Controversial and Unethical Psychology Experiments

There have been a number of famous psychology experiments that are considered controversial, inhumane, unethical, and even downright cruel—here are five examples. Thanks to ethical codes and institutional review boards, most of these experiments could never be performed today.

These and other controversial experiments led to the formation of rules and guidelines for performing ethical and humane research studies.


Harlow's Pit of Despair

Rhesus monkey clings to surrogate mother.
Martin Rogers / Getty Images

Psychologist Harry Harlow performed a series of experiments in the 1960s designed to explore the powerful effects that love and attachment have on normal development. In these experiments, Harlow isolated young rhesus monkeys, depriving them of their mothers and keeping them from interacting with other monkeys. The experiments were often shockingly cruel, and the results were just as devastating.

The infant monkeys in some experiments were separated from their real mothers and then raised by "wire" mothers. One of the surrogate mothers was made purely of wire. While it provided food, it offered no softness or comfort. The other surrogate mother was made of wire and cloth, offering some degree of comfort to the infant monkeys. Harlow found that while the monkeys would go to the wire mother for nourishment, they preferred the soft, cloth mother for comfort.

Some of Harlow's experiments involved isolating the young monkey in what he termed a "pit of despair." This was essentially an isolation chamber. Young monkeys were placed in the isolation chambers for as long as 10 weeks. Other monkeys were isolated for as long as a year. Within just a few days, the infant monkeys would begin huddling in the corner of the chamber, remaining motionless.

Harlow's distressing research resulted in monkeys with severe emotional and social disturbances. They lacked social skills and were unable to play with other monkeys. They were also incapable of normal sexual behavior, so Harlow devised yet another horrifying device, which he referred to as a "rape rack." The isolated monkeys were tied down in a mating position to be bred. Not surprisingly, the isolated monkeys also ended up being incapable of taking care of their offspring, neglecting and abusing their young.

Harlow's experiments were finally halted in 1985 when the American Psychological Association passed rules regarding treating people and animals in research.


Milgram's Shocking Obedience Experiments

Milgram's original "shock box" displayed at the Ontario Science Centre.

Isabelle Adam/Flickr/CC BY-NC-ND 2.0

If someone told you to deliver a painful, possibly fatal shock to another human being, would you do it? The vast majority of us would say that we absolutely would never do such a thing, but one controversial psychology experiment challenged this basic assumption.

Social psychologist Stanley Milgram conducted a series of experiments to explore the nature of obedience. Milgram's premise was that people would often go to great and sometimes dangerous, or even immoral, lengths to obey an authority figure.

In Milgram's experiment, subjects were ordered to deliver increasingly strong electrical shocks to another person. While the person in question was simply an actor who was pretending, the subjects themselves fully believed that the other person was actually being shocked. The voltage levels started out at 30 volts and increased in 15-volt increments up to a maximum of 450 volts. The switches were also labeled with phrases including "slight shock," "medium shock," and "danger: severe shock." The maximum shock level was simply labeled with an ominous "XXX."​

The results of the experiment were nothing short of astonishing. Many participants were willing to deliver the maximum level of shock, even when the person pretending to be shocked was begging to be released or complaining of a heart condition.

Milgram's experiment revealed stunning information about the lengths that people are willing to go in order to obey, but it also caused considerable distress for the participants involved.


Zimbardo's Simulated Prison Experiment

Empty prison cell

 Darrin Klimek / Getty Images

Psychologist Philip Zimbardo went to high school with Stanley Milgram and had an interest in how situational variables contribute to social behavior. In his famous and controversial experiment, he set up a mock prison in the basement of the psychology department at Stanford University. Participants were then randomly assigned to be either prisoners or guards. Zimbardo himself served as the prison warden.

The researchers attempted to make a realistic situation, even "arresting" the prisoners and bringing them into the mock prison. Prisoners were placed in uniforms, while the guards were told that they needed to maintain control of the prison without resorting to force or violence. When the prisoners began to ignore orders, the guards began to utilize tactics that included humiliation and solitary confinement to punish and control the prisoners.

While the experiment was originally scheduled to last two full weeks it had to be halted after just six days. Why? Because the prison guards had started abusing their authority and were treating the prisoners cruelly. The prisoners, on the other hand, started to display signs of anxiety and emotional distress.

It wasn't until a graduate student (and Zimbardo's future wife) Christina Maslach visited the mock prison that it became clear that the situation was out of control and had gone too far. Maslach was appalled at what was going on and voiced her distress. Zimbardo then decided to call off the experiment.

Zimbardo later suggested that "although we ended the study a week earlier than planned, we did not end it soon enough."


Watson and Rayner's Little Albert Experiment

Close-Up Portrait Of Rat In Cage
Shanelle Hulse / EyeEm / Getty Images

If you have ever taken an Introduction to Psychology class, then you are probably at least a little familiar with Little Albert. Behaviorist John Watson and his assistant Rosalie Rayner conditioned a boy to fear a white rat, and this fear even generalized to other white objects including stuffed toys and Watson's own beard.

Obviously, this type of experiment is considered very controversial today. Frightening an infant and purposely conditioning the child to be afraid is clearly unethical. As the story goes, the boy and his mother moved away before Watson and Rayner were able to decondition the child, so many people have wondered if there might be a man out there with a mysterious fear of furry white objects.

Some researchers have suggested that the boy at the center of the study was actually a child named Douglas Meritte. These researchers believe that the child was not the healthy boy Watson described, but actually a cognitively impaired boy who ended up dying of hydrocephalus when he was just six years old. If this is true, it makes Watson's study even more disturbing and controversial. However, more recent evidence suggests that the real Little Albert was actually a boy named William Albert Barger.


Seligman's Look Into Learned Helplessness

Camera shy stray dog
Elena Pejchinova / Getty Images

During the late 1960s, psychologists Martin Seligman and Steven F. Maier were conducting experiments that involved conditioning dogs to expect an electrical shock after hearing a tone. Seligman and Maier observed some unexpected results.

When initially placed in a shuttle box in which one side was electrified, the dogs would quickly jump over a low barrier to escape the shocks. Next, the dogs were strapped into a harness where the shocks were unavoidable.

After being conditioned to expect a shock that they could not escape, the dogs were once again placed in the shuttlebox. Instead of jumping over the low barrier to escape, the dogs made no efforts to escape the box. Instead, they simply lay down, whined and whimpered. Since they had previously learned that no escape was possible, they made no effort to change their circumstances. The researchers called this behavior learned helplessness.

Seligman's work is considered controversial because of the mistreating the animals involved in the study.

A Word From Verywell

Many of the psychology experiments performed in the past simply would not be possible today thanks to ethical guidelines that direct how studies are performed and how participants are treated. While these controversial experiments are often disturbing, we can still learn some important things about human and animal behavior from their results. Perhaps most importantly, some of these controversial experiments led directly to the formation of rules and guidelines for performing psychology studies.

7 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. Sperry L. Mental Health and Mental Disorders: an Encyclopedia of Conditions, Treatments, and Well-Being. Santa Barbara, CA: Greenwood, an imprint of ABC-CLIO, LLC; 2016.

  3. Marcus S. Obedience to Authority An Experimental View. By Stanley Milgram. illustrated. 224 pp. New York: Harper &. The New York Times. 

  4. Le Texier T. Debunking the Stanford Prison ExperimentAm Psychol. 2019;74(7):823‐839. doi:10.1037/amp0000401

  5. Fridlund AJ, Beck HP, Goldie WD, Irons G. Little Albert: A neurologically impaired childHist Psychol. 2012;15(4):302-27. doi:10.1037/a0026720

  6. Powell RA, Digdon N, Harris B, Smithson C. Correcting the record on Watson, Rayner, and Little Albert: Albert Barger as "psychology's lost boy"Am Psychol. 2014;69(6):600‐611. doi:10.1037/a0036854

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By Kendra Cherry, MSEd
Kendra Cherry, MS, is a psychosocial rehabilitation specialist, psychology educator, and author of the "Everything Psychology Book."