The psychologist is describing a person with a dissociative disorder.
A dissociative disorder is a condition which affects the memory, perception, awareness, or the entire identity of the person suffering from it. Usually this disorder is involuntary, and occurs as a defense mechanism of sorts - when the mind is too traumatized, the disorder may manifest itself in the form of dissociative identity disorder, dissociative amnesia, dissociative fatigue, or depersonalization disorder.