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Abstract

One landmark application of evolutionary game theory is the study of social dilemmas. This literature explores why people cooperate even when there are strong incentives to defect. Much of this literature, however, assumesthat interactions are symmetric. Individuals are assumed to have the samestrategic options and the same potential pay-offs. Yet many interesting questions arise once individuals are allowed to differ. Here, we study asymmetryin simple coordination games. In our set-up, human participants need todecide how much of their endowment to contribute to a public good. If agroup’s collective contribution reaches a pre-defined threshold, all groupmembers receive a reward. To account for possible asymmetries, individualseither differ in their endowments or their productivities. According to atheoretical equilibrium analysis, such games tend to have many possible sol-utions. In equilibrium, group members may contribute the same amount,different amounts or nothing at all. According to our behavioural experiment, however, humans favour the equilibrium in which everyone contributes the same proportion of their endowment. We use these experimental results to highlight the non-trivial effects of inequality on cooperation, and we discuss to which extent models of evolutionary game theory can account for these effects. This article is part of the theme issue ‘Half a century of evolutionarygames: a synthesis of theory, application and future directions’.