Abstract: Decision-making under ambiguity, first proposed by American economist Knight, refers to uncertain decisions whose probability distribution is unknown and decision maker must rely on subjective judgment instead of deductive calculation or empirical estimation. Both ambiguity decision-making and risky decision-making belong to the category of uncertain decision making, while risky decision maker is informed of the exact probability. Stress can affect ambiguity decision making, and many ambiguity decisions are often made under stress. Therefore, more and more researchers have been attracted to the research on the influence of stress on ambiguity decision-making. In this field, there have been many mature empirical studies, but unfortunately the results of these studies are not consistent. Therefore, it is of great significance to explore the influence mechanism of stress on ambiguity decision-making and clarify the relationship between decision-making cognitive process and stress. This paper systematically reviewed the empirical research literature on the impact of stress on decision making in recent five years, and summarized the effects of stress on ambiguity decision-making in behavioral and neural aspects from three aspects: learning feedback, reward sensitivity and risk preference, based on the detailed analysis of the cognitive perspective, in order to step further in terms of the consistency of different research results. Through literature analysis, it was found that many research results support the view that stress leads to the obstruction of learning feedback, but some studies have found that stress causes the improvement of vigilance and attention, making individuals more inclined to learn how to obtain the maximum and the most long-term return in the ambiguity decision-making situation. In terms of reward sensitivity, most studies showed that stress causes decision makers to overemphasize reward and ignore punishment, while the opposite conclusion is that some people believe that stress significantly reduces reward sensitivity. In terms of risk preferences, the most common conclusion is that stress increases risk-taking behavior, but studies that differ from this conclusion still exist. Although the results of these studies are different, from the perspective of cognitive processing and the influencing mechanism, the effects of stress on ambiguity decision-making tend to be consistent, which are all negative effects of feedback obstruction, heavy reward and light punishment, and increased risk taking. The reason why some studies come to different conclusions is that stress is affected by other factors in the process of ambiguity decision making. For example, some studies carried out the effect of acute stress on decision making in subjects with a male to female ratio of 1:2. It was found that stress promoted better learning feedback of subjects, which actually ignored the influence of gender factor. Studies that suggest that stress makes decision makers more conservative ignore the influence of personality, age and other factors. This paper attempts to explain why the influence of stress on ambiguity decision-making can lead to different results from two theories of "Dual-system Processing" and "Cognitive Resource Occupation". It is common that women under stress can cause "tend-and-befriend" mode of reaction, while men triggering "fight-or-flight". Therefore, studies with more female subjects are more likely to find the positive effect of stress on decision-making, while those with more male subjects are more negative. According to "Cognitive Resource Occupation", the participants' perception of stress determines the impact of stress on decision-making. Generally, identifying stress as "challenge" will lead to positive effects, while identifying it as "threat" will lead to negative effects. Finally, based on the current research progress and shortcomings, it is proposed that future research should focus on the different effects of stress type and intensity on ambiguity decision-making, and further expand the research on the interaction effects of cognition and emotion in ambiguity decision-making under stress.

Key words: decision-making under ambiguity, stress, learning feedback, reward sensitivity, risk preference

摘要： 模糊决策是指决策者无法预先知道结果发生的概率，只能依赖主观判断而进行的决策。应激会影响模糊决策，但不同研究结果并不一致，从模糊决策的认知成分入手能帮助我们更好地理解应激对模糊决策的影响。本研究从学习反馈、奖赏敏感性和风险偏好三个方面梳理了现有的行为和脑机制研究文献，发现应激对模糊决策的影响主要表现为应激导致反馈受阻、重赏轻罚、增加冒险三个方面。未来的研究应该关注应激类型和强度对模糊决策的不同影响，同时进一步拓展应激状态下模糊决策中认知与情绪的交互效应研究。

关键词: 模糊决策, 应激, 学习反馈, 奖赏敏感性, 风险偏好