Does social exchange increase voluntary cooperation?

There is a lot of empirical and experimental evidence that people give considerable amounts to charities and contribute to public goods. In many cases fellow citizens get to know the contributions of the donators. This suggests that cooperative behaviour is - at least partly - driven by desire to gain social approval. In this paper an experimental design is developed that allows to test the hypothesis that social exchanges between voluntary cooperation and social approval enhance cooperative behaviour in the presence of free-riding incentives. Our results indicate that among strangers the opportunity for social exchanges does not increase cooperation rates.