Promoting pro-social behavior with public statements of good intent

Voluntary and compulsory (but rarely enforced) public statements of good intent are frequently observed in the real world, as for example the `Banker's oath', the 'Hippocratic oath' or the requirement of many academic journals for authors to affirm that research was carried out ethically. In this study we investigate what effect such public statements have on contribution behavior in a public goods experiment. We argue that compliance with professional conduct can be seen as a public good and public statements of good intent can therefore be a low-cost policy intervention to foster contributions for the public good. Using a 'between-within subjects design' we identify three channels by which non-enforceable statements of intent are associated with higher levels of contributions to the public good. First, in a selection effect, socially-oriented participants are more likely in the experiment to make a public statement. Second, in a commitment effect, participants who make a public statement are contributing more to the public good. Third, in a coordination effect, aggregate contributions are higher when 'Statement-Makers' observe that also other group members make the statement. The latter explains why compulsory statements of good intent are more effective over time.