Faculty of Economics, University of Cambridge, Sidgwick Avenue, Cambridge, CB3 9DD, UK.
Queens' College, CB3 9ET, Cambridge, UK.
Sci Rep. 2019 Jul 26;9(1):10857. doi: 10.1038/s41598-019-47278-2.
The maintenance of cooperative behavior is fundamental for the prosperity of human societies. Empirical studies show that high cooperation is frequently associated with the presence of strong social ties, but they are silent on whether a causal mechanism exists, how it operates, and what features of the social environment are conducive to its emergence. Here we show experimentally that strong ties increase cooperation and welfare by enabling the emergence of a close-knit and strongly bound cooperative elite. Crucially, this cooperative elite is more prevalent in social environments characterized by a large payoff difference between weak and strong ties, and no gradation in the process of strengthening a tie. These features allow cooperative individuals to adopt an all or nothing strategy to tie strengthening based on the well-known mechanism of direct reciprocity: participants become very selective by forming strong ties only with other cooperative individuals and severing ties with everyone else. Once formed, these strong ties are persistent and enhance cooperation. A dichotomous society emerges with cooperators prospering in a close-knit, strongly bound elite, and defectors earning low payoffs in a weakly connected periphery. Methodologically, our set-up provides a framework to investigate the role of the strength of ties in an experimental setting.
合作行为的维持是人类社会繁荣的基础。实证研究表明，高度的合作通常与强大的社会关系的存在有关，但它们没有说明是否存在因果机制，它是如何运作的，以及社会环境的哪些特征有利于它的出现。在这里，我们通过实验表明，强关系通过形成紧密联系和强烈约束的合作精英来增加合作和福利。至关重要的是，这种合作精英在弱关系和强关系之间存在较大收益差异且没有关系强化过程的社会环境中更为普遍。这些特征允许合作个体采用一种非此即彼的策略，根据直接互惠的知名机制，基于个体的合作程度来强化关系：参与者通过只与其他合作个体建立强关系，并与其他人断绝关系，变得非常有选择性。一旦形成，这些强关系就会持久，并增强合作。一个二分社会出现了，合作者在紧密联系、强烈约束的精英中繁荣发展，而背叛者在联系薄弱的外围地区获得低回报。从方法论上讲，我们的设置为在实验环境中研究关系强度的作用提供了一个框架。
