The Stanford Prison Experiment Explained: When Power Gets Weird Fast

In 1971, a psychology experiment tried to answer a simple question: what happens when you give ordinary people power over others? The answer, it turns out, was “things escalate quickly.” The Stanford Prison Experiment is now famous not because it was well-run, but because it went off the rails so fast that it changed how psychology thinks about power, ethics, and responsibility.

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What Was the Stanford Prison Experiment?

The Stanford Prison Experiment was run in 1971 by psychologist Philip Zimbardo. A group of male college students were randomly assigned to be guards or prisoners in a fake prison set up in a Stanford University basement.

The prison wasn’t real. The stakes weren’t meant to be high. The plan was to run the study for two weeks and observe how people behaved once power dynamics were built into the system.

The experiment was shut down after six days.

How Did It Go Sideways So Quickly?

Once the roles were assigned, people settled into them faster than expected.

The guards started acting like guards. The prisoners started acting like prisoners. And the researchers, instead of stepping in early, largely let it play out.

What stands out isn’t that people suddenly became monsters. It’s that the environment made certain behaviours feel reasonable. Authority went largely unchecked, stress escalated, and what began as a simulation started to feel uncomfortably real.

So… Was This Actually Science? (Yes and…)

This is where the Stanford Prison Experiment gets controversial.

By modern standards, the study has serious problems:

• Participants weren’t fully prepared for the psychological impact

• The lead researcher was too involved in the experiment itself

• People felt pressure to stay “in role”

• There were no clear rules about when to stop

What the experiment produced wasn’t clean data. What it produced was a very public example of what happens when power is introduced without enough thought about consequences.

Roles, Power, and Losing the Plot

One idea often connected to the experiment is deindividuation — the tendency for people to lose personal judgment when they’re absorbed into a role or system.

Uniforms, mirrored sunglasses, and strict rules didn’t just look official. They changed how people interacted. Individual responsibility blurred. Behaviour became about the role, not the person.

No one needed to be told to behave badly. The setup quietly did that work.

Why People Still Bring This Up

The Stanford Prison Experiment sticks around not because it offers neat answers, but because it asks uncomfortable questions.

How much of what we do is about who we are — and how much is about the situation we’re in? What happens when authority exists without meaningful oversight? And how quickly can “this is fine” turn into something else entirely?

Those questions show up far beyond psychology labs.

What Psychology Took From This (Eventually)

Modern psychology doesn’t treat this experiment as a model. It treats it as a cautionary tale.

Today, studies involving people require ethical review boards, clear boundaries, and safeguards. Not because researchers suddenly became nicer, but because earlier work showed what can happen when enthusiasm outpaces restraint.

The lesson wasn’t that people are inherently awful. It was that systems matter — a lot.

Key Takeaways

• Power changes behaviour faster than most people expect

• Roles can override personal judgment

• The experiment failed because oversight failed

• Psychology learned important lessons the hard way

Why This Still Matters

The Stanford Prison Experiment isn’t really about prisons. It’s about systems. Whenever authority exists without clear limits, similar dynamics are possible. That’s why this study, flawed as it was, keeps resurfacing. And why this is still as important as it was in the 70s. Stay well!

References & Further Reading

If you want to go beyond the pop-psych version, these are the sources most often cited:

• Haney, C., Banks, C., & Zimbardo, P. (1973). Interpersonal dynamics in a simulated prison. International Journal of Criminology and Penology.

• Zimbardo, P. G. (1973). On the ethics of intervention in human psychological research.

• Carnahan, T., & McFarland, S. (2007). Revisiting the Stanford Prison Experiment.

• Le Texier, T. (2019). Debunking the Stanford Prison Experiment. American Psychologist.

• Reicher, S., & Haslam, S. A. (2006). The BBC prison study. British Journal of Social Psychology.