I think most of us tend to regard ourselves as one individual, a consistent self. However,in Multiplicity, Rita argues that we consist of a group of unique personalities, each with its own characteristics. She contends that we slide from one personality to another as the situation demands and these many personalities are held together by 'shared memories'.
Part I of the book provides an overview of dissociation and multiple personality that supports the concept of multiple personalities. While some of Rita's examples would be of "normal" people, some seem to better fit for those suffering from Multiple Personality Disorder(MPD). I think human beings are very adaptable, and hence these different personalities come about to help us cope with the situations we face. Hence, the "troublesome" personality is created to help us, and brings some benefit to our psyche as a survival tool.
One would imagine that coercing a personality to "behave" (as Rita recommends) would not have the desired outcome as it may retaliate, if it can, often surreptitiously (as do individuals). If we subconsciously switch on or off personalities (as Rita contends), then one may question how much control do we truly have to summon a particular personality. Rita says that there is no "true self" as we are a collection of our personalities. I believe some readers may feel that this goes too far and that more research is needed in this area to construct a more coherent theory of multiple personalities.
Part II is dedicated to finding each of these personalities within us through a series of exercises. Rita does add that it may require the help of a friend or changes in circumstances to discover all these personalities. There are so many questions that only the most motivated readers would muster the stamina to do them all and moreover Rita does not provide much (empirical) evidence if this process really works well.
I believe the theory of multiple personalities is interesting and does explain some observations that a single personality theory does not. Hence it seems that we need additional research to make this theory more coherent.
