Participant Selection: Researchers used a volunteer sample and screened for psychological stability to ensure that any observed aggression or distress was not due to pre-existing mental health issues.
Random Assignment: Participants were randomly assigned to the role of either 'prisoner' or 'guard.' This is a critical methodological step to ensure that there were no systematic personality differences between the two groups at the start.
Uniforms and Environment: Guards were given khaki uniforms, reflective sunglasses (to prevent eye contact), and clubs, while prisoners wore smocks with ID numbers and ankle chains. These symbols were designed to induce deindividuation and reinforce the power hierarchy.
Data Collection: The study used controlled observation, including video and audio recording, as well as self-report measures through interviews and mood scales to track the psychological impact of the roles.
| Feature | Conformity to Social Roles (Zimbardo) | Obedience to Authority (Milgram) | Majority Influence (Asch) |
|---|---|---|---|
| Primary Driver | The expectations of a specific social position. | Direct orders from a person in power. | The desire to fit in or be right within a group. |
| Mechanism | Identification with a role and deindividuation. | The agentic state and legitimate authority. | Normative or informational social influence. |
| Behavior | Spontaneous adoption of role-consistent actions. | Compliance with specific, explicit instructions. | Publicly agreeing with a group despite private doubt. |
Ethical Violations: The study is widely criticized for the psychological harm caused to prisoners, who suffered emotional breakdowns. Zimbardo also failed to maintain objectivity by acting as the 'Prison Superintendent,' which compromised his ability to protect participants.
Demand Characteristics: Critics argue that participants were merely 'play-acting' based on stereotypes of how prisoners and guards should behave. If participants guessed the aim of the study, their behavior may not reflect genuine conformity.
Social Identity Theory (SIT): Reicher and Haslam (2006) argued that conformity to roles is not automatic. According to SIT, people only conform to a role if they actively identify with the group. In their replication, prisoners took control because they formed a strong collective identity, while guards failed to do so.
Identify the Independent Variable: Always remember that the IV was the random assignment to roles. This allows researchers to claim that the situation, not personality, caused the behavior.
Evaluate the 'Prisoner' Experience: When discussing findings, focus on the 'pathological prisoner syndrome,' which includes passivity, dependency, and learned helplessness. This demonstrates the psychological toll of the role.
Distinguish from Milgram: Do not confuse Zimbardo with Milgram. If the question asks about 'social roles,' focus on the SPE. If it asks about 'authority figures' or 'orders,' focus on Milgram.
Check for Validity: Consider both internal validity (did the participants believe the setup?) and ecological validity (how well does a mock prison represent a real-world prison?).