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.


