Emotional reactions, perceived impact and perceived responsibility mediate the identifiable victim effect, proportion dominance effect and in-group effect respectively

This study investigated possible mediators of the identifiable victim effect (IVE), the proportion dominance effect (PDE), and the in-group effect (IGE) in helping situations. In Studies 1-3, participants rated their emotional reactions (distress and sympathy toward the victims), perceived impact of helping, perceived responsibility to help, and helping motivation toward four versions of a helping situation. Gradually increasing victim identifiability in the helping situations primarily affected emotional reactions and sympathy completely mediated the IVE. Gradually making the reference-group smaller primarily affected perceived impact, and impact completely mediated the PDE. Gradually increasing in-groupness primarily affected perceived responsibility, and responsibility completely mediated the IGE. Study 4 included real monetary allocations and largely replicated the results using a between-subject design. Together, the results shed light on how contextual factors trigger help motivation, and indicate that different helping effects are primarily mediated by different mechanisms