Why and How Do People Form Groups?

From the Lecture Series Understanding the Mysteries of Human Behavior

By Mark Leary, Ph.D., Duke University

People form groups for a variety of reasons, from feeling that they belong, to fighting a war. Simply creating the groups creates prejudice and conflict between them. Why does belonging to a group matter so much that people are willing to fight against each other, and even kill or die? How do people decide which side to pick, and how do they know that is the best side?

background image. happy guy pointing at you.
In most cases, simply being part of a group encourages prejudice against those who are not part of the group. (Image: ASDF_MEDIA/Shutterstock)

Sharing and Cooperation a Group

People are usually careful who they pick as teammates. However, there is never enough time nor enough opportunity to know every member well and realize which group is really the best choice. Thus, people form groups based on a few positive criteria, and then develop biases in favor of their group and against the others. Consequently, each person thinks their group is the best, according to their biases and prejudices.

People form groups to use its numerous benefits. Members of a group help each other in need, cooperate to reach goals, share resources, and, last but not least, provide opportunities for social interaction, companionship, and support. However, the members only receive the benefits that reflect their behavior.

Close up top view of young people putting their hands together. Friends with stack of hands showing unity and teamwork.
Sharing and cooperation are common among the members of groups, and the rules usually prevent taking advantage of others. (Image: Jacob Lund/Shutterstock)

If a group member treats others badly, nobody will be willing to share with them anymore. At the same time, an exploiter can easily take advantage of others in a group. Hence, people try to cooperate with those that are less likely to take advantage of them, not any random person that they meet.

Minimizing Risks and Costs

When a group is formed, members can enjoy the benefits while minimizing the possible costs and risks due to the rules in the group. Thus, merely being in the same group identifies others as more cooperative and trustworthy people. Although many people outside the group might also be nice and helpful, one cannot find them easily. Likewise, others may have no reason to treat the person well and help.

The easiest conclusion is that everybody outside the group is not trustworthy and is potentially working against the group for common goals or limited resources. Psychologically, it makes sense.

Learn more about where people’s personalities come from.

Positive and Negative Biases

Group members develop positive biases about their own group and negatively discriminate against other groups. A social psychologist called Henri Tajfel tried to conduct a study on factors that create prejudice, and he concluded that merely putting people in groups, even randomly, makes them view their own group better than the others, even if they have never met the others. Even though these two biases often go together, it does not mean that the existence of one guarantees the other.

For example, a person might believe that their group is the best ever. However, they do not view other groups as worthless people with no qualifications. On the other hand, the same person might believe that the other groups are also very nice and qualified, but they will still dedicate time and energy to their own group. The more general pattern is that people are positively biased about their own group, but do not hate or wish harm or bad things for the others.

Learn more about how human nature evolved.

The Interindividual-Intergroup Discontinuity Effect

When people form groups, they become less cooperative and more competitive than individuals. This is why soldiers of opposing sides can share a cup of tea and a friendly conversation when they are not fighting in the group. As individuals, they have no problems with each other, but in the group, they are competitive enough to fight against the whole group, not that single person.

The interindividual-intergroup discontinuity effect explains how reasonable, nonprejudiced people who can get along with members of the other group as individuals change when they get into their group. Why?

Full concentration at work. Group of young business people working and communicating while sitting at the office desk together with colleagues sitting in the background
When people begin working together as groups, they get more competitive and antagonistic than when they work alone. (Image: G-Stock Studio/Shutterstock)

Firstly, people are naturally more afraid of groups than individuals, like in street fight situations where nobody wants to fight with a group. Second, people do not want to be identified as unfair, greedy, competitive, or prejudiced as an individual. Thus, they treat others nicer when they are alone. When the same people form a group, they act more competitively and antagonistically to try and reach the common goals, even if it means working against other groups.

Third, people tend to think of members of a group as more similar to each other than they really are. For example, if a member of another group lies, their whole group will be viewed as a bunch of liars, while they might not be. If a member of one’s own group lies, the same conclusion is not drawn.

People form groups to protect and benefit themselves, and sometimes they view other groups negatively just because they are not in their own group.

This is a transcript from the video series Understanding the Mysteries of Human Behavior. Watch it now, on The Great Courses Plus.

Common Questions about People Form Groups

Q: Why do people tend to form groups?

People form groups to be able to obtain the benefits of cooperative relationships while minimizing the possible costs, because most groups enforce rules for how members should treat each other.

Q: Does the tendency for forming groups show discrimination?

Discrimination is a result of the tendency to form groups. People form groups to feel that they belong and to reach goals easier.

Q: Do groups need strong reasons to turn against each other?

No. Groups can get into conflicts right after people form the groups, merely because they are from other groups and not theirs.

Q: Do people perform better in groups?

People form groups because they know they can reach goals easier and faster in a group despite the limitations and rules that come along with group interactions.

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