The economic basis of cooperation: tradeoffs between selfishness and generosity

The current study examined the economics of cooperation in controlled-payoff games by using captive blue jays, Cyanocitta cristata. This investigation used a special feeding apparatus to test for the stability of cooperative choice in a series of iterated games. The jays experienced experimentally determined game theoretical payoff matrices, which determined the distribution of food to themselves and their opponent, depending on their decision to cooperate or defect. The experiment tested four game matrices, called the cooperate only, defect only, prisoner's dilemma, and opponent control treatments. This study found little cooperation in the defect only and prisoner's dilemma treatments. Cooperation occurred significantly more often in the opponent control treatment. These findings suggest that the jays attend to short-term consequences; they do not cooperate in the absence of an immediate benefit (defect only), even if a long-term benefit may exist (prisoner's dilemma). The opponent control treatment suggests that cooperation can occur when an individual's benefits depend completely on the actions of others; therefore, generosity is cheap. This study, therefore, agrees with recent studies in proposing alternative models of cooperation. Copyright 2004.