Mutual Restraint in Tree Swallows: A Test of the TIT FOR TAT Model of Reciprocity

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Science  15 Mar 1985:
Vol. 227, Issue 4692, pp. 1363-1365
DOI: 10.1126/science.227.4692.1363


The TIT FOR TAT model of reciprocity, which is based on a successful program for the game known as the Prisoner's Dilemma, was experimentally tested on a population oftree swallows (Tachycineta bicolor). Parent and nonbreeding tree swallows have conflicts of interests that resemble those in the Prisoner's Dilemma. TIT FOR TAT predicts restraint of conflict before a competitor's act of defection, retaliation after defection, and a resumption of restraint following retaliation. After a simulated act of defection by nonbreeders, parents behaved as predicted by the model.