Although Janis's concept of groupthink is influential, experimental investigations have provided only weak support for the theory. Experiment 1 produced the poor decision quality associated with groupthink by manipulating group cohesion (using group labels) and threat to group members' self-esteem. Self-reports of some groupthink and defective decision-making symptoms were independently, but not interactively, affected by cohesion and threat. Experiment 2 confirmed the success of the cohesion manipulation. Experiment 3 replicated the poor-quality decision making observed in Experiment 1 and provided support for a social identity maintenance perspective on groupthink: Groups who operated under groupthink conditions but who were given an excuse for potential poor performance produced significantly higher quality decisions than groups who worked under groupthink conditions alone. The results are used to interpret the groupthink phenomenon as a collective effort directed at warding off potentially negative views of the group.

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