1) Dissociative identity disorder is a psychological condition in which a person’s identity dissociates, or fragments, thereby creating distinct independent identities within one individual. Each separate personality can be distinct from the other personalities in a number of ways, including posture, manner of moving, tone and pitch of voice, gestures, facial expressions, and use of language. A person suffering from dissociative identity disorder may have a large number of independent personalities or perhaps only two or three.

2) Two stories of actual women suffering from dissociative identity disorder have been extensively recounted in books and films that are familiar to the public. One of them is the story of a woman with twenty-two separate personalities known as Eve. In the 1950s, a book by Corbett Thigpen and a motion picture starring Joanne Woodward, each of which was titled The Three Faces of Eve, presented her story; the title referred to three faces, when the woman known as Eve actually experienced twenty-two different personalities, because only three of the personalities could exist at one time. Two decades later, Carolyn Sizemore, Eve's twenty-second personality, wrote about her experiences in a book entitled I’m Eve. The second well-known story of a woman suffering from dissociative personality disorder is the story of Sybil, a woman whose sixteen distinct personalities emerged over a period of forty years. A book describing Sybil’s experiences was written by Flora Rheta Schreiber and was published in 1973; a motion picture based on the book and starring Sally Field followed.