Males punish top earners most, even when fairness motives are absent

When witnessing the administration of pain to an individual who behaved unfairly in an economic game, males show significantly less empathy-related neural activity than females and significantly more activity in areas associated with the processing of reward. This finding suggests that fairness concerns make males more likely to assume the role of punishing unfair behaviour and promoting cooperation; yet, in conventional laboratory games, punishment aimed at promoting cooperation cannot be distinguished from punishment seeking to reduce the income of high earners, meaning that pleasure from unfair individuals’ pain might actually derive from a desire that wealthy individuals, as opposed to unfair ones, suffer. Here we show evidence supporting that hypothesis: when fairness motives do not exist, individuals still reduce the income of others and males are significantly more likely than females to reduce the income of wealthier players.