In 1973 one of the most striking and eye-opening studies in psychology was carried out by Dr. David Rosenhan. The Rosenhan Experiment was simple: eight sane people would lie their way into being admitted to a psychiatric hospital, and then see if they could truth their way back out.

Dr. Rosenhan wasn’t very optimistic about the state of psychiatry. He believed not only that there would be difficulty in convincing the hospital staff of their sanity once there is an assumption of insanity, but also that methods for detecting and diagnosing mental disorders were only loosely or not at all based in scientific fact.

So the eight people lied their way into the hospital complaining of auditory hallucinations. These pseudopatients in reality were perfectly sane, and the group of eight included psychiatrists, doctors, and Dr. Rosenhan himself. A certain while after being admitted, they all agreed to being acting normal. They didn’t display any symptoms and would have appeared to be totally fine. The problem was that no one believed them. All of them were detained as inpatients for no less than a week, and all of them left with a diagnosis of a psychiatric disorder.

The point would seem proven right there, but Dr. Rosenhan wasn’t finished driving it home. One hospital learned of this experiment and vowed that they would have been able to detect the pseudopatients, challenging Dr. Rosenhan to send some to their hospital. Dr. Rosenhan agreed, and over the next few weeks 41 patients were identified as potential pseudopatients. The thing was, Dr. Rosenhan hadn’t sent any.

All of this went to show the inadequacy with which psychiatric disorders were identified, diagnosed, and handled, as well as the inadequacy with which patients were treated, often with unfettered misbelief, once assumptions had been made about their mental conditions, making it easier for those assumptions to be wrongly confirmed than cleared up. This study shook the foundations of the psychiatric community forever, and has had a huge impact on the culture of patient treatment and diagnosis. These days you’re a lot less likely to be wrongly institutionalized, and for that you have The Rosenhan Experiment to thank.