People spend their own money to punish and reward strangers with no future benefit.

Evidence

The results show that players incurred costs in order to reduce or augment the income of other players even though this behavior plainly had no effect on what would happen in the subsequent rounds. Analyses show that participants were mainly motivated by considerations of fairness and impartiality, trying to achieve an equal division of wealth13: 68% of the players reduced another player’s income at least once, 28% did so five times or more, and 6% did so ten times or more (out of fifteen possible times). Also, 74% of the players increased another player’s income at least once, 33% did so five times or more, and 10% did so ten times or more. — Nicolas Baumard, A mutualistic approach to morality, 180

Categorization

• XREF: This is the anonymous third-party punishment paradigm—connects to the reader’s ‘Big God’ moral-enforcement analysis and Baumard’s partner-choice model of fairness. — connects to: People punish norm violations at personal cost even without direct harm — Ernst Fehr, Third-Party Punishment and Social Norms, 147; An impartial third party who punishes at personal cost demonstrates strong reciprocity. — Ernst Fehr, Third-Party Punishment and Social Norms, 13

Related

• Impartial third parties punish norm violators at personal cost. (similarity 0.85)
• People punish free-riders partly to correct inequality, not only to enforce cooperation. (similarity 0.83)
• An impartial third party who punishes at personal cost demonstrates strong reciprocity. (similarity 0.82)
• A punisher’s own gains do not reduce punishment of unrelated violators. (similarity 0.82)
• Even unaffected bystanders punish norm violations at personal cost. (similarity 0.82)
• Costly norm enforcement by unaffected bystanders reveals strong reciprocity. (similarity 0.82)
• Third parties punish inequality even when it does not directly involve them. (similarity 0.82)
• Punishment scales with the unfairness of the wrongdoing, not with deterrence needs (similarity 0.81)
• Directly harmed victims punish more strongly than unaffected third parties. (similarity 0.80)
• Antisocial punishment is driven by low contributors’ sense of unfair treatment. (similarity 0.80)
• Second-party sanctions are contaminated by self-interest; third-party sanctions reveal true norms. (similarity 0.80)
• Low-cost punishment of norm violators is a uniquely human trait. (similarity 0.80)
• Multiple third-party punishers can make norm violations unprofitable, acting as strong norm enforcers. (similarity 0.80)
• Society punishes impropriety more harshly than inhumanity (similarity 0.80)
• Different social-preference models make distinguishable predictions about who punishes. (similarity 0.79)

Broader Connections

• People punish norm violations at personal cost even without direct harm #corroborates (0.95) — Ernst Fehr, Third-Party Punishment and Social Norms, 147
• An impartial third party who punishes at personal cost demonstrates strong reciprocity. #expands (0.85) — Ernst Fehr, Third-Party Punishment and Social Norms, 13