An Experimental Comparison of the Fairness and Learning Hypotheses

公共产品的供给一直是微观经济学中的一个重要问题。粗略地说，公共产品是任何可以同时使大量个人受益并且很难将个人排除在消费之外的项目。公共产品的例子可能包括公园、清洁空气或国防。提供公共产品的核心困难是搭便车问题；如果不可能将个人排除在公共产品的利益之外，那么如果其他人愿意提供公共产品，他/她就没有动力为提供公共产品付费。理论家们提出了许多旨在缓解搭便车问题的机制。虽然所有这些机制在理论上都是有效的，但它们并不比它们对个人行为的潜在假设更好。实验经济学通过为公共物品问题中的行为提供可控制的经验证据，在公共物品研究中发挥了不可估量的作用。众所周知，公共物品和讨价还价实验产生的结果与标准的微观经济学理论不一致。人们提出了基于人际效用函数（“公平”）或有限理性学习模型的两类理论来解释这些结果。两者都不能解释所有的实验数据，也不能明显优于另一个。我们的实验探讨了在公共产品博弈中，受试者的行为是否可以用公平假设、学习假设或两者结合的混合模型来最好地解释。我们的实验基于van de Kragt， Orbell和Dawes开发的最小贡献集公共产品博弈。我们考虑三种基本的变化。一种是将没有经验的玩家推向子游戏的完美平衡，一种是将玩家推向“公平”平衡，还有一种是将两种结果都设计成合理的结果。通过让受试者先参加前两个游戏中的一个，然后再参加第三个游戏，我们控制了受试者进入第三个游戏之前的经验。研究不同先前经验的受试者在不同会话之间的行为差异，使我们能够澄清学习和公平在产生受试者行为中的作用。

The provision of public goods has long been a important problem in microeconomics. Roughly, a public good is any item which can benefit a large number of individuals simultaneously and which it is difficult to exclude individuals from consuming. Examples of public goods might include public parks, clean air, or national defense. The central difficulty with the provision of public goods is the free rider problem; if it is impossible to exclude an individual from the benefits of a public good, he/she has little incentive to pay for provision of the public good if others are willing to provide it. Theorists have proposed a number of mechanisms designed to alleviate the free rider problem. While all of these mechanisms work in theory, they are no better than their underlying assumptions about individuals' behavior. Experimental economics has played an invaluable role in the study of public goods by providing controlled empirical evidence on behavior in public goods problems. It is well known that public goods and bargaining experiments yield results which are at odds with standard microeconomic theory. Two classes of theory, based on interpersonal utility functions (`fairness`) or on boundedly rational learning models, have been proposed to explain these results. Neither explains all of the experimental data or clearly outperforms the other. Our experiments explore whether subjects' behavior in a public goods game can best be explained by the fairness hypothesis, the learning hypothesis, or a hybrid model which combines them. Our experiments are based on the Minimum Contributing Set public goods game developed by van de Kragt, Orbell, and Dawes. We consider three basic variations. One is designed to push inexperienced players towards the subgame perfect equilibrium, one is designed to push players toward the `fair` equilibrium, and one is designed with either outcome as a plausible outcome. By having subjects participate in one of the first two games before playing the third, we control the subjects' prior experience entering the third game. Examining differences in subject behavior between sessions with differing prior experience allows us to clarify the roles of learning and fairness in generating subjects' behavior.