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.
Bibliographical noteFunding Information:
We would like to thank Ben Kerr, Alison Pearce, David Westneat, Mike Wilson, and two anonymous referees for reviewing the manuscript; the Packer/Pusey/Stephens behavior group for stimulating discussions and helpful criticism of the project; and Dack Anderson, Jolene Ruf, Claire Leung, and Geoff Harms for assistance in completing the project. This project was funded with support from the National Science Foundation (IBN-9896102 to D.W.S.) and the Graduate School at the University of Minnesota. This project was approved by the Institutional Animal Care and Use Committee at the University of Minnesota (Animal Subjects Code 0008A614181).
- Blue jay
- Game theory
- Prisoner's dilemma
- Tit for Tat