8 VERY CONTROVERSIAL HUMAN EXPERIMENTS - SCIENCE - 2025

Despite all the advances that we can enjoy thanks to science, the history of its development is full of dark and extremely controversial moments. But these controversies, which appear in almost all disciplines of research, occur especially in the field of psychology and the human sciences.

To discover all that we know today about the workings of the mind and body of people, many times very controversial experiments have been carried out with humans and that probably could not be replicated today. Some of them were well regarded at the time, while others were made in secret due to the strong rejection they would have produced even then.

All of them served to advance knowledge about our nature and capabilities, but they did so at a very high price. Even today, many of them continue to spark debate within the scientific community.

1- Experiments with conversion therapy

Conversion therapy is the name given to a series of procedures that are supposed to be capable of changing a person's sexual orientation.

Despite being prohibited in many countries, in some territories and moments in history many of its practices have been carried out. Possibly the most famous moment it happened was during the "South African Aversion Project."

This experiment took place during the apartheid era in South Africa. At this time, the government of the country had very strict regulations against gay people.

The leaders of the territory thought that those who were attracted to individuals of the same sex had a mental illness, and therefore had to undergo some type of therapy.

The problem was, there was no known therapy that could successfully modify a person's sexual orientation. That is why the South African government created the Aversion Project, in which thousands of homosexual people were subjected to all kinds of highly invasive practices to try to change their preferences.

Although various techniques were used during the project, the most widespread was the following. First, the subjects were administered drugs to put them in a suggestible state of mind.

Afterwards, they were shown erotic photographs of people of the same sex, after which they were given an electric shock to make them associate homosexuality with something painful.

Finally, they were shown erotic photographs of heterosexual couples, and they were given more drugs to increase their pleasure, thus trying to change their sexual orientation. Of course, the experiment was unsuccessful.

Unfortunately, the Aversion Project also included more such practices, such as administering sex hormones to subjects or even chemical castration in some cases.

Today, luckily, conversion therapies are totally banned in most countries, as they have been proven not to work and can be extremely harmful.

2- Milgram's experiments

For those who know a little about the world of psychology, probably the first name that comes to mind when thinking about controversial experiments with humans is that of Stanley Milgram. This researcher at Yale University conducted a series of studies on obedience that even today are famous for the controversy they generated.

Milgram wanted to find out how apparently normal people could have followed the horrible orders of Nazi leaders in World War II. To do this, he created a series of studies in which someone outside the university had to act as his assistant in a bogus study on learning.

In these "studies" the participant had to follow the orders of Milgram himself, who told them that they had to press a series of buttons to give electric shocks to a person who was in another room. The shocks were initially mild, but as the experiment progressed, they reached a point where they could be very painful or even fatal.

In reality, the person who seemed to be shocked was an actor, who was not hurt at any time; but the participants thought that the whole process was real.

Still, more than half of those who underwent the experiment actually pressed the button that was supposed to kill the other individual, simply because Milgram had told them to.

These experiments, although they helped to better understand the obedience process, were very controversial because for them to work the participants could not know at any time what was happening. Thus, most of them came to think that they had killed a person, when in reality no one had suffered any harm.

3- The "Midnight Climax" operation

Many of the worst experiments on people took place right after World War II. One of the least ethical was Operation "Midnight Climax", in which the CIA and the United States Army wanted to study the usefulness of drugs such as LSD or heroin to control people's minds.

In Operation Midnight Climax, large numbers of innocent citizens were taken to safe houses controlled by the CIA by prostitutes paid by the government. Once there, drugs like LSD were given to them without their realizing it. Afterwards, the effects of the same were observed through one-way mirrors.

In some variants of this experiment, participants were forced into sensory deprivation chambers to try to understand even better the effects of the drugs.

Although much of what we know today about some substances capable of altering consciousness was discovered thanks to this operation, the method was extremely unethical.

4- The «Monster Study»

In 1939, researchers Wendell Johson and Mary Tudor, from the University of Iowa, designed an experiment in which they wanted to study the possible causes why a person could develop language problems such as stuttering. To do this, they used 22 orphans with whom they carried out one of the least ethical studies in history.

In the "Monster Study", the children were divided into two groups. Speech therapy was given to those in the first group, and they were verbally reinforced when they were able to speak without problems.

However, those in the second group were given negative therapy, designed to cause them to stutter; and they were insulted and humiliated when they had any speech failure.

Although the results were not published at the time, years later it was learned that children in the second group developed all kinds of speech problems. Furthermore, these difficulties remained present throughout her adult life.

5- The Stanford Prison Experiment

Possibly one of the best-known and most brutal experiments in the entire history of psychology is that of Stanford prison, which was carried out in 1971.

Its purpose was to understand the influence of social roles on people's behavior. To do this, 24 student volunteers were divided into two groups: prisoners, and the guard of a fictitious prison.

After this, the 24 students were locked in a replica of a prison, and told that they had to act according to their role. At first both the guards and the prisoners continued to maintain a friendly relationship, but little by little divisions began to appear between them.

The experiment had to last a month; but within a few days the guards began to physically and psychologically abuse the prisoners. Although at first the experimenters (who were observing everything through cameras) wanted to continue with the study, the situation got out of control to such an extent that they had to stop the experiment to prevent any of the students from losing their lives.

6- The blue eyes experiment

Jane Elliott was an American teacher who became famous for her experiment to investigate the impact of racism on education. Shortly after the assassination of Martin Luther King, this teacher took the lead in her class and informed the students that the way the classes were to be conducted was about to change.

Elliott divided his students based on the color of their eyes. Those with the light irises stood at the front of the class. In addition, they were provided with more recess time, more food during lunchtime, and the ability to actively participate during the lessons. Finally, the teacher congratulated them on everything and encouraged them to express themselves and say what they thought.

On the other hand, the dark-eyed students had to sit in the back of the classroom, were given fewer privileges, and were punished for virtually everything they did.

In addition, Elliott made up several studies that allegedly claimed that people with light eyes were more intelligent due to the lower presence of melatonin in their body.

The results were very surprising: children with light eyes began to do better in class, in addition to becoming more cruel to their peers. On the contrary, those with dark eyes saw their grades gradually get worse, as did their self-esteem. Fortunately, at the end of the experiment, the teacher revealed that it had all been a montage.

7- The study of the Good Samaritan

One of the most important areas of social psychology is the study of altruism and helping behaviors. Although many experiments have been carried out in this area, one of the most famous is that of the Good Samaritan, led by several researchers at Princeton University.

The aim of this experiment was to check the probability that a random person acts altruistically and helps another person. To do this, 40 students (who did not know they were participating in an experiment) were invited to give a talk about what it means to be a Good Samaritan. In this way, they were intended to have altruism in mind.

On the way to give their talk, however, the students came across a man who was pretending to need immediate help. In some cases, the actor pretended to have fallen and could not get up; and in others, he was supposed to be having a heart attack. The idea was to see how many of the participants would help the man of their own free will.

Unfortunately, less than 50% of the students decided to stop to help the actor; and in the case of those who witnessed a heart attack, less than 10% stopped.

This experiment, although not as controversial as the previous ones, also involved deceiving the participants and subjecting them to psychological tests without their knowledge and without their consent to do so.

8- The Facebook experiment

One of the most controversial human experiments in history took place very recently, and was linked to the world's largest social network: Facebook.

When what had happened was discovered, millions of people around the world showed their outrage against the popular page, although ultimately there was no negative consequence for its leaders.

In 2012, it was revealed that the social network had analyzed the data of more than 700,000 Facebook users to secretly investigate their psychological characteristics, their emotions and the effects of different publications on them. At the same time, they were manipulated to see how they reacted to certain situations.

For example, Facebook managers collected some of the most used words by each of the users and entered them in fake posts, which they later showed them.

In this way, they found that their clients tended to "catch" the emotions they saw on the social network very quickly, especially if they were similar to those they normally expressed.

Millions of people around the world complained about being manipulated without their consent; But the truth is that Facebook got rid of any kind of negative consequence.

To this day, it is known that the social network continues to analyze and even sell data on the behavior of its users, in what is probably one of the least ethical experiments in history.