We compare two devices previously found to increase contributions to public goods in laboratory experiments: communication, and punishment (allowing subjects to engage in costly reductions of one another’s earnings after learning of their contribution decisions). We find that communication...

We compare two devices previously found to increase contributions to public goods in laboratory experiments: communication, and punishment (allowing subjects to engage in costly reductions of one another’s earnings after learning of their contribution decisions). We find that communication...

When subjects can make non-binding announcements of possible contributions to a public good numerically, there is no effect on average level of contributions in a public goods experiment relative to play without announcements. But a detailed analysis of this experiment shows that pre-play...