The Sequential Prisoner's Dilemma: Evidence on Reciprocation.

We investigate how fairness concerns influence individual behaviour in social dilemmas. Using a Sequential Prisoner's Dilemma experiment we analyse the extent to which co-operation is conditional on first-mover co-operation, repetition, economic incentives, subject pool (United Kingdom vs. United States) and gender. We find the most important variable influencing co-operation is the first-mover's choice, supporting the argument that co-operative behaviour in social dilemmas reflects reciprocation rather than unconditional altruism. However, we also find that cooperation decreases with repetition, and reciprocation falls as its material cost rises.