Neural dynamics of moral evaluation: Integrating prosociality, fairness, and social status

Moral evaluation often involves balancing multiple moral principles, such as prosociality (actions benefiting others) and fairness (equitable resource distribution), yet how these principles interact under the influence of social status remains poorly understood. To address this, we combined behavioral paradigms with event-related potentials (ERPs) to explore the temporal dynamics and neural underpinnings of third-party evaluations of allocators varying in social status. Participants rated the morality and willingness to cooperate toward resource allocations differing in prosociality (high/low) and fairness (fair/unfair). Behaviorally, sensitivity to fairness was heightened under high prosociality conditions compared to low prosociality, and social status modulated cooperation intentions- fairness effects were more pronounced for high-status allocators. Neurally, the FRN differentiated fairness more strongly under high prosociality, indicating early-stage fairness monitoring modulated by context. The P3 displayed opposing effects by status: fair proposals from high-status allocators elicited larger P3 amplitudes. These findings support a dual-phase model of moral evaluation: the early FRN reflects rapid, context-dependent fairness monitoring, while late-stage P3 integrates social status information to influence cooperative decisions. Overall, this study reveals how social status shapes third-party moral judgments through distinct neural mechanisms across different temporal stages.