Self-control and social cooperation.

Participants repeatedly played a self-control game in which choice of the higher of two monetary rewards on the present trial reduced the overall reward ('alone condition'). Other participants played a prisoner's dilemma (social cooperation) game in which choices alternated so that overall reward-reducing consequences of choosing the higher current amount were experienced by the other player ('together condition'). Participants playing the self-control game chose the lower current amount (and higher overall reward) significantly more frequently than did those playing the social cooperation game. In a second phase, half of the subjects who had played the self-control game played the social cooperation game and vice-versa. Little or no transfer was observed between conditions. In a second experiment, raising the amount of the next-trial reward increased self-control but not social cooperation. Some transfer between self-control and social cooperation was observed. The crucial variable responsible for participants' better performance (closer to optimization) in the self-control game compared to the social cooperation game may have been the higher probability in the former that choice of the lower reward on the present trial would be repeated on subsequent trials.