Introduction to Social Psychology
Senior 6 · Psychology (Languages)
Introduction to Social Psychology
Lesson 4 of 4
25 min
In August 1971 the psychologist Philip Zimbardo turned a basement corridor at Stanford University in the United States into a mock prison. Male student volunteers, screened as psychologically healthy, were randomly assigned to be “guards” or “prisoners”. Within days some guards were humiliating prisoners and some prisoners showed severe distress. The study, planned for two weeks, was stopped after six days, after a graduate student, Christina Maslach, objected to what she saw. For decades textbooks used the Stanford Prison Experiment to argue that ordinary people slip into brutal behaviour simply because a role demands it.
That conclusion is now strongly disputed, and the reasons why teach as much as the study itself (see the evaluation below).
Definition
Social role: the set of behaviours expected of a person who holds a particular position in a group or society. Examples: teacher, prefect, older sibling, customer.
Role conflict: a situation in which two roles a person holds demand incompatible actions. Example: a prefect who sees a close friend breaking a school rule.
Social norm: a shared expectation about how people in a group should behave. A descriptive norm describes what most people actually do; an injunctive norm describes what most people approve or disapprove of.
Relationship: a lasting connection between people in which each affects the other’s thoughts, feelings and behaviour over time.
Roles give us scripts. On the first day of a new job, or as a new prefect, you look around to see how people in that position behave. But the Stanford study is weak evidence that roles alone create cruelty:
The fair conclusion is that roles shape behaviour most strongly when people accept them, identify with them and are encouraged by leaders. That is a more useful lesson than “roles make people cruel”.
Every group has norms: which language to use with whom, how to greet an elder, whether to arrive at a meeting on time. Some norms are written into law. In Rwanda, adults take part in umuganda, community work on the last Saturday of every month, which is both a legal duty and a strong social expectation in every village.

Descriptive norms can be used to change behaviour. In a 2008 field experiment by Noah Goldstein, Robert Cialdini and Vladas Griskevicius, a hotel in the United States placed one of two cards in guest rooms. The standard card asked guests to reuse towels to help the environment; the other said that most guests reused their towels. About 35% of guests reused towels after the standard card and about 44% after the descriptive-norm card. However, when Gerd Bohner and Lena Schlüter (2014) ran the same idea in two German hotels, they found no clear effect. Norm messages work in some places and not others, probably depending on whether guests see the “most guests” as people like them.
In 1950 Leon Festinger, Stanley Schachter and Kurt Back studied friendships among students’ families housed in Westgate West, a set of two-storey apartment buildings at the Massachusetts Institute of Technology. Families were assigned flats by the university, not by choice, so this was a natural experiment.
Figure 1. Westgate West (Festinger, Schachter and Back, 1950): the closer two flats were, the more likely the families were to be friends.
Three findings recur in research on relationships:
| Factor | Finding | Evidence |
|---|---|---|
| Proximity | We befriend people we meet often, such as neighbours and deskmates. | Westgate West (1950) |
| Mere exposure | Simply seeing someone often makes us like them more. | Moreland and Beach (1992): four women attended a university class 0, 5, 10 or 15 times without speaking; students rated those seen more often as more attractive. |
| Similarity | We like people whose attitudes, values and often language resemble ours. | Byrne (1971): strangers with similar attitudes were liked more. |
| Field | A question social psychology helps answer |
|---|---|
| Health | Will telling people that most of their neighbours sleep under mosquito nets increase net use? |
| Education | How should groups be formed so that every student, not just the confident ones, takes part? |
| Justice | Why are confident eyewitnesses sometimes wrong, and how should police line-ups be run? |
| Unity and reconciliation | Which kinds of contact between former opponents build trust rather than resentment? |
| Language learning | Why are some students willing to speak a new language in class while others with the same knowledge stay silent? |
| Work | How do team norms affect safety, honesty and productivity? |
The prison study and the towel study also show why the field now insists on replication: repeating a study, ideally in another place and by other researchers, to see whether the result holds. A single striking study is a starting point, not a law of human nature.
National Geographic: “Unlocking the Truth About the Stanford Prison Experiment” (full episode). Watch for what former participants now say about how they were briefed and how much they were acting, and compare it with the study’s original claims.
Warning
Common mistake: quoting the Stanford Prison Experiment as proof that “anyone given power becomes cruel”. In an A-level answer, always add its weaknesses (demand characteristics, the researcher’s dual role, guards’ varied behaviour) and the contrasting BBC Prison Study.
Tip
Memory hook: “Descriptive = done; injunctive = judged.” A descriptive norm tells you what people do; an injunctive norm tells you what they judge right.
Practice
Further reading
Sources and credits
Written by Ganzaa: the text, the tables, Figure 1 and the exercises. The photo is used unchanged. This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.