Abstract
OBJECTIVE: This study aims to explore the joint mechanism of in-group favoritism and belief in a just world on individual online prosocial behaviors among college students in the context of online donation, with a focus on the mediating role of the moral self and the moderating role of belief in a just world. METHOD: A online donation scenario was created through experimental methods to manipulate participants' in-group favoritism (high vs. low) and belief in a just world (priming group vs. control group). Their moral self-level and online prosocial behavior (using comment word count as an indicator of expressive prosocial behavior) were measured. RESULTS: (1) In-group favoritism significantly and positively predicted online prosocial behavior; (2) The moral self played a significant mediating role between in-group favoritism and online prosocial behavior; (3) Belief in a just world moderated the influence of in-group favoritism on the moral self. Under the condition of activated belief in a just world, the positive predictive effect of in-group favoritism on the moral self was stronger, thereby indirectly affecting prosocial behavior through the moral self. CONCLUSION: The present study found that the moral self serves as an internal psychological mechanism through which in-group favoritism influences online prosocial behavior, and that belief in a just world moderates this mechanism. These findings provide a new theoretical perspective for understanding the driving factors of prosocial behavior in online contexts and offer practical implications for guiding college students' online prosocial behavior.