Groupthink vs group polarization: the difference, and the question that sorts any example

Groupthink is a strong drive for agreement in a group that interferes with how the group appraises its decision. Group polarization is the tendency of a group that discusses an issue to end up more extreme in the direction it already leaned. The difference is what goes wrong: groupthink damages how the group decides, and polarization changes where the group ends up. Serge Moscovici and Marisa Zavalloni described group polarization in 1969, and Irving Janis introduced groupthink in 1971.

Most explanations give one definition and one example for each term. This article gives you one question that sorts any example, and the original studies with their numbers. It also adds a point that most summaries leave out: the evidence for the two terms is not equally strong.

• Groupthink: members want agreement so much that they keep their doubts to themselves, and the group does not test its options. The process fails.
• Group polarization: after a discussion, members hold a more extreme version of the view they started with. The outcome moves.
• The sorting question is: did the group become more extreme in its original direction, or did members stay quiet to protect agreement?
• The two can happen in the same group, but each can also happen without the other.
• Polarization has appeared in hundreds of studies from more than a dozen countries. Groupthink describes real warning signs, but most tests of Janis's full model did not support it.

The difference in one table

Both terms describe what group discussion does to a decision or an opinion. The table shows where they differ.

The one question that sorts any example

Exam questions describe a group and what happened to it. To name the effect, ask what changed. Use these steps.

1. 1.Find the group discussion or the group decision in the example.
2. 2.Compare the view before the discussion with the view after it.
3. 3.If the view became more extreme in the direction that most members already favoured, the effect is group polarization.
4. 4.If members kept their doubts to themselves, or the group ignored warnings to protect agreement, the effect is groupthink.
5. 5.If both are true, name both. The two effects can occur in the same group.

The first four situations in the next table come from the studies in this article. The last two are typical exam cases.

Watch for one trap. A group that becomes more cautious after a discussion shows polarization too, if its members leaned toward caution before the discussion. The next section explains why.

Group polarization: discussion makes the lean stronger

The APA Dictionary of Psychology defines group polarization as "the tendency for members of a group discussing an issue to move toward a more extreme version of the positions they held before the discussion began". The group as a whole then responds in a more extreme way than the members' views before the discussion predict.

From the risky shift to group polarization

The research started with risk. In 1961, James Stoner wrote a master's thesis at MIT. He used a questionnaire with 12 hypothetical "life situations" by Michael Wallach and Nathan Kogan, which measured how much risk a person would accept. Group decisions were riskier than individual ones. The result became known as the "risky shift", according to a 2006 paper by Eliaz, Ray and Razin.

Stoner's participants were male graduate students of industrial management. Researchers suspected that these future managers did not want to look too cautious in front of each other. In 1962, Wallach, Kogan and Daryl Bem used a different sample and got the same result, a University of Sussex summary reports. Individual decisions after the discussion were also riskier, and the shift was still there two to six weeks later.

Then the shift went the other way. Frode Nordhøy in 1962 and Stoner in 1968 found some evidence for cautious shifts, and researchers began to use the neutral term "choice shift". The APA Dictionary now states the conclusion: discussion does not make decisions riskier as such, but moves members in the direction of their first views.

In 1969, Moscovici and Zavalloni showed the same effect with attitudes instead of risk. French secondary-school students rated statements about Charles de Gaulle on a scale from −3 to +3. The average first position was +0.90. After group discussion it was +1.19, a highly significant move toward the side that the students already favoured. A 1974 paper by Lamm, Trommsdorff and Rost-Schaude uses this study to define group polarization. In their words, it is a move of the average position toward the pole that the group preferred at the start.

Why discussion pushes views further

Two explanations have the most support.

• Social comparison: according to an EBSCO research summary on group polarization, people adjust their stated views to what they think the group values. When they learn where the others stand, some correct a wrong idea about the group. Others move further toward the valued side to stand out. This is a normative process.
• Persuasive arguments: in a discussion, members hear arguments that they had not thought of. In a group that already leans one way, members hear more new arguments for that side than against it. This is an informational process.

Daniel Isenberg's 1986 meta-analysis reviewed studies from 1974 to 1982 that tested these two explanations. Both processes were present. Sieber and Ziegler (2019) give the mean effect sizes. The values were r = .44 for mere exposure to the other members' positions, and r = .75 for persuasive arguments. Arguments did more of the work, but the two processes operate together.

A like-minded discussion works similarly to confirmation bias, but at the level of the group. It gives members more evidence for the view that they already hold.

Polarization outside the laboratory

Two studies show the effect with real social attitudes.

In 1970, David Myers and George Bishop put high school students into groups of like-minded students: high-prejudice, medium-prejudice and low-prejudice groups. The students rated statements about racial attitudes, discussed them, and rated them again. Discussion with like-minded peers significantly increased the gap between the high-prejudice and the low-prejudice groups. Control groups discussed unrelated material instead.

David Schkade, Cass Sunstein and Reid Hastie recruited 63 citizens in Colorado. The citizens lived in Boulder, a liberal city, or in Colorado Springs, a conservative city, and the researchers screened them to confirm their political lean. Small groups, usually of six people from the same city, discussed climate change, affirmative action and civil unions for same-sex couples. Each person recorded a private, anonymous view before and after the discussion.

People from Boulder became more liberal on all three issues, and people from Colorado Springs became more conservative, Hastie and Sunstein report. Opinions inside each group became more uniform, and the distance between the two cities increased. The private, anonymous statements moved too, so the shift was not only a public show of agreement.

Groupthink: agreement wins over appraisal

Irving Janis introduced groupthink in 1971 and developed it further in 1972 and 1982. He defined it as "a mode of thinking that people engage in when they are deeply involved in a cohesive in-group". In this mode, the members' wish for unanimity is stronger than their motivation to appraise the alternatives realistically. The APA Dictionary gives a shorter version: "a strong concurrence-seeking tendency that interferes with effective group decision making".

Janis built the idea from case studies of policy failures, such as the Bay of Pigs invasion and the escalation of the Vietnam War. The Bay of Pigs invasion was a failed landing of anti-Castro rebels in Cuba with US support. According to an EBSCO research summary on groupthink, Janis asked how "bright, shrewd men like John F. Kennedy and his advisers" could accept the CIA's plan.

In Janis's model, cohesion alone is not enough. The group is at risk when it is also insulated from outside opinion and has a directive leader. Two more conditions are no method to search for and appraise information, and high stress. The result is a set of eight symptoms:

• an illusion of invulnerability
• collective rationalization, which explains away warnings
• an unquestioned belief in the morality of the group
• stereotyped views of outside groups
• direct pressure on members who disagree
• self-censorship of doubts
• an illusion of unanimity
• self-appointed "mindguards", members who screen out information that contradicts the group's view before the group discusses it

Agreement is not the problem in itself. A group can agree because the plan is good. In groupthink, the agreement comes before the appraisal of the options and prevents it.

What the evidence says about groupthink

Groupthink is still an influential idea, but tests of Janis's model have given weak results. Janis worked from case studies, not from experiments, and later researchers tested the model in several ways.

The pattern is consistent. The symptoms that Janis described are useful descriptions of poor group decisions, and the label helps people notice them. But the causal chain at the centre of the theory, from high cohesion to concurrence seeking to bad decisions, has little support. Robert Baron's 2005 review concluded that the evidence "has largely failed to support the formulation's more ambitious and controversial predictions", as Rose (2011) quotes him.

Group polarization is the opposite case. It started as a surprise result and changed its name when cautious shifts appeared. Then it held up in hundreds of studies from more than a dozen countries, according to Hastie and Sunstein.

For an exam, this means one thing. Define groupthink by Janis's conditions and symptoms, but do not describe it as a proven cause of historical disasters.

Where the two overlap

The two terms are not opposites, and one example can contain both. They have three things in common.

• Both are effects of group discussion. Neither one can happen to a person alone.
• Both rest on social influence. In polarization, social comparison is a normative process and persuasive arguments are an informational one. In groupthink, pressure on dissenters and self-censorship are normative pressures.
• Both can make a group more confident than its evidence allows. Hastie and Sunstein describe groups in which the dynamics of polarization "increased their confidence and conviction". The first symptom of groupthink is an illusion of invulnerability.

The two also differ in what they need. Polarization needs only a lean that most members share before the discussion, and the group can debate openly and still move further. Groupthink, in Janis's account, needs a cohesive group with a decision to make, and it can end in a moderate plan that nobody tested.

When a cohesive, like-minded group discusses a decision, both can happen at once. The title of Baron's 2005 review links the two directly: "So right it's wrong: Groupthink and the ubiquitous nature of polarized group decision making".

The AAMC content category 7B of the MCAT outline lists group polarization and groupthink together under "Group Decision-making Processes".

How groups can reduce each effect

Janis listed remedies for groupthink in 1982. Rose (2011) summarises them in this order:

1. 1.Ask each member to act as a critical evaluator, and accept criticism as the leader.
2. 2.As the leader, stay impartial and do not state a preference at the start.
3. 3.Give the same question to separate groups with different leaders.
4. 4.Divide the group into subgroups to test the proposals.
5. 5.Ask members to discuss the options with trusted people outside the group, and to report back.
6. 6.From time to time, invite outside experts to challenge the core members.
7. 7.Give one or more members the role of devil's advocate at every meeting.
8. 8.In a conflict, spend extra time on the warning signals from rivals.
9. 9.Before the decision becomes public, hold a "second-chance" meeting for any remaining doubts.

These remedies follow from Janis's model, and the model itself has weak support. Treat them as reasonable practice, not as a proven method.

For polarization, the direction of the shift is the key fact. Hastie and Sunstein write that "the predeliberation median is the best predictor of the direction of the group's shift". They add that the effect is especially strong in groups of like-minded people, as in the Colorado study. They also report two patterns. Leaders who speak tentatively or not at all, and invite members to speak their minds, avoid some of the pressure. Investment clubs did better when their members saw each other as colleagues, not friends. These are observations, not a tested programme against polarization.

How to keep the two terms apart

Use a short memory aid: groupthink is about silence, and polarization is about distance. In groupthink, the doubts go unspoken. In polarization, the group's view moves further from the neutral point, in the direction that it already had.

Then check yourself with new examples. Cover the answer, apply the sorting question, and only then read the explanation. Our guide to memorising psychology terminology explains why a test helps memory more than a second reading.

Psychology World is a dictionary app with more than 18,000 psychology terms. Search it for groupthink, group polarization and related terms such as risky shift and choice shift. Save the entries that you find to one bookmark list. Then study the list as flashcards, as multiple-choice questions, or type each answer. The multiple-choice mode needs at least four terms in the list. The home page shows the four steps of the learning loop and what each study mode does.