Center for Behavior, Institutions and the Environment / CBIE Working Papers / Conditional Behavior A ffects the Level of Evolved Cooperation in Public Good Games

Conditional Behavior A ffects the Level of Evolved Cooperation in Public Good Games

CBIE_WP-2013-007

Abstract

Human societies are unique in the level of cooperation among non-kin. Evolutionary models explaining this behavior typically assume pure strategies of cooperation and defection. Behavioral experiments, however, demonstrate that humans are typically conditional co-operators who have other-regarding preferences. Building on existing models on the evolution of cooperation and costly punishment, we use a utilitarian formulation of agent decision making to explore conditions that support the emergence of cooperative behavior. Our results indicate that cooperation levels are signicantly lower for larger groups in contrast to the original pure strategy model. Here, defection behavior not only diminishes the public good, but also affects the expectations of group members leading conditional co-operators to change their strategies. Hence defection has a more damaging effect when decisions are based on expectations and not only pure strategies.

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Published August 14, 2013

Marco A. Janssen, Arizona State University, School of Sustainability

Miles Manning, Arizona State University, MTBI

Oyita Udiani, Arizona State University, Math and Stats Grad Students