Group (Re-) formation in public good games: The tale of the bad apple?

We analyze how different previous roles as partners or strangers in public good games affect an individual's subsequent cooperation in a partner setting. We systematically vary a group's composition from all individuals being partner over blended groups of partners and strangers to all individuals being stranger in each round. We want to explore how individuals' past experiences in blended groups of partners and strangers affect cooperation in newly formed groups with permanent members only. Our results show that previous group composition does not affect cooperation in the subsequent partner setting with one exception: Groups cooperate significantly less compared to all other settings, when one stranger entered the group. We further analyze this situation in-depth and find that only in a setting with one stranger a reaction chain based on negative reciprocity results in low contributions in the subsequent setting. Partners falsely attribute low cooperation levels to partners formerly assigned the role of a stranger. We conduct additional treatments to back up this result and to show how information about the stranger can prevent such an error.