A partir del volumen 13 número 1 de 2017 la Revista de Medicina y Cine se encuentra alojada en


I was the murderer! Or the Dissociative Identity Disorder in the cinema

I was the murderer! Or the Dissociative Identity Disorder in the cinema

Beatriz Vera Poseck

Psicología Clínica. Universidad Complutense de Madrid (Spain).

Correspondence: Beatriz Vera Poseck. Psicología Clínica. Universidad complutense de Madrid (Spain).

e-mail: Esta dirección de correo electrónico está siendo protegida contra los robots de spam. Necesita tener JavaScript habilitado para poder verlo.

Received 15 October 2006; accepted 20 October 2006


The cinema has been especially attracted by the portrayal of mental illness and those suffering from it. Of all the disturbances of the human mind currently known, Dissociative Identity Disorder (previously known as multiple personality disorder) is undoubtedly the one that has best served script-writers and directors in their films. The surprising manifestations of this illness mean that it is particularly suited as a support for some rather elusive and effect-oriented plots based on unexpected turns of the action that spark the surprise of the spectator. However, the marked interest of the seventh art in dissociative identity disorder has not led to a correct interpretation of the pathology; quite the contrary, in most cases it has been presented in a mistaken and confusing light.

Keywords: Dissociative Identity Disorder, Multiple Personality, Dissociation, Schizophrenia, Twists in Plot, Unexpected Endings.

A brief overview of the dissociative identity disorder

Dissociative identity disorder (DID) is a mental disturbance that is characterised by the presence of two or more identities or states in the same person, each with his or her own, and relatively persistent, patterns of perception, interaction and conception of the environment and of him/herself. At least two of these identities repeatedly control the individual’s behaviour.

Those with the disorder are also unable to recall important personal information and show gaps in their memory that are too profound to be attributed to simple forgetfulness. Many patients also complain of developing strong migraines.

Each personality is lived as a single and exclusive personal history, with individual memories, feelings, traits, and even different names. Some of the personalities may also know and interact with each other within a complex inner world; sometimes they may coexist peacefully and sometimes in conflict. Indeed, it is even possible that open “warfare” may break out.

In most cases there is a dominant personality, called the primary personality, which is subserved by another series of secondary personalities.

The disorder is much more common in women than in men. Its causes are unknown, but most people diagnosed with the disturbance have a secondary diagnosis of post-traumatic stress and most patients refer to sexual abuse in their infancy.

Treatment is mainly based on the use of hypnosis as a therapeutic tool; this allows the different personalities to become manifest so that the therapist may gain access to them and facilitate their integration into a single one.

The dissociative identity disorder in the cinema

DID is a very rare illness but one that is much better known by the general public than other disturbances because it has been widely explored in both the cinema and in literature. Indeed, of all the mental disturbances DID is undoubtedly the one that has been most exploited by script-writers and film directors. The reason for this is very simple: the circumstance of DID enables the director to surprise spectators with unexpected endings and surprising twists in the plot, since the peculiar manifestation of this disorder allows special effects and intellectual tromps d’oeil to be woven into the story, while the director only reveals the true nature of what has been going on at the end of the film.

Thus, the change from one personality to another offers enormous possibilities for DID to be reflected through the use of different characters portrayed by different actors; this is very noticeable in more recent films such as Fight Club (1999) by David Fincher, Identity (2003) by James Mangold, or Session 9 (2001) by Brad Anderson, as compared with older films that seemed to bet on one actor playing a double or even triple role, as in Dark Mirror (1946) by Robert Siodmak. Here, Olivia de Havilland plays two twin sisters, one of them sweet and the other malicious and cruel. Other examples are   The Three Faces of Eve (1957) by Nunnally Johnson, where Joanne Woodward plays Eva White, -a part that won her several awards, among them the envied Oscar- a young woman with three different personalities, or Raising Cain (1992) by Brian de Palma starring John Lithgow, who also plays several different parts.

Unfortunately, however, the great interest shown by the cinema in this disorder has not fostered a correct understanding of the condition: quite the opposite, DID has perhaps been one of the most inaccurately portrayed mental illnesses. This is mainly because the power of attraction of multiple personalities has tended to eclipse other characteristics and symptoms of the disorder, such that with few exceptions what the viewer sees is a stereotyped and biased version of the disturbance based merely on the presence of several different personalities, leaving aside any other symptom/sign also typical of the illness.

The different personalities that emerge from a single individual with DID coexist and relate to one another as though the whole were some kind of family: they may negate any knowledge of each other; they may be critical of each other, or they may even engage in open “warfare” with each other. Most films addressing the disorder have done so through the portrayal of extremely conflictive and violent individuals, involving murder and massacre. This is obviously due to the huge potential impact of this type of plot. In reality, however, such a negative view does not necessarily hold, and indeed there are very few documented cases in which murder or crime have been related to the illness. What may happen is that the personalities enter into conflict, one of them emerging as rebellious, mischievous, infantile and irresponsible, the other appearing as a responsible adult personality prepared to toe the line to social mores. 

Although DID is a diagnostic label that was described only relatively recently, the “spilt personality” phenomenon has attracted attention since time immemorial. More recently (at least relatively), Dr. Jekyll and Mr. Hyde has been one of the plots that has been most frequently adapted to the wide screen over several decades of cinematographic production. Since 1886, when R.L. Stevenson published the novel,  the issue has been considered as the first depiction of DID in fiction, and since the first showing of the corresponding film in 1908 more than 10 different versions have appeared on the screen, again underscoring the fascination that this phenomenon of alter ego, or DID, generates among the public at large.

The interest of the cinematographic industry in DID has persisted almost since the very first films were produced. Since the time of the silent movies dozens of films have espoused personality disorders as their central argument, together with the subsequent appearance of different egos in the same person. In black and white voiceless movies, the work of actors playing dual roles is especially interesting; they often used make-up and costume effects to portray the different “characters”. 1915, for example, saw the opening of The Case of Becky by Frank Reicher, a film starring the famous silent-movie actress Blanche Sweet that recounts the tale of Dorothy, a young women who develops a malicious second personality: Becky. Becky hates Dorothy and along the film we see the cruel havoc she wreaks on those surrounding her.

More recently, and with particular reference to DID, we have The Three Faces of Eve (1957), a film based on a true story of a young woman who develops two different personalities. The film is one of the few that does not fall back on the standard trick of portraying one of the personalities as being necessarily malicious or exhibiting criminal tendencies. The film was produced in a documentary style that reveals the clear interest of the director in underlining the true nature of the case portrayed. A few months before the film was shot, the psychiatrists Corbett Thipgen and Hervey M. Cleckly had published a book recounting the story of Chris Costner Sizemore, a sweet, timid young woman who had attended their consultancy complaining of fearsome and apparently incurable headaches. Along her therapy sessions, a new personality emerges: rebellious and truculent. The book was so successful that the same year the story was used as the basis for the film, directed by Nunally Johnson. The film starred Joanne Woodward, who successively gave life to Eva White, a docile and prim young lady; to Eva Black the brazen seductress, and the final Jane, who the therapists themselves had created to cure their patient.

The happy ending to the film, however, was not so in real life, since the true “Eve” (Chris Costner) finally developed more than 20 different personalities, as she revealed in her memoirs, published only one year later under a pseudonym. Decades later, she went on to publish another book in which she recounts how she finally managed to overcome her problems.

The Sybil phenomenon

When Shirley Ardell Mason, a young woman of 25, began to have visions, nightmares and terrifying recollections, she consulted Dr. Cornelia Wilbur. This was to be the beginning of eleven long years of therapy during which Shirley was to discover that when young she had been subjected to terrifying sexual abuse and other demeaning practices by her mother. Subjected to hypnosis and under the influence of certain drugs, such as Pentothal (colloquially known as “truth serum”), she ended up developing some sixteen different personalities, each of them with its own traits and characteristics: male, infantile, black…. After years of therapy, the doctor managed to help her to gather all her personalities into a single one, number 17, and Shirley was finally cured.

This case could have been just another of the many that abound in the scientific literature except for one thing. This is that at the beginning of the seventies a novel was published in the United States by Flora Rheta Schreiber, entitled Sybil (Sybil, 1973). It was based on the real story of Shirley and soon became a best seller. Owing to its huge success, a few years later a television film based on the novel was made under the same title, Sybil (1976) by Daniel Petries. This was also highly acclaimed. The television version starred Sally Field in the role of Sybil and Joanne Woodward in the role of the psychologist treating her.

For many professionals, this film marked a before/after in the history of DID. This is because at the time of the publication of the novel Sybil, an avalanche of new cases appeared in the United States. Hundreds of people went to the media claiming that they had multiple personalities; dozens of psychologists published case reports… DID “fever” had begun (!) and the American Psychological Association (APA) finally included the disturbance in the Diagnostic and Statistical Manual of Mental Disorders DSM-IV (American Psychiatric Association APA. Diagnostic and Statistical Manual of Mental Disorders DSM-IV-TR 4th ed. Washington, DC.: American Psychiatric Pub, Inc. 2000); that is, DID was received into official circles. Prior to publication of the novel and the film debut, DID had been considered a very rare mental disturbance, indeed so infrequent that the APA did not understand it to be a specific pathology; indeed, fewer than 50 cases had been published worldwide. Over the years after the publication of Sybil, the number of cases diagnosed rose to 40,000 (up to 1998), most of them reported in the United States. The numbers speak for themselves, and the evidence certainly leans towards the existence of a relationship between the media-hyped phenomenon and the disturbance itself. Thus, for many specialists dissociative personality disorder readily arises in susceptible and sensitive people who may find themselves conditioned by their own therapist or by pressure from the media.

DID and schizophrenia: the eternal confusion

The differences between DID and schizophrenia seem to be very clear on paper but not so in everyday clinical practice and much less so on the wide screen. In routine clinical practice, this disturbance and schizophrenia are frequently confused  and in fact some specialists have argued that the number of cases  of DID has been underestimated because the condition has often been mistakenly diagnosed as schizophrenia. This confusion is further exacerbated in the cinema, which has tended to mix and confuse the symptoms of both.

The dissociation brought about by the division of personalities in DID involves a structured separation of normally integrated processes: perception, memory, attention, thought….. In schizophrenia, these processes remain integrated but are deteriorated and corrupted.  In DID the connection with reality remains intact, while in schizophrenia there is an almost complete break with that reality. In DID, the “split” is internal, because it affects the creation of different personalities or egos. In contrast, in schizophrenia there may be an apparent “split” in that the patient hears voices or sees people who do not exist, but in this case these are no new personalities but, instead, hallucinatory creations. Thus, the “split” is in some way external. In DID, The splitting of the person’s personality occurs through a schism within the person, as though the personality were a dividing cell and as though each new cell were a new and different personality. In schizophrenia, the schism occurs between the internal ego of the person and the exterior world; the connection with reality is lost and the person comes to live in a world of falsehoods and mirage.

Because it portrays images that are always seen as being external to the character, together with thoughts and ideas that in reality are internal, the cinema helps to further exacerbate the confusion. Thus, it becomes very difficult to distinguish a split personality from a hallucination because the visual nature of the cinema requires that both DID and schizophrenia must be shown as something external, tangible, and visible to the spectator. Resources such as using two parts played by different actors or conversations between two different personalities kindle doubt in the spectator as to whether what he or she is seeing really exists or is merely a visual representation of a mental process. This is a key point since it determines whether there are hallucinations or not.

This is the case of the film Fight Club, in which it is sometimes difficult to understand Tyler Durden (Brad Pitt) as a personality of Jack (Edward Norton) because throughout the film Jack communicates with Durden as though he (Durden) really existed.

Psycho (1960) by Alfred Hitchcock is a film that has generated a plethora of discussion and deliberation about this issue. For many, the main character of Hitchcock’s oeuvre undergoes a personality splitting typical of a DID, while for others the character is a paranoid schizophrenic who in his delirium has recreated his own mother.

Secret Window (2004) by David Koepp is another film that presents a character with an apparent double personality associated with psychotic behaviour. A similar sort of situation is seen in Dressed to Kill (1980), by Brian de Palma.

One of the techniques used by specialists to determine whether the problem lies in a double personality or in delirium is to ask patients whether the voices heard come from outside their heads (hallucinations) or inside them (the other personality). The job of the psychologist is to determine whether the double personality is the manifestation of delirium or whether it a true personality schism. When all the symptoms accompanying the disturbance except one (the split) have been eliminated, it becomes very difficult to establish a differential diagnosis. Many disturbances share common symptoms and sometimes only very small, subtle details differentiate one diagnosis from another. Accordingly, the cinema often fails to offer a conclusive diagnosis and conflicting stances are generated.

DID as a justification of unexpected endings: the current trend

In recent years, we have witnessed a true explosion of films with a final ace up their sleeves: a surprising twist that leaves the spectator agape. Among this large collection of films, those based on DID are outstanding since owing to the symptomatic nature of the condition it is one of the best ways of addressing and justifying twists in the plot that would otherwise seem unreal. Films such as Session 9 (2001), Identity (2003) or Hide and Seek (2005) by John Polson are some of the most recent ones. In all of them, the key lies in presenting two or more “different” characters that are only revealed to be one and the same at the end of the film.

The plot of Session 9 revolves around two work colleagues who in the end turn out to be the two personalities of the same person. The problem arises in that throughout the film we see that his companions treat him as though he were two different people, such that the final twist is not coherent with the rest of the film. Brad Anderson fails to satisfactorily resolve the duality of the character and, irremediably, when we arrive at the unexpected ending of the film we realise that something has gone seriously awry.

To date, Identity [excepting Sybil and pending the first showing of The Crowded Room (2008) by Joel Schumacher, a film based on a serial killer who develops 16 different personalities] is the only film that has dared to draw the number of personalities to the nth power. Here we are dealing with no less than 11 different personalities that along the film present themselves to the spectator as a group of different characters shut up in a country motel on a rainy day. One by one they are murdered and all of them are seen as potential perpetrators. However, what appears to be a common-or-garden thriller proves to be a glimpse into the mind of a murderer with eleven personalities, each of which is being eliminated one by one (hence the deaths of the characters) by a psychologist along a process of therapy.

Hide and Seek, starring the Robert de Niro-Dakota Fanning tandem, narrates the story of a father and a daughter who, after the death of the mother, move to the country to recover from their loss. The young girl seems to have some kind of invisible friend (Charlie) who ends up being a killer. As the film progresses, we discover that the “friend” was her own father or, more precisely, the second personality of the father. The film, which used a novel marketing strategy such as offering several different endings depending on which movie theatre showed the film, showed in one ending a sequel based on the assumed (and of course wrong) heritability of the condition in which the young girl paints a charming but somehow disturbing picture of herself with two heads.

DID in comedy

The dissociative identity disorder has also been addressed in less formal and more playful terms. 1915 saw the showing of Double Trouble, a romantic comedy directed by Christy Cabanne that revolves around a man (Douglas Fairbanks) with two different personalities who declare open war on each other. Florian is an introvert and finds it very difficult to relate to others, especially women. Brassfield, in contrast, is sociable and extroverted and is keen to join the world of politics.

Of special interest is the version of Doctor Jekyll and Mr. Hyde starring Jerry Lewis in The Nutty Professor (1963), in which Julius Kelp, a socially inept, bumbling professor of chemistry, discovers a magic potion that changes him into Buddy Love, an attractive and seductive playboy. Thus, although during the morning he continues as the withdrawn professor of chemistry during the evening he becomes the famous and acclaimed Buddy Love. Unfortunately, the effects of the potion are unpredictable and disappear at the most inopportune moments, leading to some very funny situations.

Another film meriting special comment is Zelig (1983) by Woody Allen. This time, Allen plays the part of a man with the surprising ability of being able to metamorphose into whoever is beside him: fat, Asian, doctor, Mafioso….. Only Dr. Eudora Fletcher (Mia farrow) seems to be able to cure Zelig through her therapy sessions. As the good doctor explains, just like the lizard endowed with the incredible ability to change colour and pass unnoticed before they eyes of others, the human chameleon Zelig also protects himself by blending in (literally) with those surrounding him. Behind the parodying and fictitious nature of Zelig, Allen, with a passionate interest in psychoanalysis, shows that he has a good command of the underpinnings of human personality. The truth is that although extremely surprising the plot of this comedy is based on real elements. Thus, the different personalities of a person with DID may adopt surprising characteristics: the personality may, for example, be of the other sex or of a different age; he or she may use a new vocabulary; he/she may speak in another language or even develop specific accents in another language, The handwriting of a patient with DID may also vary and some personalities may be left- or right-handed. Zelig is thus a film that takes all traits to comic extremes (Article based on 1).


  1. Vera Posek B. Imágenes de la locura. La psicopatología en el cine. Madrid: Calamar Ediciones; 2006.