The impact of social exclusion and interpersonal trust on aggressive behavior among left-behind middle school students.

BACKGROUND: Aggressive behavior negatively affects adolescents' physical and psychological development. Social exclusion-defined as the thwarting of an individual's need to belong through rejection-is a well-established risk factor for aggression. In contrast, interpersonal trust, the expectation of reliability and goodwill from others, facilitates rational interpretations of social interactions and may reduce aggressive tendencies. However, to the authors' knowledge, no prior experimental research has examined the interactive effects of social exclusion and interpersonal trust on aggression among Chinese middle school students. Additionally, left-behind children, who are separated from one or both parents due to labor migration, typically report higher levels of social exclusion, lower interpersonal trust, and greater aggression than non-left-behind children, suggesting a distinct dynamic among these variables. METHODS: To address this gap, we conducted an experimental study involving 82 middle school students (39 left-behind children and 43 non-left-behind children), in which social exclusion, interpersonal trust, and aggressive behavior were measured and experimentally manipulated. RESULTS: The results revealed significant main effects of left-behind experience, social exclusion, and interpersonal trust on aggressive behavior. Crucially, two key two-way interactions were identified. First, the interaction between interpersonal trust and left-behind experience showed that while high trust predicted lower aggression in both groups, this protective effect was significantly weaker for left-behind students. Second, the interaction between social exclusion and interpersonal trust indicated that high trust significantly buffered the negative impact of social exclusion on aggression. However, the two-way interaction between left-behind experience and social exclusion and three-way interactions were not significant. CONCLUSIONS: These findings demonstrate that interpersonal trust mitigates the negative effects of both social exclusion and left-behind experiences on aggressive behavior, highlighting its potential as a target for intervention among at-risk youth.