We explore how risk-taking in the card game contract bridge, and in a financial gamble, correlate with variation in the dopamine receptor D4 gene (DRD4) among serious tournament bridge players. In bridge risk-taking, we find significant interactions between genetic predisposition and skill....

We study the experimental play of the repeated prisoner’s dilemma when intended actions are implemented with noise. In treatments where cooperation is an equilibrium, subjects cooperate substantially more than in treatments without cooperative equilibria. In all settings there was considerable...

Online labor markets have great potential as platforms for conducting experiments. They provide immediate access to a large and diverse subject pool, and allow researchers to control the experimental context. Online experiments, we show, can be just as valid - both internally and externally - as...

It is standard in experimental economics to use decontextualized designs where payoff structures are presented using neutral language. Here we show that cooperation in such a neutrally framed Prisoner’s Dilemma is equivalent to a PD framed as contributing to a cooperative endeavor. Conversely,...

It has been argued that punishment promotes the evolution of cooperation when mutation rates are high (i.e. when agents engage in ‘exploration dynamics’). Mutations maintain a steady supply of agents that punish free-riders, and thus free-riders are at a disadvantage. Recent experiments,...

We experimentally investigate the nature of cooperation in various repeated games, with subjects from Romania and USA. We find stark cross-country differences in the propensity to sustain multilateral cooperation through bilateral rewards and punishments. U.S. groups perform well because...

What is the extent and nature of religious prosociality? If religious prosociality exists, is it parochial and extended selectively to co-religionists, or is it generalized regardless of the recipient? Further, is it driven by preferences to help others or by expectations of reciprocity? We...

Recent work using decontextualized economic games suggests that cooperation is a dynamic decision-making process: automatic responses typically support cooperation on average, while deliberation leads to increased selfishness. Here we performed two studies examining how these temporal effects...

Large-scale cooperation, or the willingness of individuals to incur costs in order to help others, is a defining trait of the human species. However, cooperation poses a theoretical puzzle: since it is individually costly to cooperate, it seems that natural selection should favor non-cooperation...

When people have the chance to help others at a cost to themselves, are cooperative decisions driven by intuition or reflection? To answer this question, recent studies have tested the relationship between reaction times and cooperation, reporting both positive and negative correlations. To...