Irving Janis lists some of the symptoms of groupthink in his study of high-level governmental decision makers:

1. Prime among these is the sharing of an illusion of invulnerability which leads to over optimism and causes planners to fail to respond to clear warnings of danger and be willing to take extraordinary risks.
2. The participants in groupthink ignore warnings and construct rationalizations in order to discount them.
3. Participants of groupthink have an unquestioned belief in the inherent morality of their in group actions, inclining the members to ignore the ethical or moral consequences of their decisions.
4. Participants of groupthink hold stereotyped views of the leaders of enemy gro…