Groupthink is a psychological phenomenon that occurs within groups of people. It is the mode of thinking that happens when the desire for harmony in a decision-making group overrides a realistic appraisal of alternatives. Group members try to minimize conflict and reach a consensus decision without critical evaluation of alternative ideas or viewpoints. Antecedent factors such as group cohesiveness, structural faults, and situational context play into the likelihood of whether or not groupthink will impact the decision-making process.

The primary socially negative cost of groupthink is the loss of individual creativity, uniqueness, and independent thinking. As a social science model, groupthink has an enormous reach and influences literature in the fields of communications, political science, social psychology, management, organizational theory, and information technology.

The majority of the initial research on groupthink was performed by Irving Janis, a research psychologist from Yale University. In an influential 1972 book, his original definition of the term was “A mode of thinking that people engage in when they are deeply involved in a cohesive ingroup, when the members’ strivings for unanimity override their motivation to realistically appraise alternative courses of action.“:8–9 Since Janis’s work, other studies have attempted to reformulate his groupthink model. ‘T Hart (1998) developed a concept of groupthink as “collective optimism and collective avoidance,” while McCauley (1989) pointed to the impact of conformity and compliance pressures on groupthink decisions.


Although it is possible for a situation to contain all three of these factors, all three are not always present even when groupthink is occurring. Janis considered a high degree of cohesiveness to be the most important antecedent to producing groupthink and always present when groupthink was occurring; however, he believed high cohesiveness would not always produce groupthink. A very cohesive group abides to all group norms; whether or not groupthink arises is dependent on what the group norms are. If the group encourages individual dissent and alternative strategies to problem solving, it is likely that groupthink will be avoided even in a highly cohesive group. This means that high cohesion will lead to groupthink only if one or both of the other antecedents is present, situational context being slightly more likely than structural faults to produce groupthink.


To make groupthink testable, Irving Janis devised eight symptoms indicative of groupthink (1977).

Type I: Overestimations of the group—its power and morality

Illusions of invulnerability creating excessive optimism and encouraging risk taking.

Unquestioned belief in the morality of the group, causing members to ignore the consequences of their actions.

Type II: Closed-mindedness

Rationalizing warnings that might challenge the group’s assumptions.

Stereotyping those who are opposed to the group as weak, evil, biased, spiteful, impotent, or stupid.

Type III: Pressures toward uniformity

Self-censorship of ideas that deviate from the apparent group consensus.

Illusions of unanimity among group members, silence is viewed as agreement.

Direct pressure to conform placed on any member who questions the group, couched in terms of “disloyalty”

Mind guards — self-appointed members who shield the group from dissenting information.

Groupthink, resulting from the symptoms listed above, results in defective decision-making. That is, consensus-driven decisions are the result of the following practices of groupthinking

Incomplete survey of alternatives

Incomplete survey of objectives

Failure to examine risks of preferred choice

Failure to reevaluate previously rejected alternatives

Poor information search

Selection bias in collecting information

Failure to work out contingency plans.

Janis argued that groupthink was responsible for the Bay of Pigs Invasion ‘fiasco’ and other major examples of faulty decision-making. The UK bank Northern Rock, before its nationalisation, is thought to be a recent major example of groupthink. In such real-world examples, a number of the above groupthink symptoms were displayed.