The Stanford Prison Experiment


Stanford Prison Experiment

Investigated conformity to social roles, using the roles of prisoner and prison guard.

Zimbardo's aim was to assess how strongly an individual conforms to their role.

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21 male volunteer college students were drawn from a pool of 75 and paid $15 a day. They were checked for mental and physical health and randomly divided into prisoners and guards.

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Using a controlled observation, a realistic mock prison was created at Stanford University.

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Guards arrived first, set up the prison and decided the rules. They were not allowed to use physical violence. They worked shifts and went home in between. The prisoners were arrested by real police, taken to the station where they were finger-printed and then taken blindfolded to the mock prison. They were randomly allocated to the cells and were all strangers.

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  • Prisoners quickly became passive and negative in their attitudes while the guards became more active.
  • Five prisoners had to be released because of  extreme reactions to the situation but the rest endured the study until it ended after six days.
  • The guards showed pathology of power meaning that they enjoyed the absolute control they had over the prisoners. This was exhibited by many actions such as making toilet visits a privilege and making the prisoners do press ups.
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The fake prison situation can create a realistic role play to study the relationships between prisoners and guards and its destructive effect on human nature.

Haney et al. also believed they had shown how normal people are changed by the prison situation to show extreme reactions, supporting Zimbardo's situational hypothesis. 

As a consequence, he went on to campaign for prison reform.

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  • Control: This was high in this observation, where everything was filmed and recorded.
  • Consent: This was given but participants were not fully informed. For example, prisoners were not aware they would be arrested at the time.
  • Ecological validity: real prisons are worse; this was a clearly artificial setting so it lacks validity.
  • Ethics: There were severe reactions by the prisoners. Although there was a very thorough debreif afterwards, Haney et al. failed to protect the ppts.
  • Observers bias: Zimbardo has since admitted he lost his objectivity as the prison governor and got to invloved.
  • Not all participants showed conformity to their role. Some maintained their identity and resistance.
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