What method can help prevent groupthink in cohesive groups?

Requiring each group member to defend an alternative estimate during discussion is an effective method for preventing groupthink in cohesive groups. This approach promotes critical thinking and encourages individuals to express dissenting opinions. By actively defending alternative perspectives, group members are less likely to conform to the majority opinion uncritically. This process stimulates discussion and allows for diverse viewpoints to be aired, which can lead to more informed and balanced decision-making.

In contrast, rewarding groups for reaching consensus quickly may inadvertently pressure members to suppress their honest opinions in favor of harmony, thereby increasing the risk of groupthink. Designating a team leader could also exacerbate the problem, as it might lead to a hierarchical structure where individual contributions are overshadowed by the leader's influence. Lastly, while team-building activities can enhance relationships and cohesion, they do not specifically address the potential for groupthink during decision-making processes.