Definitions of abnormality

 "If sanity and insanity exist how shall we know them?" David Rosenhan: 'On being sane in insane Places" (1973).

 "How can you tell who's sane and who's insane?' Homer Simpson: 'Stark raving dad' (1991).

In 1973 the psychologist David Rosenhan rang up eight of his friends and asked them what they were doing for the next few weeks. This call launched one of the most famous psychological experiments ever conducted.

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