In 1973 a psychologist sent sane volunteers to mental institutions. All were diagnosed with psychiatric disorders.

It was called the Rosenhan experiment, and if you’ve taken enough psychology courses, this should be old news to you. The experiment was conducted by psychologist David Rosenhan back in 1973. It was published in the journal Science under the title “On being sane in insane places.” Today, the study is reflected on for its importance in psychiatric diagnosis. 

The experiment was carried out in two parts. The first involved sending three women and five men to mental institutions. Each volunteer was to simulate auditory hallucinations to gain admittance into different psychiatric hospitals. Every single one of them was admitted and diagnosed with a psychiatric disorder. 

The volunteers, after diagnosis, were instructed by Rosenhan to act normally and to say that they felt fine and had no more hallucinations. The staff still believed that they were all mentally ill. Some were confined for months. The second part involved a hospital offended by the experiment challenging Rosenhan to send more volunteers to the hospital and see if they could be detected. Rosenhan claimed he sent 193 volunteers to the hospital, and 41 were identified. 

The real twist came when he revealed that he lied, and had truly not sent a single volunteer; the hospital staff had tagged 41 real patients as mentally sane. Rosenhan concluded from this in his study that “we cannot distinguish the sane from the insane in psychiatric hospitals.”