In 1973, the American psychologist David Rosenhan sent eight healthy people, and also himself, to visit mental institutions and claim they were hearing voices. All were certified mad; some were incarcerated for a month. Rosenhan’s paper, “On Being Sane in Insane Places,” created a media sensation and a crisis in psychiatry. Doctors, it seemed, unlike suspicious fellow patients, could not tell a lucid stooge from a lunatic.

The ensuing controversy led to the tightening of the “Diagnostic and Statistical Manual of Mental Disorders” (DSM), the “psychiatrists’ bible” that lists mental disorders and their symptoms. The DSM, first published in 1952, is produced by the American Psychiatric Association (APA), which, every decade or two, assembles a hundred or so mental health professionals to review disorders in the light of new science or shifting cultural norms.

A DSM review process is underway, with a new edition—DSM-5—due for publication in 2013. But psychiatry