Final answer:
A sign that a group is suffering from groupthink is a lack of diverse perspectives and alternative ideas. Encouragement of critical thinking and dissent is a way to avoid groupthink.
Step-by-step explanation:
Groupthink is a phenomenon that occurs when a group prioritizes maintaining harmony and conformity over critical thinking and diverse perspectives. One sign that a group is suffering from groupthink is a lack of diverse perspectives and alternative ideas, as group members may self-censor or withhold information to avoid disrupting the group. Encouragement of critical thinking and dissent, on the other hand, is a sign that a group is not experiencing groupthink. Open and honest communication can also help prevent groupthink by allowing different viewpoints to be expressed and considered.