Group Polarization

不言而喻，在社会中，许多(如果不是最重要的)决定都是由群体做出的。团体参与是地方性的，无论是在大量人口中投票，还是由小委员会审议。对群体决策的标准看法是，它促进了思想和信息的交流，这必然会导致更好的结果。这一观点与一种显著的经验规律形成鲜明对比，这种规律被称为群体极化，在这种规律下，审议小组的成员可以预测地朝着成员预先审议倾向所指示的方向走向更极端的点。这个项目的目的是为了弥合群体决策的标准幼稚观点和经验文献之间的差距。该项目关注两个不同的群体两极分化过程。第一个过程是关于风险前景的群体决策，群体成员表现出选择的转变：相对于他们作为群体之外的个人接受的风险水平，他们倾向于承担更极端的风险水平(要么风险更高，要么更谨慎)。研究人员提出了一种基于个人决策模型的选择转变解释。因此，他们提供的框架不仅适用于群体中观察到的选择变化，也适用于个人决策中普遍观察到的偏差。本提案中分析的第二个进程是在面临分歧威胁的小组中运作的。这一威胁在解释偏好强度在群体互动中起着重要作用，而且是以非累加的方式实现的。研究人员提出了一个动态的群体商议模型，其中每个成员都希望实施一个不同的政策，每个成员喜欢的政策会对其他成员施加外部性。研究人员讨论了这个模型如何适应“极端主义”和“宽容”的概念，并提供了一种方法来研究这两个概念之间的形式关系。拟议的框架有可能允许研究人员根据他们在平衡中强加的“极端主义”水平来对不同的绝对多数规则进行排名。

It is self-evident that in society, many if not the most important decisions are made by groups. Group involvement is endemic, whether it be voting among large populations or deliberation by small committees. A standard view of group decision-making is that it facilitates exchanges of ideas and information, which necessarily lead to better outcomes. This view stands in contrast to a striking empirical regularity, dubbed group polarization, whereby members of a deliberating group predictably move toward a more extreme point in the direction indicated by the members' predeliberation tendencies. The aim of this project is to bridge the gap between the standard naive view of group decision-making and the empirical literature.The project focuses on two distinct processes of group polarization. The first process operates in group decisions over risky prospects, where group members exhibit choice-shifts: They tend to take on more extreme levels of risk (either riskier or more cautious), relative to the levels of risk they would accept as individuals outside the group. The researchers propose an explanation for choice shifts, which is based on a model of individual decision-making. Hence, the framework they offer applies not only to choice shifts observed in groups but also to commonly observed biases in individual decision making. The second process analyzed in this proposal operates in groups that face a threat of disagreement. This threat plays an important role in explaining the fact that preference intensities matter in group interaction, and do so in non-additive ways. The researchers propose a dynamic model of group deliberation where each member wishes to implement a distinct policy, and the favorite policy of each member imposes externalities on the other members. The researchers discuss how this model can accommodate notions of `extremism' and `tolerance', and offer a methodology to study the formal relation between these two concepts. The proposed framework has the potential of allowing the researchers to rank different supermajority rules by the level of `extremism' that they impose in equilibrium.