Understanding the proximate and ultimate sources of human cooperation is a fundamental issue in all behavioural sciences. In this article we review the experimental evidence on how people solve cooperation problems. Existing studies show without doubt that direct and indirect reciprocity are...

We examine the characteristics of effective leaders in a simple leader-follower voluntary contributions game. We focus on two factors: the individual's cooperativeness and the individual's beliefs about the cooperativeness of others. We find that groups perform best when led by those who are...

We investigate the impact of wage comparisons for worker productivity. We present three studies which all use three-person gift-exchange experiments. Consistent with Akerlof and Yellen's (1990) fair wage-effort hypothesis we find that disadvantageous wage discrimination leads to lower efforts...

We report evidence from public goods experiments with and without punishment which we onducted in Russia with 566 urban and rural participants of young and mature age cohorts. Russia is interesting for studying voluntary cooperation because of its long history of collectivism, and a huge...