There are a few approaches to psychological disorders. These are the biological, psychodynamic, behavioral, cognitive, humanistic, cultural and diathesis-stress approach. For disorders like the DID, it involves the unconscious mind making up different personalities. The common approach to split personality disorders is the psychodynamic approach. This focuses on the conflict between the conscious and unconscious part of the mind. The disorder arises because you repress your urges, so your unconscious mind conjures a personality to resolve this conflict.