Have you ever wondered what some of the craziest, most groundbreaking psychological studies were? You're not alone. Here are some true mind-benders---and they may challenge what you think you know.

The Rosenhan study was performed in the 1970s but is still relevant today.

The researchers feigned hallucinations to enter psychiatric hospitals. Afterward, they behaved as they normally would. They told the staff they felt fine and no longer experienced hallucinations. In the hospital, they were diagnosed with mental disorders (mainly schizophrenia), forced to stay for a prolonged period (average of 19 days), forced to admit to having those illnesses, and had to agree to take antipsychotics as a condition of their release.

The accidental second part of the study occurred when offended clinicians requested Rosenhan send actors to their psychiatric hospital. They felt they'd be able to distinguish who were the real patients and who were the fake ones. Out of 193 patients over 3 months, the staff rated 41 as imposters, and 42 as suspected imposters. Rosenhan had sent no one.

The Pygmalion effect comes to mind.

In one study, the researchers told the teachers they were testing to see which students were gifted. Instead, they selected a few students at random, then told the teachers that they were the gifted ones.

When the researchers returned later, the students they had selected were, in fact, performing better than the other ones, even though they weren't gifted.

Tl;dr higher expectations of people lead to increased performance.

A lot of Beth Loftus' work on memory is super important and worth knowing. In short, they show that memory is fallible and can be tricked--you can make a person remember an event that never happened pretty easily. Her research is one of the big reasons why eye-witness testimony should be often taken with a grain of salt--someone who's "absolutely sure" they remember seeing the defendent...might have just seen some other person and may not be remembering as clearly as they think.

B.F. Skinner's "Skinner Box" experiments, which accidentally laid the groundwork for everything from slot machines to Loot Boxes in modern video games.

He built a box, with a lever inside that would deposit some food into the box. He introduced a pigeon, and the pigeon figured out fairly quickly that the lever gives it food, and so pulls the lever whenever it's hungry.

However, when Skinner modified the box so that the lever would not give food every time, but on a pseudo-random schedule, requiring the bird to pull the lever multiple times to receive the food, the bird would no longer pull the lever only when it was hungry, but would compulsively pull the lever constantly.

Replace bird with Grandma, food lever with a slot machine, and Skinner with Casino, and you've got yourself a recipe to exploit the sh_t out of some desperate and bored people.

A group is shown a symbol, such as the number 0. Each person is asked to say what they see. Every member of the group except 1 is part of the experiment. All of them give the same wrong answer, saying it is a 2, not a zero. The last person will often fold and also say 2 despite their eyes saying it is a 0. While some did say 0, all subjects took longer and felt a strong desire to keep the group consensus.

Also great party trick.

Edit: Shout out to u/ialen2 below for the links to the Asch experiments, they posted it minutes after me but it got buried.

Bruce Alexander's Rat Park experiments - showing that given normal living conditions and normal social bonds, rats will not become addicted to drugs even if those drugs are freely available.

The actual study regarding the effects on the brain after listening to Mozart. So many people believe "playing Mozart for your baby will make them smarter."

1. The study was conducted on college students, not infants.
2. Listening to Mozart only improved one aspect of cognition, which was spatial reasoning (the ability to figure out how objects can fit or be oriented).
3. The effect was temporary, wearing off after less than an hour.

The reason that this study should be more well known is to understand the breakdown between what a study finds and how the message is misinterpreted by the time it disseminates to the general public.

Martin Seligman's book, Learned Optimism, made me much more mindful about something called "explanatory styles." People tend to trend towards optimistic or pessimistic explanatory styles to describe events (good or bad) that happen to them.

Pessimists tend to explain bad things as:

• personal ("This is all my fault"),
• permanent ("This will last forever"), and
• pervasive ("This will undermine everything else I do").

Pessimists will also tend to explain good things as the opposite:

• non-personal ("This only happened because of the rest of my team"),
• non-permanent ("This won't last"), and
• non-pervasive ("This was a one-time fluke in this one project").

Optimists will do the opposite. They explain good events as personal, permanent, and pervasive while providing explanations to bad things that treat them as temporary setbacks.

As a natural cynic and pessimist, I'm doing my best to catch myself when I fall into a cycle of pessimism, and trying to find evidence to suggest that bad things aren't as bad as I'm making them. It's really hard, but I think I'm slowly working towards a healthier balance.

The Monster Study. In speech therapy, kids were given either only positive or only negative feedback and then their progress was charted. To explain this a little further, the kids in the negative feedback group were told that they had a severe speech impediment whether they actually stuttered or not. Kids who didn't even have a stutter developed severe stutters as a result of the researchers constantly telling them that there was a problem with their speech. After hearing it over and over again, they finally started to believe it. Such a messed up study.

Edit: Here's a quote :

To the non-stuttering youngsters ... who were to be branded stutterers, [the graduate student conducting the study] said: "The staff has come to the conclusion that you have a great deal of trouble with your speech... You have many of the symptoms of a child who is beginning to stutter. You must try to stop yourself immediately. Use your will power... Do anything to keep from stuttering... Don't ever speak unless you can do it right. You see how [the name of a child in the institution who stuttered severely] stutters, don't you? Well, he undoubtedly started this very same way."

The children ... responded immediately. After her second session with 5-year-old Norma Jean Pugh, Tudor wrote, "It was very difficult to get her to speak, although she spoke very freely the month before." Another in the group, 9-year-old Betty Romp, "practically refuses to talk," a researcher wrote in his final evaluation. "Held hand or arm over eyes most of the time." Hazel Potter, 15, the oldest in her group, became "much more conscious of herself, and she talked less," Tudor noted. Potter also began to interject and to snap her fingers in frustration. She was asked why she said 'a' so much. "Because I'm afraid I can't say the next word." "Why did you snap your fingers?" "Because I was afraid I was going to say 'a.'"

All the children's schoolwork fell off. One of the boys began refusing to recite in class. The other, eleven-year-old Clarence Fifer, started anxiously correcting himself. "He stopped and told me he was going to have trouble on words before he said them," Tudor reported. She asked him how he knew. He said that the sound "wouldn't come out. Feels like it's stuck in there."

The sixth orphan, Mary Korlaske, a 12-year-old, grew withdrawn and fractious. During their sessions, Tudor asked whether her best friend knew about her 'stuttering,' Korlaske muttered, "No." "Why not?" Korlaske shuffled her feet. "I hardly ever talk to her." Two years later, she ran away from the orphanage and eventually ended up at the rougher Industrial School for Girls --- simultaneously escaping her human experimentation.

A.E., Fisher, conducted an experiment with puppies.

With three test groups, puppies in the first group were treated kindly every time they approached a researcher. Puppies in the second group were punished for approaching the researchers. And puppies in the third group were randomly treated kindly or punished.

The study found that the third group of puppies wound up being the most attached to the researchers.

Universe 25 by Calhoun.

Basically a study of overpopulation. The population of 8 mice in a 9 square feet pen initially doubled every 55 days before growth dropped dramatically after almost a year. Between this point and the final 600th day, the population saw utter breakdown. Aggressive females expelled their young, and the males split into two categories. One was very aggressive violent males who would attack each other, and the other was the 'beautiful ones' - they completely withdrew from mating and all sexual behavior and spent every waking moment grooming. Breeding eventually totally stopped and the behaviors of the mice remained the same until death.

Calhoun has suggested this social breakdown might be the fate of humans.

Harry Harlow's experiments on attachment helped establish the modern paradigm for attachment theory (Mary Ainsworth's "strange situation" experiment was also integral to attachment theory, Harlow's study came first).

Basically (this is a very general summary), Harlow and his assistants cared for the physical needs of these baby rhesus monkeys. Some of the monkeys were given a "mom" that they could nurse from but was not comforting/soft. Other monkeys had a "mom" that they couldn't nurse from but were covered with soft cloth. Both groups of monkeys would be scared by a loud toy.

The principals of strict behaviorism (which was thriving at this time in the history of psychology) would lead you to think that the monkeys who had the mother who could nurse them would find comfort in her while scared, and that the monkeys with the soft "mom" who couldn't nurse would not turn to their moms for comfort.

The opposite happened. The monkeys with the soft moms clung to them for comfort after being scared. The monkeys with the nursing moms did not run to them for comfort.

This was groundbreaking because it threw a curveball at behaviorism and set the course for more research into child development and attachment. Choosing the soft mom and rejecting the nursing mom demonstrated that it's not enough just to have your physical needs met (i.e. food), we also need comfort and reassurance to form attachments to caregivers.

One that hasn't been mentioned yet: the selective attention experiment: tell people to pay really close attention to one thing and they're likely to miss even the most obvious other things that are happening. If this reminds you at all of the echo chambers in certain 'news' organizations these days, you just may have spotted the gorilla...

In the late 1960s, a schoolteacher named Jane Elliot wanted to teach her Iowa 2nd grade students about racism in a way that would really hit home, but how? None of them had seen a black person except on television.

She realized her class was evenly divided between brown eyed and blue eyed pupils (Elliot, herself, had green eyes) and an idea came to her.

One day she walked into class with a Webster's Dictionary that she had covered with brown paper. She announced to her class that this book contained breakthrough science that proved brown-eyed people were inferior to blue-eyed people, and that class would be "adjusted" accordingly.

She segregated her students by eye color for the day.

During the day's lesson, whenever blue-eyed ('superior') students made mistakes, she encouraged them to keep trying. When brown eyed ('inferior') students made mistakes, she said "See? This is because you're inferior."

When brown-eyed students did well, she didn't acknowledge it. When blue-eyed students did well, she lavished praise upon them and lauded their 'superiority'.

As the day wore on, brown-eyed students who had previously been good students began to become disruptive, visibly dejected and expressed a lack of interest in school. Blue-eyed students--even those who had previously been 'bad' students--saw a tremendous improvement in their performance, demeanor, and behavior.

The next day, Elliot announced to the class that she had made a mistake in her reading. Actually, it was the brown-eyed students were superior and the blue-eyed students were inferior.

The class was again segregated, and praise or criticism was leveled to each student accordingly as it had been the day before. Blue-eyed students began acting out and talking about quitting school, while brown-eyed students began to score high marks, learn quicker, and behaved better.

On the third day, she announced to the class that the book was just a dictionary--there was no study, and that she wanted to teach them how judging people based on the color of their skin felt by choosing to treat them differently based on the color of their eyes.

Although the experiment sounds cruel, most of her students interviewed decades later expressed positive opinions about it.

Asch's and Sherif's studies on conformity.

Asch's was a participant was given a line, then a set of three lines of varying lengths, and they had to match the length to the standalone line. Even when they were very obviously completely different lines, a confederate would answer B (if the correct answer was C) and the participant would often go along with that.

Sherif's study was similar. The experimenter would shine a laser pointer (or something) on a blank wall. They would then ask the participants how far it moved (even though it didn't). The first participant was a confederate and would say something like "oh about 4 inches" and then the next person, the participant would ballpark it from that, "like 6 inches" even though they clearly saw it didn't move.

The Stanford marshmallow experiment. They took kids and offered them one marshmallow now or two marshmallows fifteen minutes later. As kids got older they overwhelmingly chose the two over the one. The results show one of the major aspects of maturity: the ability to delay gratification and conceptualize future rewards. This is what makes (most of us) more sophisticated than kids.

Kahneman and Tversky's prospect theory, and loss aversion in particular.

If you win 10 dollars, you're only slightly happy, but you would be disproportionately sadder if you lost 10 dollars, even though the amount of money is the same. People are more impacted by loss than gain, and this explains many of the weird illogical money decisions people make.

Why buy bonds/GIC's when stocks historically make more money? These psychologists won the Nobel prize for their work.

Basically, the researcher, Bandura, had kids in the experimental group watch an adult hit, kick, and otherwise abuse a Bobo doll. Then, when the kids were released to play with it on their own, those who saw adults abuse the doll also used it in that way, hitting and kicking and yelling at it. This has lots of implications about how we acquire behavior but the one that is most important to me is about parenting. A parent who yells at or goes so far as to even hit their kid is essentially doing the same thing as in this experiment; they're setting an example for the child's behavior. And as we see with Bobo dolls, the child will learn.

But yeah, this experiment essentially proved the concept of modeling, which brought new elements into how psychologists saw learning.

Edit: oh yeah and there were also observed effects when the adults were rewarded or punished for beating up the Bobo doll. It showed that people learn about consequences from watching others.

For the sake of remembering all these psychological experiments, Ebbinghaus's memory experiments are quite relevant to know about.

His experiments showed that people forget around 50% of what they have learned after about a day (and 75% after 2 days, and so on) unless they try - and succeed - at recalling it. Then you forget more slowly the next time. If you space your recall tests right before you would naturally forget then this is the most efficient way to remember something in the long run (called the Spacing Effect). There is software that can automate this for you in the event you ever need to memorize something (which almost everyone does at least occasionally, and students do constantly).

Another finding related to his work in memory is that if you have a test in a few days cramming is better for remembering, but only in the extremely short run: you'll forget it all after about a week. So if you need to pass a test tomorrow: cram. If you need to pass a test in 6 weeks, 6 months, or 6 years: spaced repetition.

The Backfire Effect was discovered in the 1950s when a researcher infiltrated a UFO cult that predicted the end of the world, and their group's rescue in the nick of time by a group of benevolent aliens who represented the astral incarnation of Jesus Christ.

When the world didn't end on the predicted date, the researcher was watching specifically to see how they would respond to their worldview being so dramatically disproven. Instead of admitting they were wrong, they doubled down and invented reasons why they'd been right all along.

On further study, the backfire effect seems to affect primarily people with conservative worldviews -- people who believe false conservative ideas are more likely to hang on to those false ideas even after presented with debunking evidence. (Liberals are also motivated to resist evidence that debunks false liberal ideas, but are less likely to invent false justifications for their resistance.)

Here's a great article that describes it.

The Illusion of Truth experiments are extremely relevant in today's society, particularly on Reddit.

There are a few basic tenets.

1. People are more likely to believe something if they hear it multiple times, even if they know it's a lie.
2. If people hear information and then find out later that it was a lie the original information they heard is sticky and they will be more likely to remember it is true. This can occur even if the lie were discovered very quickly.

Kahneman and Tversky's Prospect Theory. Kahneman recently won the Nobel for this and other work. It shows that people are really bad at understanding probabilities and are very influenced by how the message is framed, and whether it is framed as a gain or loss. For a simple example, asking "This surgery has an 80% chance of failure. Do you still want to have it?" Vs. "This surgery has a 20% success rate, do you want to have it?" Gets different answers even though the question is the same. The actual scenarios they used in the original experiments are fascinating and available online- look it up! It definitely changed how I interpret probabilistic decisions.

Not a psychologist, but a psychology major. To add on to the many studies already mentioned, I think Mary Ainsworth's Strange situation is pretty important. She came up with the attachment theory. Basically saying how you form relationships as an infant predicts how you form relationships as an adult.

The Wason selection task. https://en.wikipedia.org/wiki/Wason_selection_task#Use_of_logic

Basically "Are people able to understand if/then statements?" as a larger indicator to ask if people are critical thinkers.

Less than 10% of people got the right answer in more than one study, but if you put it into a context of societal rules, there is a pronounced improvement of how many people get the right answer.

The cognitive dissonance experiment (Festinger) with the result that is the opposite of what you might expect: people following someone's orders were more likely to later decide they agreed with those orders when they were paid LESS to do so. The dissonance: our brains can't handle the conflict between our actions and our thoughts, so it adjusts our beliefs to fit our actions. "If I did that (especially without getting paid much), I must have believed in it." In a replication experiment: If you read scripts to raise funds for a randomly selected organization, you will believe more in that organization (unless you were paid a lot to read the words).

Implication: Signing loyalty oaths actually makes you more loyal (unless you were forced to, and keep that in mind). Also: Sharing statements on social media doesn't just reflect beliefs, it deepens them.

Thanks to Reddit user Berkamin posing the following question: "Psychologists of Reddit: besides Pavlov's classically conditioned dogs, the Stanford prison experiment, and the childhood delayed gratification experiment, what other paradigm-establishing psychological experiments should everyone know about?"

Submissions have been edited for clarity, context, and profanity.