行为决策中出现的分离效应

The Disjunction Effect in Decision Making

分离效应（the disjunction effect）是指：当决策者知道事件E会发生，他会采取行动A；当知道事件E不会发生，他仍会采取行动A；而当不知道事件E是否会发生的情况下，他会拒绝行动A。这一现象违背了理性决策理论的确定事件原则（sure─thing principle）。对分离效应的解释主要有基于理由的假设、思维惰性假设和齐当别模型。分离效应是否真的存在以及应该采用何种实验设计来进行研究都还有待进一歩探讨。2005年诺贝尔经济学奖获得者Aumann对事作分离情境和事件非分离情境的区分，为进一歩研究离效应指明了新的方向。理解分离效应及其成因有利于人们做出”理性”的决策。

A disjunction effect occurs when one will do A given event E occurs and will do A given event E does not occur， yet will do A when the outcome of event E is unknown， which violates Savage’s “Sure-Thing Principle”. The present article reviewed the three assumptions about why the disjunction effect occurs， which are the reason-based account， the reluctance-to-think account and the equate-to-differentiate model. Whether the effect really exists or not， and what kind of experimental design would be fitting for investigating the effects should be further tested in the future research. Future research might also benefit from the insights of the work of Nobel Prize Laureate Aumann. Understanding the mechanism of the disjunction effect is conducive to making a “rational” decision.