Previous studies have shown that individuals are less likely to help a person in need when there are "bystanders" present who can also offer help. We designed an experiment to re-examine this "bystander effect" using modified dictator games. We find lower giving rates in the presence of...

We study the effects of voluntary participation on cooperation in collective action problems. Voluntary participation may foster cooperation through a mechanism of assortative selection of interaction partners based on false consensus bias, or through a mechanism whereby the decision to not...

We study the effects of voluntary participation on cooperation in collective action problems. Voluntary participation may foster cooperation through an entry mechanism, which leads to assortative selection of interaction partners, or an exit mechanism, whereby the opportunity to leave the...

We study the effects of voluntary participation on public good provision. Voluntary participation may foster cooperation through two mechanisms: an entry mechanism, which leads to assortative selection of interaction partners, or an exit mechanism, whereby the opportunity to leave the...

We measure the social norms of sharing income with kin and neighbors in villages in Kenya. We find a plurality of norms: from a strict norm prohibiting wealth accumulation to a norm facilitating saving. Several individual and social network characteristics predict the norms upheld; the pro-saving...

We study the effects of voluntary participation on cooperation in collective action problems. Voluntary participation may foster cooperation through an entry mechanism, which leads to assortative selection of interaction partners, or an exit mechanism, whereby the opportunity to leave the...

We study the effects of voluntary participation on public good provision. Voluntary participation may foster cooperation through two mechanisms: an entry mechanism, which leads to assortative selection of interaction partners, or an exit mechanism, whereby the opportunity to leave the...

We study the effects of voluntary participation on cooperation in collective action problems. Voluntary participation may foster cooperation through a mechanism of assortative selection of interaction partners based on false consensus bias, or through a mechanism whereby the decision to not...