Department of Economics, Massachusetts Institute of Technology, Cambridge, MA 02139.
Department of Economics, Massachusetts Institute of Technology, Cambridge, MA 02139
Proc Natl Acad Sci U S A. 2020 May 26;117(21):11344-11349. doi: 10.1073/pnas.1921984117. Epub 2020 May 12.
Indirect reciprocity is a foundational mechanism of human cooperation. Existing models of indirect reciprocity fail to robustly support social cooperation: Image-scoring models fail to provide robust incentives, while social-standing models are not informationally robust. Here we provide a model of indirect reciprocity based on simple, decentralized records: Each individual's record depends on the individual's own past behavior alone, and not on the individual's partners' past behavior or their partners' partners' past behavior. When social dilemmas exhibit a coordination motive (or strategic complementarity), tolerant trigger strategies based on simple records can robustly support positive social cooperation and exhibit strong stability properties. In the opposite case of strategic substitutability, positive social cooperation cannot be robustly supported. Thus, the strength of short-run coordination motives in social dilemmas determines the prospects for robust long-run cooperation.
间接互惠是人类合作的基础机制。现有的间接互惠模型未能强有力地支持社会合作：形象评分模型未能提供强有力的激励，而社会地位模型在信息上也不稳健。在这里，我们提供了一种基于简单分散记录的间接互惠模型：每个人的记录仅取决于个人自身的过去行为，而不取决于个人的伙伴的过去行为或他们的伙伴的伙伴的过去行为。当社会困境表现出协调动机（或战略互补性）时，基于简单记录的宽容触发策略可以强有力地支持积极的社会合作，并表现出很强的稳定性。在相反的战略替代性情况下，积极的社会合作不能得到强有力的支持。因此，社会困境中短期协调动机的强度决定了长期合作的前景。
