Material on multiple personality disorder is highly controversial within psychology and psychiatry these days. There has been a dramatic increase in the diagnosis of multiple personality disorder, and many clinical specialists think that this is caused by childhood sexual abuse, especially ritual Satanic abuse. The fact that hypnosis is also considered by some as a state of multiple consciousness means that these two phenomena are closely linked.
Baker, Robert. They Call it Hypnosis. Prometheus Books. A psychologist examines (critically) the notion that hypnosis is a special state and argues along with many other psychologists that hypnosis ought to be understood as closely related to perfectly normal states of consciousness and social role playing. The book has a good treatment of the history of hypnosis and how it has been considered at various times. Especially strong on the valid and invalid uses of hypnosis. Whatever else hypnosis may be, most experts on the topic agree that age regression, getting at deeply repressed memories, putting people in contact with past lives, and the like are bogus claims.
Bliss, E.L. Multiple Personality, Allied Disorders, and Hypnosis. Oxford University Press, 1986. A defense of the disorder as representing responses to traumatic experiences.
Gault, Alan. A History of Hypnotism. Cambridge University Press, 1992. A large, scholarly, and encyclopedic treatment of the topic.
Hilgard, Ernest R. Divided Consciousness: Multiple Controls in Human Thought and Action. Wiley, 1977. A distinguished psychologist and the foremost expert on hypnotism presents his own model suggesting that hypnosis represents a state of divided consciousness and dissociation. This book is quite technical in places but remains the best introduction. Hilgard=s earlier, Hypnotic Susceptibility (Harcounrt, Brace, Janovich, 1965) is also worth consulting.
Lynn, S.J., & Rhue, J. (Eds.) Theories of Hypnosis: Current Models and Perspectives. Guilford Press, 1991. A solid compendium of papers, some fairly technical.
Piper, August. Hoax and Reality: The Bizarre World of Multiple Personality Disorder. Jason Aronson, 1997. The title tells you everything you need to know.
Ross, C.A. Multiple Personality Disorder: Diagnosis, Clinical Features, and Treatment. Wiley, 1989. A treatment that is favorable to the notion of MPD as a separate syndrome with its own special causes. Ross is a leading proponent of the idea that MPD is caused by ritual abuse.
Shorter, Edward. From Paralysis to Fatigue: A History of Psychosomatic Illness in the Modern Era. (*) Free Press, 1992. Readable and fascinating. The author places dissociative disorders in the historical context of the development of hypnosis and hysteria (psychologically induced bodily paralysis).
Spanos, Nicholas P. Multiple Identities and False Memories. American Psychological Association, 1996. Spanos is a leading critic of the idea that there is any special hypnotic state, and in this book he shows that MPD is indeed like hypnosis in that both can be explained through ordinary social and cognitive factors. He also discusses spirit possession as a closely related phenomenon. A good review of the literature on these topics.