(B) In October 1977, a man named Billy Milligan was arrested and charged with abducting and
raping three women on the Ohio State University Campus in the US. What came next made
national headlines. Billy Milligan's public defenders decided that he should plead not guilty by
reason of insanity, claiming that he suffered from multiple personality disorder as a result of
alleged severe physical and sexual abuse as a child by his stepfather. They stated that two of his
other personalities, also known as "alters", committed the crimes he was accused of.
In fact, multiple personality disorder (MPD), or dissociative identity disorder (DID) as it was
renamed in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text
Revision (DSM-IV-TR), is a disorder that causes an individual, known as the host personality, to
have at least two distinct personalities or identities existing within them. Each personality or alter
ego, has their own gender, age and race as well as their own thoughts, emotions, and physiological
reactions. Some alters have been known to have different accents and/or different abilities to the
host. For example, they may paint or sing well, something that the host might not be able to do.
When an alter ego is in control, the individual is generally unaware of what that alter is doing or
thinking. Individuals with DID have at least two identities but can have as many as 100 with ten
being the average number.
It is believed that dissociative identity disorder occurs as a way to cope with severe
childhood trauma, such as physical and/or sexual abuse. In order for a child to deal with the trauma,
he or she detaches or dissociates themselves from the memory in order to protect themselves
psychologically. This detachment can become so extreme that it develops into separate and distinct
personalities that can emerge in response to further psychological stresses. However, there is some
controversy as to whether DID is a real disorder, even though it is listed as such in
the DSM-IV-TR. Many psychiatrists question its validity as a disorder for a number of reasons.
Only 3% of psychiatric hospital patients have been diagnosed with it; the majority of child abuse
victims never develop the disorder, and many DID sufferers were never abused as children