These Are The Most Disturbing Psychological Experiments In Human History


Robin Andrews

Science & Policy Writer


We can’t help but be interested in extremes. A few weeks back, we attempted to gather together some of the more visually gruesome ways to perish by nature’s hand – and now, we thought we’d treat you, so to speak, with some of the most disturbing psychological experiments ever conducted.

“Most disturbing” is a tricky criterion to meet, but we’ll certainly give it our best shot. So, let’s start with a classic, shall we?


1 – The Milgram Experiment

Arguably the most infamous psychological experiment of all time, the Milgram experiment has continued to shock and bemuse researchers and the general public ever since it was originally carried out, with variants of it appearing in recent research and even high-profile TV shows.

First conducted by Yale University psychologist Stanley Milgram back in 1963, it was motivated by the trial of Adolf Eichmann, a German Nazi lieutenant colonel and one of the architects of the Holocaust. While on trial, he famously effused that “he was just following orders”, and Milgram wanted to explore this further. Do people do terrible things just because an authority figure ordered them too?

To find out, a deception was devised. In one room, 40 (male-only) participants sat; they were told that in the other, a man being trained to learn paired words awaited their questions.


If they asked a question to test him on said knowledge and he failed to answer correctly, they administered an electric shock. The shocks were at higher voltages for each subsequent question, and cries of pain could be heard from the man in the room until he was apparently made unconscious.

Of course, there weren’t any electric shocks being administered, and the man was an actor. The point was to see how far people would keep going simply because an authority figure was telling them it was fine to do so.

Clearly, such an experiment provided the scientific community with some decidedly ethical pitfalls to explore. It was game-changing in what it aimed to discover, but the potential to inflict trauma on the participants is easy to see – and contemporary replications of the experiment have attempted to circumvent those to varying degrees.

The original paper, published rather appropriately in the Journal of Abnormal Psychology, makes for some fascinating, unnerving reading.


“Profuse sweating, trembling, and stuttering were typical expressions of [the subjects’] emotional disturbance,” it notes. “One unexpected sign of tension – yet to be explained – was the regular occurrence of nervous laughter, which in some subjects developed into uncontrollable seizures.”

Forget about the disturbing nature of the study’s methods, though: what it found out was decidedly chilling. In the original experiment, it was thought that 0.1 percent of participants would go through the entire set of electric shocks. In fact, around two-thirds of subjects continued to shock away, even at the point of apparent unconsciousness on the actor’s part – and still, even in today’s experiments, the majority obey their orders.

2 – The Little Albert Experiment

Don’t be fooled by the adorable-sounding name – this one’s pure nightmare fuel. Taking place at Johns Hopkins University in 1920, John Watson and graduate student Rosalie Rayner let a 9-month-old baby, named “Albert B”, meet a white rat and a collection of other furry objects. He enjoyed it at first, but after a while, Watson snuck up behind the baby and made frighteningly loud noises whenever the rat and toys were available.


Soon, the jump scaring stopped, but, learning to link the fear with the floofies, the baby adversely reacted to their presence. This is an example of emotional conditioning, a variant on classic conditioning, the type people most famously associate with Pavlov and his dog, who was similarly taught to associate food with a ringing bell.

According to the American Psychological Association (APA), only in 2010 was the baby’s identity finally revealed: He was named Douglas Merritte, the son of a wet nurse who was paid $1 for her baby’s participation, which is $13.04 in today’s money.

3 – The Stanford Prison Experiment

Hoo, boy. This one, if you haven’t heard of it already, is legendary for just how chaotic, unpredictable, and disturbing it turned out to be. In the end, the outcome became so infamous that a plaque has been erected at the site of the experiment.


Psychologist Philip Zimbardo, given funding by the US Office of Naval Research, was tasked with finding out what caused friction between guards and prisoners in both the US Navy and the Marine Corps. Setting a makeshift prison up in the basement of Stanford University, a group of physically strong and psychology stable students were recruited, fake arrested at their homes, and split into a group of “prisoners” and “guards".

The researchers sat back, asked them to behave like it was a bona fide jail, and watched what happened. What transpired next has been the focus of movies, documentaries, articles, and heated debate all over the world, but here are the highlights.

Despite having some initial difficulty getting into the role of the guards, on day two, things escalated quickly. One “guard” took on the role of a cruel warden partly out of boredom. Prisoners, referred to only by their numbers, rebelled and formed a blockade within their cells.

As noted by a feature on the BBC, that triggered a change in the guards, who reacted by removing the prisoners of their humanity. They forcefully stripped the prisoners, made them do Sisyphean physical exercises, refused to let them sleep, put them in solitary confinement, prevented them from using the toilet, and more.


The original study noted that “soon, the prison began to smell of urine and feces.”

The prisoners were also split up, with some placed in a privileged, “good” cell, and others placed in a “bad” cell; occasionally, some were switched around. This created suspicion among the more rebellious prisoners that the guards had turned other prisoners into informants, which broke down any unity and trust they had while engendering solidarity among the guards.

Within just a few days, sadistic authoritarianism took hold and prisoners began to drop out. The first left after 36 hours, and “was suffering from acute emotional disturbance, disorganized thinking, uncontrollable crying, screaming and rage.”

Several others soon displayed symptoms of extreme psychological distress, and the experiment was terminated after just six days – over a week earlier than planned – after Zimbardo’s future wife, Christina Maslach, expressed concern.


“Our ex-con consultants later informed us that a very similar kind of tactic is used by real guards in real prisons to break prisoner alliance,” the study explains. “In fact, in a real prison the greatest threat to any prisoner's life comes from his fellow prisoners.”

Once again, the conclusions of the study were equally as distressing: Otherwise good people can do terrible things when given unlimited power.

4 – The Monster Study

With a nickname like that, you know you’re in trouble. Back in the late 1930s, University of Iowa speech pathologist and childhood stutterer Wendell Johnson became convinced that, based on his own life experiences, his affliction commenced simply because he was told he was stuttering by a teacher – and thus, a self-fulfilling prophecy began.


Each case is different, but Wendell was wrong. Such feedback can reinforce stuttering once it’s begun, but that’s not how it starts. According to the NHS, its roots are linked to developmental and potentially neurological problems.

In any case, back then, Wendell wanted to prove his hypothesis. Recruiting graduate student Mary Taylor to lead the charge, they both openly tested the idea if telling a nonstuttering child that they were stuttering could induce the condition.

To do this, they used 22 young orphans, all of whom stuttered, and ideal for testing their theory thanks to a lack of an authority figure in their lives. Ten were known stutterers and were split into two groups of five, half of which were always told their speech is fine and half of which were always told their speech was as bad as people said. The nonstutterers were also divided similarly.

Immediately, the nonstutterers who were told they were stuttering became very reluctant to speak. Some complained of not being able to get the sound out, and their self-esteem plummeted. Detrimental psychological effects linger in some of them to this day, and several became recluses. Although stutter-like behavior was observed, none actually developed the condition.


The study itself was never published, but remnants of it can still be found in the somewhat regretful Taylor thesis, originally published in 1939.

As it turns out, you can’t make a stutterer, but you can partake in an admittedly scientifically valuable but extremely grim experiment that culminated in a multi-million dollar lawsuit against the university and the state. In the end, the unwitting subjects were paid $925,000 for their troubles.


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