Kindness or fairness: prosociality and fairness jointly modulate moral judgments

This study explores how third-party judges weigh the importance of prosociality and fairness when making judgments on complex moral decisions that encompass both elements, and the role of social distance between the judge and the decision-maker in this process. In the experiments, participants acted as third-party observers, watching decisions made by decision-makers in complex moral tasks and evaluating their moral levels. The tasks completed by the decision-makers involved distributing tokens between themselves and others (prosociality) and allocating tokens given to others between two recipients (fairness). The results showed that: 1) the effects of prosociality and fairness on moral judgments are not independent but interactive. Under high prosocial conditions, the difference in moral ratings between fair and unfair decisions is significantly greater than that under low prosocial conditions; at the neural level, the amplitudes of EEG components FRN and P3 exhibit patterns consistent with behavior; 2) when judging highly prosocial but unfair decisions, as the social distance between the decision-maker and the participant decreases, the participant's moral rating of the decision decreases, but their willingness to cooperate increases, demonstrating a dissociation between moral rating and willingness to cooperate. This study suggests that in judging complex moral decisions with multiple components, prosociality and fairness are not independent but interactively influence judgments together. The study reveals the flexibility of moral judgments and the interactions between various moral factors, providing new insights into the psychological mechanisms of complex moral judgments in different social contexts.