Emerging Perspectives on Judgment and Decision Research: Cognitions, Preferences, and Social Sharedness: Past, Present, and Future Directions in Group Decision Making

Research on group decision making has several distinctive roots in social sciences. Besides psychological and sociological interests about how people make decisions as a collective (e.g., Coleman, 1990; Witte & Davis, 1996), group decision making has also been a major research topic in the interdisciplinary area, called social choice theory, that intersects economics and political science (Arrow, 1963; Black, 1958; Fishburn, 1973; Ordeshook, 1986). Although these disciplines differ in many ways about how and on what to focus (e.g., empirical versus analytical emphasis, consensus versus choice), perhaps one of the most profound differences is how they characterize “legitimate” inputs for collective choices -what elements are regarded as justifiable inputs to render group decisions. In this chapter, we start with a discussion on this “legitimate input” issue. We then demonstrate that distinguishing two levels on inputs conceptually provides a useful overarching picture to synthesize our empirical knowledge about decision making in consensus groups. In so doing, we aim to show that a single most powerful determinant of actual consensus outcomes may be “social sharedness,” the degree of knowledge sharing among people, at both levels of social aggregation.