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The 10 most disturbing psychological experiments in history

The 10 most disturbing psychological experiments in history

July 19, 2024

Nowadays, the national and international associations of Psychology have a code of ethical conduct that regulates the practices in psychological investigations.

Experimenters must comply with various rules regarding confidentiality, informed consent or charity. The review committees are responsible for enforcing these standards.

The 10 most chilling psychological experiments

But these codes of conduct have not always been so strict, and many past experiments could not have been carried out at the moment because they failed to comply with any of the fundamental principles. The following list compiles ten of the most famous and cruel experiments in the science of behavior .


10. Little Albert's experiment

At the Johns Hopkins University in 1920, John B. Watson conducted a study of classical conditioning , a phenomenon that associates a conditioned stimulus with an unconditioned stimulus until they produce the same result. In this type of conditioning, you can create a response from a person or animal to an object or sound that was previously neutral. Classical conditioning is commonly associated with Ivan Pavlov, who rang a bell each time he fed his dog until the mere sound of the bell made his dog salivate.

Watson he tested classic conditioning in a 9-month-old baby he called Albert . Little Albert began wanting the animals of the experiment, especially a white rat. Watson began to match the presence of the rat with the loud sound of a metal hitting the hammer. Little Albert began to develop a fear of the white rat, as well as most of the animals and furry objects. The experiment is considered particularly immoral today because Albert was never sensitive to the phobias that Watson produced. The child died of an unrelated illness at age 6, so the doctors could not determine whether his phobias would have persisted in his adulthood.


9. Asch compliance experiments

Solomon Asch He experimented with conformity at Swarthmore University in 1951, placing a participant in a group of people whose task was to match the lengths of a series of lines. Each individual had to announce which of three lines was the closest in length to a reference line. The participant was placed in a group of actors who were told to give the correct answer twice and then change by saying the wrong answers. Asch wanted to see if the participant would settle and give the wrong answers knowing that otherwise he would be the only one in the group to give the different answers.

Thirty-seven of the 50 participants agreed on the wrong answers despite the physical evidence on the contrary. Asch did not ask for the informed consent of the participants, so today, this experiment could not have been carried out.


8. The spectator effect

Some psychological experiments that were designed to test the bystander effect are considered unethical by today's standards. In 1968, John Darley and Bibb Latané They developed an interest in witnesses who did not react to crimes. They were particularly intrigued by the killing of Kitty Genoves, a young woman whose murder was witnessed by many, but none avoided it.

The couple conducted a study at Columbia University in which they presented a participant with a survey and left him alone in a room so he could fill it out. A harmless smoke began to seep into the room after a short period of time. The study showed that the participant who was alone was much faster at reporting the smoke than the participants who had the same experience but were in a group.

In another study by Darley and Latané, subjects were left alone in a room and told that they could communicate with other subjects through an intercom. Actually, they were only listening to a radio recording and had been told that their microphone would be turned off until it was their turn to speak. During the recording, one of the subjects suddenly pretends to be having an attack. The study showed that the time it took to notify the researcher varied inversely with respect to the number of subjects . In some cases, the investigator was never contacted.

7. Milgram's obedience experiment

The psychologist at Yale University Stanley Milgram I wanted to understand better why so many people participated in such cruel acts during the Nazi Holocaust.He theorized that people generally obey authority figures, which raised the questions: "Could it be that Eichmann and his million accomplices in the Holocaust just carried out orders? Or, could we consider them all accomplices? " In 1961, obedience experiments began to take place.

The participants thought that they were part of a study of memory. Each trial had a couple of individuals divided into "teacher and student". One of the two was an actor, so there was only one true participant. The investigation was manipulated so that the subject was always the "teacher". The two were placed in separate rooms and the "teacher" was given instructions (orders). He or she pressed a button to penalize the student with an electric shock each time he gave an incorrect answer. The power of these downloads would increase each time the subject made a mistake. The actor began to complain more and more as the study progressed to shouting for the alleged pain. Milgram he discovered that most of the participants complied with orders while continuing to apply discharges despite the obvious suffering of the "apprentice" .

If the alleged discharges had existed, most subjects would have killed the "student". When this fact was revealed to the participants after the study concluded, it is a clear example of psychological damage. Currently it could not be carried out for that ethical reason.

  • Discover this experiment in this post: "The Milgram Experiment: crimes for obedience to authority"

6. Experiments with Harlow primates

In the 1950s, Harry Harlow , from the University of Wisconsin, investigated childhood dependence on rhesus monkeys instead of human babies. The monkey was separated from its true mother, who was replaced by two "mothers", one made of cloth and one made of wire. The "mother" of cloth served for nothing more than its comfortable feeling, while the wire "mother" fed the monkey through a bottle. The monkey spent most of his time next to the cloth mother and only about an hour a day with the mother of cable despite the association between the wire model and the food.

Harlow also used intimidation to prove that the monkey found the cloth "mother" as a major referent. He scared the monkey pups and watched as the monkey ran towards the fabric model. Harlow also carried out experiments where he isolated monkeys from other monkeys in order to show that those who did not learn to be part of the group at a young age, were unable to assimilate and mate when they were older . Harlow's experiments ceased in 1985 due to the APA rules against mistreatment of animals, as well as humans.

However, the Department of Psychiatry of the School of Medicine and Public Health of the University of Wisconsin has recently begun similar experiments that involve isolating infant monkeys by exposing them to frightening stimuli. They hope to uncover data on human anxiety, but resistance from animal protection organizations and the general public has been met.

5. Learned helplessness, by Seligman

The ethics of the experiments of Martin Seligman about learned helplessness would also be questioned today for its mistreatment of animals. In 1965, Seligman and his team used dogs as subjects to test how control could be perceived. The group placed a dog on one side of a box that was divided in two by a low barrier. Then they administered a shock that was avoidable if the dog jumped over the barrier to the other half. The dogs quickly learned how to avoid electrical shocks.

Seligman's group tied up a group of dogs and administered shocks that they could not avoid. Then, by placing them in the box and applying them again, the dogs did not try to jump the barrier, they just cried . This experiment demonstrates learned helplessness, as well as other experiments framed in social psychology in humans.

4. The experiment of the cave of the thieves, of Sherif

Muzafer Sherif carried out the experiment of the thieves' cave in the summer of 1954, carrying out group dynamics in the midst of conflict. A group of pre-teen children were taken to a summer camp, but they did not know that the monitors were actually the researchers. The children were divided into two groups, which remained separate. The groups only came in contact with each other when they were competing in sporting events or other activities.

The experimenters orchestrated the increase in tension between the two groups , in particular maintaining the conflict. Sherif created problems such as water shortages, which would require cooperation between the two teams, and demanded that they work together to achieve a goal. In the end, the groups were no longer separated and the attitude between them was friendly.

Although the psychological experiment seems simple and perhaps harmless, today it would be considered unethical because Sherif used deception, since the boys did not know that they were participating in a psychological experiment. Sherif also did not take into account the informed consent of the participants.

3. The study of the monster

At the University of Iowa, in 1939, Wendell Johnson and his team hoped to discover the cause of the stutter trying to turn orphans into stutterers. There were 22 young subjects, 12 of whom were non-stutterers. Half of the group experienced positive teaching, while the other group was treated with negative reinforcement. The teachers continually told the last group that they were stutterers. No one in any of the groups became stutterers at the end of the experiment, but those who received negative treatment developed many of the self-esteem problems that stutterers usually show.

Maybe Johnson's interest in this phenomenon has to do with his own stuttering when he was a child , but this study would never pass the evaluation of a review committee.

2. Blue-eyed students versus brown-eyed students

Jane Elliott she was not a psychologist, but she developed one of the most controversial exercises in 1968 by dividing the students into a group of blue eyes and a group of brown eyes. Elliott was an elementary school teacher in Iowa and was trying to give her students practical experience about discrimination the day after Martin Luther King Jr . I was murdered. This exercise is still important for current psychology and transformed Elliott's career into one focused on training diversity.

After dividing the class into groups, Elliott would cite that scientific research showed that one group was superior to the other . Throughout the day, the group would be treated as such. Elliott realized that only one day would be enough for the "higher" group to become more cruel and the "lower" group more insecure. The groups then changed so that all the students suffered the same damages.

Elliott's experiment (which he repeated in 1969 and 1970) received a lot of criticism given the negative consequences on students' self-esteem, and that is why it could not be carried out again today. The main ethical concerns would be deception and informed consent, although some of the original participants continue to consider the experiment as a change in their lives.

1. The Stanford prison experiment

In 1971, Philip Zimbardo , from Stanford University, conducted his famous prison experiment, which aimed to examine the behavior of the group and the importance of the roles. Zimbardo and his team chose a group of 24 male college students, who were considered "healthy," both physically and psychologically. The men had registered to participate in a "psychological study of life in prison," for which they were paid $ 15 a day. Half were randomly assigned prisoners, and the other half were assigned prison guards. The experiment was conducted in the basement of the Stanford Psychology Department, where Zimbardo's team had created an impromptu prison. The experimenters worked hard to create a realistic experience for the prisoners, including false arrests in the homes of the participants.

Prisoners were given a fairly standard introduction to prison life, which an embarrassing uniform. The guards were given vague instructions that they should never be violent with the prisoners, but they had to maintain control. The first day passed without incident, but the prisoners rebelled on the second day with barricades in their cells and ignoring the guards. This behavior surprised the guards and supposedly led to the psychological violence that broke out in the following days . The guards began to separate the "good" and "bad" prisoners, and distributed punishments that included push-ups, solitary confinement and public humiliation to the rebellious prisoners.

Zimbardo explained: "In a few days, the guards became sadistic and the inmates became depressed and showed signs of acute stress. "Two prisoners abandoned the experiment; One eventually became a psychologist and prison consultant. The experiment, which originally was to last two weeks, ended early when Zimbardo's future wife, psychologist Christina Maslach, visited the experiment on the fifth day and said: "I think it's terrible what you're doing to those Boys".

Despite the unethical experiment, Zimbardo is still a psychologist who works today. He was even honored by the American Psychological Association with a Gold Medal in 2012 for his career in the science of Psychology.

  • More information about Zimbardo's research on: "The Stanford Prison Experiment"

5 Most Disturbing & Unethical Human Experiments (July 2024).


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