Wikipedia:Multiplicity (psychology)

Multiplicity is the psychological phenomenon in which a body can display multiple distinct personas. This phenomenon can feature in identity disturbance, dissociative identity disorder, and other specified dissociative disorders, among other things. Some individuals describe their experience of multiplicity as a form of neurodiversity, rather than something that demands a diagnosis. Since 1994, the Diagnostic and Statistical Manual of Mental Disorders (DSM) no longer refers to it as "multiple personality disorder", favoring other terms. Multiplicity can also be referred to as personality style defined as "an individual's relatively consistent inclinations and preferences across contexts."

History
Throughout history, concepts of phantoms, muses, and fluid "selves" have been applied to this phenomenon. This has been extended to concepts such as tulpamancy. Additionally, some individuals throughout history have stated that they had been taken over by a spirit, soul, or ghost.

Plato described the soul ("psyche") as tripartite, calling them Logos (rationality), Eros (erotic love), and Thymus (desire). According to Carter,[ Who?] Shakespeare showed examples of this via characters such as Hamlet and Macbeth who had distinct personalities. Carter claimed that Freud supported the notion of different personalities when he came up with the Id, Ego, and Superego, arguing that a split separates the conscious and unconscious mind. Carl Jung proposed: "The many contains the unity of the one without losing the possibilities of the many."

Carter says that Italian psychologist Roberto Assagioli developed psychosynthesis, and hypothesized that an individual may not be consciously aware of their many personae. American psychologist John G. Watkins used hypnosis to bring out different personalities.

Multiplicity as personality styles
Stephen Braude and Rita Carter use a different definition of personality style, defining "personality style" as "personality" and proposing that a person may have multiple selfs and not have any relatively consistent inclinations and preferences in personality. This may happen as an adaptation to a change of environment and role within a person's life and may be consciously adopted or encouraged, in a similar way to acting or role-playing. For example, a woman may adopt a kind, nurturing personality when dealing with her children but change to a more aggressive, forceful personality when going to work as a high-flying executive as her responsibilities change.