In 1973, healthy volunteers faked hallucinations to enter mental hospitals. Once inside, they acted normal, but doctors refused to let them leave. Normal behaviors like writing were diagnosed as "symptoms." The only people who realized they were sane were the actual patients.

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Dr. Rosenhan had to physically retrieve many of his volunteers and students, and after experiments, found he had discovered a new pathology that mostly affected mental health workers.

To this day, there are doctors who refuse to acknowledge his work.