In 1973 David Rosenhan published On Being Sane in Insane Places in the journal Science. Rosenhan sent healthy individuals to twelve different psychiatric hospitals. The healthy individuals faked having auditory hallucinations. All were diagnosed as mentally ill and committed. They were put through a forced treatment regime of therapy and antipsychotics as a condition of their release.
The psychiatric hospitals then challenged Rosenhan to send people with fake illnesses to test the psychiatrists and other mental health staff. The psychiatric hospital declared that at least 41 people were fake patients sent by Rosenhan.
Rosenhan revealed it was a ruse. He had sent no fake patients to the hospital over the course of those few weeks.
His research demonstrated how difficult it is to accurately diagnose mental illness. It also illustrated the dangers of involuntary commitment and institutionalized abuse. The Rosenhan Experiment hastened the reduction (but not full abandonment) of involuntary commitment, it resulted in many people being released from institutions and changed the mental health culture in psychiatric hospitals.