Doctoral Dissertation Research: Ambiguity Aversion and Strategic Play in One-Shot Normal-Form Games

不确定条件下的行为研究是经济学的核心领域之一。人们可以区分两种不确定性：客观的和主观的。客观不确定性指的是不同结果发生的客观概率是明确的，例如抛一枚公平的硬币。主观不确定性是指不同结果发生时没有明确的客观概率，例如投资股票市场。尽管主流经济理论没有区分客观不确定性和主观不确定性，但这种区分似乎对行为起着重要作用。人们尤其不喜欢主观的不确定性——用经济学术语来说，他们厌恶模棱两可。该研究的目的是通过实验调查当游戏情境中出现主观不确定性时，人们对模糊性的厌恶程度。我们的实验游戏是一次决策情境，其中收益不仅取决于玩家的决策，还取决于其他人的决策。由于玩家事先不知道其他人的决定是什么，他们面临着其他人会怎么做的不确定性，因此他们自己的收益也不确定。这种不确定性是主观的，因为玩家不知道其他人做出每个决定的可能性有多大。虽然有很多关于模糊厌恶在个体决策中的实验研究，但在游戏情境下的研究还比较少。鉴于博弈论（在现代经济学中扮演核心角色）忽略了模糊性厌恶，调查模糊性厌恶在多大程度上对游戏行为产生影响是很重要的。这样的研究可以让我们更好地理解当前博弈论的局限性，并可能为未来将歧义厌恶纳入博弈论的努力提供动力。

The study of behavior under uncertainty is one of the central areas in economics. One can distinguish between two types of uncertainty: objective and subjective. Objective uncertainty is present when there are clear objective probabilities with which different outcomes occur, e.g. when one flips a fair coin. Subjective uncertainty is present when there are no clear objective probabilities with which the different outcomes occur, e.g. when one invests in the stock market. Even though mainstream economic theory makes no distinction between objective and subjective uncertainty, this distinction seems to play an important role for behavior. In particular people seem to dislike subjective uncertainty -- in economic terminology they are ambiguity averse.The aim of the proposed research is to investigate experimentally to what extent people are ambiguity-averse when the subjective uncertainty arises in the context of a game. Our experimental game is a one-shot decision situation in which payoffs depends not only on the players' decisions but also on the decisions of other people. As players do not know in advance what the decision of the other persons are, they face uncertainty regarding what the other persons will do and hence regarding their own payoff. This uncertainty is subjective since players are not told how likely it is that the other persons will make each decision. Although there are many experimental studies on ambiguity aversion in individual decision making, there is a lack of such studies in the context of games. Given that game theory (which plays a central role in modern economics) ignores ambiguity aversion, it is important to investigate to what extent ambiguity aversion does have an impact on behavior in games. Such investigation could give us a better understanding of the current limitations of game theory and it may provide motivation for future efforts to incorporate ambiguity aversion into game theory.