Repeated interactions provide a prominent but paradoxical hypothesis for human cooperation in one-shot interactions. Intergroup competitions provide a different hypothesis that is intuitively appealing but heterodox. We show that neither mechanism reliably supports the evolution of cooperation...

Intelligence and personality significantly affect social outcomes of individuals. We study how and why these traits affect the outcome of groups, looking specifically at how these characteristics operate in repeated interactions providing opportunity for profitable cooperation. Our experimental...

We use laboratory experiments to study the causal effects of favorable and unfavorable competitive market experience on cooperation in a subsequent social dilemma game. The issues we study are part of the broader topic of whether there are behavioral spillovers between different spheres of...

This paper provides evidence that free riders are heavily punished even if punishment is costly and does not provide any material benefits for the punisher. The more free riders negatively deviate from the group standard the more they are punished. As a consequence, the existence of an...

This paper presents a formal theory of reciprocity. Reciprocity means that people reward kind actions and punish unkind ones. The theory takes into account that people evaluate the kindness of an action not only by its consequences but also by the intention underlying this action. The theory...

We experimentally investigate behavior and beliefs in a sequential prisoner's dilemma. Each subject had to choose an action as first-mover and a conditional action as second-mover. All subjects also had to state their beliefs about others' second-mover choices. We find that subjects' beliefs...

We explore the relationship between individuals' disposition to cooperate and their inclination to engage in peer punishment as well as their relative importance for mitigating social dilemmas. Using a novel strategy-method approach we identify individual punishment patterns and link them with...

We investigate whether there is a link between conditional cooperation and betrayal aversion. We use a public goods game to classify subjects by type of contribution preference and by belief about the contributions of others; and we measure betrayal aversion for different categories of subject....

Lebanon is the country with the highest density of refugees in the world, raising the question of whether the host and refugee populations can cooperate harmoniously. We conduct a lab-in-thefield experiment in Lebanon studying intra- and inter-group behavior of Syrian refugees and Lebanese...

A large literature in behavioral economics has emphasized in the last decades the role of individual differences in social preferences (such as trust and altruism) and in influencing behavior in strategic environments. Here we emphasize the role of attention and working memory, and show that...