Abstract:

Partner choice refers to the individual’s behavior of choosing or refusing to engage in partnerships with other individuals based on whether they can bring benefits to him/her. Partner choice is an independent mechanism that promotes cooperative behavior. The theory of reciprocity based on partner control condition has dominated the discussion of non-kin cooperation for a long time. In contrast to the partner control condition, under which individuals focus on how to avoid being exploited by a defector to facilitate cooperation (e.g., the “tit-for-tat” strategy), under the partner choice condition, individuals can focus on both avoiding exploitation by leaving a defector and finding a better partner to get more substantial benefits. Briefly, it comprises three main aspects. First, partner choice itself can promote cooperation through leaving defectors and choosing partners; only partner choice is enough to bring about cooperative behaviors. Second, individuals can seek reliable cooperators to promote higher-level cooperation based not only on simple behaviors of others but also on stable information at the trait level (such as generosity, moral character, etc.). Third, in terms of internal mechanisms, in the process of partner choice, individuals may promote cooperation primarily through the punishment mechanism of walking away from uncooperative individuals (i.e., ostracism), the reward mechanism of seeking better cooperators, the assortative matching mechanism, and the competition mechanism of winning partners by developing competitive altruism. The punishment and reward mechanisms concern individual behavior, while the assortative matching and competition mechanisms involve the entire social system. In partner choice, individuals focus on finding more cooperative partners that leads to greater benefits rather than punishing others. Therefore, the promotion of cooperative behavior by partner choice needs to be explained more with the reward mechanism, the assortative matching mechanism and the competition mechanism.

In the future, studies should investigate various aspects of partner choice. First, tools should be developed to measure partner choice ability from the perspectives of behavioral and cognitive ability and to explore the timing and constraints of partner replacement from the perspective of rule or system design. Second, the ecological validity of partner choice research should be improved by adding the cost of “quitting” in the experimental paradigm, allowing individuals to use a wider range of information to select partners, and using a gambling paradigm that can produce mutualistic cooperation. Third, studies should further explore the internal mechanisms of the promotion of cooperative behavior by partner choice. Under the condition of partner choice, individuals may see cooperation as their goal, rather than as the means to obtain material benefits. In addition, partner choice may not only involve the judgment of a partner’s generosity and morality, but also may involve the evaluation of common ground with a partner in their goals, behavioral norms, skills, and personality traits. Fourth, studies should solve the problem of low cooperation tendency under the condition of static network or partner control in light of partner choice, such as by exploring the proportion of dynamic network in an individual's interpersonal network that can best promote cooperative behavior in a static network. Finally, indigenous research should be carried out to explore partner choice and cooperation issues in the context of Chinese culture.

Key words: partner choice, partner control, cooperative behavior, evolution, game