WHEN IN DOUBT ... COOPERATION IN A NOISY PRISONERS-DILEMMA

In the last decade, there has been a resurgence of interest in problems of cooperation, stimulated largely by Axelrod's work. Using an innovative tournament approach, Axelrod found that a simple strategy, tit-for-tat (TFT), was most successful in playing the repeated prisoner's dilemma (PD) in a noiseless environment. However, recent analytical work has shown that monitoring problems caused by noise significantly impair TFT's effectiveness. The primary purpose of the present research is to discover whether there exist alternative strategies that perform well in noisy PDs. To investigate this question, the authors conducted a computer tournament. The results of the tournament demonstrated that, consistent with analytical work, TFT performed rather poorly. In contrast, strategies that were generous (i.e., cooperated more than their partners did) were quite effective. © 1991, Sage Publications. All rights reserved.