The Speed of Learning in Noisy Games: Partial Reinforcement and the Sustainability of Cooperation
实验发现，在重复囚徒困境中，收益的随机性会显著削弱玩家学会合作的能力，即使他们能完美监控彼此过去的行为；而在单次对局中，随机收益通过减缓合作衰减速度反而提高了合作水平。这些结果与心理学中的部分强化效应一致，并表明个体学习速度的微小变化可能对集体行为产生重大影响。
In an experiment, players’ ability to learn to cooperate in the repeated prisoner’s dilemma was substantially diminished when the payoffs were noisy, even though players could monitor one another's past actions perfectly. In contrast, in one-time play against a succession of opponents, noisy payoffs increased cooperation, by slowing the rate at which cooperation decays. These observations are consistent with the robust observation from the psychology literature that partial reinforcement (adding randomness to the link between an action and its consequences while holding expected payoffs constant) slows learning. This effect is magnified in the repeated game: When others are slow to learn to cooperate, the benefits of cooperation are reduced, which further hampers cooperation. These results show that a small change in the payoff environment, which changes the speed of individual learning, can have a large effect on collective behavior. And they show that there may be interesting comparative dynamics that can be derived from careful attention to the fact that at least some economic behavior is learned from experience.