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

一段时间以来，经济学家和社会科学家思考的一个问题是，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重复博弈理论，即对群体（博弈）成员之间的决策进行的研究，其中决策是一遍又一遍地做出的。 更准确地说，与这个答案相关的具体游戏是重复的囚徒困境。 在囚徒困境中，合作对社会有益，但不合作符合每个参与者的私人最佳利益，因此，当只玩一次时，不会发生合作。 然而，当囚徒困境重复出现时，可以通过将未来的选择与当前的选择联系起来来维持合作，从而使当前时期偏离合作所获得的收益被未来时期的损失所抵消。 具体来说，收益受到未来所有参与者相互不合作的可信威胁的阻碍。然而，重复博弈是对现实世界的极大简化。 实际上，虽然许多经济情况都具有重复的相互作用，但相互作用的性质会随着时间而变化。 随机博弈捕捉到了这一特征，随机博弈是重复博弈的概括，其中每个周期的博弈都会发生变化，并且至少部分是由偶​​然决定的。该项目是随机博弈领域的实验室实验。 特别是，该实验利用了重复的囚徒困境，其中囚徒困境的收益在每个时期都是随机确定的。 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的行为方式的重要一步。从更广泛的角度来看，实验中随机囚徒困境的主要经济例子是企业在商业周期中的勾结。 在这种环境下，企业希望在非竞争性的价格或数量上进行共谋、合作，并在许多时期进行竞争。 需求因经济的繁荣和萧条而波动，这改变了他们在每个时期面临的确切互动。 这项实验可以通过深入了解企业可能更容易串通的情况来指导反垄断法。

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.