Xiaofei (Sophia) Pan and Daniel Houser Publish Research in PLoS ONE

Feature Story, News | April 22, 2011

Are formal incentives like pecuniary benefits and punishment the only way for groups to rewards co-operative behavior? Research newly publisehd in PLoS ONE from Xiaofei (Sophia) Pan and Daniel Houser points to a potentially more efficient strategy.

ICES PhD student Xiaofei (Sophia) Pan and Professor of Economics and ICES Director Daniel Houser utilized a controlled laboratory experiment to test the theory that competition for unique and displayable rewards (“trophies”) induces more co-operative behavior in group members. The results of their paper “Competition for Trophies Triggers Male Generosity” indicate that such competitiveness does increase co-operation in male members of the group, but not in female group members. The “trophy” reward system has the potential to promote the same co-operative group behavior that pecuniary punishments and rewards attempt to induce, but without the resulting inefficiencies of the latter.


Background: 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. At the same time, evolutionary biologists have long recognized that cooperation, especially food sharing, is typically efficiently organized in groups living on wild foods, even absent formal economic incentives. Despite its evident importance, the source of this voluntary compliance remains largely uninformed. Drawing on costly signaling theory, and in light of the widely established competitive nature of males, we hypothesize that unique and displayable rewards (trophies) out of competition may trigger male generosity in competitive social environments.

Principal Findings: Here, we use 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. Further, we find that males’ competition for trophies is the driving force behind treatment differences. In contrast, it appears that female competitiveness is not modulated by trophy rewards.

Significance: Our results suggest new approaches to promoting cooperation in human groups that, unlike punishment mechanisms, do not sacrifice efficiency. This could have important implications in any domain where voluntary compliance matters — including relations between spouses, employers and employees, market transactions, and conformity to legal standards.

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