Overview – Zimbardo et al (1973)
Zimbardo et al (1973) is a key study in the social area of psychology that investigated how social roles and situational factors influence behaviour. By placing psychologically healthy male volunteers in a simulated prison environment and randomly assigning them to the roles of guards or prisoners, Zimbardo found that participants quickly adopted their assigned roles, with some guards becoming increasingly authoritarian and prisoners showing signs of distress and passivity. Zimbardo demonstrated the powerful influence of social situations and roles on behaviour, contributing to our understanding of situational explanations of behaviour. However, the study has also been criticised for ethical and methodological issues.
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The Stanford prison study
Aim
The aim of the Zimbardo et al (1973) Stanford Prison Study was to find out to what extent ordinary psychologically healthy people would conform to the social roles of a prison situation – particularly the roles of prisoner and guard – simply because the situation demanded it.
The inspiration for the study came from the idea that conformity is a form of social influence in which people change their behaviour, beliefs, or attitudes in response to the expectations of their social environment. In other words, it’s when individuals align their actions and thoughts with the unspoken rules or expectations of the social environment around them rather than thinking and acting independently. It can take several forms (e.g. changing your behaviour publicly to fit in with a group while secretly disagreeing), but one of of the most powerful ways conformity operates is through social roles.
Different social situations have different expectations for behaviour – different social norms. And these norms give rise to social roles that people play according to the social situation. For example:
- In the role of employee, you are expected to show up on time and do your work.
- In the role of customer in a shop, you are expected to pay for the items you buy.
- In the role of student at school, you are expected to raise your hand to speak and complete your homework.
Conforming to social roles isn’t necessarily a bad thing. We need people to play these social roles in order to behave correctly and predictably and maintain an orderly society.
But the researchers wanted to see whether people would conform to social roles even when those roles require extreme or harmful actions. By creating a mock prison environment, Zimbardo aimed to test whether normal and psychologically healthy individuals would adopt the social roles of ‘prisoner’ and ‘guard’.
Method
Participants and sampling
Zimbardo et al recruited participants by placing an advertisement in a local newspaper asking for male volunteers to take part in a study of prison life. This meant that the study used volunteer (self-selected) sampling, as participants chose to respond to the advertisement and put themselves forward to take part.
The characteristics of the participants were as follows:
- 21 male students
- These were selected from a total of 75 applicants for their mental stability and lack of antisocial tendencies.
- These 21 participants were randomly divided into two groups:
- 10 ‘guards’
- 11 ‘prisoners’
Procedure
The procedure was as follows:
- Zimbardo and his team converted the basement of the psychology department at Stanford University into a fake prison.
- ‘Prisoners’ were arrested by real police and then subjected to real police booking procedures (e.g. fingerprinting and mug shots). They were put in cells in groups of 3 and were confined throughout the experiment.
- ‘Guards’ worked in 8 hour shifts and were instructed to refer to the prisoners by their assigned numbers rather than their names. A realistic prison routine was established with meal times, etc.
- The prisoners wore jackets with their number on, and a chain around one ankle. Guards wore khaki uniforms, mirrored sunglasses to prevent eye contact, and carried handcuffs and wooden batons.
- The study was scheduled to run for 2 weeks.
Results
The results of this observational study were extreme:
- The guards became increasingly sadistic. For example, they forced the prisoners to continually repeat their assigned numbers and made them go to the toilet in buckets in their cells. As punishment, the guards refused to allow prisoners to empty these buckets, took away their mattresses and made them sleep on the concrete floor, and took away their clothes.
- The prisoners became increasingly submissive. Many stopped questioning the guards’ behaviour and sided with the guards against rebellious prisoners
- After 35 hours, one prisoner began to “act crazy, to scream, to curse, to go into a rage that seemed out of control” and had to be released. Three other prisoners had to be released for similar reasons throughout the duration of the experiment.
- The guards’ sadism became so harmful that Zimbardo stopped the experiment after just 6 days instead of the scheduled 2 weeks.
Conclusions
Situational vs. dispositional factors
A key debate in social psychology is which drives human behaviour more:
- Situational factors (i.e. the environment): This side argues that external forces – such as social pressure, authority figures, roles, cultural expectations, and the environment – are the primary drivers of behaviour. Under the right (or wrong) conditions, almost anyone can act in unexpected or extreme ways regardless of their personal character.
- Dispositional factors (i.e. the individual): This side argues that a person’s internal characteristics – such as personality traits, genetics, moral compass, intelligence, and personal values – determine how they act. According to this view, a person with strong morals or a steady disposition will remain consistent across different situations.
The findings of the Stanford prison study support the situational explanation because participants conformed to social roles to a significant extent. Remember, Zimbardo specifically screened all participants beforehand to ensure they were mentally stable and free of antisocial tendencies, which rules out preexisting personality traits to explain these behaviours.
Since the roles of guard and prisoner were assigned by random coin flip, the differences in how participants behaved can’t plausibly be blamed on their individual personalities. Instead, normal and psychologically healthy students transformed into either sadistic guards or broken submissive prisoners according to the role they had been randomly assigned.
Conformity to social roles
In interviews with participants afterwards, both the prisoners and the guards expressed shock at how out-of-character their behaviour had become. These people did not necessarily have a sadistic disposition, but were instead conforming to the social roles of the situation.
However, it should be noted that not all participants conformed to their roles to the same extent. Some guards did not sadistically exert control and some prisoners did not break down and become totally submissive.
Overall, the study suggests that while situational factors are important, individual dispositions play an important role in behaviour too. Further, some studies designed to replicate Zimbardo’s have challenged his emphasis on social roles.
Evaluation
Strengths of the Stanford prison study:
- High internal validity: By carefully screening participants for psychological stability and randomly assigning them to the roles of ‘guard’ or ‘prisoner’ Zimbardo successfully ruled out individual personality differences as the cause of the observed behaviours. Because the participants were placed in these roles entirely by chance, the dramatic shifts in their behaviour can be attributed more confidently to the situational pressures of the mock prison environment.
- Practical applications: Zimbardo’s study demonstrates the influence of conformity to social roles, which is an important psychological insight that has resulted in useful applications in society. For example, Zimbardo’s research prompted reform in the way juvenile prisoners were treated (at least initially).
Weaknesses of the Stanford prison study:
- Replication issues: An attempt to replicate Zimbardo’s findings was conducted by Reicher and Haslam (2006) and broadcast on the BBC. In their study, participants did not automatically conform to their assigned social roles. Instead, the prisoners actively banded together, challenged the authority of the guards, and established a more equal system. Reicher and Haslam used Social Identity Theory to explain this, arguing that conformity to social roles is not automatic or inevitable, but depends on whether individuals actively choose to identify with the social group in question.
- Questions of ecological/external validity: Both the guards and prisoners knew they were taking part in a study, and so this might have affected how they behaved. For example, they might have felt they were expected to act a certain way. This is somewhat confirmed by post-study interviews: Many of the participants said they were just acting. As such, the findings of this study may not apply to real life situations.
- Ethical concerns: It’s clear the study subjected many of the participants to high levels of stress, as evidenced by the prisoner who “went crazy” and had to be released, as well as the other participants who had to be released. Further, participants did not explicitly consent to all aspects of the experiment, such as being ‘arrested’ at home.