Eight sane people got themselves committed to psychiatric hospitals — on purpose

In 1973, psychologist David Rosenhan and seven healthy volunteers faked a single symptom to get admitted to psychiatric hospitals, then acted completely normal afterward. Staff never caught on — other patients often did — and all were discharged only after agreeing they had an illness 'in remission'. It became a landmark critique of how easily a diagnosis turns into a label you can't shake.

— David Rosenhan, On Being Sane in Insane Places — Science, 1973