Overinclusion but not social exclusion shifts sacrificial harm acceptance in online ostracism paradigm

Abstract The cognitive-motivational repercussions of social exclusion have been extensively studied, particularly its adverse effects on cognitive functions such as decision-making. However, its influence on moral decision-making remains underexplored. In an era where a significant portion of social interaction takes place online, social exclusion is increasingly manifested through a lack of digital attention. The present study therefore examined moral decision-making across different levels of inclusionary status using an online ostracism paradigm. This paradigm simulates social interaction on a mock social-media platform that mirrored the digital dynamics of social connection through Likes , whereby participants experienced exclusion ( N  = 31; 1 Like), inclusion ( N  = 30; 5 Likes) and overinclusion ( N  = 30; 9 Likes). Across mixed-effects models and a dual frequentist–Bayesian approach, overinclusion was associated with greater acceptance of sacrificial harm in self-beneficiary moral dilemmas, whereas exclusion and inclusion did not differ. Over-included participants also reported lower arousal in response to the dilemmas, and mediation analyses provided evidence consistent with a partially arousal-mediated overinclusion effect (attenuated when controlling for empathy traits). Additionally, higher affective empathy traits were associated with a lower tendency for sacrificial harm. This study demonstrates that moral decision-making remains unaffected by the short-term social exclusion, whereas overinclusion promotes sacrificial harm acceptance through the partial mediation of arousal. We conclude by outlining testable accounts for the null effect of exclusion, while highlighting implications for chronically over-included online users (e.g., influencers), and reporting hypothesis-generating hierarchical drift-diffusion predictions for future work.