Understanding the processes by which task groups function is a major concern of social psychologists who study small groups. Equally important to the applied group researcher is the understanding of how group processes are altered by the external environment. Research suggests that organizations respond to stress with a centralization of authority so that decision making becomes concentrated in the higher levels of an organizational hierarchy. In this study, this hypothesis was extended to the small-group level of analysis, and the effects of stress on group status and decision making were examined. Experimental results clarify and delimit the centralization-of-authority hypothesis: Rather than centralizing authority and decision making under stress, group leaders and group members become more receptive to information provided by others. Implications for group decision making are discussed.Modern complex and high-risk technologies are inherently contradictory. On one hand, they greatly extend the range of human potential; for example, military anti-air warfare (AAW) systems allow military personnel to "see" aircraft at great distances. On the other hand, these systems also increase the potential for catastrophic error; in an AAW environment, the amount and complexity of information that must be processed in a short period of time once a target has been identified is enormous. We note several characteristics of these high-technology systems: (a) They pervade the aerospace, military, petrochemical, and nuclear industries; (b) they involve complex tasks that usually require interdependent or team performance; (c) during emergency or crisis conditions, operators have to make critical decisions under extreme stress; and (d) operator error is usually cited as a primary cause of system failure (see Perrow, 1984). Thus, although the necessity for effective performance under stress has been present since our ancestors were first chased with a club, it is likely that modern systems have both increased the stress under which humans must perform, as well as the consequences of poor performance.The deleterious effects of stress on human performance are well documented and have been a focus of research in the social and behavioral sciences for a number of years. Numerous studies have demonstrated cognitive, behavioral, and emotional responses to stress at the individual level (Harris, 1981;Keinan, 1987;Taylor, Buunk, & Aspinwall, 1990). Considerably less is known about the effects of stress on group performance. This is particularly surprising for several reasons. First, the complexity and scope of modern-day tasks often require group efforts (see