Patient and impatient punishers of free-riders

Costly punishment of cheaters who contribute little or nothing to a cooperating group has been extensively studied as an effective means to enforce cooperation. The prevailing view is that individuals use punishment to retaliate against transgressions of moral standards like fairness or equity. However, there is much debate regarding the psychological underpinnings of costly punishment. Some authors suggest that costly punishment must be a product of humans’ capacity for reasoning, self-control, and long-term planning, while others argue that it is the result of an impulsive, present oriented, emotional drive. Here we explore the inter-temporal preferences of punishers in a multilateral cooperation game and show that both interpretations might be right as we can identify two different types of punishment: punishment of free-riders by cooperators, which is predicted by patience (future orientation) and free-riders’ punishment of other free-riders, which is predicted by impatience (present orientation). Therefore, the picture is more complex as punishment by free-riders unlikely comes from a reaction against a moral transgression, but instead from a competitive, spiteful drive. Thus, punishment grounded on morals may be related to lasting or delayed psychological incentives, while punishment triggered by competitive desires may be linked to short-run aspirations. These results indicate that the individual’s time horizon is relevant for the type of social behaviour she opts for. Integrating such differences in inter-temporal preferences and the social behaviour of agents might help to achieve a better understanding of how human cooperation and punishment behaviour has evolved.

针对向合作群体贡献微薄或毫无贡献的搭便车者（free-riders）实施的代价性惩罚，作为强化合作的有效手段已得到广泛研究。主流观点认为，个体实施惩罚是为了报复违背公平或公正等道德准则的行为。然而，学界围绕代价性惩罚的心理学基础仍存在诸多争议。部分学者认为，代价性惩罚是人类推理、自我控制与长期规划能力的产物；而另有学者则主张，其源于冲动、当下导向的情绪驱动。本研究通过多边合作博弈（multilateral cooperation game）探究惩罚者的跨期偏好（inter-temporal preferences），结果表明两种解读均具备合理性：我们可识别出两类截然不同的惩罚行为——合作者（cooperators）对搭便车者的惩罚可由耐心（未来导向）预测，而搭便车者对其他搭便车者的惩罚则可由急躁（当下导向）预测。因此，实际图景更为复杂：搭便车者实施的惩罚并非源于对道德越界的反抗，而是源自竞争性、恶意的驱动。由此可见，基于道德的惩罚或与持久或延迟的心理动机相关联，而由竞争性欲望触发的惩罚则可能与短期诉求挂钩。上述结果表明，个体的时间视野与其所选择的社会行为类型密切相关。将跨期偏好的这类差异与行为主体的社会行为相结合，或有助于我们更深入地理解人类合作与惩罚行为的演化历程。