Psychology and science have contributed a lot to human development. It has enabled us to understand the human body and its strengths. Psychologists have performed many various successful experiments. They have provided useful findings of human behavior.

Some doctors conducted illegal studies on human beings. The participants had no idea about the real purpose. The study left them emotionally scarred and physically harmed. Some even died. These atrocities shocked the world. We present to you 10 of the most disturbing human experiments in history.

1 In the infamous “Monster Study,” orphan kids were divided into two groups. The team praised the first group for its speech. They gave negative speech therapy to the second group. These kids were constantly humiliated them for every fluency mistake. Due to this study, some of the subjects retained speech problems for the rest of their lives.

In Iowa, 22 orphan kids were subjected to a stuttering experiment. This study was also called “Monster Study.” This happened in 1939 under the supervision of Wendell Johnson, a psychologist. None of the kids knew about the real intention of the study. All they knew was that they would be receiving speech therapy.

Johnson divided the orphan kids into two groups. In each group, he placed five stutters. The first group received positive speech therapy. The team continuously appreciated these kids for their speech. However, in the second group, the team ridiculed all the kids for their speech.

One of the team members told these kids, “You have many of the symptoms of a child who is beginning to stutter. You must try to stop yourself immediately. Don’t ever speak unless you can do it right.”

The experiment ended after six months. Kids in the second group suffered from the psychological impact of the study. Some of them retained speech problems throughout their entire life. Finally, in 2007, the State of Iowa issued compensation to seven of the orphan children of $1.2 million. (1, 2)

2 David Reimer, an identical twin, had his penis damaged during circumcision. John Money, a psychologist, advised David’s parents to raise him as a girl. However, David had no idea about the truth. At the age of 13, David began to feel uneasy with this new identity. Finally, the truth came out. Later he committed suicide.

In Manitoba, Canada, two identical twin boys were born in 1965. David Reimer was one of the twins. During his circumcision, his penis was burned beyond surgical repair. At that time, David was seven months old. His parents consulted John Money, a psychologist. He suggested his parents raise David as a girl for a healthy future. He recommended the parents set up David for sex reassignment surgery.

For John Money and his team, this case became an experiment. They explored the social learning concept of gender identity. John Money asked both the twins to engage in multiple experiments. In one of those, he forced the twins to rehearse sexual acts involving “thrusting movements.” David played the bottom role. John gave him estrogen hormone for breast development.

However, David had no idea about all this. It is only at the age of 13, he realized that he did not identify with being a girl. He talked to his parents. Finally, they revealed the truth. He underwent the surgery to reverse the sex reassignment. In 2004, he committed suicide by shooting himself, mainly due to unresolved conflicts with his parents and a broken marriage. (1, 2)

3 Led by Dr. Aubrey Levin, the “Aversion Project” was launched in South Africa. At that time, homosexuality was seen as a mental illness. This project aimed to identify gay soldiers and treat them. These soldiers received chemical castration and electric shock treatment. This was done to cure them.

During the Apartheid Era in South Africa, homosexuality was permitted among soldiers. However, it came with its own price. It was seen as a mental illness. Therefore, the military system discriminated against these soldiers. They were not given military leadership positions and were not entrusted with sensitive information.

Dr. Aubrey Levin and his team forced gay soldiers to undergo therapy. This included chemical castration and electric shock treatment. Those who were not “cured” by these methods were pressured to undergo sexual realignment procedures.

These soldiers were not prepared for these atrocities. Eventually, some of the soldiers suffered from depression and committed suicide. This experiment lasted for 18 years.

In 1995, the Medical Association of South Africa issued a public apology for this unethical study. Even after this failed experiment, Dr. Aubrey continued to engage in such forbidden studies. Finally, in 2014, he was sentenced to five years in prison. (1, 2)

4 Philip Zimbardo conducted the Stanford prison experiment in 1971. In the study, he assigned volunteers to be either “guards” or “prisoners” in a mock prison. Soon, the “guards” started exercising their authority. They became violent towards “prisoners.” Due to this inhuman treatment, the experiment was stopped midway.

Professor Philip Zimbardo conducted a social psychology experiment at Stanford University in 1971. It attempted to evaluate the psychological impact of perceived power. He divided subjects into two groups. One group was designated as “guards” who would exercise authority on the other group members, called “prisoners.”

He kept them in a mock prison. He took on the role of the superintendent. Guards received wooden batons and police uniforms to establish their authority. Prisoners wore worn-out clothes along with a chain around one ankle. According to Zimbardo, slowly the guards internalized their new identities. They soon became violent towards prisoners.

Zimbardo had intended the experiment to last for two weeks. However, on the sixth day, Zimbardo’s girlfriend visited the mock prison. She urged him to terminate the study right away. He realized that she was right. So, he stopped the experiment. While the study led to the revelation of some significant facts, it was strongly criticized for its unethical approach. (1, 2)

5 In Guatemala, without any consent, the doctors infected people with syphilis and other sexually transmitted diseases in the 1940s. The study intended to test the medication for curing these diseases. Eighty-three people lost their lives in this devious experiment.

John Charles Cutler, a physician, conducted a series of frightening experiments in Guatemala between 1946 and 1948. Over 1,300 soldiers, prostitutes, mentally-ill patients, prisoners, and even children participated in this study. The team injected these subjects with sexually transmitted diseases like syphilis, gonorrhea, or chancroid without their consent.

The doctors wanted to determine the effect of penicillin on the prevention and treatment of venereal diseases. The team paid infected prostitutes to have sex with prisoners and spread the disease. Unfortunately, 83 people lost their lives due to this study.

Cutler died in 2003. Later, American historian Susan M. Reverby began an inquiry of Cutler’s original documents. She published it in 2010. In October 2010, US President Barack Obama contacted the president of Guatemala, Álvaro Colom. He apologized for the unethical research and its horrifying impact. (1, 2)