Groupthink is a psychological phenomenon that occurs within a group of people in which the desire for harmony or conformity in the group results in an irrational or dysfunctional decision-making outcome. Cohesiveness, or the desire for cohesiveness, in a group may produce a tendency among its members to agree at all costs. This causes the group to minimize conflict and reach a consensus decision without critical evaluation.
Groupthink is a construct of social psychology, but has an extensive reach and influences literature in the fields of communication studies, political science, management, and organizational theory, as well as important aspects of deviant religious cult behaviour.
Groupthink is sometimes stated to occur (more broadly) within natural groups within the community, for example to explain the lifelong different mindsets of those with differing political views (such as "conservatism" and "liberalism" in the U.S. political context  or the purported benefits of team work vs. work conducted in solitude). However, this conformity of viewpoints within a group does not mainly involve deliberate group decision-making, and might be better explained by the collective confirmation bias of the individual members of the group.
The term was coined in 1952 by William H. Whyte Jr.. Most of the initial research on groupthink was conducted by Irving Janis, a research psychologist from Yale University. Janis published an influential book in 1972, which was revised in 1982. Janis used the Bay of Pigs disaster (the failed invasion of Castro's Cuba in 1961) and the Japanese attack on Pearl Harbor in 1941 as his two prime case studies. Later studies have evaluated and reformulated his groupthink model.
Groupthink requires individuals to avoid raising controversial issues or alternative solutions, and there is loss of individual creativity, uniqueness and independent thinking. The dysfunctional group dynamics of the "ingroup" produces an "illusion of invulnerability" (an inflated certainty that the right decision has been made). Thus the "ingroup" significantly overrates its own abilities in decision-making and significantly underrates the abilities of its opponents (the "outgroup"). Furthermore, groupthink can produce dehumanizing actions against the "outgroup". Members of a group can often feel peer pressure to "go along with the crowd" in fear of rocking the boat or of what them speaking up will do to the overall to how their teammates perceive them. Group interactions tend to favor clear and harmonious agreements and it can be a cause for concern when little to no new innovations or arguments for better policies, outcomes and structures are called to question. (McLeod). Groupthink can often be referred to as a group of "yes men" because group activities and group projects in general make it extremely easy to pass on not offering constructive opinions.
Some methods that have been used to counteract group think in the past is selecting teams from more diverse backgrounds, and even mixing men and women for groups (Kamalnath). Groupthink can be considered by many to be a detriment to companies, organizations and in any work situations. Most positions that are senior level need individuals to be independent in their thinking. There is a positive correlation found between outstanding executives and decisiveness (Kelman). Groupthink also prohibits an organization from moving forward and innovating if no one ever speaks up and says something could be done differently.
Antecedent factors such as group cohesiveness, faulty group structure, and situational context (e.g., community panic) play into the likelihood of whether or not groupthink will impact the decision-making process.
Groupthink being a coinage - and, admittedly, a loaded one - a working definition is in order. We are not talking about mere instinctive conformity - it is, after all, a perennial failing of mankind. What we are talking about is a rationalized conformity - an open, articulate philosophy which holds that group values are not only expedient but right and good as well. 
Irving Janis pioneered the initial research on the groupthink theory. He does not cite Whyte, but coined the term again by analogy with "doublethink" and similar terms that were part of the newspeak vocabulary in the novel Nineteen Eighty-Four by George Orwell. He initially defined groupthink as follows:
I use the term groupthink as a quick and easy way to refer to the mode of thinking that persons engage in when concurrence-seeking becomes so dominant in a cohesive ingroup that it tends to override realistic appraisal of alternative courses of action. Groupthink is a term of the same order as the words in the newspeak vocabulary George Orwell used in his dismaying world of 1984. In that context, groupthink takes on an invidious connotation. Exactly such a connotation is intended, since the term refers to a deterioration in mental efficiency, reality testing and moral judgments as a result of group pressures.
He went on to write:
The main principle of groupthink, which I offer in the spirit of Parkinson's Law, is this: "The more amiability and esprit de corps there is among the members of a policy-making ingroup, the greater the danger that independent critical thinking will be replaced by groupthink, which is likely to result in irrational and dehumanizing actions directed against outgroups".
Janis set the foundation for the study of groupthink starting with his research in the American Soldier Project where he studied the effect of extreme stress on group cohesiveness. After this study he remained interested in the ways in which people make decisions under external threats. This interest led Janis to study a number of "disasters" in American foreign policy, such as failure to anticipate the Japanese attack on Pearl Harbor (1941); the Bay of Pigs Invasion fiasco (1961); and the prosecution of the Vietnam War (1964-67) by President Lyndon Johnson. He concluded that in each of these cases, the decisions occurred largely because of groupthink, which prevented contradictory views from being expressed and subsequently evaluated.
After the publication of Janis' book Victims of Groupthink in 1972, and a revised edition with the title Groupthink: Psychological Studies of Policy Decisions and Fiascoes in 1982, the concept of groupthink was used[by whom?] to explain many other faulty decisions in history. These events included Nazi Germany's decision to invade the Soviet Union in 1941, the Watergate scandal and others. Despite the popularity of the concept of groupthink, fewer than two dozen studies addressed the phenomenon itself following the publication of Victims of Groupthink, between the years 1972 and 1998. This was surprising considering how many fields of interests it spans, which include political science, communications, organizational studies, social psychology, management, strategy, counseling, and marketing. One can most likely explain this lack of follow-up in that group research is difficult to conduct, groupthink has many independent and dependent variables, and it is unclear "how to translate [groupthink's] theoretical concepts into observable and quantitative constructs".
Nevertheless, outside research psychology and sociology, wider culture has come to detect groupthink in observable situations, for example:
Type I: Overestimations of the group -- its power and morality
Type II: Closed-mindedness
Type III: Pressures toward uniformity
Janis prescribed three antecedent conditions to groupthink.
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.
As observed by Aldag and Fuller (1993), the groupthink phenomenon seems to rest on a set of unstated and generally restrictive assumptions:
It has been thought that groups with the strong ability to work together will be able to solve dilemmas in a quicker and more efficient fashion than an individual. Groups have a greater amount of resources which lead them to be able to store and retrieve information more readily and come up with more alternative solutions to a problem. There was a recognized downside to group problem solving in that it takes groups more time to come to a decision and requires that people make compromises with each other. However, it was not until the research of Janis appeared that anyone really considered that a highly cohesive group could impair the group's ability to generate quality decisions. Tight-knit groups may appear to make decisions better because they can come to a consensus quickly and at a low energy cost; however, over time this process of decision-making may decrease the members' ability to think critically. It is, therefore, considered by many to be important to combat the effects of groupthink.
According to Janis, decision-making groups are not necessarily destined to groupthink. He devised ways of preventing groupthink:
The devil's advocate in a group may provide questions and insight which contradict the majority group in order to avoid groupthink decisions. A study by Hartwig  insists that the devil's advocacy technique is very useful for group problem-solving. It allows for conflict to be used in a way that is most-effective for finding the best solution so that members will not have to go back and find a different solution if the first one fails. Hartwig also suggests that the devil's advocacy technique be incorporated with other group decision-making models such as the functional theory to find and evaluate alternative solutions. The main idea of the devil's advocacy technique is that somewhat structured conflict can be facilitated to not only reduce groupthink, but to also solve problems.
A similar term to groupthink is the Abilene paradox, another phenomenon that is detrimental when working in groups. When organizations fall into the Abilene paradox, they take actions in contradiction to what their perceived goals may be and therefore defeat the very purposes they are trying to achieve. Failure to communicate desires or beliefs can cause the Abilene paradox.
As explained in the Abilene paradox, the Watergate scandal is an example of this. Before the scandal had occurred, a meeting took place where they discussed the issue. One of Nixon's campaign aides was unsure if he should speak up and give his input. If he had voiced his disagreement with the group's decision, it is possible that the scandal could have been avoided.
Other examples of how groupthink could be avoided or prevented:
After the Bay of Pigs invasion fiasco, President John F. Kennedy sought to avoid groupthink during the Cuban Missile Crisis using "vigilant appraisal". During meetings, he invited outside experts to share their viewpoints, and allowed group members to question them carefully. He also encouraged group members to discuss possible solutions with trusted members within their separate departments, and he even divided the group up into various sub-groups, to partially break the group cohesion. Kennedy was deliberately absent from the meetings, so as to avoid pressing his own opinion.
Cass Sunstein reports that introverts can sometimes be silent in meetings with extroverts; he recommends explicitly asking for each person's opinion, either during the meeting or afterwards in one-on-one sessions. Sunstein points to studies showing groups with a high level of internal socialization and happy talk are more prone to bad investment decisions due to groupthink, compared with groups of investors who are relative strangers and more willing to be argumentative. To avoid group polarization, where discussion with like-minded people drives an outcome further to an extreme than any of the individuals favored before the discussion, he recommends creating heterogeneous groups which contain people with different points of view. Sunstein also points out that people arguing a side they do not sincerely believe (in the role of devil's advocate) tend to be much less effective than a sincere argument. This can be accomplished by dissenting individuals, or a group like a Red Team that is expected to pursue an alternative strategy or goal "for real".
Testing groupthink in a laboratory is difficult because synthetic settings remove groups from real social situations, which ultimately changes the variables conducive or inhibitive to groupthink. Because of its subjective nature, researchers have struggled to measure groupthink as a complete phenomenon, instead frequently opting to measure its particular factors. These factors range from causal to effectual and focus on group and situational aspects.
Park (1990) found that "only 16 empirical studies have been published on groupthink", and concluded that they "resulted in only partial support of his [Janis's] hypotheses". Park concludes, "despite Janis' claim that group cohesiveness is the major necessary antecedent factor, no research has shown a significant main effect of cohesiveness on groupthink." Park also concludes that research on the interaction between group cohesiveness and leadership style does not support Janis' claim that cohesion and leadership style interact to produce groupthink symptoms. Park presents a summary of the results of the studies analyzed. According to Park, a study by Huseman and Drive (1979) indicates groupthink occurs in both small and large decision-making groups within businesses. This results partly from group isolation within the business. Manz and Sims (1982) conducted a study showing that autonomous work groups are susceptible to groupthink symptoms in the same manner as decisions making groups within businesses. Fodor and Smith (1982) produced a study revealing that group leaders with high power motivation create atmospheres more susceptible to groupthink. Leaders with high power motivation possess characteristics similar to leaders with a "closed" leadership style--an unwillingness to respect dissenting opinion. The same study indicates that level of group cohesiveness is insignificant in predicting groupthink occurrence. Park summarizes a study performed by Callaway, Marriott, and Esser (1985) in which groups with highly dominant members "made higher quality decisions, exhibited lowered state of anxiety, took more time to reach a decision, and made more statements of disagreement/agreement". Overall, groups with highly dominant members expressed characteristics inhibitory to groupthink. If highly dominant members are considered equivalent to leaders with high power motivation, the results of Callaway, Marriott, and Esser contradict the results of Fodor and Smith. A study by Leana (1985) indicates the interaction between level of group cohesion and leadership style is completely insignificant in predicting groupthink. This finding refutes Janis' claim that the factors of cohesion and leadership style interact to produce groupthink. Park summarizes a study by McCauley (1989) in which structural conditions of the group were found to predict groupthink while situational conditions did not. The structural conditions included group insulation, group homogeneity, and promotional leadership. The situational conditions included group cohesion. These findings refute Janis' claim about group cohesiveness predicting groupthink.
Overall, studies on groupthink have largely focused on the factors (antecedents) that predict groupthink. Groupthink occurrence is often measured by number of ideas/solutions generated within a group, but there is no uniform, concrete standard by which researchers can objectively conclude groupthink occurs. The studies of groupthink and groupthink antecedents reveal a mixed body of results. Some studies indicate group cohesion and leadership style to be powerfully predictive of groupthink, while other studies indicate the insignificance of these factors. Group homogeneity and group insulation are generally supported as factors predictive of groupthink.
Groupthink can have a strong hold on political decisions and military operations, which may result in enormous wastage of human and material resources. Highly qualified and experienced politicians and military commanders sometimes make very poor decisions when in a suboptimal group setting. Scholars such as Janis and Raven attribute political and military fiascoes, such as the Bay of Pigs Invasion, the Vietnam War, and the Watergate scandal, to the effect of groupthink. More recently, Dina Badie argued that groupthink was largely responsible for the shift in the U.S. administration's view on Saddam Hussein that eventually led to the 2003 invasion of Iraq by the United States. After the September 11 attacks, "stress, promotional leadership, and intergroup conflict" were all factors that gave rise to the occurrence of groupthink. Political case studies of groupthink serve to illustrate the impact that the occurrence of groupthink can have in today's political scene.
The United States Bay of Pigs Invasion of April 1961 was the primary case study that Janis used to formulate his theory of groupthink. The invasion plan was initiated by the Eisenhower administration, but when the Kennedy administration took over, it "uncritically accepted" the plan of the Central Intelligence Agency (CIA). When some people, such as Arthur M. Schlesinger Jr. and Senator J. William Fulbright, attempted to present their objections to the plan, the Kennedy team as a whole ignored these objections and kept believing in the morality of their plan. Eventually Schlesinger minimized his own doubts, performing self-censorship. The Kennedy team stereotyped Fidel Castro and the Cubans by failing to question the CIA about its many false assumptions, including the ineffectiveness of Castro's air force, the weakness of Castro's army, and the inability of Castro to quell internal uprisings.
Janis argued the fiasco that ensued could have been prevented if the Kennedy administration had followed the methods to preventing groupthink adopted during the Cuban Missile Crisis, which took place just one year later in October 1962. In the latter crisis, essentially the same political leaders were involved in decision-making, but this time they learned from their previous mistake of seriously under-rating their opponents.
The attack on Pearl Harbor on December 7, 1941, is a prime example of groupthink. A number of factors such as shared illusions and rationalizations contributed to the lack of precaution taken by U.S. Navy officers based in Hawaii. The United States had intercepted Japanese messages and they discovered that Japan was arming itself for an offensive attack somewhere in the Pacific Ocean. Washington took action by warning officers stationed at Pearl Harbor, but their warning was not taken seriously. They assumed that the Empire of Japan was taking measures in the event that their embassies and consulates in enemy territories were usurped.
The U.S. Navy and Army in Pearl Harbor also shared rationalizations about why an attack was unlikely. Some of them included:
On January 28, 1986, the US launched the Space Shuttle Challenger. This was to be monumental for NASA, as a high school teacher was among the crew and was to be the first American civilian in space. NASA's engineering and launch teams rely on group work, and in order to launch the shuttle the team members must affirm each system is functioning nominally. The Thiokol engineers who designed and built the Challenger's rocket boosters warned that the temperature for the day of the launch could result in total failure of the vehicles and deaths of the crew. The launch resulted in disaster and grounded space shuttle flights for nearly three years.
The Challenger case was subject to a more quantitatively oriented test of Janis's groupthink model performed by Esser and Lindoerfer, who found clear signs of positive antecedents to groupthink in the critical decisions concerning the launch of the shuttle. The day of the launch was rushed for publicity reasons. NASA wanted to captivate and hold the attention of America. Having civilian teacher Christa McAuliffe on board to broadcast a live lesson, and the possible mention by president Ronald Reagan in the State of the Union address, were opportunities NASA deemed critical to increasing interest in its potential civilian space flight program. The schedule NASA set out to meet was, however, self-imposed. It seemed incredible to many that an organization with a perceived history of successful management would have locked itself into a schedule it had no chance of meeting.
In the weeks and months preceding the 2016 United States presidential election, there was near-unanimity among news media outlets and polling organizations that Hillary Clinton's election was extremely likely. For example, on November 7, the day before the election, The New York Times opined that Clinton then had "a consistent and clear advantage in states worth at least 270 electoral votes". The Times estimated the probability of a Clinton win at 84%. Also on November 7, Reuters estimated the probability of Clinton defeating Donald Trump in the election at 90%, and The Huffington Post put Clinton's odds of winning at 98.2% based on "9.8 million simulations".
The disconnect between the election results and the pre-election estimates, both from news media outlets and from pollsters, may have been due to three factors: news and polling professionals couldn't imagine a candidate as unconventional as Trump becoming president; Trump supporters may have been under-sampled by surveys or may have lied to or misled pollsters out of fear of social ostracism; and polls may have been unable to account for Russian interference in the 2016 United States elections.
In the corporate world, ineffective and suboptimal group decision-making can negatively affect the health of a company and cause a considerable amount of monetary loss.
Aaron Hermann and Hussain Rammal illustrate the detrimental role of groupthink in the collapse of Swissair, a Swiss airline company that was thought to be so financially stable that it earned the title the "Flying Bank". The authors argue that, among other factors, Swissair carried two symptoms of groupthink: the belief that the group is invulnerable and the belief in the morality of the group. In addition, before the fiasco, the size of the company board was reduced, subsequently eliminating industrial expertise. This may have further increased the likelihood of groupthink. With the board members lacking expertise in the field and having somewhat similar background, norms, and values, the pressure to conform may have become more prominent. This phenomenon is called group homogeneity, which is an antecedent to groupthink. Together, these conditions may have contributed to the poor decision-making process that eventually led to Swissair's collapse.
Another example of groupthink from the corporate world is illustrated in the United Kingdom-based companies Marks & Spencer and British Airways. The negative impact of groupthink took place during the 1990s as both companies released globalization expansion strategies. Researcher Jack Eaton's content analysis of media press releases revealed that all eight symptoms of groupthink were present during this period. The most predominant symptom of groupthink was the illusion of invulnerability as both companies underestimated potential failure due to years of profitability and success during challenging markets. Up until the consequence of groupthink erupted they were considered blue chips and darlings of the London Stock Exchange. During 1998-1999 the price of Marks & Spencer shares fell from 590 to less than 300 and that of British Airways from 740 to 300. Both companies had already featured prominently in the UK press and media for more positive reasons to do with national pride in their undoubted sector-wide performance.
Recent literature of groupthink attempts to study the application of this concept beyond the framework of business and politics. One particularly relevant and popular arena in which groupthink is rarely studied is sports. The lack of literature in this area prompted Charles Koerber and Christopher Neck to begin a case-study investigation that examined the effect of groupthink on the decision of the Major League Umpires Association (MLUA) to stage a mass resignation in 1999. The decision was a failed attempt to gain a stronger negotiating stance against Major League Baseball. Koerber and Neck suggest that three groupthink symptoms can be found in the decision-making process of the MLUA. First, the umpires overestimated the power that they had over the baseball league and the strength of their group's resolve. The union also exhibited some degree of closed-mindedness with the notion that MLB is the enemy. Lastly, there was the presence of self-censorship; some umpires who disagreed with the decision to resign failed to voice their dissent. These factors, along with other decision-making defects, led to a decision that was suboptimal and ineffective.
Researcher Robert Baron (2005) contends that the connection between certain antecedents which Janis believed necessary has not been demonstrated by the current collective body of research on groupthink. He believes that Janis' antecedents for groupthink are incorrect, and argues that not only are they "not necessary to provoke the symptoms of groupthink, but that they often will not even amplify such symptoms". As an alternative to Janis' model, Baron proposed a ubiquity model of groupthink. This model provides a revised set of antecedents for groupthink, including social identification, salient norms, and low self-efficacy.
Aldag and Fuller (1993) argue that the groupthink concept was based on a "small and relatively restricted sample" that became too broadly generalized. Furthermore, the concept is too rigidly staged and deterministic. Empirical support for it has also not been consistent. The authors compare groupthink model to findings presented by Maslow and Piaget; they argue that, in each case, the model incites great interest and further research that, subsequently, invalidate the original concept. Aldag and Fuller thus suggest a new model called the general group problem-solving (GGPS) model, which integrates new findings from groupthink literature and alters aspects of groupthink itself. The primary difference between the GGPS model and groupthink is that the former is more value neutral and more political.
OLater scholars have re-assessed the merit of groupthink by reexamining case studies that Janis originally used to buttress his model. Roderick Kramer (1998) believed that, because scholars today have a more sophisticated set of ideas about the general decision-making process and because new and relevant information about the fiascos have surfaced over the years, a reexamination of the case studies is appropriate and necessary. He argues that new evidence does not support Janis' view that groupthink was largely responsible for President Kennedy's and President Johnson's decisions in the Bay of Pigs Invasion and U.S. escalated military involvement in the Vietnam War, respectively. Both presidents sought the advice of experts outside of their political groups more than Janis suggested. Kramer also argues that the presidents were the final decision-makers of the fiascos; while determining which course of action to take, they relied more heavily on their own construals of the situations than on any group-consenting decision presented to them. Kramer concludes that Janis' explanation of the two military issues is flawed and that groupthink has much less influence on group decision-making than is popularly believed.
Groupthink, while it is thought to be avoided, does have some positive effects. A case study by Choi and Kim  shows that with group identity, group performance has a negative correlation with defective decision making. This study also showed that the relationship between groupthink and defective decision making was insignificant. These findings mean that in the right circumstances, groupthink does not always have negative outcomes. It also questions the original theory of groupthink.
Whyte (1998) suggests that collective efficacy plays a large unrecognised role in groupthink because it causes groups to become less vigilant and to favor risks, two particular factors that characterize groups affected by groupthink. McCauley recasts aspects of groupthink's preconditions by arguing that the level of attractiveness of group members is the most prominent factor in causing poor decision-making. The results of Turner's and Pratkanis' (1991) study on social identity maintenance perspective and groupthink conclude that groupthink can be viewed as a "collective effort directed at warding off potentially negative views of the group". Together, the contributions of these scholars have brought about new understandings of groupthink that help reformulate Janis' original model.
According to a new theory many of the basic characteristics of groupthink - e.g., strong cohesion, indulgent atmosphere, and exclusive ethos - are the result of a special kind of mnemonic encoding (Tsoukalas, 2007). Members of tightly knit groups have a tendency to represent significant aspects of their community as episodic memories and this has a predictable influence on their group behavior and collective ideology.
If the committee's other conclusions are as outdated as its etymology, we're all in trouble. 'Groupthink' (one word, no hyphen) was the title of an article in Fortune magazine in March 1952 by William H. Whyte Jr. ... Whyte derided the notion he argued was held by a trained elite of Washington's 'social engineers.'
[...] critics of twitter point to the predominance of the hive mind in such social media, the kind of groupthink that submerges independent thinking in favor of conformity to the group, the collective.
[...] leaders often have beliefs which are very far from matching reality and which can become more extreme as they are encouraged by their followers. The predilection of many cult leaders for abstract, ambiguous, and therefore unchallengeable ideas can further reduce the likelihood of reality testing, while the intense milieu control exerted by cults over their members means that most of the reality available for testing is supplied by the group environment. This is seen in the phenomenon of 'groupthink', alleged to have occurred, notoriously, during the Bay of Pigs fiasco.
Groupthink by Compulsion [...] [G]roupthink at least implies voluntarism. When this fails, the organization is not above outright intimidation. [...] In [a nationwide telecommunications company], refusal by the new hires to cheer on command incurred consequences not unlike the indoctrination and brainwashing techniques associated with a Soviet-era gulag.