Multiple personality disorder (MPD), commonly also known as dissociative identity disorder (DID) is a psychological ailment in which a person suffers from having several disparate identities (called ‘alters’) each of which has a distinct way of perceiving and responding to the world around and consequently different character traits, behavioral patterns and temperaments. Each of the alters may assume a different name, and have distinct ways of speaking (even different vocabularies and languages), dressing and carrying himself or herself, as well as a different stock of memories and feelings. In some cases, the alters may even have diverse physical characteristics: thus, one alter may be allergic to certain substances while the other may not be; one may have normal vision while the other may have eyesight problems. The switch from one personality to another may occur very swiftly in a matter of seconds, and the person typically has no recollection of his or her thoughts and actions as another person. The switch occurs as a response to a change in the patient’s immediate environment and is induced by a process of self-hypnosis, whereby the person enters a trance-like state in which he or she behaves completely differently from his or her ‘normal’ conduct. This is why the condition is called dissociative identity disorder. The number of alters may vary greatly from patient to patient; though a fairly large percentage of the patients have less than 10 distinct identities, in some cases the number may be close to a hundred. Some of the alters may be completely fantastical and even non-human. Other manifest symptoms of this condition include depression, suicidal tendencies, forgetfulness, vacant spells during which the person loses all sense of space and time, and a frequent inability to recollect where one has been or what he or she has been doing.
It has been observed that an overwhelming majority of the sufferers of this condition are women. The chief cause behind MPD is a history of abuse or trauma during childhood. A child who has gone through severe trauma, such as a major accident, or has had the experience of being mentally, physically or sexually abused may develop this ailment. This happens because the impressionable psyche of the child finds it too unbearable to withstand the mental stress caused by such disturbing experiences. As defense mechanism, the ego dissociates itself from the traumatic experience and assumes several other forms that manifest themselves as the different alters. Thus, the best way to treat MPD is through sessions of hypnosis that help the alter egos interact with one another and thereby gradually reconcile with the individual’s primary personality.