Cooperation as self-interested reciprocity in the Centipede

Cooperation is a pervasive social phenomenon but more often than not economic theories have little to say about its causes and consequences. In this paper, we explore the hypothesis that cooperative behaviour might be motivated by purely selfish interest when the “social” payoff in a game is increasing. We report the results of a series of experiments on the centipede game. The experiments are organized in two subsequent steps. Subjects first participate in a 2-period trust game, randomly matched with unknown partners. We apply the strategy method in order to elicit their social preferences. On the basis of their pre-game behaviour, individuals are divided into three main social groups: selfish individuals, pure altruists and reciprocators. At the second step of the experiment, subjects play a repeated 6-move centipede game with increasing final payoff. Each subject plays twice in a low stake and in a high centipede game, and he/she is informed about his/her co-player social preferences. We identify the origin of cooperation within homogeneous and heterogeneous social groups.