multiple personality, a very rare psychological disorder in which a person has two or more distinct personalities, each with its own thoughts, feelings, and patterns of behavior. The personalities often are direct opposites and dominate at different times, with abrupt transitions triggered by distressful events or memories. Each may be entirely unaware of the other but aware of unexplained gaps in remembered time. In psychiatry the condition is known as dissociative identity disorder. The term "split personality," denoting schizophrenia, refers to an unrelated disorder in which the split (separation) is between thought and feeling.
Multiple personality was first recognized and described by the French physician Pierre Janet in the late 19th cent. Public awareness of the disorder increased in contemporary times after a case was the subject of The Three Faces of Eve (1957). In the 1980s and early 90s, such factors as recognition of child abuse, public interest in memories recovered from childhood (whether of actual or imagined events), allegations of so-called satanic ritual abuse, and the willingness of many psychotherapists to assume a more directive role in their patients' treatment, led to what came to be regarded as a rash of overdiagnoses of multiple personality.
The cause of multiple personality is not clearly understood, but the condition seems almost invariably to be associated with severe physical abuse and neglect in childhood. It is believed that amnesia, the key to formation of the separate personalities, occurs as a psychological barrier to seal off unbearably painful experiences from consciousness. The disorder often occurs in childhood but may not be recognized until much later. Social and psychological impairment ranges from mild to severe. The primary treatment is psychotherapy to help the individual integrate the separate personalities.
See study by J. Acocella (1999).
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.