The 7 Most Famous Psychological Experiments of All-Time

Human behavior is a puzzle to us, even after millennia of experience and decades of directed scientific experimentation. This is probably why people love to share and discuss new psychological studies online — even bad ones — especially if they seem to reinforce our own preconceived notions about people.

Below are seven of the most well known psychological experiments. Sadly, most of them are infamous because of their poor scientific method and unspeakable cruelty.

7. Ring a bell?

You may have heard someone describe a reaction as “Pavlovian”, or make reference to Pavlov’s Dogs. This experiment in classical conditioning paired the feeding of food with the ringing of a bell, such that the sound of the bell became associated with eating. Subsequently, Dr. Ivan Pavlov’s dogs learned to drool in response to the bell alone.

6. Waiting for s’more = success at life.

Stanford University professor Walter Mischel conducted the Marshmallow Test in the 1960s and ‘70s, but he also used cookies and other small rewards. A child was given a little treat like a marshmallow and told they could eat it now, or wait for a little bit (no more than twenty minutes) and receive another one, doubling their reward.

Follow up studies indicated that children who delayed gratification ended up doing better in life overall, obtaining higher SAT scores and healthier bodies. Brain scans of these same kids in 2011 (no longer kids) revealed that delayers had more active prefrontal cortices — an area of the brain associated with executive functions such as planning and decision making.

5. What kids see, they do.

Dr. Albert Bandura’s Bobo Doll Experiment at Stanford pitted male and female children against an inflatable clown doll that righted itself upon falling. One set of children watched as aggressive or nonaggressive adults interacted with the blow-up clown. After a series of complex interactions meant to cause frustration, the children were then left alone with the Bobo doll.

Children who had witnessed the aggressive behavior, particularly if the adult in question was the same sex as the child, were significantly more likely to play aggressively with the Bobo doll themselves. Boys were twice as aggressive than the aggressive girls. This study was considered vital to social learning theory, though it continues to receive justifiable criticism.

4. The experiment that had to be cut short.

One of the more disturbing film strips we watched in Advanced Behavioral Psychology was The Stanford Prison Experiment. Dr. Philip Zimbardo separated two sets of paid volunteers into “prisoners” and “guards” in 1971. He was studying the effects of social situations on human personalities and behavior, and was so alarmed by what happened, he cut the study short at six days.

The volunteers for both groups were young, middle class college students. The prisoners were rounded up and processed in a manner similar to real life arrestees, but the guards were given only uniforms — no training. By Day 2, there was a prison uprising which was quelled with overkill tactics, and by Day 3, a “prisoner” had to be released from the experiment because he was having a breakdown.

Guard behavior toward prisoners reached rock bottom so quickly that some prisoners were made to clean toilets with their bare hands. Guards who didn’t think they were being recorded were caught doing terrible things to prisoners at night. The experiment had to be stopped.

3. Just following orders.

In 1961, Yale psychologist Stanley Milgram wanted to know why the Nazis were able to do the horrific things they did to persons in concentration camps. He wondered if all humans submit to authority, even if it causes harm to others. The ad above was put out to entice regular folk to participate, and The Milgram Study of Obedience began.

Participants were told they were administering an electric shock, of which they themselves felt a mild sample, to an unseen learner of paired words — the memory test ruse. Every time the learner got a pair wrong, they were to “shock” him, and the voltage went up in increments of 15 each time.

Nobody was actually getting shocked, but there were some pretty convincing screams and commotion coming from another room. When “teachers” protested, they were told that they must continue the experiment, in this manner:

Please continue.
The experiment requires that you continue.
It is absolutely essential that you continue.
You have no other choice, you must go on.

If the subject refused after those four prompts, the experiment would end. If they did not, nervously carrying on, it would end after three 450 volt shocks were “administered”. Shockingly, sixty-five percent of participants were willing to go all the way, implying that the majority of people will do anything an authority figure tells them.

2. The monster is the experiment.

The Monster Study is not the study of monsters. It is, instead, a monstrously unethical experiment with orphans.

In 1939, University of Iowa grad student Mary Tudor, under the supervision of Wendell Johnson, attempted to induce stuttering in children with normal speech by chastising them for stuttering and teaching orphanage staff to do the same. Under such mistreatment, the six children soon reduced their speaking, became incredibly self conscious, and believed there was truly something wrong with their speech.

The orphanage had to ask Tudor to come back to undo the damage her “study” did.

And number 1, the profoundly unethical aversion conditioning of Little Albert.

Imagine purposefully making a baby terrified of anything white and fluffy, from innocuous little rats to Santa’s beard — and then failing to reverse it. Now you have an inkling of the horrific Little Albert conditioning study published by John Watson in 1920.

The baby was first exposed to a little white rat, a dog, a rabbit, a monkey, and a variety of masks. He naturally was curious about these items and showed no fear of them.

Next, he was shown the white rat again, but this time, Watson made a loud banging sound every time the baby touched the rat. Eventually, Albert would become distressed merely upon seeing the rat he previously enjoyed petting. He would cry and crawl away.

He then generalized this fearful response to the other stimuli with which he had previously been presented. He is believed to have died from hydrocephalus at the age of six, never cured of his conditioned fear of white furry things. His mother was paid $1 for her baby’s participation in this egregiously unethical and barely scientific study.