Heterogeneity in the Motivations for Punishment: An Experimental Study

We explores the motivations behind costly punishment in social dilemmas, specifically focusing on reciprocity and inequality aversion. To distinguish these motivations, we introduce uncertainty into the payoff function of a public goods game, preventing participants from predicting others' contributions based on their payoffs. In this situation, participants should choose between others' contributions and others' payoffs as the criterion for their punishment. We also include a random income game to test the plausibility of our classification by removing intentionality from the contribution decisions. Our results show heterogeneity in the motivations to punish, leading to different types of punishers: the self-interested type, the reciprocal type, the inequality-averse type, and the ``other" type who is inconsistent. Furthermore, in the random income game, overall punishment tends to be lower, but only reciprocal punishment decreases with the existence of intention. Additionally, the reciprocal type strongly punishes free-riding behaviors but also imposes some punishment for payoff inequality. These findings reveal that inequality aversion is a critical motivation for punishment---that is, that a significant number of individuals rely on inequality aversion as their sole motivation for punishment while others incorporate it into their punishment based on reciprocity.

本研究深入探讨了社会困境中高额惩罚背后的动机，特别关注互惠与不平等厌恶。为区分这些动机，本研究将不确定性引入公共物品博弈的收益函数，阻止参与者根据其收益预测他人的贡献。在此情境下，参与者应在他人贡献与他人收益之间选择作为其惩罚的标准。此外，本研究还纳入了随机收入博弈，以消除贡献决策中的意图性，从而检验分类的合理性。结果显示，惩罚动机存在异质性，导致不同类型的惩罚者出现：自私型、互惠型、不平等厌恶型和不一致的“其他”型。此外，在随机收入博弈中，总体惩罚水平趋于降低，但只有互惠惩罚随意图的存在而减少。互惠型参与者对搭便车行为实施严厉惩罚，同时对收益不平等也施加了一定的惩罚。这些发现揭示了不平等厌恶是惩罚的重要动机——即，大量个体将不平等厌恶作为其惩罚的唯一动机，而其他人则将其融入基于互惠的惩罚策略中。