|MadSci Network: Medicine|
The web site of the National Alliance for the Mentally Ill, http://www.nami.org/, describes Dissociative Identity Disorder (DID), previously referred to as multiple personality disorder (MPD), as involving a disturbance of identity in which two or more separate and distinct personality states (or alternate identities, and sometimes called 'alters') control the individual's behavior at different times. DID is believed to be caused by physical (or sexual) abuse in childhood. Young children who are abused may learn to use dissociation as a defense. In effect, the child slips into a state of mind in which it seems that the abuse is not really occurring to him or her, but to somebody else. In time, such a child may begin to "split off" alter identities. In treatment for DID, the therapist seeks to make contact with "alters" to understand their roles and functions in the patient's life. The goal of the therapist is to enable the patient to achieve breakdown of the patient's separate identities and their unification into a single identity.
When under the control of one identity, the person is usually unable to remember some of the events that occurred while other personalities were in control. A very common complaint in people with DID is episodes of amnesia, or time loss. These individuals may be unable to remember events in all or part of a proceeding time period. They may repeatedly encounter unfamiliar people who claim to know them, find themselves somewhere without knowing how they got there, or find items that they don't remember purchasing among their possessions.
This means that it is likely that the a person with DID taking a polygraph test as one 'alter' may not remember what the other alter did, and so would not be lying, but recounting remembered experience.
The problem is that there is still debate about this disorder. So it is a bit of a stretch to decide whether a person with DID could 'lie' to a lie detector when both the disorder and the use of a lie detector are not well understood.
These views are discussed in the Belmont University student P. Michelle Campbell's paper "The Diagnosis of Multiple Personality Disorder: The Debate Among Professionals". (http://www.ac.wwu.edu/~n9140024/CampbellPM.html)
Nicholas P. Spanos wrote about the tremendous growth in the diagnosis of DID since the mid-1970s in the book'Multiple Identities and False Memories: A Sociocognitive Perspective,' published by the American Psychological Association (APA), and written by Dr. Spanos shortly before his death in a plane crash in 1994. It is a wide-ranging and thoroughly documented examination of the scientific literature on the disorder and its possible connection to recovered memories of childhood sexual abuse, reports of satanic ritual abuse, past-life regression and claims of alien abduction. (http://www.apa.org/releases/book.html)
In his book "Rewriting the Soul: Multiple Personality and the Sciences of Memory", Ian Hacking uses DID and its links with the contemporary concept of child abuse to scrutinize today's moral and political climate, especially our power struggles about memory and our efforts to cope with psychological injuries. (http://pup.princeton.edu/titles/5673.html)
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