In the film Fight Club, Edward Norton plays a man who finds the world around him and his own desires for happiness utterly in conflict. Nameless throughout the film, he eventually meets Tyler Durden, a kind of personification of his own id. At the end of the film, the twist is that Norton’s character and Durden are actually different personalities within the same person, in what is supposed to be a form of Dissociative Identity Disorder, or DID.
According to the DSM, diagnostic criteria for DID require 1) the existence of multiple “identity or personality states,” each of which exhibits independent opinions, 2) that two or more of the subject’s personalities are at some point in control, 3) amnesia of “important personal information,” and 4) that symptoms are not caused by substances or medical conditions. Following these conditions, the movie’s presentation of the disorder does seem to fit. Edward Norton’s character does in fact possess multiple personalities. The personality of Tyler Durden takes over his actions when he is asleep, and he also appears to him as a realistic hallucination while he is awake. As stated in the DSM criteria, Edward Norton’s character has no memory of actually “being” Durden, suffering complete amnesia of all the actions Durden performs (the one exception to this is a sexual encounter with Marla, which Norton’s character only experiences as a vague dream). Although it is not explicitly stated, the viewer can reasonably assume that Tyler’s personality is not manifested by drug use or any actual medical condition; Norton’s character does visit a doctor, who only tells him he needs sleep.
Despite the technical alignment of the film’s portrayal of DID with its DSM criteria, it would still appear that the film capitalizes on popular stereotypes of the disorder. One prevalent media stereotype seems to be that the disorder is only manifested in severe cases. Another potential discrepancy that is not addressed in the DSM (or in the textbook, for that matter) is the capacity of DID sufferers to actually interact with their other personalities. Although this may not be impossible, it is certainly not a normal feature of DID.