Evaluation on Zimbardo's study

• Zimbardo controlled several elements of the study. Zimbardo ensured that he had only emotionally stable participants that were selected and they were randomly assigned to either prison or guard. They did this to try and make sure individual personality differences could not explain the results and that any differences in the behaviour observed was due to the situation and not the personality.

  This is a strength because it means the study has high internal validity and we can be confident in drawing conclusions about the influence of roles on behaviour.
• The Stanford Prison Experiment was a realistic set-up of how prisons work. Zimbardo gathered quantitative data about prisoner conversations during the study and found that 90% of the time they spoke about prison life. One even said that it was a real prison, but run by psychologists, rather than the government.

  This demonstrates that the experiment reflected real life and participants would have behaved accordingly.

  This further suggests that the study has high validity because the setting is believable.
• Zimbardo was criticised for exaggerating the power of the situation and minimising the power of dispositional factors. (Personality of "Guards"). Fromm noticed that only about 1/3 of the guards behaved in a brute manner, 1/3 applied the rules fairly, and the final 1/3 tried to help the prisoners and empathised with them. (Relaxed thee rules, gave them cigarettes).

  This suggests that Zimbardo's conclusions were exaggerated and that many guards showed behaviour that demonstrated that they were able to choose between "Right & Wrong" behaviour, despite the pressure to conform in the situation.