5.5 Social Influence Part 2: Groups

In this topic, we will look at social groups and explore questions such as:

  • what they are
  • why we want to be part of them
  • how they are formed
  • what keeps them together
  • what makes them work well and not so well
  • some benefits and risks of group process dynamics.

But before we look at these questions in more detail, let’s start this part of the chapter with a short exercise.

Reflection Activity

Please take a moment to think about how you would define a group. How many people does it need to have a group and in what ways do these people need to be connected for you to call them a group?

Now please go back to the second topic of this chapter (the social self) where you were asked to complete the Twenty Statements Test. Have a look at how often you completed the statement “I am ….”  with listing a group membership.

Now please take a moment to think about which other groups you feel part of (besides the ones that you may have listed in the Twenty Statements Test (TST) that you completed earlier in this Chapter). Try to come up with at least five and try to describe how far these groups differ and how far they may be similar in terms of their purpose, what keeps them together, and why you joined them in the first place.

What Makes a Group?

Now that you have done your own reflections on groups, we will have a look at what social psychology has to say about groups. We will start by considering the question: What makes a group?

According to Kassin et al. (2020), a group is defined as:

a set of individuals who have direct interactions with each other over a period of time and share a common fate, identity, or set of goals. (p. 313)

For example, you form part of a group of students enrolled in a subject at a university. You may soon graduate with other students who are studying for the same degree as you are and join the graduation ceremony, where all students wear the same outfit. In this way, you may explicitly identify with the group of students. Once graduated, it is likely that you will no longer identify as a student of your university, but as alumni. Groups may also be based on relatively “fixed” characteristics such as sex, country of origin, religion, citizenship, educational level, etc. (some of these can be changed with more or less effort, others cannot be changed, such as the country that you were born in). All these groups vary in terms of how distinct they are from other groups.

Figure 5.5.1. A group of James Cook University students, image from J. Rafferty, used under a CC BY NC-ND licence

The Need for Group Membership

We will now have a closer look at the question of why people need/ want to join groups in the first place.

Different disciplines take a different look at the need for and purpose of group membership. For example, from an evolutionary perspective, group membership served the purpose of protection and survival.

Figure 5.5.2. “Dinosaurs and Cavemen” by Orin Zebest is used under CC BY 2.0

Social psychology highlights the need for personal and social identity as an important driver for group membership. According to the social identity approach, people categorise themselves according to personal identities and social identities (Haslam, 2014; Jetten et al., 2020; Tajfel & Turner, 1979). Personal identity refers to a person’s sense of self, while social identity relates to a person’s sense of who they are as a member of a group (Jetten et al., 2020; Kassin et al., 2020). Both these identities affect people’s cognition and behaviour (Haslam, 2014; Jetten et al., 2020; Tajfel & Turner, 1979). Since we covered people’s sense of self (and how it may impact their behaviour) in topic 5.2, we will now just focus on exploring people’s social identities and consider several theories and approaches that help explain them. As an introduction to these theories, please watch the following short video [2:56]:

As noted in the video, in the most basic sense, people distinguish between groups that they form part of and groups they do not form part of, referred to as ingroup and outgroup. These two sets of groups may be defined as follows:

Ingroups Outgroups
Groups with which an individual feels a sense of membership, belonging and identity” (Kassin et al., 2020, p. 144) Groups with which an individual does not feel a sense of membership, belonging or identity (Kassin et al., 2020, p. 144)

The video also noted that the formation and evaluation of social identity and group membership involves three components: social categorisation, social identification and social comparison. Please click on the buttons below to find out more about these three components.

Social Identity Theory and Self-Categorisation Theory

The social identity theory and self-categorisation theory, in combination, can help explain why people identify with groups and why this identification impacts a person’s cognition and behaviour (Haslam, 2014; Rudert et al., 2021). The social identity theory proposes that in many social situations, people prefer to identify and act as a group member rather than as an individual (Ellmers & Haslam, 2012). The association with groups serves to enhance a person’s self-esteem, a process that is further supported by favouring ingroups over outgroups (Kassin et al., 2020).

Figure 5.5.3. “K Pop band” by Kiyoung Kim is used under a CC BY 2.0 licence

What is important to highlight here again is that according to the social identity theory, the enhancement of self-esteem is regarded as a main driver for people’s desire to belong to groups. Another important point to make is that identification with a group encourages behaviours that are consistent with those supported by the group (and these may differ from behaviours that an individual may choose if acting on their own – we will look at this in more detail further below).

The self-categorisation theory is an extension of social identity theory, holding that people categorise themselves either as a group member or as an individual, depending on each situation, and that this categorisation influences their behaviour (Turner & Reynolds, 2012).

People tend to associate with multiple groups, depending on the context and have therefore multiple social identities, each with their own set of norms (Drury et al., 2019). People’s identification with a group and adherence to its norms depends on how salient the social identity is in each situation (Tajfel & Turner, 1979; Venu et al., 2021). We will look at social identity, social categorisation and how it may all affect people’s behaviour in real life in more detail in the final topic of this eBook.

The Influence of Groups on Individual Behaviour

We will now briefly consider how group membership may influence the behaviour of individual group members. For this purpose, please watch the following Crash Course video from minute 5:59 (you were prompted to watch the first half of this video for the previous topic):

In this second part of the video, Green Hank discussed phenomena like:

  • social facilitation
  • social loafing
  • deindividuation
  • group polarization
  • groupthink.

To learn more about these phenomena and other problems (and solutions) associated with group performance, you may wish to read:


Kassin et al., 2020, pp. 318-332.

Stereotypes, Prejudice and Discrimination

As mentioned above, classifying ourselves and others into groups comes with some risks, since we classify according to attributes that we perceive as being important characteristics of the other and a whole group. As we have learned in the previous topics, our perceptions are not always accurate but prone to error. Similarly, the categories that we use may also be subjective and thus inaccurate. In fact, we frequently overgeneralise our beliefs about a particular group of people. These beliefs are known as stereotypes. Unfortunately, these beliefs also influence our attitudes towards a whole group, which may make us feel prejudiced against certain groups. Both our stereotypical beliefs and negative attitudes towards a group can then affect our behaviours in the sense that we may discriminate against people based on their group membership (which we may have assigned to them).  To learn more about the topic of stereotypes, prejudice and discrimination, please watch the following Crash Course video, which explains all three components in more detail [9:54]:

To further deepen your understanding of the processes and risks of stereotypes, prejudice and discrimination, you may also wish to read:


Chapter 4 in Kassin et al., 2020, pp. 140-182.

The optional reading listed above also discusses various strategies or approaches to reduce prejudice and discrimination, including intergroup contact, changing cognitions and changing cultures. To learn about a project that aimed to raise awareness of the issue of discrimination in the US (and the experience of being discriminated against), please watch the following video [53:00]:


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Neuroscience, Psychology and Conflict Management Copyright © 2024 by Judith Rafferty is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.