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?

1. The [Pygmalion effect](http://en.wikipedia.org/wiki/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.
   — PhilosophicalFarmer


2. 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 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 taking 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.] (http://www.bonkersinstitute.org/rosenhan.html)
   — manlikerealities


3. 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 not be remembering as clearly as they think.
   — PMMeKaraokeRequests






4. 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 slot machine, and Skinner with Casino, and you've got yourself a recipe to exploit the shit out of some desperate and bored people.
   — JoshwaarBee


5. Somebody can fill in the details: 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.
   — ToyVaren


6. 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.
   — wepwepwepwe






7. 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.
   — luminousbeing9


8. The cognitive dissonance theory by Festinger.Its the procedure through which if we’re pressured to do something we don’t like or it’s contrary to our beliefs,we rate it better than we usually would although the act and our stance are contradictory,and all that happens because of our need for internal consistency
   — ventou