Cooperation through image scoring in humans

Abstract

The ``tragedy of the commons,'' that is, the selfish exploitation ofresources in the public domain, is a reason for many of our everydaysocial conflicts. However, humans are often more helpful to others thanevolutionary theory would predict, unless indirect reciprocity takesplace and is based on image scoring (which reflects the way anindividual is viewed by a group), as recently shown by game theorists.We tested this idea under conditions that control for confoundingfactors. Donations were more frequent to receivers who had been generousto others in earlier interactions. This shows that image scoringpromotes cooperative behavior in situations where direct reciprocity isunlikely.