Social Learning and Norms in a Public Goods Experiment with Inter-Generational Advice

We study a linear public goods game using an inter-generational approach. Subjects in one generation leave advice for the succeeding generation via free-form messages. Such advice can be private knowledge (advice left by one player in generation "t" is given only to his or her immediate successor in generation "t"+ 1), public knowledge (advice left by players of generation "t" is made available to all members of generation "t"+ 1), and common knowledge (where the advice is not only public but is also read aloud by the experimenter). Common knowledge of advice generates a process of social learning that leads to high contributions and less free-riding. This behaviour is sustained by advice that is generally exhortative, suggesting high contributions, which in turn creates optimistic beliefs among subjects about others' contributions. We suggest that socially connected communities may achieve high contributions to a public good even in the absence of punishment for norm violators. Copyright 2006 The Review of Economic Studies Limited.