Prosociality differences in neural reward processing during cooperation and competition: an ERP investigation

Introduction Reward evaluation is shaped by social context and individual traits, but how prosociality modulates neural gain–loss differentiation during real interpersonal cooperation and competition remains unclear. This study examined the feedback-related negativity difference wave (dFRN) in cooperative and competitive tasks. Methods Forty participants (20 females; mean age = 22 years) completed face-to-face cooperation and competition tasks while EEG was recorded. Prosociality was measured with the Prosocial Scale. dFRN was calculated as loss-evoked minus gain-evoked mean voltage at Fz, FCz, and Cz within 220–300 ms after reward feedback. A 2 (Social Context) × 2 (Prosociality) mixed ANOVA and linear mixed-effects models using continuous prosociality scores were conducted. Results A significant Social Context × Prosocial Trait interaction emerged. High-prosocial participants showed a more negative dFRN in cooperation than in competition, whereas low-prosocial participants showed no reliable context difference. Continuous-score mixed-effects models adjusted for sex supported this association (b = −0.315 μV per scale point, SE = 0.152, z = −2.07, p = 0.039, 95% CI [−0.614, −0.016]); the group-based contrast ( p = 0.054) and robust-standard-error analysis ( p = 0.051) were marginal. Discussion These findings suggest that prosociality is associated with context-dependent reward differentiation, with shared cooperative outcomes eliciting stronger loss–gain differentiation among high-prosocial individuals. Causal interpretation is limited by the fixed task order, differing outcome-generation rules, and unmodeled dyadic dependence.