Zimbardo's Stanford Prison experiment

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Social Roles

  • The 'parts' people play as members of various social groups. These are accompanied by expectations we and others have of what is appropriate behaviour in each role.
  • E.g. being a parent would show being caring, a student would be obedient.
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  • Advertised for students and selected student who were deemed 'emotionally stable'
  • Study would last for two weeks and participants were paid $15 a day
  • Set up a mock prison in the basement of Stanford University psychology department.
  • Students were randomly assigned the roles of guards or prisoners
  • Prisoners were arrested in their homes to heighten realism of the study, ***** searched, given a uniform and prison numers.
  • Prisoners locked in rooms for 23 hours a day, had 16 rules to follow, routines were heavily regulated.
  • Prison guards: own uniform including wooden club, keys, handcuffs and sunglasses, went home after shifts. Were told they had complete control over the prisoners. 
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  • Stopped after 6 days instead of 14
  • Threat to psychological and physical health of prisoners
  • Prisoners shouted swore at the guards, ripped their uniforms. 
  • Guards harrassed prisoners, did frequent headcounts etc.
  • Two prisoners suffered nervous breakdown
  • One suffered a nervous rash
  • One prisoner went on hunger strike - punished by putting him in 'the hole'.
  • Was shunned by other prisoners 
  • Prisoners began to do as they were told - although it caused them distress. 
  • Guards became brutal and aggressive. 
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  • Conformed to social roles. 
  • Deindividualisation - lose sense of identity. Conformed to the norms of the group.
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  • Had control over variables. 
  • E.g. choosing emotionally stable participants and randomly assigning roles - rules out personality differences 
  • Control over variables = increases internal validity - confident in drawing conclusions.
  • Collected data efficiently
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  • Lack of realism - Banuazizi and Mohavedi (1975) argued participants were play acting not conforming. 
  • Performances based on stereotypes
  • Lacks ecological validity - isn't completely realistic
  • Unrepresentative - 24 healthy male, middle class, white, college students. 
  • Fromm (1973) - Zimbardo exaggerated findings, only 1/3 of guards performed in a brutal manner.  
  • Rest tried to help the prisoners, sympathised. 
  • beahviour of guards show they're able to exercise right and wrong choices despite situational pressures to conform
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Ethical issues

  • Decpetion - Being arrested unexpectedly at home
  • Experiment was abandoned after 6 days
  • Extensive group and individual debriefings were held
  • Benefits gained about understanding human behaviour
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Evaluation Extra

  • Lack of research support:
  • Steve Reicher and Alex Haslam's (2006) replicated the study, found prisoners took control of the prison, guards were subjected to harrassment. 
  • Social Identity Theory (Tajfel 1981) - guards failed to develop a shared society identity as a cohesive group, the prisoners did. 
  • Prisoners actively identified themselves as members of a social group. 
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