We extend the dual-self model to include altruistic preferences. This explains (1) why people may have preferences for equality in the laboratory but not in the field, (2) why intermediate donations may occur in dictator games, (3) why cognitive load and time pressure may increase giving, and...

We explore the extent to which altruism, as measured by giving in a dictator game (DG), accounts for play in a noisy version of the repeated prisoner’s dilemma. We find that DG giving is correlated with cooperation in the repeated game when no cooperative equilibria exist, but not when...

Online labor markets such as Amazon Mechanical Turk (MTurk) off er an unprecedented opportunity to run economic game experiments quickly and inexpensively. Using Mturk, we recruited 756 subjects and examined their behavior in four canonical economic games, with two payoff conditions each: a...

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....

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 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,...

Cooperation is central to human societies. Yet relatively little is known about the cognitive underpinnings of cooperative decision-making. Does cooperation require deliberate self-restraint? Or is spontaneous prosociality reined in by calculating self-interest? Here we present a theory of why...