Doctoral Dissertation Research: Cooperation in Stochastic Games: A Prisoner's Dilemma Experiment

经济学家和社会科学家思考了一段时间的一个问题是，当私人激励与社会激励发生冲突时，社会合作的适当先决条件是什么？这个问题的一个答案来自于重复博弈理论，即研究团队成员之间的决策过程（游戏邦注：即玩家需要反复做出决策）。更准确地说，与这个答案相关的特定博弈是重复囚徒困境。在囚徒困境中，合作对社会是有益的，但不合作符合每个参与者的个人最佳利益，因此，当只玩一次时，没有合作发生。然而，当囚徒困境重复出现时，合作可以通过将未来选择与当前选择联系起来来维持，这样，一个人在当前时期偏离合作所获得的收益将被未来时期的损失所抵消。具体来说，未来所有参与者相互不合作的可信威胁阻碍了这种收益。然而，重复的游戏是对现实世界的极度简化。实际上，虽然许多经济状况具有重复的相互作用，但这种相互作用的性质随着时间的推移而变化。这一特征体现在随机游戏中，这是一种重复游戏的概括，在这种游戏中，每个时期的游戏都会发生变化，并且至少部分是由偶然决定的。这个项目是随机博弈领域的一个实验室实验。特别地，这个实验利用了一个重复的囚徒困境，在这个困境中，囚徒的回报是？S困境是随机确定的。最重要的是，考虑到未来选择和当前选择之间的联系是为了维持合作而建立的，改变未来选择的性质是理解人们在这些环境中如何行为的重要一步。从更广泛的角度来看，随机囚犯的主要经济例子是什么？实验中的S困境是企业在经济周期中相互勾结。在这种环境下，企业希望在非竞争性价格或数量上串通、合作，并在许多时期内进行竞争。由于经济的繁荣和萧条，需求波动，这改变了他们在每个时期所面临的确切互动。这个实验可以通过洞察企业可能更容易串通的条件，潜在地指导反垄断法。

One question that economists and social scientists have contemplated for some time is what are the proper prerequisites for societal cooperation when private incentives conflict with social ones? One answer to this question comes from the theory of repeated games, the study of decision making amongst members of a group (the game) where the decision is made over and over again. More precisely, the specific game associated with this answer is the repeated prisoner's dilemma. In the prisoner's dilemma, cooperation is socially beneficial but it is in the private best interest of each player to not cooperate and thus, when only played once, no cooperation occurs. However, when the prisoner's dilemma is repeated, cooperation can be sustained by linking future choices to current choices so that the gain that one would obtain by deviating from cooperation in the present period is offset by a loss in future periods. Specifically, the gain is deterred by the credible threat of mutual non-cooperation by all players in the future.Repeated games, however, are a drastic simplification of the real world. Realistically, while many economic situations feature repeated interaction, the nature of the interaction changes through time. This feature is captured by stochastic games, a generalization of repeated games in which the game played each period changes and is determined, at least partially, by chance.This project is a laboratory experiment in the field of stochastic games. In particular, the experiment utilizes a repeated prisoner's dilemma in which the payoffs of the prisoner?s dilemma are stochastically determined each period. Most importantly, given the link between future choices and current choices that is established to sustain cooperation, altering the nature of future choices is a substantial step towards understanding how people behave in these environments.From a broader perspective, the main economic example for the stochastic prisoner?s dilemma in the experiment is collusion among firms over the business cycle. In this environment, firms desire collusion, cooperation on non-competitive prices or quantities, and compete over many periods. The demand fluctuates because of booms and busts in the economy, which changes the exact interaction they face each period. This experiment can potentially guide antitrust law by providing insight into conditions where firms may find it easier to collude.