Dissociative Identity Disorder (DID) is characterized by the presence of two or more separate personality states (dissociative identities), accompanied by gaps in personal agency and sense of self. This means that the person experiencing DID has the impression that certain thoughts, actions, and emotions don't belong to them, as they are sourced from another distinct identity.
You may see DID referred to as
Multiple Personality Disorder or
Split Personality Disorder. These terms are outdated and inaccurate, as DID is a dissociative disorder, not a personality disorder. The new term came into use in 1994.
People with DID describe their experiences in a variety of ways. Some see themselves as multiple people or entities coexisting within one body, while others view themselves as a person composed of independent parts or sides. Dissociative identities may be called alters, parts, headmates, friends, voices, and more. Some people with DID use the term
system to describe themselves collectively.
Each identity within a DID system has a unique experience of the world and distinct relationships with self, body, external individuals, and the environment. This comes with differences in thinking, feeling, moving, sensing, understanding, and interacting. Identities may be experienced covertly through intrusions of feelings, thoughts, and sensations that don’t feel like they belong to the individual. They can also be experienced overtly as different identities taking control of consciousness and functioning, also known as switching.
DID often involves experiences of amnesia, which can include the inability to recall traumatic events, the recent past, daily life details, or the activities of different alters. Amnesia is a diagnostic requirement according to the
American Psychiatric Association (APA), but it is not included in the
World Health Organization (WHO) definition of DID. Even without total amnesia, people with dissociative identities often feel a lack of ownership of particular memories, as if the remembered event happened to somebody else.