What is Groupthink?
Groupthink, a term coined by social psychologist Irving
Janis (1972), occurs when a group makes faulty decisions because group pressures lead to a deterioration of “mental efficiency, reality testing, and moral judgment” (p. 9). Groups affected by groupthink ignore alternatives and tend to take irrational actions that dehumanize other groups. A group is especially vulnerable to groupthink when its members are similar in background, when the group is insulated from outside opinions, and when there are no clear rules for decision making.
Some References
Janis, Irving L. (1972). Victims of Groupthink. New
York: Houghton Mifflin.
Janis, Irving L. (1982). Groupthink: Psychological
Studies of Policy Decisions and Fiascoes. Second
Edition. New York: Houghton Mifflin.

Symptoms of groupthink
In order to make groupthink testable, Irving Janis devised eight symptoms that are indicative of groupthink.
1.
A feeling of invulnerability creates excessive optimism and encourages risk taking.
2.
Discounting warnings that might challenge assumptions.
3.
An unquestioned belief in the group’s morality, causing members to ignore the consequences of their actions.
4.
Stereotyped views of enemy leaders.
5.
Pressure to conform experienced by members of the group who might otherwise disagree.
6.
Shutting down of ideas that deviate from the apparent group consensus.
7.
An illusion of unanimity with regards to going along with the group.
8.
Mindguards — self-appointed members who shield the group from dissenting opinions.