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18th June 2020

The Psychology of Teams: Group biases

How many times have you wished to better understand what is holding your team back? Research into group psychology may have the answer to this question. In this article, we explore five common group biases; shared information bias, decision-making bias, groupthink, polarization and escalation of commitment. We explain how they can obstruct performance and the best methods to overcome them. Whether you work in a large team, small team or individually, we think that it is really important and interesting stuff to understand!


Decision Making

During decision making, groups of people have to come together and agree on the best course of action by combining their different options and thoughts. In group decision making, there are often many factors that come into play including, individual’s assumptions, beliefs, personal goals and preferences, and attitudes which bias the process. For example, individuals will consider departmental politics, they may be concerned with impression management or they may intentionally hold back information during the decision-making process. This will affect the decision made by the group. Additionally, once an initial decision is made, the group will tend to stick to this decision and other information shared will be processed in a biased way in favour of the original decision [2]. Therefore, when subsequent information arises which doesn’t support the initial decision, it is less likely to be incorporated into the decision-making; even when it should be.

How can we make effective team decisions?

  • Ensure that an open-minded attitude is kept towards your own and other’s assumptions. Evaluate each individuals’ assumptions against the evidence to reduce the effect of bias.
  • Critically analyse and use all the information before coming to a decision. Keep searching for new information. If new information is found re-evaluate all the information to come to a new decision (this may or may not be the same as the original).


Sometimes the desire for harmony in the group may result in an irrational or dysfunctional decision-making outcome [3]. Groupthink often appears when there is strong group cohesion i.e. individuals in the group have very similar attitudes, opinions, feelings and experiences; when there is strong directive leadership and; when the group size is small. There are many characteristics of groupthink:

  • The group starts to develop an illusion that they are invulnerable which can lead to over-optimism and risk-taking.
  • The ethical and moral consequences of the group’s decisions are under-acknowledged.
  • ‘Outsiders’ of the group are seen as different and their views are discredited.
  • When group members are silent in the discussion, this is perceived as agreeing with the decisions. Often this is not the case and the silent individuals are afraid to speak up against the group’s decision.

How can we overcome groupthink?

  • Build diverse teams with individuals of different genders, cultures, education and professional backgrounds. People from a variety of backgrounds are likely to have differing opinions. This encourages constructive challenge (which results in better quality decision-making).
  • Foster critical thinking. Then the group analyses implicit assumptions and members ask themselves why they think that; what is the evidence and; are there any other ways of seeing the situation?
  • Make sure that there is a “devil’s advocate”. A person who draws attention to weaknesses and flaws in the group’s arguments so that each decision can be fully justified.


Polarisation occurs when a group of people make a more extreme decision than each individual would have made on their own. The group can either take a ‘risky shift’ whereby the group takes a riskier decision than the individuals on their own would take or a ‘cautious shift’ whereby the group becomes more risk averse than the individual group members would be. Polarisation can occur for four reasons:

1. Certain individuals in the group may be highly persuasive in their arguments. This means that less avid supporters of an opinion may change their views.

2. If the group all share similar opinions, then they will become more confident that these opinions are correct and so are willing to take a more risky decision or stance.

3. Some group members may change their opinion and conform to the group as they want to feel part of the group, especially if the group’s opinions more socially desirable than their own.

4. When you are part of a group there is a diffusion of responsibility and you may feel less responsible for the decision of the group. Therefore, individuals are more likely to take on radical opinions and not be as concerned about the consequences.

How can we prevent polarisation?

  • Individuals must ask themselves whether they’d have the same opinion or make the same decision if they were personally responsible for it. Each decision made by the group needs to be thought through with all group members held accountable. Moreover, the implications of the decision on other people needs to be considered.
  • Be aware that individuals don’t have to agree with the group all of the time. Ensure that everyone knows that it is safe to disagree with the group and there won’t be any repercussions.
  • All arguments should be considered against the evidence to ensure that it is valid.

Shared information Bias

When working together with other individuals as a team, there will be common information that everyone knows and there will be unique information that only one individual knows. Individuals are typically good at sharing common information, but they tend to inadvertently withhold unique information which is called ‘shared information bias’.

Even when the group does uncover unique information from an individual, they are more likely to talk about the common information which can discourage further sharing of any unique information. The common information is treated more favourably and important than the unique information. This results in lots of unique information remaining unknown to the group which prevents them from making the best quality decisions based on all the facts [1].

Imagine 3 people have separately interviewed a candidate for a job and the interviewers are now discussing the candidate in a meeting. All the interviewers asked the candidate 3 of the same questions and they also asked 2 different questions (which were not the same as the other interviews). When in the meeting they spend a large proportion of time discussing the candidates answers to the first 3 questions; information which they are all aware of and is common to the group. However, they spend much less time talking about the unique information they uncovered from the last 2 questions. This means that one interviewer fails to tell the group that the candidate said they were fired from their previous job for breaking patient confidentiality. Therefore, this potentially important information is missed and not incorporated into the decision making; this is an example of shared information bias.

How can we avoid shared information bias?

  • Establish your goals are as a group and what information you need from each individual to achieve them. Consider rewards or sanctions for sharing and not sharing information.
  • Ensure psychological safety (this is defined as being able to show and employ one’s self without fear of negative consequences of self-image, status or career) within the group to encourage brainstorming and open sharing without fear of criticism. This will encourage individuals to share more information about what they know about the topic and so more unique information will be revealed.

 Escalation of Commitment

Escalation of commitment is when a great deal of resources e.g. time, money, labour etc, have been invested in a decision which has led to a disappointing outcome. Instead of changing the course of action, the individual or group continues the same behaviour. Therefore, the resources invested are not wasted in the hope that it will eventually achieve positive results. However, this irrational behaviour often results in increasingly negative outcomes and further loss of investment. Escalation of commitment is commonly seen in activities such as gambling where people who have lost lots of money continue to play as they think they’ll win on the next game or so and don’t want to have invested all their money for nothing. Escalation of commitment is often exacerbated when groupthink or polarisation is already in play.

How can we prevent escalation of commitment?

  • Ensure that the group knows about the costs from the beginning so they are aware of the cost of subsequent withdrawal and they can incorporate this into their strategy and decision-making.
  • Ensure that leaders or groups are not penalised for inconsistency. Allow decision-makers to change their strategy and direction if the evidence suggests that this is necessary.
  • (If appropriate) Remind the group that the adverse outcome is beyond anyone’s control, this helps to prevent the team from defending and remaining committed to a losing strategy.

Sharing these ideas with your team can help

Teams are often not aware of the numerous group biases that can take place which affect their interactions with one another and the decisions they make. To prevent these group biases, build diverse teams, ensure there is psychological safety and critically evaluate the decisions against the evidence. The result will be a more functional team who make the best decisions based on evidence.

Do you recognise group biases within your team?

 If you work in a team which is affected by some of these group biases then don’t feel at a loss – we can help! At Impact, we are a team of Business Psychologists who have many years of experience working with diverse teams, senior leadership teams and executive boards. We’ll help you to identify the issues that are occurring in your team and provide you with effective evidence-based solutions. Please get in touch if you’d like us to help you. Additionally, if you’d like to understand more about what we do, check out our website here.


1.Stasser, G. & Titus, W. (1985). Pooling of Unshared Information in Group Decision Making: Biased Information Sampling During Discussion. Journal of Personality and Social Psychology, 48(6), 1467-1478.

2.Greitemeyer, T., & Schulz-Hardt, S. (2003). Preference-consistent evaluation of information in the hidden profile paradigm: Beyond group-level explanations for the dominance of shared information in group decisions. Journal of personality and social psychology84(2), 322.

3.Janis, I. L. (1972). Victims of groupthink: A psychological study of foreign-policy decisions and fiascoes.