CeDEx Discussion Paper, The University of Nottingham 2003-01
People contribute more to public goods, the more others give ('crowding-in'). We investigate two possible causes of crowding-in: reciprocity, the usual explanation, and conformism, a neglected alternative. The issue is important since conformism has more scope to bring about endogenous social interaction effects outside the laboratory. We use Bardsley's (2000) Conditional Information Lottery design to control 'others' behaviour' without deception. We observe how contributions correlate within a group and between groups. Our main result is that conformism does cause crowding-in. The common presumption of reciprocity therefore deserves to be questioned, even in the laboratory.
public goods reciprocity conformism social interaction deception