Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an 710119, Shaanxi, China.
Center of Mathematics for Social Creativity, Research Institute for Electronic Science, Hokkaido University, Sapporo 060-0812, Japan;
Proc Natl Acad Sci U S A. 2018 Jan 2;115(1):30-35. doi: 10.1073/pnas.1707505115. Epub 2017 Dec 19.
Network reciprocity has been widely advertised in theoretical studies as one of the basic cooperation-promoting mechanisms, but experimental evidence favoring this type of reciprocity was published only recently. When organized in an unchanging network of social contacts, human subjects cooperate provided the following strict condition is satisfied: The benefit of cooperation must outweigh the total cost of cooperating with all neighbors. In an attempt to relax this condition, we perform social dilemma experiments wherein network reciprocity is aided with another theoretically hypothesized cooperation-promoting mechanism-costly punishment. The results reveal how networks promote and stabilize cooperation. This stabilizing effect is stronger in a smaller-size neighborhood, as expected from theory and experiments. Contrary to expectations, punishment diminishes the benefits of network reciprocity by lowering assortment, payoff per round, and award for cooperative behavior. This diminishing effect is stronger in a larger-size neighborhood. An immediate implication is that the psychological effects of enduring punishment override the rational response anticipated in quantitative models of cooperation in networks.
网络互惠在理论研究中被广泛宣传为促进合作的基本机制之一，但支持这种互惠类型的实验证据直到最近才发表。当以不变的社会联系网络组织时，人类主体会进行合作，前提是满足以下严格条件：合作的收益必须超过与所有邻居合作的总成本。为了放宽这一条件，我们进行了社会困境实验，其中网络互惠受到另一种理论上假设的促进合作的机制——昂贵的惩罚的辅助。结果揭示了网络如何促进和稳定合作。正如理论和实验所预期的那样，在较小的邻里关系中，这种稳定效应更强。与预期相反，惩罚通过降低分类、每轮收益和对合作行为的奖励，降低了网络互惠的好处。在更大的邻里关系中，这种减弱效应更强。一个直接的含义是，持久惩罚的心理影响超过了网络中合作的定量模型所预期的理性反应。
