The Rosenhan experiment was a famous experiment on the validity of the psychiatric diagnosis that the psychologist David Rosenhan carried out between 1968 and 1972. It was published in 1973 in the journal Science under the title "On being sane in insane places " . The study is considered an important and influential critique of psychiatric diagnosis .
Rosenhan's experiment consisted of two parts. In the first part, healthy collaborators or "pseudopatients" (three women and eight men) simulated acoustic hallucinations to be admitted to twelve psychiatric hospitals in five states of the United States . All were effectively admitted and diagnosed with psychiatric illnesses. After being hospitalized, the pseudo-patients behaved normally and informed those in charge of the establishments that they were well and that they had not suffered any further hallucinations. Not only did the medical officers not detect any of the pseudo-patients, but they believed that they were manifesting symptoms of real mental illness. Several were held for months. All were forced to admit that they suffered from a mental illness and to accept medication with antipsychotics as a condition to be discharged. The second part took place when one of the psychiatric facilities challenged Rosenhan to send pseudopatients to his hospital for its staff to detect. Rosenhan agreed, and in the following weeks, of the 193 patients the hospital treated, it identified 41 as possible pseudopatients, 19 of whom had aroused the suspicions of at least one psychiatrist and one other staff member. Actually, Rosenhan hadn't sent anyone to the hospital.
The study concluded: "It is clear that in mental hospitals we cannot distinguish the sane from the insane." Likewise, he illustrated the dangers of depersonalization and labeling in psychiatric institutions. The study suggested that the use of community mental health facilities that were concerned with specific problems rather than establishing psychiatric labels could be a solution and recommended educating workers to make them more aware of the social psychology involved in those facilities.