Abstract
This study examined how undergraduate bystanders respond to cyber-ostracism events and the moderating role of rejection sensitivity in shaping helping behaviors using two experiments. In Experiment 1 (N = 276), we first measured participants' rejection sensitivity, then manipulated cyber-ostracism using a social media interaction scenario, and finally, measured helping behavior towards the (non-)ostracism target using a questionnaire. Experiment 2 (N = 258) sought to replicate and extend the findings of Experiment 1 using a methodologically refined design, in which we employed a modified Cyberball paradigm to manipulate cyber-ostracism and measured bystanders' helping behavior through their resource allocation decisions (i.e., token sharing). The results revealed that witnessing cyber-ostracism significantly promoted bystanders' helping behavior. This facilitative effect was more pronounced among bystanders with high rejection sensitivity. These findings shed light on the psychological mechanisms underlying bystanders' helping responses in the context of cyber-ostracism and provide a new perspective for understanding interpersonal interactions in digital environments.