How US scientists diagnosed sane people as schizophrenic, tricked by a secret experiment

It was a secret experiment. There was a graduate student, a housewife, a painter, a paediatrician, a psychiatrist and three psychologists. Using fake names, they visited 12 hospitals across the United States and claimed to hear voices. Their mission was to see what would happen. What they found rocked psychiatry.

David Rosenhan, a psychologist at Stanford University, published the results of the experiment in a 1973 issue of the journal Science. “On Being Sane in Insane Places” would become one of the most influential studies in the history of psychiatry.

According to Rosenhan, each of what he called the “pseudo patients” told hospital staff about hearing voices that used the words “empty”, “hollow” and “thud”. The pseudo patients claimed the voices were difficult to understand but sounded as if they came from the same sex as that of the fake patients. Other than making claims about voices and giving themselves phoney names and false occupations, the pseudo patients – Rosenhan among them – made up nothing else. None of them had any significant history of mental illness.

All of them were admitted to psychiatric units, at which point they stopped reporting any psychiatric symptoms. Still, nearly every person in the experiment was diagnosed with schizophrenia. Their hospital stays ranged from seven to 52 days. Doctors prescribed them more than 2,000 pills, including antipsychotics and antidepressants, which the pseudo patients largely discarded.

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In the hospitals, staff often misinterpreted the pseudo patients’ behaviours to fit within the context of psychiatric treatment. For example, the pseudo patients took copious notes while studying the environment of the psychiatric ward. One nurse reportedly wrote in the chart, “Patient engages in writing behaviour”.

Although none of the pseudo patients were unmasked by hospital staff, other patients on the psychiatric units became suspicious of them. Some 35 patients expressed doubts that the pseudo patients were actually mentally ill, according to the study.