students, and its association with NSSI appears to operate largely through self-control. Moreover, the pathway to NSSI differs markedly between students with and without a left-behind experience. These findings provide an empirical basis for designing more targeted NSSI interventions.