Stanford Prison Experiment

Stanford Prison Experiment: Background

Historically there have been many instances of people perpetrating human rights abuses when they are in a position of authority such as soldiers, guards, police officers or teachers. This is why finding out why authority figures become abusive is an important topic of research in social psychology.

One of the most famous and controversial experiments regarding social conformity was Phillip Zimbardo’s (1971) Stanford Prison Experiment, which investigated the power of social norms and roles and the influence of authority figures. During the 1970s in the USA, there was a lot of public debate about the rapidly growing prison population and police brutality. This prompted Zimbardo to investigate the extent to which a person’s behaviour would change depending on the role they take on.

Zimbardo showed that the temporary situations that surround an individual could influence anyone to act negatively (situational influence) more so than their personality (dispositional influence). By creating a realistic environment and power dynamic between the two groups, Zimbardo created pressure to conform to specific group roles.

Stanford Prison Experiment Variables

The Standford prison experiments divided participants into two groups: 'prisoners' and 'guards'. This reflects the independent variable of the study. Participants were randomly assigned to the two groups, and there was no control group. Zimbardo’s team gave the different groups clothing and accessories that matched their role. The ‘guards’ received uniforms, sunglasses and batons and the ‘prisoners’ wore a robe with a number and shackles. The ‘prisoners’ were confined day and night, whereas the ‘guards’ could go home.

The study’s dependent variable was the effect that the role assignation had on individuals’ behaviour. The study has been criticised for not having a clearly defined dependent variable since Zimbardo wanted to see what would happen. This lack of dependent variables sets the study as an observational study with no experimental design.

Participants in the Stanford prison experiment

Twenty-four subjects were recruited through a local newspaper advertisement, where participants would be given a reward of $15 per day to participate in a study about ‘prison life’. They were mostly white, middle-class male university students. None of them had been in prison before. Participants were tested for any pre-existing psychological or medical conditions. After Zimbardo tested and briefed the candidates, he sent them home.

Fig. 1. Original newspaper advertisement through which participants were recruited.

Stanford Prison Experiment: Description

During the summer break at Stanford University, Zimbardo built a mock prison in the hallways of the psychology department. After having randomly assigned the role of either prisoner or guard to the subjects, he had the ‘prisoners’ arrested by the actual local Palo Alto police without warning. They were blindfolded and brought to a real police station to have their fingerprints and picture taken, then ‘charged’ with assault and brought to the mock prison.

Here the guards made the ‘prisoners’ get undressed and put on shackles and robes, then confined them in the mock ‘cells’ that had no amenities except for a mattress. They stayed in the prison day and night, whereas ‘guards’ worked in shifts and could return home when they were not on duty. The guards were told not to harm the ‘prisoners’ or withhold food or drink from them. However, throughout the study, violence started to escalate:

• Day 1: Uneventful.

• Day 2: The prisoners barricaded themselves in a room with their mattresses. A cycle of retaliation between the two groups began. One ‘prisoner’ has a nervous breakdown.

• Days 3-5: The ‘guards’ found increasingly extreme methods to establish control over the ‘prisoners’ by:

  • Locking those who didn’t comply in a cupboard.
  • Waking ‘prisoners’ up in the middle of the night for headcounts.
  • Stripping ‘prisoners’ naked and using a fire extinguisher on them.
  • Verbally assaulting and humiliating them.
  • Making ‘prisoners’ defecate in a bucket and not allowing them to empty it.
  • Withholding mattresses.

• Day 6: The study was cut short by Zimbardo.

Stanford Prison Experiment Results

Zimbardo’s experiment is an example of normative social influence and situational influence. All of the participants started as part of the same group but, when randomly assigned new social roles, started to identify and behave without explicit prompting.

Nobody died during the experiment, as Zimbardo cut it short when the behaviour of the guards started to get out of hand. All participants were debriefed by Zimbardo’s team, giving them the opportunity to discuss the events of the study. Surprisingly, Zimbardo never faced legal charges despite endangering the participants under his care.

Significance of the Stanford Prison Experiment

Although Zimbardo’s study was so influential that it determined policy in the USA prison system, Zimbardo’s study and his interpretation of the results have been extensively criticised.

Researchers Banuazizi and Mohavedi (1975) claimed that the participants in the study were only playing up to stereotypes and not to actual societal roles, hence, limiting the validity of the study. Another researcher, Peter Gray (2013), commented that the guards were encouraged to act in a psychologically oppressive manner, suggesting that in some way, Zimbardo may have produced the results through the instructions he gave the ‘guards’.

Erich Fromm (1973) criticised Zimbardo’s experiment for exaggerating the results of the study; specifically, two-thirds of the guards did not act abusively, as opposed to the one-third who did. Additionally, Haslam and Reicher (2002) aimed to replicate the experiment in the BBC prison study. In this study, the ‘guards’ and ‘prisoners’ did not automatically conform to their roles and this led to a collapse of the prison system in the study.

Despite the limitations that the study presents, the observed behaviour is of significance in societies. The study provided evidence that people adapt to certain situations they find themselves in. This effect is bigger when individuals adapt to highly stereotypical roles. Further, the study showed that individuals would continue with their roles to the point that they would exert physical punishments on others.

These types of behaviours have been detected across history. During the holocaust, over 6 million Jews were murdered by the german absolutist regiment during World War II. Although these days many people will argue that they would have helped the Jews, the reality was that many individuals conformed with the regiment and engage in very destructive behaviours.

This is evidence of the relevance and significance that the Standford prison experiment.

Stanford Prison Experiment Ethical Issues

The Stanford Prison Experiment shaped ethical standards for psychological experiments because it was such a cautionary example of what not to do. Although the participants reported distress and mental trauma throughout the study, Zimbardo did not listen to them. His objectivity was compromised because he had taken on the role of the prison warden. Based on this, future research started to be controlled and tracked by ethical committees. These committees ensure that ethical standards are met.

Today, the experiment would not have been possible because of two reasons:

1. The study did not protect participants from harm since they were humiliated and mistreated.
2. The study did not ask for written informed consent.

These points reflect the ethical standards that studies need to comply with today to be accepted by ethics commissions.