Abnormal Psychology

Dissociative and Somatoform Disorders 347

your face in a mirror). These researchers found evidence that genetic infl uences ac-

count for 48% of the variance in measures of pathological dissociative experiences

and 55% of the variance in measures of nonpathological experiences. In other

words, almost half the variation in abnormal dissociations could be attributed to

genes. Perhaps most interesting, the fi ndings suggested that the same genetic infl u-

ences underlie both sorts of dissociative experiences—which may suggest (counter

to current thinking) that pathological experiences are simply an extreme on a con-

tinuum that also contains normal dissociative experiences.

Psychological Factors

The primary psychological factor associated with DID is hypnotizability—patients

with this diagnosis are highly hypnotizable and can easily dissociate (Bliss, 1984;

Frischholz et al., 1990, 1992). That is, they can spontaneously enter a trance state

and frequently experience symptoms of dissociation, such as depersonalization or

derealization. These abilities play a critical role in a psychologically based theory of

DID, described in the upcoming section on feedback loops.

Social Factors: A Cultural Disorder?

Social factors have apparently affected the frequency of diagnosis of DID. From the

beginning of the 20th century through the 1920s, DID was rarely diagnosed, and

it continued to be rarely diagnosed until 1976 (Kihlstrom, 2001; Lilienfeld et al.,

1999; Spanos, 1994). What happened in 1976? The television movie Sybil was

aired and received widespread attention. This movie portrayed the “true story” of a

woman with DID. The movie apparently affected either patients or therapists (who

became more willing to make the diagnosis), or both. (Years later, it was revealed

that the patient who was known as Sybil did not have alters, but rather had been

encouraged by her therapist to “name” her different feelings as if they were alters;

thus, what Sybil’s therapist wrote about her alters was not based on Sybil’s actual

experiences [Borch-Jacobsen, 1997; Rieber, 1999].)

Consistent with the view that DID is a disorder induced by social factors present

in some cultures, many countries, such as India and China, have an extremely low

or zero prevalence rate of DID (Adityanjee, Raju, & Khandelwal, 1989; Draijer &

Friedl, 1999; Xiao et al., 2006). In other countries, such as Uganda, people with

DID symptoms are considered to be experiencing the culturally sanctioned posses-

sion trance, not suffering from DID (van Dujil, Cardeña, & de Jong, 2005).

FEEDBACK LOOPS IN ACTION: Two Models for the Emergence of Alters

Two models of dissociative identity disorder—the posttraumatic model and the

sociocognitive model—are based on the existence of feedback loops among neuro-

logical, psychological, and social factors. However, the two models emphasize the

roles of different factors and have different accounts of how the factors infl uence

each other.

The Posttraumatic Model In addition to dissociating or entering hypnotic trances

easily, most DID patients have at least one alter that reports having suffered severe,

often recurring, physical abuse (which would imply a stress response; neurological

factor) when young (Lewis et al., 1997; Ross et al., 1991). This trauma, induced by

others (social factor), may increase the ease of dissociating (psychological factor),

which in turn produces DID. In fact, children who experienced severe physical abuse

later report that during the traumatic events their minds temporarily left their bod-

ies as a way of coping; that is, they dissociated. Putting these observations together,

theposttraumatic model (Gleaves, 1996) proposes that after frequent episodes of

abuse with accompanying dissociation, the child’s dissociated state can develop its

own memories, identity, and way of interacting with the world, thus becoming an

“alter” (Putnam, 1989).

Several studies support some aspects of the posttraumatic model. As would be

expected from this model, some people with DID do have documented histories

of severe physical abuse in childhood (Lewis et al., 1997; Putnam, 1989; Swica,

Some researchers attribute the increased

prevalence of dissociative identify disorder since

1976 to the movie Sybil, based on the book of

the same name, which claimed to portray the

“true story” of a woman with DID. In a scene near

the end of the movie, Sybil (played by Sally Field,

lying down) and her psychiatrist (Joanne

Woodward) work to “integrate” the different

alters. In fact, it was later revealed that the real

life “Sybil” had been explicitly encouraged to give

names to different aspects of her personality, but

did not actually dissociate, as her psychiatrist had

declared she did.

Courtesy Everett Collection

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