Zimbardo's research

Stanford Prison Experiment - Procedure

  • Mock prison in the basement of the psychology department at Stanford University. 
  • Recruited 24 'emotionally stable' students determined by psychological testing - randomly assigned roles of guards or prisoners. 
  • To increase realism, 'prisoners' were arrested in their homes and delivered to the 'prison' - blindfolded, *****-searched, deloused and issued a uniform and number. 
  • Daily routines were heavily regulated: 16 rules to follow.
  • De-individuation (loosing a sense of personal identity): 
  • Prisoners names were never used. 
  • Guards had their own uniform - wooden club, handcuffs, keys and mirror shades. They were told they had complete power.
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Stanford Prison Experiment - Findings

  • Within 2 days, the prisoners rebelled against their treatment; ripped their uniforms, shouted and swore at the guards, who retaliated with fire extinguishers. 
  • Guards harrassed prisoners constantly by conducting frequent head counts, sometimes in the middle of the night. 
  • Guards took up their roles with enthusiasm. Their behaviour threatened the psychological and physical health of the prisoners. For example: 
    • After the rebellion was put down, the prisoners became subdued, anxious and depressed. 
    • 3 prisoners were released early because they showed signs of psychological disturbance. 
    • One prisoner went on a hunger strike; the guards attempted to force-feed him and punished him by putting him in 'the hole', a tiny dark closet.
  • Study was stopped after 6 days instead of the planned 14. 
  • The situation revealed the power of the stimulation to influence people's behaviour. Guards, prisoners and researchers all conformed to their social roles within the prison. 
  • The more the guards identified with their roles, the more brutal and agressive their behaviour became. 
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Strength - Control over variables

P - A strength of the SPE is that the researchers had some control over variables. 

E - Emotionally stable participants were recrutied and randomly assigned the roles of guard or prisoner. The guards and prisoners had those rolse only by chance. So their behaviour was due to the pressures of the situation and not their personalities. 

CA - However, there was major ethical issues with the SPE. One issue arose because Zimbardo was both lead researcher and prison superintendent. A student who wanted to leave the study spoke to Zimbardo, who responded as a superintendent worried about the running of his prison rather than as a researcher. This limited Zimbardo's ability to protect his participants from harm becasue his role as a superintendent conflicted with his lead researcher role. 

E - Nevertheless, control increases the study's internal validity. We can be more confident in drawing conclusions about the influences of social roles on behaviour. 

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Limitation - Lack of realism

P - A limitation with the SPE is a lack of realism. 

E - Banuazizi and Mohavedi (1975) suggest participants were play-acting. Their performances reflected stereotypees of how prisoners and guards are supposed to behave. One guard bassed his role on a character from the film 'Cool Hand Luke'. Prisoners rioted becuase they thought that is what real prisoners did. 

CA - On the other hand, Zimbardo's data showed 90% of the prisoners' conversations were about prison life. The simulation seemed real to them, increasing the study's internal validity. 

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Limitation - Understated dispositional influences

P - A limitation is that Fromm (1973) argues that Zimbardo understated dispositional influences. 

E - Only a third of the guards behaved brutally. Another third applied the rules fairly. The rest supported the prisoners, offering them cigarettes and reinstating privelleges. Zimbardo's conclusion - that participants conformed to social roles - may be over-stated, exaggerating the power of the situation. 

E - The differences in the behaviour of the guards show that they could exercise right and wrong choices, despite situational pressures to confrom to a role.

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Limitation - lacks research support

P - SPE lacks research support and has been contradicted by subsequent research. 

E - Reicher and Haslam (2006) partially replicated the SPE, with different findings. Prisoners eventually took control. Tajfel's (1981) social identity theory (SIT) explains this. Guards in the replication failed to develop shared social identity as a group, but prisoners did and refused to accept limits of their assigned roles. 

E - So the brutality of the guards in the original SPE was due to the shared social identity as a cohesive group, rather than conformity to their social roles.

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