Published online by Cambridge University Press: 17 May 2016
Laboratory research studying behavior in the Prisoner's Dilemma (PD) game is consistent with the commonplace perception that social exchange is risky. Although they often do cooperate, people also often defect. Thus, the decision to enter a PD game with a stranger, about whom one has no good basis for predicting behavior, is a bet on cooperation. Many investigators have explored a range of cognitive processes and individual differences putatively bearing on the choice to enter such games, but few have asked how people perceive, assess, and respond to social risk in general. That is what we ask here. From the well known finding that people are risk-averse in the domain of gains and risk-tolerant in the domain of losses, we predict that, with game incentives constant, people will be more willing to enter social relationships when game payoffs are framed as losses than when they are framed as gains. We tested this prediction in a student population playing PD games. Results strongly supported the prediction, suggesting that human sociality may have evolved more as a defensive response to the possibility of loss than as an opportunistic attempt to capture gain.