The 10 most disturbing psychological experiments in history.

Ten of the most famous and cruel experiments in behavioral science.

Today, national and international psychological associations have a code of ethical conduct that regulates practices in psychological research.

Experimenters must comply with various rules concerning confidentiality, informed consent or beneficence. 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 experiments of the past could not have been carried out today because they breached some of the fundamental principles. The following list compiles ten of the most famous and cruel experiments in behavioral science..

10. The Little Albert Experiment

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

Watson tested classical conditioning on a 9-month-old infant he named Albert. Little Albert began by liking the animals in the experiment, especially a white rat. Watson began to pair the rat's presence with the loud sound of metal hitting a hammer. Little Albert began to develop a fear of the white rat, as well as most furry animals and objects. The experiment is considered particularly immoral today because Albert was never sensitive to the phobias Watson produced in him. The boy died of an unrelated illness at age 6, so doctors were unable to determine whether his phobias would have persisted into adulthood.

9. Asch's compliance experiments

Solomon Asch experimented with conformity at Swarthmore College in 1951, putting 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 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 switch by saying the incorrect answers. Asch wanted to see if the participant would conform 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 physical evidence to the contrary. Asch did not ask for informed consent from the participants, so today, this experiment could not have been conducted.

8. The bystander 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 developed an interest in bystanders who did not react to crimes. They were especially intrigued by the murder of Kitty Genoves, a young woman whose murder was witnessed by many, but none prevented it.

The pair 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 would begin to seep into the room after a short period of time. The study showed that the participant who was alone was much quicker to report the smoke than 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. In reality, they were just 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 a seizure. The study showed that the time it took to notify the investigator varied inversely with respect to the number of subjects.. In some cases the investigator was never notified.

7. Milgram's obedience experiment

Yale University psychologist Stanley Milgram wanted to better understand 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 were just following orders? Or, could we consider them all to be accomplices?" In 1961, obedience experiments began.

Participants thought they were part of a memory study. Each trial had a pair of individuals divided into "master and pupil." One of the two was an actor, so there was only one true participant. The research was manipulated so that the subject was always the "master". The two were placed in separate rooms and the "teacher" was given instructions (commands). He or she would press a button to penalize the student with an electric shock each time he or she gave an incorrect response. The power of these shocks would increase each time the subject made a mistake. The actor would begin to moan more and more as the study progressed until he or she was screaming from the supposed pain. Milgram found that most participants complied with orders by continuing to shock despite the obvious suffering of the "trainee.".

Had the alleged shocks existed, most subjects would have killed the "learner." When this fact was revealed to the participants after the study concluded, it is a clear example of psychological harm. It could not be conducted today for that ethical reason.

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

6. Harlow's primate experiments

In the 1950s, Harry Harlowof the University of Wisconsin, investigated infant dependency with rhesus monkeys instead of human infants. He removed the monkey from its real mother, who was replaced by two "mothers", one made of cloth and one made of wire. The cloth "mother" served no purpose other than its comfortable feel, while the wire "mother" fed the monkey through a bottle. The monkey spent most of its time next to the cloth mother and only about an hour a day with the wire mother despite the association between the wire model and food.

Harlow also used intimidation to prove that the monkey found the cloth "mother" to be a greater referent. He would scare baby monkeys and watch as the monkey would run to the cloth 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 got older..... Harlow's experiments ceased in 1985 due to APA rules against the mistreatment of animals as well as humans.

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

5. Seligman's Learned Helplessness

The Ethics of Experiments by Martin Seligman on learned helplessness would also be questioned today for their 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. They then administered a shock that was avoidable if the dog jumped over the barrier to the other half. The dogs quickly learned how to avoid electric shocks.

Seligman's group tethered a group of dogs and administered shocks that they could not avoid. Then, by placing them in the crate and shocking them again, the dogs made no attempt to avoid the shocks, the dogs made no attempt to jump the barrier, they just cried.. This experiment demonstrates learned helplessness, as well as other experiments framed in human social psychology.

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

Muzafer Sherif conducted the robbers' cave experiment in the summer of 1954, conducting group dynamics in the midst of conflict. A group of pre-adolescent 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 were kept separate. The groups only came into contact with each other when they were competing in sporting events or other activities.

The experimenters orchestrated the increase in tension between the two groupsThe experimenters orchestrated the increased tension between the two groups, in particular by maintaining conflict. Sherif created problems such as water shortages, which would require cooperation between the two teams, and required them to 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, as the boys did not know they were participating in a psychological experiment. Sherif also disregarded the informed consent of the participants.

3. The monster study

At the University of Iowa in 1939, Wendell Johnson and his team hoped to discover the cause of stuttering by trying to turn orphans into stutterers. There were 22 young subjects, 12 of whom were the nonstutterers. Half of the group experienced positive teaching, while the other group was treated with negative reinforcement. The teachers continually told the latter group that they were stutterers. No one in either group became stutterers at the end of the experiment, but those who received negative treatment developed many of the same self-esteem problems as those who did not. that stutterers often display.

Perhaps Johnson's interest in this phenomenon has to do with his own stuttering as a child. his own stuttering as a child, but this study would never passbut this study would never pass muster with a review committee.

2. Blue-eyed versus brown-eyed students.

Jane Elliott was not a psychologist, but she developed one of the most controversial exercises in 1968 by dividing students into a blue-eyed group and a brown-eyed group. Elliott was an elementary school teacher in Iowa and was trying to give her students a hands-on experience about discrimination the day after Martin Luther King Jr.. was assassinated. This exercise still has relevance to psychology today and transformed Elliott's career into one focused on diversity training.

After dividing the class into groups, Elliott would cite that scientific research showed one group to be superior to the other. Throughout the day, the group would be treated as such. Elliott realized that it would only take one day for the "superior" group to become more cruel and the "inferior" group more insecure. The groups then switched so that all students suffered the same prejudice.

Elliott's experiment (which he repeated in 1969 and 1970) received a lot of criticism because of the negative consequences on students' self-esteem, and therefore could not be carried out again today. The main ethical concerns would be deception and informed consent, although some of the original participants still consider the experiment to be life-changing.

1. The Stanford Prison Experiment

In 1971, Philip ZimbardoZimbardo, of Stanford University, conducted his famous prison experiment, which aimed to examine group behavior and the importance of roles. Zimbardo and his team chose a group of 24 male college students, who were considered "healthy," both physically and psychologically. The men had signed up to participate in a "psychological study of prison life," 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 Stanford's Psychology Department, where Zimbardo's team had set up a makeshift prison. The experimenters went to great lengths to create a realistic experience for the prisoners, including fake arrests in the participants' homes.

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

Zimbardo explained, "Within days, the guards became sadistic and the inmates became depressed and showed signs of acute stress. "Two prisoners dropped out of the experiment; one eventually became a psychologist and prison consultant. The experiment, originally intended to last two weeks, ended prematurely when Zimbardo's future wife, psychologist Christina Maslach, visited the experiment on the fifth day and told him, "I think it's terrible what you're doing to those boys."

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

• Read more about Zimbardo's research in: "The Stanford Prison Experiment."