11 Most Controversial Psychological Experiments in History

A glimpse of some borderline, unethical and extremely controversial psychological experiments conducted in history.

11 Most Controversial Psychological Experiments in History
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History has been evidence of countless psychological experiments that have helped the humankind with its results. Some have adhered to the norms while others have been borderline unethical.

Today, there are strict rules that must be followed when conducting such psychological experiments.

For example, the Psychological Association of the United States has a binding Code of Conduct that must be followed to the ‘T’ when conducting any kind of experiment.


Experimenters are bound with the law to adhere to everything from consent to confidentiality of the experiments.

Moreover, there are review boards and panels who are in charge of reinforcing these strict ethics.

Having said that, the norms were not always this stern. That is precisely how some of the following psychological experiments came to be known as controversial in the history of mankind!

 1. The Facebook Experiment

The Facebook Experiment in 2012
Source: Pixabay

The Facebook Experiment of 2012 created quite an uproar amongst indignant users.

Nearly 700,000 Facebook users were subjected to secret psychological tests to see the effects of their emotional words on the “likes” and “statuses” they posted.

The details of the experiment were exposed by a scientific paper where it was revealed that the users were being subjected to ongoing research by taking “a small percentage” of their words from news feeds and testing them for a positive or negative reaction.

Putting aside the extreme outrage of people, the researchers of the experiment revealed that social media users were prone to “emotional contagion” because of which they mimicked the emotional response of others across the entire social network.

Notwithstanding the results, Facebook suffered stern criticism and users were seen referring to this social media platform with words like “super disturbing,” “terrifying” and “creepy.”

 2. Operation Midnight Climax

The US Military and CIA have a ravishing history of deceit and bad decisions.

This research project that has been dubbed as the Operation Midnight Climax was conducted in the 1950s under the direction of Allen Dulles, the CIA Director.

This operation was conducted with the motive of exploring the usage of “mind-control” drugs and testing the effects of LSD, Truth Serum, and Heroin on individuals.

Unknowing and non-consenting US citizens were lured to safe houses by CIA-paid prostitutes, and mind-altering substances such as LSD were slipped into their drinks.

These individuals were then monitored behind a one-way glass.

These experiments were sometimes sadistic too as the CIA operators were known to torture the victims by locking them up in sensory deprivation chambers while they ignorantly dozed on LSD.

The patients were also restrained and recorded without their consent.

During the course of the next 10 years, the government benefited immensely with extensive knowledge of surveillance technology, mind-altering drugs, and even sexual blackmail.

This psychological experiment that started in 1953 is still remembered not just for its ethics (or the lack of it) but also for its pure evil.

 3. The Aversion Project

The South African Aversion Project was yet another outrageous experiment that was conducted on people. The South African apartheid era was a difficult time to live in for homosexuals.

During that time, the state controlled the sexuality of the people, and the government had strict anti-homosexual laws. Being gay in that era meant that you were abnormal and that you had a disease.

It was considered to be a mental illness, and aversion therapies and techniques were applied in South Africans to cure them of this illness.

The homosexuals were also forced to join the military against their wishes.

The Aversion Project mainly consisted of drugging lesbians and gay men and subjecting them to electroconvulsive behavior therapy. In this therapy, the homosexuals were shown photos of same-sex erotica after drugging them.

Thereafter, they were electrically shocked, and they were shown pictures of the opposite sex erotica. The technique obviously did not work, and the victims were then subjected to hormone therapy.

In some cases, this therapy also included chemical castration.

Moreover, more than 900 men and women had to undergo a gender reassignment surgery to reorient them, without their consent, of course.

 4. Unnecessary Sexual Reassignment

Talking about horrid and controversial psychological experiments, a seven-month-old boy was “accidentally castrated” when he was undergoing a routine circumcision.

After successfully maiming the penis of David Peter Reimer, the psychologist/doctor convinced his parents that the boy was more likely to successfully reach sexual maturation if he underwent a sexual reassignment surgery as a female.

Dr. John Money kept updating the parents on the successful reassignment but during the process, completely failed to take David’s consent.

During his entire childhood, David was incredibly depressed because he was cruelly ostracized and teased by his peers.

He also insisted that never once had he identified himself as a female. Ultimately, he committed suicide at the thirty-eight years of age.

 5. The Milgram Experiments

A psychologist from Yale University named Stanley Milgram conducted one of the most popular obedience studies that have been carried out in psychology to date.

His psychological experiment consisted of analyzing the conflict between personal conscience and obedience to authority.

In 1963, Milgram examined justifications that were offered by the people accused during World War II on their acts of genocide.

More often than not, their defense was based on the word “obedience” and that they were merely following their superior’s orders.

Therefore, Milgram wanted to examine whether the Germans were naturally obedient as justified for the Nazi killings during that time or there was another reason behind the cruelty.

Based on this experiment, Milgram chose participants through newspaper advertising, urging them to participate in a study at Yale University.

Each participant was then paired with another participant. One was the learner, and the other was the teacher. The learner was actually a confederate of Milgram who was pretending to be an actual participant.

The learner was taken to one room whereas the teacher was taken to the other. The teacher’s room consisted of an electric shock generator as well as a row of switches that ranged from 15 volts to 450 volts.

The aim of the experiment was to research exactly how far people were willing to go in order to obey an instruction if that entailed harming another person.

Milgram was very interested in understanding how ordinary people could so easily be influenced into carrying out atrocities on other people.

Despite the nobility of his cause, the entire experiment was highly unethical as the participants were given incomplete information to lure them into the study.

 6. Stanford Prison Experiment

The SPE experiment was conducted in 1971 at Stanford University. It was one of the most compelling psychological studies and went on to talk about human nature in all its simplicity.

In the study, participants pretended to be either guards or inmates in a mock prison at the university. The experiment then began, and the “mock guards” started mistreating the “prisoners.”

The premise of the experiment was that when people are given a certain amount of power over others, they will eventually start to abuse that power.

On the flip side, people who are put in a powerless situation will often be driven to submission or even madness.

Given its controversial nature, the Stanford Prison Experiment has been cited in countless introductory psychology textbooks.

The findings of the experiment were extremely wrong, not just because of the absence of concrete or questionable ethics but due to deceit. 

 7. The Monster Study

The Monster Study experiment of 1939 was an admirable experiment on the part of Dr. Wendell Johnson who was a speech pathologist. He wanted to understand the cause of stuttering.

Therefore, he conducted an experiment on a group of children at an orphanage in Davenport Iowa. Johnson did not agree with the prevalent belief that stuttering was an inborn trait and therefore, could not be corrected.

As a part of the study, Johnson experimented on 22 orphans and put them into two groups of stutterers and non-stutterers.

Only half of the kids in the stuttering group were actually stutterers.

Throughout the experiment, the non-stutterers enjoyed heavy praise, thanks to their conventional speech patterns.

On the other hand, the stuttering group continually received negative reinforcement, and they were always put on edge as a reminder not to stutter.

Johnson concluded that the kids who did have stutters in the stuttering group were actually worse than before and the ones who didn’t in the same group started stuttering by the end of the experiment.

Having established that the problem was developmental instead of being an innate trait, Johnson bid adieu to the 11 stuttering orphans.

Courtesy of Dr. Johnson, a good number of kids and their parents were left with a lifelong struggle.

 8. Monkey Drug Trials

Monkey Drug Trials Psychological Experiment
Source: Geoff Gallice/Wikimedia Commons

The Monkey Drug Trial in 1969 is another one of those psychological experiments that entirely crossed the line.

Despite this trial helping psychologists understand drug addiction better, the three researchers who conducted this experiment at the University of Michigan Medical School completely overstepped their mark.

The researchers hooked Macaque monkeys on illegal substances and injected unwitting primates with several drugs such as cocaine, morphine, amphetamines, and alcohol.

They did this to see if the monkeys would later actively administer doses of these substances to themselves.

Many monkeys did, and the researchers were able to establish a link between psychological dependence and drug abuse.

However, the experiment still has questionable scientific value as the same results might not hold credibility in humans.

In addition to that, despite the establishment of a link, the method was definitely unethical as well as cruel as some of the monkeys died during the experiment.

 9. Robbers Cave Experiment

The Robbers Cave Experiment was organized by the psychologist Muzafer Sherif in the Robbers Cave State Park, Oklahoma.

Sherif requisitioned boys of the age group of 11 and 12 for the experiment and split them into two groups.

Initially, both the groups were blissfully unaware of each other’s existence. After bonding for a few days, the two groups competed with each other in many games.

Given the nature of the games, there was already competition and tension amongst the two groups of boys.

The situation heightened when Sheriff manipulated the results of the game to bring the game scores exceptionally close.

The last part of the experiment, fortunately, involved both the groups working together to achieve a common objective.

According to the results of the investigation, it was deduced that one group had boys who all got along with each other.

This experiment is clearly controversial as it uses children as test subjects without their consent or even awareness.

 10. Brown Eyed Versus Blue Eyed Students

Jane Elliott is a famous teacher who got popular for her brown eyes/blue eyes exercise. This experiment went on to demonstrate the impact of racism on education.

The morning after the assassination of Martin Luther King, Elliott reached her class and informed her students that the way in which things were done was going to change.

She placed the blue-eyed children at the front of the classroom.

They were given an additional recess time, pride of place in the front of the classroom, a second helping of meals during lunch and active participation in class discussions. On the contrary, the brown-eyed children had to sit at the back of the class.

Moreover, they were severely reprimanded for all those things that the blue-eyed kids usually got away with.

Elliott even went through all the trouble of making up a scientific fact that supposedly stated blue-eyed people to be more intelligent than the brown-eyed ones, thanks to the presence of melanin.

The results of the study were stunning. The blue-eyed students performed much better in the assignments whereas the brown-eyed students who usually showed a much better performance in the class were found struggling.

The blue-eyed students were also vicious with the brown-eyed ones.

The next day, Elliott reversed the exercised and the same results were found. However, the brown-eyed students were not as vicious with their taunts.

At the end of the exercise, both the groups of children hugged each other and cried.

They had learned an essential lesson in racism, even though the process was not entirely moral.

 11. The Little Albert Experiment

The Little Albert Experiment
Source: John B Watson/Wikimedia Commons

John Watson is a popular psychologist, and people know him as the “Father of Behaviorism.” He was known to use orphans in many of his experiments.

In one of those especially unethical and well-known experiments, Watson employed the use of Little Albert, an orphan of nine months old.

In this experiment, Watson exposed Little Albert to many sights and sounds.

This included monkeys, rabbits, different masks and a burning newspaper. In the second part of the experiment, Little Albert was introduced to a white rat.

Much like the earlier things, Little Albert was not scared of the rat. But then, every time Albert touched the rat, Watson made loud noises with a bar made of steel.

This distressed Little Albert as he thought that the noise was coming from the rat. Over time, he showed fear of anything white and/or fluffy.

This proved Watson’s hypothesis that it was possible to condition the element of fear in people.


History has shown the cruelty of humans towards other human beings and species in their quest to find answers to some questions.

In this quest, they forgot about ethics and morals which led to severe repercussions and in some cases, scared adulthood where children are involved.

However, it is good that people have learned from history and now, researchers need to seek prior permission before conducting experiments with human subjects.

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