Altruistic or fair? The influence of empathy on third-party punishment: an event-related potential study

Although most individuals strongly prefer social fairness and punish behaviours that violate fairness norms, recent psychological studies have shown that empathy towards 'perpetrators' who violate fairness norms can affect people's fairness decision-making, resulting in tolerance for unfair behaviour, even as direct 'victims' of unfair behaviour. However, in real life, people more often view unfair events from a third-party perspective, and little is known about how empathy affects fairness decisions by third parties whose self-interests are not threatened and their neurocognitive mechanisms. The present study examined effects of empathy directed towards a 'perpetrator' on third-party punishment using event-related potentials. The results suggest that, in the nonempathy condition, unfair offers induced stronger unfairness aversion in third-party decision makers and increased motivation and cognitive resource investment to alleviate this negative emotion compared to fair offers, reflecting the greater amplitude differences of fairness effects on the anterior N1 component, medial frontal negative, and smaller late positive components in the nonempathy condition. However, in the empathy condition, the differential impact of the fairness effect disappeared. These findings reveal the neural basis for trade-offs between altruistic and fairness motives in third-party fairness decision-making processes involving empathy.