Session Size and its Effect on Identity Building: Evidence from a public goods experiment

The effect of session size has largely been ignored in experimental studies, despite the possibility that it may play a role by changing people’s perception of the potential chance of encountering a certain type of people and by affecting the strength of the potential link between people. This paper investigates how the effect of an induced common identity on individual cooperative behavior differs depending on session size in a repeated public goods experiment with constant group size and partner matching. We find that induced identity significantly enhances cooperation only when the session size is small and only in the initial period. In all other periods, the effect of induced identity on cooperation is the same in small and large sessions, suggesting that session size is not a confounding factor of identity in repeated interaction settings.