Search

Human groups can often maintain high levels of cooperation despite the threat of exploitation by individuals who reap the benefits of cooperation without contributing to its costs 1-4 . Prominent theoretical models suggest that cooperation is particularly likely to thrive if people join forces to curb free riding and punish their non-contributing peers in a coordinated fashion 5 . However, it is unclear whether and, if so, how people actually condition their punishment of peers on punishment behaviour by others. Here we provide direct evidence that many people prefer coordinated punishment. With two large-scale decision-making experiments (total n = 4,320), we create minimal and controlled conditions to examine preferences for conditional punishment and cleanly identify how the punishment decisions of individuals are impacted by the punishment behaviour by others. We find that the most frequent preference is to punish a peer only if another (third) individual does so as well. Coordinated punishment is particularly common among participants who shy away from initiating punishment. With an additional experiment we further show that preferences for conditional punishment are unrelated to well-studied preferences for conditional cooperation. Our results highlight the importance of conditional preferences in both positive and negative reciprocity, and they provide strong empirical support for theories that explain cooperation based on coordinated punishment.

Social cooperation often requires collectively beneficial but individually costly restraint to maintain a public good1-4, or it needs costly generosity to create one1,5. Status quo effects6 predict that maintaining a public good is easier than providing a new one. Here we show experimentally and with simulations that even under identical incentives, low levels of cooperation (the 'tragedy of the commons'2) are systematically more likely in Maintenance than Provision. Across three series of experiments, we find that strong and weak positive reciprocity, known to be fundamental tendencies underpinning human cooperation7-10, are substantially diminished under Maintenance compared to Provision. As we show in a fourth experiment, the opposite holds for negative reciprocity ('punishment'). Our findings suggest that incentives to avoid the 'tragedy of the commons' need to contend with dilemma-specific reciprocity., Competing Interests: Competing interest The authors declare no competing interests.

We study the relative effectiveness of contracts that are framed either in terms of bonuses or penalties. In one set of treatments, subjects know at the time of effort provision whether they have achieved the bonus/avoided the penalty. In another set of treatments, subjects only learn the success of their performance at the end of the task. We fail to observe a contract framing effect in either condition: effort provision is statistically indistinguishable under bonus and penalty contracts., (© The Author(s) 2017.)

We investigate the effects of inequality in wealth on the incentives to contribute to a group output when agents are inequity averse and may differ in ability. We show that equality may lead to a reduction of contributions below levels generated by purely selfish agents. But introducing inequality motivates more productive agents to exert higher efforts and help the group to coordinate on equilibria with less free-riding. As a result, less able agents may benefit from initially disadvantageous inequality. Moreover, the more inequity averse the agents, the more inequality should be imposed even by an egalitarian social planner.

We experimentally investigate how different information about others' individual contributions affects people's willingness to cooperate in a one-shot linear public goods game. We find that when information about individual contributions is provided, contributions are generally higher than when only average information is available. This effect is particularly strong when others' individual contributions are relatively homogeneous. When both types of information are provided, this effect is moderated. In the case of individual feedback we find the willingness to contribute to be higher the lower the variation in others' contributions, but with pronounced heterogeneity in individuals' reactions. While the majority of people are mainly guided by others' average contributions, more people follow the bad example of a low contributor than the good example of a high contributor. Overall, we provide evidence that information (and lack thereof) about others' individual contributions affects people's willingness to cooperate in systematic ways.