or their roles? That question was at the heart  of the controversial Stanford Prison Experiment,  

conducted in 1971. For psychology professor  Philip Zimbardo, who led the research team,  

the experiment demonstrated the power of group  identity and situational variables. However,  

over the years, its methods have been  scrutinized, and the results questioned.

This is Unveiled and today we’re  looking at the Extraordinary REAL  

Reason The Stanford Prison Experiment Is Wrong. 

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Psychology is considered to be a ‘soft science’,  as opposed to a ‘hard science’ like mathematics  

and physics. ‘Hard sciences’ are based on  empirical, objective, and quantifiable research,  

and produce testable predictions. In contrast,  ‘soft sciences’, like psychology and sociology,  

study human behavior, which can  be difficult, or even impossible,  

to quantify and measure. As a result, these  fields lean more on theoretical frameworks and  

involve subjective interpretation. Recording  how kind or cruel someone is, for example,  

is more ambiguous than measuring,  say, an object’s size or speed. 

In order to study human psychology, a number of  steps have to be taken to ensure that experiments  

are valid and reliable. In science, ‘validity’  means that an experiment measures what it’s  

intended to measure. ‘Reliability’ means that  the results are consistent across time - that is,  

that the same experiment can be replicated  and will produce the same results. Biases  

are especially important in psychology, as  results have to be natural and not influenced  

by the experiment itself. Participants  are often not even told the full nature  

of the study they are participating  in, to avoid altering their behavior.

The Stanford Prison Experiment is one of the most  famous experiments in the history of psychology,  

both among psychologists and the general  public. It’s been the subject of several books,  

documentaries, and movies, ensuring its place  in popular culture. Before the experiment,  

Zimbardo had been conducting research into  anti-social behavior, in particular by seemingly  

ordinary people. What makes normal people do bad  things? He had read about the brutality of guards  

in American prisons, and wanted to know if these  guards were already disposed towards violence,  

or if their roles and the situation influenced  their behavior. To answer this question,  

Zimbardo and his research team set up a simulated  prison in the basement of the Stanford psychology  

department and brought in male students to  roleplay as guards and prisoners. He wanted  

to see if the student guards would mirror  the behavior of real ones. The pretend  

‘prisoners’ were arrested at their homes and  booked at a police station. At the prison,  

they were stripped naked, deloused, and dressed in  a smock without underclothes. To dehumanize them,  

they were referred to only by numbers, not  names. The guards were given instructions to  

do whatever necessary to maintain order  apart from actual physical violence. 

The experiment was supposed to run for  two weeks. But after only six days,  

the guards had become so abusive that  psychologist Christina Maslach confronted  

Zimbardo and he shut the experiment down.  Zimbardo concluded that the situation,  

not individual personalities, had caused the  guards to become abusive. But was he right? 

Despite the experiment’s renown, critics  have denounced it as one of the most  

flawed and unethical experiments in the  history of psychology. From inception,  

the experiment was littered with problems.  For one, it was unethical, as students did  

not consent to psychological humiliation  and torture, and researchers refused to let  

them leave when they asked to do so. It also  arguably was not valid, because students knew  

they weren’t in a real prison and that they were  playing parts. In terms of the sample studied,  

the participants weren’t representative  of the general population - who aren’t  

all male college students! On top of all  that, and perhaps worst of all, there was  

the potential of bias from the involvement  of Zimbardo himself in his own experiment. 

Often, researchers hope for a certain result from  an experiment, and there’s a danger that they can,  

consciously or unconsciously, manipulate variables  to achieve the desired outcome. That’s why,  

for example, clinical trials to test whether new  drugs work are generally double-blind studies. In  

a double-blind study, neither the participants  nor the researchers know which participants are  

receiving the real drug, and which participants  are receiving a placebo treatment. This ensures  

that reactions and measurements aren’t biased.  But instead of watching his experiment from afar,  

Zimbardo took on the highest role in the study,  that of Superintendent, thus tainting the results  

from the start. He committed himself heavily to  playing the part, eventually conceding that “It  

wasn't until much later that I realized how far  into my prison role I was at that point - that I  

was thinking like a prison superintendent rather  than a research psychologist”. Even if Zimbardo  

had been trying his hardest to be unbiased,  unconscious reactions or behaviors can have an  

influence on other participants and the ultimate  results. As Superintendent, he inevitably conveyed  

expectations to the participants on how to behave.  For example, when he overlooked certain abuses,  

it communicated a message to the participants  and biased their subsequent behaviors. 

In a carefully constructed psychological  experiment, there are controls to counter  

unconscious biases. But in the Stanford Prison  Experiment, the design was actually built around  

them instead. Unfortunately, this manipulation  also went further, and was far from unconscious.  

Over time, research into the study has shown that  much of it was purposefully led in the direction  

that Zimbardo desired. Audio recordings recovered  from the Stanford archive show that Zimbardo  

coached the guards on how to act, telling them  to be “tough”. One prisoner later claimed that  

he had faked a mental breakdown in order to  leave the prison and return to his studies,  

although Zimbardo disputes his account. Critics  of the experiment argue that test subjects knew  

what was expected of them and acted accordingly.  Prisoners were supposed to be helpless and scared,  

and guards cruel and evil. Zimbardo has admitted  that even before the experiment was completed,  

he was anti-prison, and expected certain results  - namely, that the experiment would demonstrate  

the toxicity of prison systems. All in all, the  experiment suffered from a variety of issues,  

rendering the results invalid. Perhaps  the main problem with the study can be  

summarized by a quote from one of  the ‘guards’ in the experiment,  

who recalled: “I believed that I was doing  what the researchers wanted me to do”. 

The experiment is difficult to replicate, due  to the numerous ethical issues. But in 2002,  

psychologists Alex Haslam and Steve Reicher  attempted to replicate elements of the experiment,  

with the assistance of the BBC. They found  that the guards and prisoners did internalize  

their new identities, but that leadership  played a major role in the emergence of  

both tyranny and resistance. This puts into  question the original study’s reliability. 

While the experiment remains fascinating,  the consensus among psychologists is that  

there were too many methodological flaws for  it to be considered valid or reliable. Overall,  

it’s a better case study for how NOT to run a  scientific experiment! Many of the issues stemmed  

from the overinvolvement of the researchers,  particularly Zimbardo himself. As such, the  

experiment ceased to be an exploration of  natural human behavior. The Stanford Prison  

Experiment isn’t alone in this regard -  other famous psychological experiments  

like Robbers Cave or the Marshmallow Test  haven’t held up over time. Psychological  

experiments are extremely tricky, as both  unconscious and conscious biases can skew  

the results. And this is what happened  with the Stanford Prison Experiment. 

What’s your verdict in this case? Is there any  worthwhile data to be drawn from the experiment,  

or should the entire thing be written  off completely? What do you find most  

shocking about the way in which it was  conducted? And what would be different,  

if something similar were to be staged again?  Either way, it certainly has its place in the  

history of psychological study, even if  that’s only as a prime example of flawed  

and failed research. There are many lessons  to learn (and that have been learned) from it,  

as the true circumstances behind  it have been gradually unraveled. 

Is there another story in the history of  psychology that you’d like to see us cover  

next? Another experiment that you think is a major  problem? Let us know in the comments below. But,  

for now, that’s the REAL reason why the  Stanford Prison Experiment is WRONG. 

What do you think? Is there anything we missed?  Let us know in the comments, check out these other  

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