Cooperation Without Sanctions: Theory and Experiments




Pan, Xiaofei

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Cooperation is indispensable in human societies, and much progress has been made towards understanding human pro-social decisions. Formal incentives, such as punishment, are suggested as potential effective approaches despite the fact that punishment can crowd out intrinsic motives for cooperation and detrimentally impact efficiency. This dissertation examines the role of non-monetary reward in promoting prosocial behaviors. Following the theory of Holländer (1990), the first chapter provides evidence from a laboratory experiment indicating that people under competition value approval highly, but only when winners earn visible rewards through approval. The evidence implies that approval’s value is tied to signaling motives. While the first chapter attempts to explain aggregate pro-social behavior using economic theory that can be generalized across contexts, the second and the third chapters resort to theories of evolutionary psychology, with an emphasis on gender effects. The second chapter examines gender differences in prosociality using theories from evolutionary psychology and empirical evidence from experimental economics. This chapter is to bridge this gap between the source of gender differences in pro-sociality and experimental research by arguing that differences in male and female motives for prosociality stem, at least in part, from gender differences in mating strategies. In particular, in: (i) signaling behaviors; (ii) conformance to social norms; and (iii) approaches toward resolving intra- and inter-group dilemmas. Drawing on costlysignaling theory that is heavily discussed in the second chapter and in light of the widely established competitive nature of males, the third chapter uses a controlled laboratory experiment to show that cooperation is sustained in a generosity competition with trophy rewards, but breaks down in the same environment with equally valuable but non-unique and non-displayable rewards. In particular, males’ competition for trophies is the driving force behind treatment differences. In contrast, it appears that female competitiveness is not modulated by trophy rewards.



Cooperation, Sanction, Experiment, Gender differences, Social approval, Efficiency