Chapter written for the Handbook of Reciprocity, Gift-Giving and Altruism

Most economic models are based on the self-interest hypothesis that assumes that all people are exclusively motivated by their material self-interest. In recent years experimental economists have gathered overwhelming evidence that systematically refutes the self-interest hypothesis and suggests...

This paper surveys recent experimental and field evidence on the impact of concerns for fairness, reciprocity and altruism on economic decision making. It also reviews some new theoretical attempts to model the observed behavior.