The 7 most controversial psychological experiments of all time

Last updated on March 17th, 2023 at 04:59 am

Psychology is a fascinating field that seeks to understand the human mind and behavior. Psychologists have uncovered numerous insights into how we think, feel, and act through research, experiments, and observations.

However, not all psychological experiments have been met with widespread acceptance and approval. Some experiments have been so controversial that they have sparked ethical debates and even legal action.

From the infamous Stanford Prison Experiment to the controversial Milgram obedience study, let’s delve into the details of each experiment, examine the ethical considerations that arose, and discuss their lasting impact on psychology.

The Stanford Prison Experiment

Kickstarting our list is the controversial Stanford Prison Experiment. Dr. Philip Zimbardo conducted this experiment in 1971 to observe what would happen when you put good people in bad situations.

He took 24 male students and split them into two groups: prisoners and prison guards. The prisoners were stripped of their clothes and given smocks, while the guards were given uniforms and nightsticks.

The study was intended to last two weeks but shut down after six days due to the horrific conditions.

The ‘prisoners’ were constantly harassed and abused by the ‘guards.’ As a result, some even began to show signs of mental breakdowns due to psychological and physical abuse.

This study is still controversial today, with many people arguing that the participants should never have been put in such a position in the first place. However, it undeniably helped shape our understanding of how power can affect people’s behavior.

The Priming Experiment (Elderly Words Provoke Walking Slow)

Next on our list is a study conducted in 1998 by John Bargh. This experiment is often known as the ‘elderly words provoke walking slow’ study, which aimed to observe how subliminal messaging can affect behavior.

They had two groups complete a word association task to do this. One group was given words related to the elderly (for example, ‘wrinkled,’ ‘grey,’ and ‘bingo’), while they gave others neutral words.

The participants were then asked to walk down a hallway, with the researchers timing how long it took them to reach the end.

Unsurprisingly, those in the first group who had been exposed to words related to the elderly walked down the hall significantly slower than those in the second group.

This study was controversial at the time as it questioned how much control we have over our behavior.

At the time, many people were worried that if advertisers and others could influence our behavior in such a way, we would no longer be able to make our own decisions.

However, this was mainly so controversial because it was later debunked. A different lab led by Stephane Doyen could not produce the same results.

While there’s a lot of hearsay and rumors, social priming is a controversial phenomenon that can have dangerous consequences.

Bargh’s original experiment was flawed, inconsistent, lacked thoroughness, biased, and subject to equipment errors.

Even today, it’s still unclear exactly how much subliminal messaging can influence our behavior. 

The Milgram Experiment

Another well-known and controversial experiment is the Milgram experiment conducted in 1961 by Stanley Milgram. This study observed how far people would go in obeying an authority figure, even if it meant harming another person.

Not coincidently, this experiment took place three months after the trial of Adolf Eichmann had started in Jerusalem. 

This iconic experiment attempted to break down the effects of genocide psychologically and see whether Eichmann and others like him were ‘following orders’ during the Holocaust or were evil beings.

He recruited participants and told them they were participating in a study about memory and learning.

They were then paired with another participant, who was an actor, and the test subjects were told to shock them whenever they got an answer wrong.

The shocks were fake, but the actors pretended to be in pain. Even pre-recorded electrical shock sounds were played through the room to ensure the shock seemed authentic.

The actors were strapped to the chair, and the participant was told that this was to ensure the actors could not leave, no matter how bad it got.

The participants were also given a real electric shock before the test to provide them with an idea of what the actors would be going through.

And so the test commenced.

The test was simple. Lists of pairs of words were given and recalled by the participant and the actor.

The participant would then provide a list of four possible answers, and the actor would use a button to identify which sequence of words was correct.

If they were wrong, they would receive an electric shock, and the voltage would be turned up by 15 volts, with the max being 450 volts.

Of course, as the voltage was increased, the actors would pretend to be in more pain. In later versions of the experiment, some actors would even beg for mercy or plead that they had a heart condition. But still, the shocks continued.

Whenever the participant started to show signs that they wanted to stop the experiment, or at least not carry on, the experimenters replied with these statements, in this order of severity.

1. Please continue or Please go on.
2. The experiment requires that you continue.
3. It is absolutely essential that you continue.
4. You have no other choice; you must go on.

They would move on to the next if the first statement didn’t work. The experiment would stop if the participant didn’t continue after the fourth prompt.

As the test was run, 65% of the participants made it to the final 450-volt mark, all participants making it to at least the 300-volt mark, showcasing that people will go to great lengths to obey authority figures.

This study was controversial because it showed how easily people could be coerced into harming others, even if they don’t want to. It also raised ethical concerns about the use of deception in research.

Despite these concerns, the Milgram experiment is still considered a critical study, providing insight into how people respond to authority figures.

The ‘Little Albert’ Experiment

One of the most controversial psychological experiments of all time is the ‘Little Albert’ experiment, conducted by John Watson and Rosalie Rayner in 1920. This study aimed to observe how fear could be conditioned in a child.

To do this, they used a nine-month-old boy who was called Albert. He was exposed to several animals, including rats, rabbits, and dogs. Each time he saw them, he was given a slight shock.

After some time, Albert began to show signs of fear whenever he saw any of the animals, even if he wasn’t shocked. This showed that fear can be conditioned in children and doesn’t happen naturally.

The ‘Little Albert’ experiment was controversial because it showed how easy it is to manipulate a child’s emotions. It also raised ethical concerns about the use of animals in research.

Despite these concerns, the ‘Little Albert’ experiment is still considered a critical study, as it provides insight into how fear is learned, enabling us to understand better and treat anxiety disorders.

The Facebook Emotion Experiment

One of the most recent and controversial psychological experiments is the Facebook emotion experiment, conducted by a team of researchers from Cornell University in 2014. This study aimed to observe how social media can affect our emotions.

To do this, they manipulated the news feeds of over 700,000 Facebook users, showing some users positive content and others negative content. They then monitored how these users responded emotionally.

The study results showed that those exposed to positive content were more likely to post positive content themselves, and vice versa for those exposed to negative content.

This study was controversial because it showed that social media could impact our emotions. It also raised ethical concerns about the manipulation of people’s news feeds.

Despite these concerns, the Facebook emotion experiment is still considered an important study, providing insight into how social media can affect our moods and behaviors.

You can see how these controversial psychological experiments have shaped our understanding of the human mind.

While they may have raised some ethical concerns, they are still essential studiesproviding valuable insights into our thinking and behaviore.

Operation Midnight Climax

In the 1950s, the CIA ran what was known as ‘Operation Midnight Climax’ under the highly controversial MKULTRA program.

Under this program, the CIA used prostitutes to lure men back to safe houses in New York and San Francisco, where they would be drugged without their knowledge (usually slipping them into drinks) and observed through one-way mirrors.

Such drugs included illegal chemicals, such as LSD.

Over the decade this program was run, the government was provided with information on how mind-altering drugs and narcotics affected the human mind and their uses. Additionally, it helped develop better surveillance equipment, and there are reports of sexual blackmail.

However, the operation was reportedly shut down in 1965, though some say it continued unofficially under different names.

The Monster Study

In concluding our list, we have one of the most traumatic and controversial studies ever, which became known as The Monster Study of 1939.

It started with two researchers, Wendall Johnson and Mary Tudor, who were deep-diving into how the process and outcomes of positive reinforcement work.

Tudor was interested in how stuttering could be lessened or even cured by providing positive reinforcement to those who spoke without issues.

Sounds reasonable for now.

To figure this out, Wendall and Johnson divided 22 orphaned children between six and nine with no history of speech problems into two groups.

The first group was constantly bombarded with positive feedback and praise for how excellent and fluent their speech was, regardless of what their speech was like.

However, the second group was treated a little differently. They would receive negative feedback and be punished, regardless of their speech fluency.

Things got so bad for this group that one girl even ran away from the orphanage where this was taking place, as reported by the New York Times at the time.

If you put yourself in that position and imagine what life must have been like as a six-year-old going through such trauma, and you have no understanding of why you’ll be quick to see how cruel and controversial this experiment was.

These children carried that trauma with them for the rest of their lives.