According to Psychiatry, DSM-IV offers experts a set of standardized diagnostic criteria that represent a consensus in the field that has been subjected to empirical testing for reliability and validity. Those syndromes however that are novel, tentative, or speculative may at times overlap with established diagnoses. And although DSM-IV diagnostic criteria, avoids controversial syndromes, such as sexual addiction, road rage, homosexual panic, black rage, and codependency. One area of utmost discrepancy is DID, Dissociative identity disorder, known formerly as multiple personality disorder (MPD).

The Epidemic Begins

Not unlike the UFO epidemic, it started with fiction. Robert Louis Stevenson's classic 1885 novel, The Strange Case of Dr. Jekyll and Mr. Hyde, describes the case of a scientist who ingests a mysterious potion that transforms him into an entirely different person, is among the first tales reminiscent of the modern-day notion of DID.

Beginning in the mid- to late 1970s, however, cases of DID  began to be reported in substantial numbers. As of 1986, the number of reported DID cases had swollen to approximately 6,000. This massive increase followed closely upon the release of the best-selling book (later made into a widely viewed television film), Sybil (Schreiber, 1973) in the mid-1970s, which told the story of a young woman with 16 personalities who reported a history of severe and sadistic child abuse at the hands of her mother.

Interestingly, however, a well-known psychiatrist who was intimately involved with the Sybil case some years ago contended that Sybil's DID was largely the product of therapeutic suggestion. Herbert Spiegel, who served as a backup therapist for Sybil, maintained that Sybil's primary therapist, Cornelia Wilbur, encouraged her to develop and display different personalities in therapy. According to Spiegel, Wilbur referred to Sybil's personallties by different names and communicated with them individually. Spiegel further maintained that Wilbur and Flora Schreiber, who authored the best-selling book about Sybil, insisted that Sybil be described in the book as a "multiple" to make the book more appealing to the publisher (see Acocella, 1998). As we will see shortly, the role of therapeutic suggestion in Sybil's case and in other cases of DID is probably the most contentious issue in the DID literature. But could be significant for also other situations like UFO abduction stories and so on.

The number of reported DID cases at the turn of the 21st century is difficult to ascertain, although one estimate places the number of DID cases as of 1998 at approximately 40,000 (Marmer, 1998). Moreover, a number of celebrities, including Roseanne Arnold, have announced that they suffer from DID, and television coverage of DID has skyrocketed over the past two decades (Showalter, 1997; Spanos, 1996). The reasons for the recent "epidemic" (Boor, 1982) in the number of reported DID cases remain controversial.

Two other historical changes in the characteristics of patients with DID are worth noting. First, the number of DID personalities has increased dramatically over time. Whereas most cases of DID prior to the 1970s were characterized by only one or two personalities, recent cases of DID are typically characterized by considerably more personalities (North, Ryall, Ricci, & Wetzel, 1993). For example, Ross, Norton, and Wozney (1989) reported that the mean number of DID personalities was 16, precisely the number reported by Sybil (Acocella, 1998). Second, although few individuals with DID prior to Sybil reported a history of child abuse, a substantial proportion of DID cases that followed in the wake of Sybil reported such a history (Spanos, 1996).

Diagnostic Features

According to the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV; American Psychiatric Association [APA], 1994), DID is one of several "dissociative disorders," all of which are marked by profound disturbances in memory, identity, consciousness, and/or perception of the external environment. DID is characterized by the presence of two or more distinct personalities or "personality states" (i.e., temporary patterns of behavior) that recurrently assume control over the individual's behavior. These alternate personalities, or "alters," often exhibit personality features that differ markedly from those of the primary or "host" personality. In some cases, these features appear to be the exact opposite of those exhibited by the host personality. For example, if the host personality is shy and retiring, one or more of the alters may be outgoing or flamboyant. Some therapists (e.g., Allison, 1974) have even argued that patients with DID possess an "Inner self-helper," a part of the personality that is aware of everything that is occurring to the alters and that can assist in their integration.

In addition, according to DSM-IV, individuals with DID report significant episodes of amnesia for important personal information. For example, they may report periods of "lost time" lasting hours or days in which they cannot recall where they were or what they were doing. This amnesia is often reported to be asymmetrical, whereby the host personality knows little about the behaviors of the alters, but not vice versa (American Psychiatric Association, 1994).

Nevertheless, the scientific standing of amnesia as a feature of DID is controversial. Allen and Iacono (2001) concluded that controlled laboratory studies examining the transfer of explicit and implicit memories offer relatively little support for the claim that patients with DID actually experience amnesia across alters (but see Dorahy, 2001, for a somewhat different conclusion). In addition, research by Read and his colleagues (see, e.g., Read & Lindsay, 2000) demonstrates that one can readily induce reports of autobiographical memory gaps in normal subjects by asking them to recall multiple events from early childhood. Specifically, individuals who are asked to recall multiple events from early childhood (as often occurs in depth-oriented psychotherapy) typically do so obligingly. As a consequence, when they are asked such questions as "Was there ever a period of time when you remembered less of your childhood than you do now?" they will typically respond "Yes," because they are accurately reporting that they now recall (or at least believe that they recall) more of their childhood history than they once did. In fact, these and similar questions are used commonly in investigations of DID to verify the presence of amnesia (see Ross, 1997). Self-reports of autobiographical memory gaps in patients with DID must therefore be interpreted with caution.
 

Demographic and Familial Correlates

Relatively little is known about the demographic or familial correlates of DID. Until recently, it was widely assumed that DID is exceedingly uncom mon. DSM-111 (American Psychiatric Association, 1980), for example, stated that MPD, as it was then called, "is apparently extremely rare" (p. 258). Nevertheless, DSM-IV is conspicuously silent regarding DID's prevalence, and notes only that reports of its prevalence have been highly variable across studies. Indeed, although some authors (e.g., Piper, 1997) claim that genuine DID is very rare (see also Rifkin, Ghisalbert, Dimatou, Jin,

Sethi, 1998), other authors maintain that DID is at least as common as schizophrenia. For example, Ross (1997) estimated that between 1% and 2% of the North American population meets criteria for DID. These discrepancies among authors are difficult to resolve given the absence of clear-cut external validating variables (Robins & Guze, 1970) for DID (see footnote 1).

Virtually all prevalence studies show a marked female predominance, with most sex ratios ranging from 3 to I to 9 to 1 across clinical samples (American Psychiatric Association, 1994). Some authors, however, argue that this imbalanced sex ratio may be an artifact of selection and referral biases, and that a large proportion of males with DID end up in prisons (or other forensic settings) rather than in clinical settings (Putnam & Loewenstein, 2000).

The nature and features of DID alters are highly variable both across and within individuals. The number of alters has been reported to range from one (the so-called "split" personality) to hundreds or even thousands. One clinician reported a case of a patient with DID who had 4,500 alters (Acocella, 1998). These alters are not uncommonly of different sexes, ages, and even races. There have even been reported alters of Mr. Spock, Teenage Mutant Ninja Turtles, lobsters, chickens, gorillas, tigers, unicorns, God, the bride of Satan, and the rock star Madonna (Acocella, 1998; Ganaway, 1989).

Some of the reported differences among alters have been striking. For example, alters have been reported to differ in their allergies, handwriting, voice patterns, eyeglass prescriptions, handedness, and other psychological and physical characteristics. Frank Putnam, a major DID researcher, even reported a case of DID in which one alter, but not other alters, exhibited cardiac arrhythimas (Lichtenstein Creative Media, 1998).

Nevertheless, virtually all of these reported differences derive from anecdotal and uncontrolled reports. Moreover, most of these reports have not controlled adequately for naturally occurring variability in these characteristics over time. Both handwriting and voice, for example, often show at least some variability over time within individuals, especially in response to situational variables (e.g., fatigue, stress), and some allergies have been demonstrated to be susceptible to classical conditioning. As a consequence, these and other reported differences across alters are difficult to interpret with confidence (see also Merkelbach, Devilly, & Rassin, 2002, and Spanos, 1996, for a critique).

Several researchers have also reported psychophysiological differences across alters. For example, investigators have reported differences among alters in respiration rate (e.g., Bahnson & Smith, 1975), electroencephalo, graphic (brain wave) activity (e.g., Ludwig, Brandsma, Wilbur, Bendefeldt, & Jameson, 1972), and skin conductance responses (e.g., Brende, 1984). Nevertheless, these and other differences (see also Putnam, Zahn, & Post, 1990) do not provide especially compelling evidence for the existence of qualitatively distinct differences among alters. As Allen and Movius (2000) noted, such differences could be attributable to changes in mood or cognition over time or to temporal changes in variables (e.g., levels of muscle tension) that are largely under volitional control (see also Merkelbach et al., 2002). Moreover, at least some of these differences may be attributable to Type I error given the large number of psychophysiological variables examined in many of these investigations (Allen & Movius, 2000).
 

Controversy

One long-standing controversy concerns the question of whether individuals with DID harbor qualitatively distinct "personalities," each with its own unique pattern of life experiences, personality traits, and attitudes. Some authors, like Braun (1986), maintain that patients with DID possess separate personalities in addition to "fragments," that is, aspects of personalities. Indeed, the older term "multiple personality disorder" in DSMIII and DSM-111-R (American Psychiatric Association, 1987) clearly implies the existence of largely independent cohabiting personalities.

Nevertheless, many advocates of the DID diagnosis now argue that DID is not characterized by the presence of independent and fully developed personalities (Ross, 1990, 1997). Coons (1984), for example, contended that "it is a mistake to consider each personality totally separate, whole, or autonomous. The other personalities might best be described as personality states, other selves, or personality fragments" (p. 53). Ross (1989) similarly asserted that "much of the skepticism about MPD is based on the erroneous assumption that such patients have more than one personality, which is, in fact, impossible" (p. 81; see also Spiegel, 1993). This caveat notwithstanding, the first major criterion for DID in DSM-IV is "the presence of two or more distinct identities or personality states (each with its own relatively enduring pattern of perceiving, relating to, and thinking about the environment and self)" (p. 487). This wording implies the presence of more than one discrete and fully developed personality.

The question of whether patients with DID possess distinct coexisting personalities is of more than semantic significance. For example, in legal  cases questions have arisen concerning whether individuals with DID should be held criminally responsible if one of their alter personalities committed a crime or whether each alter personality is entitled to separate legal representation. Some trial judges have even required all DID personalities to be sworn in before providing testimony (Slovenko, 1999). In addition, if patients with DID truly possess independent and fully developed personalities, this poses significant challenges to models of DID's etiology. For example, how do these ostensibly complete personalities, each presumably with its own set of personality traits and attitudes, form? For patients who possess hundreds of alters, is each personality genuinely independent of the others, or are certain personalities merely variants or slightly different manifestations of the others?
 
 

Two competing Models

DID's "Existence": A Pseudocontroversy

The principal controversy regarding DID's scientific status has often been framed in terms of whether this condition "exists" (e.g., Arrigo & Pezdek, 1998; Dunn, Paolo, Ryan, & van Fleet, 1994; Mal, 1995; see also Hacking, 1995). Nevertheless, as we have argued elsewhere (Lilienfeld et al., 1999), the question of DID's "existence" is a pseudocontroversy. There is little dispute that DID "exists," in that individuals with this condition exhibit multiple identity enactments (i.e., apparent alters). This point was aptly put by McHugh (1993): "Students often ask me whether multiple personality disorder (MPD) really exists. I usually reply that the symptoms attributed to it are as genuine as hysterical paralysis and seizures" (p. 4). Somatoform conditions, like DID, are clearly genuine, although their origins remain largely obscure. The central question at stake is not DID's existence but rather its etiology. As we will learn shortly, some researchers contend that DID is a spontaneously occurring response to childhood trauma, whereas others contend that it emerges in response to suggestive therapist cueing, media influences, and broader sociocultural expectations.

There is general agreement, however, that at least some individuals have successfully malingered DID. For example, Kenneth Bianchi, one of the Hillside Strangler murderers, is widely believed to have faked DID to escape criminal responsibility (Orne, Dinges, & Orne, 1984). Nevertheless, outside of criminal settings, cases of malingered DID are believed to be quite rare, and there is agreement among both proponents and skeptics of the DID diagnosis that the substantial majority of individuals with this condition are not intentionally producing their symptoms (see Draijer & Boon, 1999, for a discussion of the problem of intentionally produced DID).

In general, two major competing views regarding the etiology of DID have emerged (see Gleaves, 1996): the posttraurnatic model (PTM) and the sociocognitive model (SCM). To oversimplify these views slightly, the former model posits that core DID features, particularly alters, are discovered by therapists, whereas the latter model posits that these features are largely created by therapists. Because we believe that the bulk of the research evidence supports the SCM, we devote much of the remainder of the chapter to a discussion of this model. Nevertheless, we also believe that certain aspects of the PTM have yet to be convincingly falsified and therefore require additional investigation. Moreover, we believe that a meaningful rapprochement between at least certain aspects of these two models may ultimately prove possible.
 
 

The Posttraumatic Model

Proponents of the PTM (e.g., Gleaves, 1996; Gleaves, May, & Cardena, 2001; Ross, 1997) posit that DID is a posttraumatic condition that arises primarily from a history of severe physical and/or sexual abuse in childhood. They typically argue that individuals who undergo horrific trauma in early life often dissociate or compartmentalize their personalities into alters as a means of coping with the intense emotional pain of this trauma. According to Ross (1997), "MPD is a little girl imagining that the abuse is happening to someone else" (p. 59). In support of this assertion, proponents of the PTM cite data suggesting that a large proportion-perhaps 90% or more-of individuals with DID report a history of child abuse (Gleaves, 1996).

The essence of the PTM has been articulated by philosopher Daniel Dennett (1991):

... the evidence is now voluminous that there are not a handful or a hundred but thousands of cases of MPD diagnosed today, and it almost invariably owes its existence to prolonged early childhood abuse, usually sexual, and of sickening severity... These children have often been kept in such extraordinarily terrifying and confusing circumstances that I am more amazed that they survive psychologically at all than I am that they manage to preserve themselves by a desperate redrawing of their boundaries. (p. 150)

Proponents of the PTM attribute the dramatic recent increase in the reported prevalence of DID to the heightened awareness and recognition of this condition by psychotherapists. Specifically, they maintain that clinicians have only recently become attuned to the presence of possible DID in their clients and as a consequence now inquire more actively about symptoms of this condition (Gleaves, 1996). They also point out that a number of conditions, such as posttraumatic stress disorder (PTSD) and obsessive compulsive disorder, were apparently underdiagnosed until recently (e.g., Zohar, 1998), and that a relatively abrupt massive increase in the reported prevalence of a condition does not necessarily call into question its validity. In many cases, proponents of the PTM advocate the use of hypnosis, sodium amytal (so-called "truth serum"; see Piper, 1993, for a critique of the claim that sodium amytal is a "truth serum"), guided imagery, and other suggestive therapeutic techniques to call forth alters that are otherwise inaccessible and to recover apparently repressed memories of child abuse.
 
 

The Sociocognitive Model

In contrast, proponents of the SCM (Spanos, 1994, 1996; see also Aldridge-Morris, 1989; Lilienfeld et al., 1999; Lynn & Pintar, 1997; McHugh, 1993; Merskey, 1992; Sarbin, 1995) contend that DID is a socially constructed condition that results from inadvertent therapist cueing (e.g., suggestive questioning regarding the existence of possible alters), media influences (e.g., film and television portrayals of DID), and broader sociocultural expectations regarding the presumed clinical features of DID. For example, proponents of the SCM believe that the release of the book and film Sybil in the 1970s played a substantial role in shaping conceptions of DID in the minds of the general public and psychotherapists (see Spanos, 1996). Interestingly, as noted earlier, reported cases of child abuse in DID patients became widespread only following the release of Sybil.

Spanos (1994) and other proponents of the SCM contend that individuals with DID are engaged in a form of "role playing" that is similar in some ways to the intense sense of imaginative involvement that some actors report when playing a part. Because individuals who engage in role playing essentially "lose themselves" in the enacted part, this phenomenon should be not be confused with simulation or conscious deception. Some authors have erroneously assumed that the SCM posits that individuals with DID are intentionally producing these features. But the SCM is careful to distinguish role playing from simulation (Lillenfeld et al., 1999; in contrast, see Gleaves, 1996).

According to the SCM, the dramatic "epidemic" in DID cases over the past several decades stems largely from iatrogenic (therapist-induced) influences and the increased media attention accorded to DID. Specifically, as DID has become more familiar to psychotherapists and the general public, an autocatalytic feedback loop (see Shermer, 1997, for examples) has been set in motion. In this feedback loop, therapeutic and societal expectations regarding the features of DID have given rise to greater numbers of cases of DID, in turn influencing therapeutic and societal expectations re garding the features of DID, in turn giving rise to greater number of cases of DID, and so on. It is critical to emphasize that the SCM does not contend that DID is entirely latrogenic, because media influences and broader sociocultural expectations often play an Important role in the genesis of DID. The notion that the SCM posits that DID is entirely iatrogenic represents another frequent misconception concerning this model. For example, Gleaves and colleagues (2001) referred to the SCM as the "latrogenic" theory of DID (see Brown, Frischholz, & Scheflin, 1999; and Gleaves, 1996, for other examples).

Nevertheless, proponents of the SCM maintain that suggestive therapeutic practices-such as hypnosis, guided imagery, and repeated prompting of alters (see Chapter 8 for a discussion of these and other suggestive practices)-often play a substantial role in the genesis of DID. For example, they point to evidence demonstrating that detailed, complex, and nontrivial pseudomemories of life experiences can be elicited by suggestive memory recovery procedures. These experiences include being lost in a shopping mail (Loftus & Pickrell, 1995; Pezdek, Finger, & Hodge, 1997), knocking over a punchbowl at a wedding (Hyman, Husband, & Billings, 1995; Hyman & Pentland, 1996), being discouraged from using one's left hand (see Lindsay, 1996), choking and witnessing an occurrence of demonic possession as a child (Mazzoni, Loftus, & Kirsch, 2001), and being abused as a child in a past life (Spanos, Menary, Gabora, DuBreuil, & Dewhirst, 1991). Lindsay (1998) contended that such laboratory studies come nowhere near to "approximating the power of the suggestive influences that are brought to bear in some forms of memory-recovery work, in which individuals may be exposed to suggestions several hours per week for months or even years" (p. 490). Proponents of the SCM therefore maintain that suggestive therapeutic procedures can quite plausibly induce the production of alters and the autobiographical memories (e.g., child abuse) associated with them.

Another important brick in the edifice of the SCM is the assumption that DID is merely one variant of a broader constellation of conditions characterized by multiple identity enactments, including cases of purported demonic possession, channeling, mass hysteria, transvestism, and glossolalia (speaking in tongues), that traverse cultural and historical boundaries (Spanos, 1996). From this perspective, DID is not a unique condition but rather a superficially different manifestation of the same diathesis that gives rise to other conditions marked by dramatically different behaviors over time. Although the protean manifestations of these role enactments are shaped by cultural and historical expectations, their underlying commonalties are suggestive of a shared etiology (Lilienfeld et al., 1999; see also Hacking, 1995).

Some proponents of the SCM (e.g., Spanos, 1994, 1996) have placed more emphasis on social role expectations and latrogenic influences than on individual difference variables. Nevertheless, the SCM is compatible with the possibility that individual differences in certain personality traits, such as fantasy proneness (Lynn, Rhue, & Green, 1988) or absorption (Tellegen & Atkinson, 1974), render certain individuals especially susceptible to suggestive therapeutic, media, and cultural influences. In addition, this model is compatible with findings indicating that a substantial proportion of patients with DID meet criteria for borderline personality disorder (BPD) and other psychiatric conditions marked by unstable and unpredictable behavior, such as bipolar disorder (Ganaway, 1995; Lilienfeld et al., 1999). For example, clients with BPD-who typically exhibit severe disturbances of identity, dramatic mood swings, sudden changes in feelings toward other people, and impulsive and seemingly inexplicable behaviors (e.g., self-mutilation)-may often be seeking an explanation for these puzzling symptoms, as may their therapists. Therapists who repeatedly ask such questions as "Is it possible that there is another part of you with whom I haven't yet spoken?" may gradually begin to elicit previously "latent alters" that ostensibly account for their clients' otherwise enigmatic behaviors.

Many of the key features of the SCM were summed up by Frances and First (1998), who ironically were two of the principal architects of DSMIV.

Dissociative Identity Disorder ... is a fascinating condition. Perhaps too much so. The idea that people can have distinct, autonomous, and rapidly alternating personalities has captured the attention of the general public, of some therapists, and of hordes of patients. As a result, especially in the United States, there has been a marked increase in the diagnosis of Dissociative Identity Disorder. Much of the excitement followed the appearance of books and movies (like Sybil and The Three Faces of Eve) and the exploitation of the diagnosis by enthusiastic TV talk show guests.... Many therapists feel that the popularity of Dissociative Identity Disorder represents a kind of social contagion. It is not so much that there are lots of personalities as that there are lots of people and lots of therapists who are very suggestible and willing to climb onto the bandwagon of this new fad diagnosis. As the idea of multiple personality pervades our popular culture, suggestible people coping with a chaotic current life and a severely traumatic past express discomfort and avoid responsibility by uncovering "hidden personalities" and giving each of them a voice. This is especially likely when there is a zealous therapist who finds multiple personality a fascinating topic of discussion and exploration. (pp. 286-287)

Advocates of the SCM have invoked a variety of pieces of evidence in support of this position (Lillenfeld et al., 1999; Spanos, 1994, 1996). I will  next present the major sources of evidence consistent with the SCM and examine common criticisms of this model.

One source of evidence in favor of the SCM are the typical treatment practices employed by many proponents of the PTM. Claims by some proponents of the PTM to the contrary (Brown et al., 1999; Gleaves, 1996), many standard therapeutic practices for DID are geared toward encouraging the appearance of alters and treating them as though they were distinct identities.

Inspection of the mainstream DID treatment literature reveals that therapists are often encouraged to reify the existence of multiple identities by mapping the system of alters and to establish contact with alters if they are not otherwise forthcoming (Piper, 1997). These reifying techniques are especially common in the early stages of psychotherapy (Ross, 1997).

For example, Kluft (1993) argued that "when information suggestive of MPD is available, but an alter has not emerged spontaneously, asking to meet an alter directly is an increasingly accepted intervention" (p. 29). Kluft has further acknowledged that his most frequent hypnotic instruction to patients with DID is "Everybody listen" (see Ganaway, 1995). Braun (1980) wrote that "after inducing hypnosis, the therapist asks the patient 'if there is another thought process, part of the mind, part, person or force that exists in the body' " (p. 213). Bliss (1980) noted in the treatment of DID that "alter egos are summoned, and usually asked to speak freely... When they appear, the subject is asked to listen. [The subject] is then introduced to some of the personalities" (p. 1393). Putnam (1989) suggested using a technique known as the "bulletin board," which allows patients with DID to have a "place where personalities can 'post' messages to each other... I suggest that the patient buy a small notebook in which personalities may write messages to each other" (p. 154). Ross (1997) and other therapists (e.g., Putnam, 1989) have recommended giving names to each alter in order to " 'crystallize' it and make it more distinct" (p. 311). Ross also advocated the use of "inner board meetings" as "a good way to map the system, resolve issues, and recover memories" (p. 350). He described this technique as follows:

The patient relaxes with a brief hypnotic induction, and the host personality walks into the boardroom. The patient is instructed that there will be one chair for every personality in the system.... Often there are empty chairs because some alters are not ready to enter therapy. The empty chairs provide useful information, and those present can be asked what they know about the missing people. (p. 351)

These and other treatment recommendations derived from the mainstream DID literature (see Piper, 1997, pp. 61-68, for additional examples) strongly suggest that many therapists are explicitly encouraged to reify the existence of alters by acknowledging and validating their independent existence. From a behavioral or social learning perspective, the process of attending to and reifying alters may adventitiously reinforce patients' displays of multiplicity.

Another treatment practice that may inadvertently facilitate the emergence of alters is hypnosis. Clinicians who treat patients with DID frequently use hypnosis in an effort to discover or call forth presumed latent alters (Spanos, 1994, 1996). The evidence regarding the use of hypnosis with patients with DID provides mixed support for the SCM. On the one hand, the results of several studies reveal few or no differences in the diagnostic features (e.g., alters, number of DID criteria) of patients with DID who have and have not been hypnotized (e.g., Putnam, Guroff, Silberman, Barban, & Post, 1986; Ross & Norton, 1989; see also Gleaves, 1996, for a review). In addition, several studies indicate that many or most patients with DID have never been hypnotized (Gleaves, 1996), strongly suggesting that hypnosis is not necessary for the emergence of DID.

On the other hand, the finding that hypnotized and nonhypnotized patients with DID do not differ significantly in many characteristics (e.g., number of DID criteria) is difficult to interpret in light of ceiling effects (Lilienfeld et al., 1999; Powell & Gee, 1999). Specifically, given that almost all of the patients in these studies met criteria for DID according to various diagnostic criterion sets (e.g., DSM-111), the differences in the number of DID criteria between hypnotized and nonhypnotized patients is not surprising.

In addition, in a reanalysis of the data set of Ross and Norton (1989), Powell and Gee (1999) found that hypnotized patients exhibited greater variance in the number of alters at the time of diagnosis and in later treatment. Although the meaning of this finding is not entirely clear, it may reflect bimodal attitudes toward latrogenesis among practitioners who use hypnosis, with some (who believe that hypnosis is potentially iatrogenic) using hypnosis never or rarely and others (who believe that hypnosis is not iatrogenic) using hypnosis frequently. Powell and Gee also found that clinicians who used hypnosis reported a significantly higher number of patients with DID in their caseloads than did practitioners who did not use hypnosis. Although this finding is open to several interpretations (e.g., DID specialists may be more likely to use hypnosis than are other clinicians), it is consistent with iatrogenesis.

Moreover, the SCM does not posit that hypnosis is necessary for the creation of DID alters. Hypnotic procedures do not possess any inherent or unique features that are necessary to facilitate responsivity to suggestion (Spanos & Chaves, 1989). Other methods, such as suggestive and leading questions, may be equally likely to induce clients' adoption of multiple identities (Spanos, 1996).

There is compelling evidence that a large proportion-perhaps even a substantial majority-of patients with DID exhibit very few or no unambiguous signs of this condition (e.g., alters) prior to psychotherapy. For example, Kluft (1991) estimated that only 20% of patients with DID exhibit unambiguous signs of this condition and that the remaining 80% exhibit only transient "windows of diagnosability," that is, short-lived periods during which the core features of DID are observable. Moreover, individuals with DID typically are in treatment for an average of 6-7 years before being diagnosed with this condition (Gleaves, 1996). Such evidence raises the possibility that these patients often develop unambiguous features of DID only after receiving psychotherapy.

Moreover, although systematic data are lacking, there is general agreement in the DID literature that many or most patients with DID are unaware of the existence of their alters prior to psychotherapy. For example, Putnam (1989) estimated that 80% of patients with DID possess no knowledge of their alters before entering treatment, and Dell and Eisenhower (1990) reported that all 11 of their adolescent patients with DID had no awareness of their alters at the time of diagnosis. Similarly, Lewis, Yeager, Swica, Pincus, and Lewis (1997) reported that none of the 12 murderers with DID in their sample reported any awareness of their alters.

Some authors have also reported that the number of DID alters tends to increase over the course of treatment (Kluft, 1988; Ross et al., 1989). In addition, although the number of alters per DID case at the time of initial diagnosis has remained roughly constant over time (Ross et al., 1989), the number of alters per DID case in treatment has increased over time (North et al., 1993).

These findings are consistent with the SCM, as they suggest that many therapeutic practices for DID may inadvertently encourage the emergence of new alters. Moreover, as we noted elsewhere (Lillenfeld et al., 1999), one would be hard-pressed to find another DSM-IV disorder whose principal feature (i.e., alters) is often unobservable prior to standard treatment and becomes substantially more florid following this treatment.

Nevertheless, some proponents of the PTM argue that these findings are potentially consistent with this model. Specifically, they maintain that the alters were "latent" at the time of diagnosis and became observable only after elicitation by therapists (Gleaves, 1996). Nevertheless, without independent evidence of these alters this position raises concerns regarding the falsifiability of the PTM. That is, if the number of alters either decreased or remained constant over the course of therapy, proponents of the PTM could maintain that treatment for DID either ameliorated the symptoms of DID or held potential deterioration at bay. In contrast, the finding that the number of alters increases over the course of therapy has been interpreted by proponents of the PTM as indicating that psychotherapy successfully uncovered alters that were latent (Gleaves, 1996). Because a model that is consistent with any potential set of observations is impossible to falsify and is therefore of questionable scientific utility (Popper, 1959), proponents of the PTM will need to make explicit what types of evidence could falsify this model.

Some critics of the SCM (e.g., Brown et al., 1999; Gleaves, 1996) have attempted to argue that suggestive therapeutic practices can produce additional alters in patients who already meet criteria for DID, but that these practices cannot create DID itself. This assertion hinges on the assumption that iatrogenic influences can lead patients with one alter to develop additional alters, but cannot lead patients with no alters to develop one or more alters. The theoretical basis underlying this assumption has not been clearly articulated by critics of the SCM (Lilienfeld et al., 1999). Moreover, this assertion appears extremely difficult ', if not impossible, to falsify given that many critics of the SCM maintain that DID alters can be "latent" (e.g., Kluft, 1991). That is, if a patient with no alters developed alters following suggestive therapeutic practices, critics of the SCM could readily maintain that this, patient merely had latent alters and in fact suffered from DID all along (Piper, 1997). In addition, even some of the most ardent proponents of the PTM acknowledge that DID can be iatrogenically created in certain cases. Ross (1997), for example, estimated that approximately 17% of DID cases are predominantly iatrogenic (see also Coons, 1989).

Thus, the more important question appears to be not whether DID can be largely created by iatrogenic factors, but rather the relative importance of iatrogenesis compared with other potential causal variables, including media influences, sociocultural factors, and individual differences in personality.
 
 

Distribution of Cases across Clinicians

The distribution of DID cases across therapists is strikingly nonrandom, demonstrating that a relatively small number of clinicians account for a large number of cases of DID. For example, a 1992 survey study in Switzerland revealed that 66% of DID diagnoses were made by .09% (!) of all clinicians. Moreover, 90% of respondents reported that they had never seen a single patient with DID, whereas three psychiatrists reported that they had seen over 20 patients with DID (Modestin, 1992). Ross and colleagues (1989) reported that members of the International Society for the Study of Multiple Personality and Dissociation were between 10 and 11 times more likely than members of the Canadian Psychiatric Association to report having seen a case of DID. In addition, Mal (1995) found evidence for substantial variability in the number of DID diagnoses across Canadian psychiatrists and reported that the lion's share of DID diagnoses derived from a relatively small number of psychotherapists. These findings dovetail with those of Qin, Goodman, Bottoms, and Shaver (1998), who reported that reports of satanic ritual abuse derive from a small number of psychotherapists. Reports of satanic ritual abuse are closely associated with diagnoses of DID (Mulhern, 1991).

Findings on the nonrandom distribution of DID cases are compatible with several explanations. For example, such findings could be explained by positing that patients with actual or possible DID are selectively referred to DID experts. Alternatively, perhaps certain therapists are especially adept at either detecting or eliciting the features of DID. Nevertheless, these findings are consistent with the SCM and with Spanos's (1994, 1996) contention that only a handful of clinicians are diagnosing DID, producing DID symptoms in their patients, or both.

At this point the data do not permit one to select among these possibilities, which are not mutually exclusive. Nevertheless, these findings provide one useful test of the SCM, because if DID diagnoses were not made disproportionately by a subset of clinicians-namely those who are ardent proponents of the DID diagnosis-the SCM would be called into question. Longitudinal investigations examining whether patients tend to exhibit the core features of DID prior to or following referrals to DID specialists would help to determine whether these findings are attributable primarily to iatrogenesis or to either differential referral patterns or the use of more sensitive diagnostic practices.
 
 

Role-Playing Studies

Another source of evidence in support of the SCM derives from laboratory studies of role playing. These investigations are designed to test the hypothesis, derived from the SCM, that cues, prompts, and suggestions from a psychotherapist can trigger participants without DID to display the overt features of this condition.

In one of these studies, Spanos, Weekes, and Bertrand (1985) provided participants with suggestions for DID (e.g., "I think perhaps there might be another part of [you] that I haven't talked to") in the context of a simulated psychiatric interview. They found that many role-playing participants, but not control participants (who were not provided with these suggestions), spontaneously adopted a different name, referred to their host personality in the third person (e.g., "He"), and exhibited striking differences between the host and alter "personalities" on psychological measures (e.g., sentence completion tests, semantic differential questionnaires). In addition, most role-playing participants, but not control participants, spontaneously reported amnesia for their alters following hypnosis. It is crucial to note that participants were not explicitly told or asked to display any of these features, which are similar to those exhibited by patients with DID. These findings were essentially replicated with a similar methodology by Spanos, Weekes, Menary, and Bertrand (1986; but see Frischholz & Sachs, 1991, cited in Brown et al., 1999). Stafford and Lynn (1998) similarly found that given adequate situational inducements, normal participants can readily role play a variety of life history experiences often reported among patients with DID, including reports of physical, sexual, and satanic ritual abuse.

Role-playing studies have been commonly misinterpreted by critics of the SCM. For example, Gleaves (1996) argued that "to conclude that these studies prove that DID is simply a form of role-playing is unwarranted" (p. 47). Similarly, Brown and colleagues (1999) contended that role playing studies do not demonstrate that DID "can be created in the laboratory" (p. 580) and that "these role enactments are not identical with alter behavior in MPD patients, nor are they proof that a major psychiatric condition, MPD, has been created" (p. 581). But role-playing studies were not designed to reproduce the full range or subjective experience of DID symptoms, nor to create DID itself, but rather to demonstrate the ease with which subtle cues and prompts can trigger normal participants to display some of the key features of this condition. The findings of these studies provide support for the SCM, because they demonstrate that (1) the behaviors and reported experiences of DID are familiar to many members of the population, and (2) individuals without DID can be readily induced to exhibit some of the key features of DID following prompts and cues, even though these features were not explicitly suggested to them. Were this not the case, the SCM could not account for many of the core features of DID. Role-playing studies therefore provide corroboration for one important and falsifiable precondition of the SCM, although they do not provide dispositive evidence for this model (Lilienfeld et al., 1999).
 
 

Cross-Cultural Studies

As noted earlier, the SCM posits that the overt expression of multiple identity enactments is shaped by cultural and historical factors. Consistent with this claim is the fact that until fairly recently DID was largely unknown outside of North America (see also Hochman & Pope, 1997, for data suggesting considerably greater acceptance of DID in North American countries compared with non-North American English-speaking countries). For example, a 1990 survey in Japan (Takahashi, 1990) revealed no known cases of DID in that country. In addition, until recently DID was rare in England, Russia, and India (Spanos, 1996). Interestingly, the cross-cultural expression of DID appears to be different in India than in North America. In the relatively rare cases of DID reported in India, the transition between alters is almost always preceded by sleep, a phenomenon not observed in North American cases of DID. Media portrayals of DID in India similarly include periods of sleep prior to the transitions between alters (North et al., 1993).

Gleaves (1996) noted that DID has recently been diagnosed in Holland (see also Sno & Schalken, 1999) and several other European countries, and used this finding to argue against the SCM. Nevertheless, this finding is difficult to Interpret. In Holland, for example, the writings of several well-known researchers, (e.g., van der Hart, 1993; van der Kolk, van der Hart, & Marmar, 1996) have resulted in substantially increased media and professional attention to DID.

Moreover, "culturally influenced" is not equivalent to "culture-bound," In other words, the fact that a condition initially limited to only a few countries subsequently spreads to other countries does not necessarily indicate that this condition is independent of cultural influence. To the contrary, the fact that the features of DID are becoming better known in certain countries would lead one to expect DID to be diagnosed with increasing frequency in these countries. Indeed, the spread of DID to countries in which the characteristics of this condition are becoming more familiar constitutes one important and potentially falsifiable prediction of the SCM.

A variety of pieces of evidence, including the typical treatment practices of DID proponents, the clinical features of patients with DID before and after psychotherapy, the distribution of DID cases across psychotherapists, data from role-playing studies, and cross-cultural epidemiological data, provide support for several predictions of the SCM. In addition, these data call into question a "strong" form of the PTM (e.g., Gleaves, 1996), namely, a version of the PTM that essentially excludes sociocultural influence as an explanation of DID's etiology. These data may, however, be consistent with a "weak" form of the PTM that accords a predisposing role to early trauma but also grants a substantial causal role to sociocultural influences, including iatrogenesis. Nevertheless, to provide more compelling support for the PTM, the proponents of this model will need to make more explicit predictions that could in principle permit this model to be falsified.
 

The Child Abuse Controversy

As noted earlier, a linchpin of the PTM is the assumption that DID is caused by early trauma, particularly severe abuse, in childhood. Indeed, some authors regard DID as a form or variant of PTSD (see Gleaves, 1996). Many authors have accepted rather uncritically the claim that severe abuse is an important precursor, if not cause, of DID. For example, Carson and Butcher (1992) asserted that "while it is somewhat amazing that this connection [between DID and child abuse] was not generally recognized until 1984, there is now no reasonable doubt about the reality of this association" (p. 208). Gleaves and colleagues (2001) concluded that here is a clear body of evidence linking DID or dissociative experiences in general with a history of childhood trauma" (p. 586). In contrast, our reading of the research literature suggests a considerably more complex and ambiguous picture, and raises important questions regarding the hypothesized association between early abuse and DID.
 
 

Corroboration of Abuse Reports

Some investigators have reported high prevalences of child abuse among patients with DID (see Gleaves, 1996, p. 53). Nevertheless, in virtually none of these studies was the abuse independently corroborated (e.g., Boon & Draijer, 1993; Coons, Bowman, & Milstein, 1988; Ellason, Ross, & Fuchs, 1996; Putnam et al., 1986; Ross et al., 1989, 1990; Schultz, Braun, & Kluft, 1989; Scroppo, Drob, Weinberger, & Eagle, 1998). The absence of corroboration in these studies is problematic in light of findings that memory is considerably more malleable and vulnerable to suggestion than previously believed (Loftus, 1993, 1997; Malinowski & Lynn, 1995; see also Chapter 8). Recent evidence demonstrates that memories of traumatic experiences (e.g., wartime combat) are not immune to this problem (Southwick, Morgan, Nicolaou, & Charney, 1997).

In addition, the phenomenon of "effort after meaning," whereby individuals interpret potentially ambiguous events (e.g., hitting, fondling) in accord with their implicit theories regarding the causes of their conditions, renders some reports of relatively mild or moderate child abuse difficult to interpret without independent corroboration (see Rind, Tromovitch, & Bauserman, 1998). Furthermore, it is difficult to exclude the possibility that the same inadvertent cues emitted by therapists that promote the creation of alters may also promote the creation of false abuse memories (Spanos, 1994), although little is known about the prevalence of suggestive therapeutic practices among DID therapists. As a consequence, it is difficult to rule out the possibility that the reported association between DID and child abuse is at least partly spurious and contaminated by therapists' methods of eliciting information.

Several investigators have attempted to corroborate the retrospective abuse reports of patients with DID. For example, Coons and Milstein (1986) and Coons (1994) claimed to provide objective documentation for the abuse reports of some DID patients. Close inspection of these studies, however, reveals various methodological shortcomings. In neither study were diagnoses of DID made blindly of previous abuse reports. This methodological shortcoming is problematic because certain therapists may be especially likely to attempt to elicit features of DID among patients with a history of severe abuse. In the Coons study, DID diagnoses were made only after medical histories and psychiatric records (many of which may have contained information regarding abuse histories) were reviewed. Moreover, because standardized interviews were not administered in Coons and Milstein and were administered only to an unknown number of participants in Coons, the possibility of diagnostic bias is heightened. Finally, the patients in Coons "were diagnosed personally by the first author over an 11 year period" (p. 106). Because there is no evidence concerning whether these patients met criteria for DID prior to treatment, the possibility of iatrogenic influence is difficult to exclude.

More recently, Lewis and colleagues (1997) reported findings from a study of 12 murderers with DID that in their words, "establishes, once and for all, the linkage between early severe child abuse and dissociative identity disorder" (p. 1703). Some authors have cited Lewis and colleagues' findings as providing strong evidence for the corroboration of abuse reports among patients with DID (e.g., Gleaves et al., 2001). Nevertheless, the objective documentation of abuse provided by Lewis and colleagues was often quite vague (see also Klein, 1999). For example, in several cases, there are indications only that the "mother [was] charged as unfit" or that 11 emergency room records report[ed] severe headaches." In addition, their findings are difficult to interpret for several other reasons. First, the objective documentation of childhood DID symptoms was similarly vague in many cases and was often based on the presence of imaginary playmates and other features (e.g., marked mood changes) that are extremely common in childhood. Second, because violent individuals tend to have high rates of abuse in childhood (Widom, 1988), Lewis and colleagues' findings are potentially attributable to the confounding of DID with violence. Third, diagnoses of DID were not performed blindly with respect to knowledge of reported abuse history. Fourth, the murderers' handwriting samples, which differed over time and were used by Lewis and colleagues to buttress the claim that these individuals had DID, were not evaluated by graphoanalysts or compared with the handwriting samples of normals over time. Fifth, the possibility of malingering (which is often a particular problem among criminals) was not evaluated with psychometric indices. These methodological limitations raise serious questions regarding Lewis and colleagues' claim that their study convincingly demonstrates an association between child abuse and later DID.

A more indirect approach to the corroboration of child abuse among patients with DID was adopted by Tsai, Condie, Wu, and Chang (1999), who used magnetic resonance imaging with a 47-year-old female with DID. Reasoning from previous investigations that had reported a reduction in hippocampal volume in individuals with combat trauma (e.g., Bremner, Randall, Scott, & Bronen, 1995) and child abuse (Bremner, Randall, Vermctten, & Staib, 1997; Stein, Koverola, Hanna, &, Torchia, 1997), Tsai and colleagues hypothesized that patients with DID (given their presumed history of early abuse) would similarly exhibit decreased hippocampal volume. As predicted, they found significant bilateral reductions in hippocampal volume in their patient with DID, which is broadly consistent with predictions derived from the PTM. Nevertheless, this finding must be interpreted cautiously for two major reasons. First, because it is based on only one patient, its generalizability to other individuals with DID is unclear. Second, decreased hippocampal volume is not specific to PTSD or other conditions secondary to trauma, and has also been reported in schizophrenia (Nelson, Saykin, Flashman, &- Riordan, 1998) and depression (Bremner et al., 2000). Consequently, decreased hippocampal volume may be a nonspecific marker of long-term stress (Sapolsky, 2000).

Moreover, several pieces of data raise questions regarding the veracity of some reports of child abuse in studies of DID. In the study by Ross and colleagues (1991), 26% of patients with DID reported being abused prior to age 3, and 10.6% reported being abused prior to age 1. Dell and Eisenhower (1990) noted that 4 of 11 adolescent patients with DID reported that their first alter emerged at age 2 or earlier, and 2 of these patients reported that their first alter emerged between the ages I of 2. Memories reported prior to age 3 are of extremely questionable validity, and it is almost universally accepted that adults and adolescents are unable to remember events that occurred prior to age I (Fivush & Hudson, 1990). It is possible that the memories reported in these studies were accurate, but that they were dated incorrectly. Nonetheless, the nontrivial percentages of individuals in the studies of Ross and colleagues and Dell and Eisenhower who reported abuse and the emergence of alters at very young ages raise concerns regarding the accuracy of these memories.

Finally, Ross and Norton (1989) found that patients with DID who had been hypnotized reported higher rates of child abuse than patients with DID who had not been hypnotized. Because there is little evidence that hypnosis enhances memory (Lynn, Lock, Myers, & Payne, 1997; see Chapter 8), this finding is consistent with the possibility that hypnosis produces an increased rate of false abuse reports. Nevertheless, this conclusion must remain tentative in view of the absence of corroboration of the abuse reports and the correlational nature of Ross and Norton's data.
 
 

Interpretation of the Child Abuse-DID Association

Even if the child abuse reports of most patients with DID were corroborated, several important questions arise concerning the interpretation of these reports. In particular, it remains to be determined whether a history of child abuse is (1) more common among patients with DID than among psychiatric patients in general and (2) causally associated with risk for subsequent DID.

With respect to the first issue, base rates and referral biases pose potential problems for interpreting the child abuse data. Because the prevalence of reported child abuse among psychiatric patients tends to be high (e.g., Pope & Hudson, 1992), these data are difficult to interpret without a psychiatric comparison group. Moreover, the co-occurrence between reported abuse and DID could be a consequence of several selection artifacts that increase the probability that individuals with multiple problems seek treatment. Berksonian bias (Berkson, 1946) is a mathematical artifact that results from the fact that an individual with two problems can seek treatment for either problem. Clinical selection bias (see du Fort, Newman, & Bland, 1993) reflects the increased likelihood that patients with one problem will seek treatment if they subsequently develop another problem. Either or both of these artifacts could lead to the apparent relation between child abuse and DID. Indeed, Ross (1991) found that nonclinical participants with DID reported substantially lower rates of child abuse than did patients with DID recruited from a clinical population. This finding is consistent with the hypothesis that selection biases account at least partly for the high levels of co-occurrence between reported child abuse and DID. Moreover, Ross and colleagues (1989) reported that American psychiatrists reported a substantially higher prevalence of child abuse among patients with DID (81.2%) than did Canadian psychiatrists (45.5%). This finding suggests the possibility of biases in the assessment or elicitation of child abuse reports and raises questions concerning the claim that child abuse is necessary for most cases of DID (Spanos, 1994).

If a clear correlation between early child abuse and DID were demonstrated, it would still be necessary to demonstrate that this abuse plays a causal role in subsequent DID. This task will be difficult given that studies of child abuse in patients with DID are necessarily quasi-experimental. Nevertheless, data from causal modeling studies could help to shed light on this question. In addition, studies of monozygotic (identical) twins discordant for early abuse history could provide more compelling evidence for a causal role of abuse in DID. Specifically, if it could be demonstrated that only the MZ twin with a history of early abuse exhibited significant levels of dissociative features (including features of DID), then this finding would buttress the contention that early abuse, rather than a host of other nuisance variables that distinguish patients with dissociative disorders from other individuals (e.g., genetic differences in the propensity toward suggestibility), plays an etiological role in DID.

The PTM hinges on the assumption that early trauma, particularly child abuse, is a risk factor for DID. Consistent with this assumption, many authors have found that a large proportion, and probably a majority, of patients with DID report a history of early and sometimes severe child abuse. Nevertheless, careful inspection of this literature raises significant questions concerning the child abuse-DID link. Most of the reported confirmations of this association derive from studies lacking objective corroboration of child abuse (e.g., Ross et al., 1990). Moreover, even those studies that purport to provide such corroboration (e.g., Coons, 1994; Lewis et al., 1997) are plagued by methodological shortcomings. In addition, the reported high levels of child abuse among patients with DID may be attributable to selection and referral biases. Finally, it is unclear whether early abuse plays a causal role in DID. These limitations suggest the need for further controlled research before strong conclusions regarding the child abuse-DID link (e.g., Gleaves, 1996; Gleaves et al., 2001) can be drawn.
 
 

Conclusion

Perhaps the primary controversy surrounding DID is the question of whether it is a socially constructed and culturally influenced condition rather than a naturally occurring response to early trauma.  A number of important lines of evidence converge to provide support for the SCM. Specifically, 10 findings are consistent with the major theses of the SCM:
 

1. The number of patients with DID has increased dramatically over the past few decades (Elzinga et al., 1998).

2. The number of alters per individual with DID has similarly increased over the past few decades (North et al., 1993), although the number of alters at the time of initial diagnosis appears to have remained constant (Ross et al., 1989).

3. Both of these increases coincide with dramatically increased therapist and public awareness of the major features of DID (Fahy, 1988).

4. Mainstream treatment techniques for DID appear to reinforce patients' displays of multiplicity, reify alters as distinct personalities, and encourage patients to establish contact with presumed latent alters (Spanos, 1994, 1996).

5. Many or most patients with DID show few or no clear-cut signs of this condition (e.g., alters) prior to psychotherapy (Kluft, 1991).

6. The number of alters per individual with DID tends to increase substantially over the course of DID-oriented psychotherapy (Piper, 1997).

7. Psychotherapists who use hypnosis tend to have more patients with DID in their caseloads than do psychotherapists who do not use hypnosis (Powell & Gee, 1999).

8. The majority of diagnoses of DID derive from a relatively small number of psychotherapists, many of whom are specialists in DID (Mal, 1995).

9. Laboratory studies suggest that nonclinical participants provided with appropriate cues and prompts can reproduce many of the overt features of DID (Spanos et al., 1985).

10. Until fairly recently, diagnoses of DID were limited largely to North America, where the condition has received widespread media publicity (Spanos, 1996), although DID is now being diagnosed with considerable frequency in some countries (e.g., Holland) in which it has recently become more widely publicized.

These 10 sources of evidence do not imply, however, that DID can typically be created in vacuo by iatrogenic or sociocultural influences. As noted earlier, a large proportion of patients with DID have histories of cooccurring psychopathology, particularly borderline personality disorder (BPD; Ganaway, 1995). Therefore, it seems plausible that iatiogenic and sociocultural influences often operate on a backdrop of preexisting psychopathology, and exert their impact primarily on individuals who are seeking a causal explanation for their instability, identity problems, and impulsive and seemingly inexplicable behaviors.

We should also note that several of these 10 sources of evidence are fallible and open to multiple causal interpretations (Lillenfeld et al., 1999). For example, the finding that the number of alters per individual tends to increase over the course of psychotherapy is potentially consistent with the assertion (Ross, 1997) that psychotherapy for DID is often accompanied by a progressive uncovering of previously latent alters. In addition, the finding that diagnoses of DID have increased dramatically over the past few decades is potentially attributable to the advent of superior diagnostic and assessment practices among DID practitioners. Moreover, diagnoses of several other disorders, including PTSD and obsessive-compulsive disorder (OCD), have increased dramatically over the past two decades (Zohar, 1998).

Although none of these 10 lines of evidence is by itself dispositive, the convergence of evidence across all of these sources of data provides a potent argument for the validity of the SCM (Lillenfeld et al., 1999; see also Lynn & Pintar, 1997). Our conclusions differ sharply from those of Brown and colleagues (1999), who contended that "the entire data base of 'scientific evidence' [for the SCM] consists of a grand total of three experimental studies-all coming out of the same laboratory" (p. 617). Brown and colleagues were referring here to the laboratory role-playing studies of Spanos and his colleagues (e.g., Spanos et al., 1985).

Nevertheless, Brown and colleagues (1999) drew this conclusion only because they restricted themselves entirely to strictly experimental studies (i.e., those involving random assignment to conditions and manipulation of a discrete independent variable) when evaluating the scientific status of the SCM. This approach is grossly underinclusive, because a variety of lines of quasi-experimental and observational evidence (e.g., the higher rates of psychopathology of patients with DID after versus before psychotherapy, the markedly nonrandom distribution of DID cases across practitioners) are relevant to the validity of the SCM. In many well-developed "hard" sciences, including geology, astronomy, meteorology, and paleontology, nonexperimental evidence is used routinely to test causal hypotheses, and the same evidentiary guidelines should hold in psychology. Indeed, as the 19th century philosopher William Whewell observed, most scientific hypotheses are tested by evaluating the "consilience of evidence" across diverse and maximally independent sources of information (Shermer, 2001). The consillence of evidence for the SCM is striking, and strongly suggests that iatrogenic and sociocultural influences play at least some etiological role in DID.

This conclusion does not imply, however, that the PTM has been falsified. With respect to the fourth major controversy examined in this chapter, namely, the child abuse-DID link, extant studies provide relatively weak support for the contention that child abuse is a causal risk factor for DID (cf. Gleaves et al., 2001). Nevertheless, this possibility cannot be excluded on the basis of existing data. Studies that provide corroborated abuse reports and psychiatric comparison groups, and that control for selection and referral biases, are required to bring clarity to this area (Lilienfeld et al., 1999). In addition, causal modeling studies may help to exclude alternative hypotheses for the high levels of cooccurrence between reported child abuse and later DID. If such abuse can be corroborated and shown to be associated with risk for DID, such studies will be especially informative if they incorporate potential third variables that could account for this correlation (e.g., adverse home environment).

If future studies provide more convincing evidence for the child abuse-DID association, such evidence might necessitate a rapprochement between the SCM and PTM. Indeed, some important aspects of these two models may ultimately prove commensurable. For example, early trauma could predispose individuals to develop high levels of fantasy proneness (Lynn et al., 1988), absorption (Tellegen & Atkinson, 1974), or related traits. In turn, such traits may render individuals susceptible to the kinds of iatrogenic and cultural influences posited by the SCM, thereby increasing the likelihood that they will develop DID and related dissociative disorders following exposure to suggestive influences. This and even more sophisticated etiological models of DID await direct empirical tests.
 
 

References

Acocella, J. (1998, April 6). The politics of hysteria. New Yorker, pp. 64-79.

Aldridge-Morris, R. (1989). Multiple personality: An exercise in deception. Hillsdale, NJ: Erlbaum.

Allen, J. J. B., & Iacono, W. G. (2001). Assessing the validity of amnesia in dissociative identity disorder: A dilemma for the DSM and the courts. Psychology, Public Policy, and Law, 7, 311-344.

Allen, J. J. B., & Movius, H. L. (2000). The objective assessment of amnesia in dissociative identity disorder using event-related potentials. International Journal of Psycbophysiology, 38, 21-41.

Allison, R. (1974). A new treatment approach for multiple personality. American Journal of Clinical Hypnosis, 17, 15-32.

American Psychiatric Association. (1980). Diagnostic and statistical manual of mental disorders (3rd ed.). Washington, DC: Author.

American Psychiatric Association. (1987). Diagnostic and statistical manual of mental disorders (3rd ed., rev.). Washington, DC: Author.

American Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington, DC: Author.

Arrigo, J. M., & Pezdek, K. (1998). Textbook models of multiple personality: Source, bias, and social consequences. In S. J. Lynn & K. M. McConkey (Eds.), Truth in memory (pp. 372-393). New York: Guilford Press.

Bahnson, C. B., & Smith, K. (1975). Autonomic changes in a multiple personality. Psychosomatic Medicine, 37, 85-86.

Berkson, J. (1946). Limitations of the application of the four-fold table analysis to hospital data. Biometrics Bulletin, 2, 47-53.

Bernstein, E. M., & Putnam, F. W. (1986). Development, reliability, and validity of a dissociation scale. Journal of Nervous and Mental Disease, 174, 727-735.

Bliss, E. L. (1980). Multiple personalities: A report of 14 cases with implications for schizophrenia and hysteria. Archives of General Psychiatry, 37, 1388-1397.

Boon, S., & Draijer, N. (1993). Multiple personality disorder in the Netherlands: A clinical investigation of 71 cases. American Journal of Psychiatry, 150, 489-494.

Boor, M. (1982). The multiple personality epidemic: Additional cases and inferences regarding diagnosis, etiology, dynamics, and treatment. Journal of Nervous and Mental Disease, 170, 302-304.

Braun, B. G. (1980). Hypnosis for multiple personalities. In H. J. Wain (Ed.), Clinical hypnosis in medicine (pp. 209-217). Chicago: Year Book Medical.

Braun, B. G. (1986). Issues in the psychotherapy of multiple personality disorder. In B. G. Braun (Ed.), Treatment of multiple personality disorder (pp. 1-28). Washington, DC: American Psychiatric Press.

Bremner, J. D., Narayan, M., Anderson, E. R., Staib, L. H., Miller, H. L., & Charney, D. S. (2000). Hippocampal volume reduction in major depression. American Journal of Psychiatry, 157, 115-117.

Bremner, J. D., Randall, P., Scott, T. M., & Bronen, R. (1995). MRI-based measurement of hippocampal volume in patients with combat-related posttraurnatic stress disorder. American Journal of Psychiatry, 152, 973-981.

Bremner,J. D., Randall, P., Vermetten, E., & Staib, L. (1997). Magnetic resonance imaging-based measurement of hippocampal volume in posttraurnatic stress disorder related to childhood physical and sexual abuse: A preliminary report. Biological Psychiatry, 41, 23-32.

Brende, J. 0. (1984). The psychophysio logic manifestations of dissociation: Electodermal responses in a multiple personality patient. Psychiatric Clinics of North America, 7, 41-50.

Brown, D., Frischholtz, E. J., & Scheflin, A. W. (1999). iatrogenic dissociative identity disorder: An evaluation of the scientific evidence. Journal of Psychiatry and Law, 2 7, 549-637.

Carson, R. C., & Butcher, J. N. (1992). Abnormal psychology and modern life (9th ed.). New York: Harper Collins.

Coons, P. M. (1984). The differential diagnosis of multiple personality disorder: A comprehensive review. Psychiatric Clinics of North America, 7, 51-67.

Coons, P. M. (1989). iatrogenic factors in the misdiagnosis of multiple personality disorder. Dissociation, 2, 70-76.

Coons, P. M. (1994). Confirmation of childhood abuse in child and adolescent cases of multiple personality disorder and dissociative identity disorder not otherwise specified. Journal of Nervous and Mental Disease, 182, 461-464.

Coons, P. M., Bowman, E. S., & Milstein, V. (1988). Multiple personality disorder: A clinical investigation of 50 cases. Journal of Nervous and Mental Disease, 176, 519-527.

Coons, P. M., & Milstein, V. (1986). Psychosexual disturbances in multiple personality: Characteristics, etiology, and treatment. Journal of Clinical Psychiatry, 47, 106-111.

Cormier, J. E, & Thelen, M. H. (1998). Professional skepticism of multiple personality disorder. Professional Psychology: Research and Practice, 29, 163-167.

Dell, P. E (198 8). Professional skepticism about multiple personality. Journal of Nervous and Mental Disease, 176, 528-531.

Dell, P. E (200 1). Why the diagnostic criteria for dissociative identity disorder should be changed. Journal of Trauma and Dissociation, 2, 7-37.

Dell, P. E, & Eisenhower, J. W. (1990). Adolescent multiple personality disorder: A preliminary study of eleven cases. Journal of the American Academy of Child and Adolescent Psychiatry, 29, 359-366.

Dennett, D. C. (1991). Consciousness explained. Boston: Little, Brown.

Dorahy, M. J. (2001). Dissociative identity disorder and memory dysfunction: The current state of experimental research and its future directions. Clinical Psychology Review, 21, 771-795.

Draijer, N., & Boon, S. (1999). The limitations of dissociative identity disorder: Patients at risk, therapists at risk. Journal of Psychiatry and Law, 27, 423458.

du Fort, G. G., Newman, S. C., & Bland, R. C. (1993). Psychiatric comorbidity and treatment seeking: Sources of selection bias in the study of clinical populations. Journal of Nervous and Mental Disease, 181, 467-474.

Dunn, G. E., Paolo, A. M., Ryan, J. J., & van Fleet, J. N. (1994). Belief in the existence of multiple personality disorder among psychologists and psychiatrists. journal of Clinical Psychology, 50, 454-457.

Ellason, J. W., Ross, C. A., & Fuchs, D. L. (1996). Lifetime Axis I and Axis 11 comorbidity and childhood trauma history in dissociative identity disorder. Psycbiatry: Interpersonal and Biological Processes, 59, 255-266.

Elzinga, B. M., van Dyck, R., & Spinhoven, P. (1998). Three controversies about dissociative identity disorder. Clinical Psychology and Psychotherapy, 5, 13-23.

Fahy, T. A. (1988). The diagnosis of multiple personality disorder: A critical review. British Journal of Psychiatry, 153, 597-606.

Fivush, R., & Hudson, J. A. (Eds.). (1990). Knowing and remembering in young children. New York: Cambridge University Press.

Frances, A., & First, M. B. (1998). Your mental health: A layman's guide to the Psychiatrist's Bible. New York: Scribner.

Ganaway, G. K. (1989). Historical versus narrative truth: Clarifying the role of exogenous trauma in the etiology of MPD and its variants. Dissociation, 2,205-220.

Ganaway, G. K. (1995). Hypnosis, childhood trauma, and dissociative identity disorder: Toward an integrative theory. International Journal of Clinical and Experimental Hypnosis, 43, 127-144.

Gleaves, D. H. (1996). The sociocognitive model of dissociative identity disorder: A reexamination of the evidence. Psychological Bulletin, 120, 42-59.

Gleaves, D. H., May, M. C., & Cardena, E. (2001). An examination of the diagnostic validity of dissociative identity disorder. Clinical Psychology Review, 21, 577608.

Hacking, 1. (1995). Rewriting the soul: Multiple personality and the science of memory. Princeton, NJ: Princeton University Press.

Hochman,J., & Pope, H. G. (1997). Debating dissociative diagnoses. American Journal of Psychiatry, 153, 887-888.

Hyman, 1. E., Jr., Husband, T. H., & Billings, F. J. (1995). False memories of childhood experiences. Applied Cognitive Psychology, 9, 181-197.

Hyman, 1. E., Jr., & Pentland, J. (1996). The role of mental imagery in the creation of false childhood memories. Journal of Memory and Language, 35, 101-117.

Klein, D. E (1999). Multiples: No amnesia for child abuse. American Journal of Psychiatry, 156, 976-977.

Kluft, R. P. (198 8). The phenomenology and treatment of extremely complex multiple personality disorder. Dissociation, 1, 47-58.

Kluft, R. P. (1991). Multiple personality disorder. In A. Tasman & S. M. Goldfinger (Eds.), American Psychiatric Press Review of Psychiatry (Vol. 10, pp. 161-188). Washington, DC: American Psychiatric Association Press.

Kluft, R. P. (1993). Multiple personality disorders. In D. Spiegel (Ed.), Dissociative disorders: A clinical review (pp. 17-44). Lutherville, MD: Sidran Press.

Lewis, D. 0., Yeager, C. A., Swica, Y., Pincus, J. H., & Lewis, M. (1997). Objective documentation of child abuse and dissociation in 12 murderers with dissociative identity disorder. American Journal of Psychiatry, 143, 1703-1710.

Lichtenstein Creative Media. (1998). The infinite mind [Radio broadcast]. National Public Radio.

Lilienfeld, S. 0., Lynn, S. J., Kirsch, L, Chaves, J. E, Sarbin, T. R., Ganaway, G. K., & Powell, R. A. (1999). Dissociative identity disorder and the sociocognitive model: Recalling the lessons of the past. Psychological Bulletin, 125,507-523.

Lindsay, D. (1996). Commentary on informed clinical practice and the standard of care: Proposed guidelines for the treatment of adults who report delayed memories of childhood trauma. In J. D. Read & D. S. Lindsay (Eds.), Recollections of trauma: Scientific evidence and clinical practice (pp. 361-370). New York: Plenum Press.

Lindsay, D. S. (1998). Depolarizing views on recovered memory experiences. In S. J. Lynn & K. M. McConkey (Eds.), Truth in memory (pp. 481-494). New York: Guilford Press.

Loftus, E. E (1993). The reality of repressed memories. American Psychologist, 48, 518-537.

Loftus, E. F. (1997, September). Creating false memories. Scientific American, pp. 70-75.

Loftus, E. F., & Pickrell, J. E. (1995). The formation of false memories. Psychiatric Annals, 25, 720-725.

Ludwig, A. M., Brandsma, J. M., Wilbur, C. B., Bendefeldt, E, & Jameson, D. H. (1972). The objective study of a multiple personality: Or, are four heads better than one? Archives of General Psychiatry, 26, 298-310.

Lynn, S. J., Lock, T G., Myers, B., & Payne, D. (1997). Recalling the unrecallable: Should hypnosis be used to recover memories in psychotherapy? Current Directions in Psychological Science, 6, 79-83.

Lynn, S. J., & Pintar, J. (1997). A social narrative model of dissociative identity disorder. Australian Journal of Clinical and Experimental Hypnosis, 25, 1-7.

Lynn, S. J., Rhue, J. W., & Green, J. P. (1988). Multiple personality and fantasy proneness: Is there an association or dissociation? British Journal of Experimental and Clinical Hypnosis, 5, 138-142.

Mai, E M. (1995). Psychiatrists' attitudes to multiple personality disorder: A questionnaire study. Canadian Journal of Psychiatry, 40, 154-15 7.

Malinowski, P., & Lynn, S. J. (1995, August). The pliability of early memory reports. Paper presented at the Annual Convention of the American Psychological Association, Washington, DC.

Marmer, S. S. (1998, December). Should dissociative identity disorder be considered a bona fide psychiatric diagnosis? Clinical Psychiatry News.

Mazzoni, G. A., Loftus, E. F., & Kirsch, 1. (2001). Changing beliefs about implausible autobiographical memories. Journal of Experimental Psychology: Applied, 7, 51-59.

McHugh, P. R. (1993). Multiple personality disorder. Harvard Mental Health Newsletter, 10(3), 4-6.

Merckelbach, H., Devilly, G. J., & Rassin, E. (2002). Alters in dissociative identity disorder: Metaphors or genuine entities? Clinical Psychology Review, 22, 481497.

Merckelbach, H., & Muris, P. (2001). The causal link between self-reported trauma and dissociation: A critical review. Behaviour Research and Therapy, 39, 245-254.

Merckelbach, H., Muris, P., Horselenberg, R., & Stougie, S. (2000). Dissociative experiences, response bias, and fantasy proneness in college students. Personality and Individual Differences, 2S, 49-58.

Merskey, H. (1992). The manufacture of personalities: The production of multiple personality disorder. British Journal of Psychiatry, 160, 327-340.

Modestin, J. (1992). Multiple personality disorder in Switzerland. American Journal of Psychiatry, 149, 88-92.

Mulhern, S. (1991). Satanism and psychotherapy: A rumor in search of an inquisition. In J. T Richardson, J. Best, & D. G. Bromley (Eds.), The Satanism scare (,np, 145-172)

Hippocampal assumed properties of child sexual abuse using college samples. Psychological Bulletin, 124, 22-53.

Robins, E., & Guze, S. B. (1970). Establishment of diagnostic validity in psychiatric illness: Its application to schizophrenia. American Journal of Psychiatry, 126, 107-111.

Ross, C. A. (1989). Multiple personality disorder: Diagnosis, clinical features, and treatment, New York: Wiley.

Ross, C. A. (1990). Twelve cognitive errors about multiple personality disorder. American Journal of Psychotherapy, 44, 348-356.

Ross, C. A. (1991). Epidemiology of multiple personality disorder and dissociation. Psychiatric Clinics of North America, 14, 503-517.

Ross, C. A. (1997). Dissociative identity disorder: Diagnosis, clinical features, and treatment of multiple personality. New York: Wiley.

Ross, C. A., Anderson, G., Fleisher, W. P., & Norton, G. R. (199 1). The frequency of multiple personality disorder among psychiatric inpatients. American journal of Psychiatry, 148, 1717-1720.

Ross, C. A., Miller, S. D., Reagor, P. Bjornson, L., Fraser, G. A., & Anderson, G. (1990). Structured interview data on 102 cases of multiple personality disorder from four centers. American Journal of Psychiatry, 147, 596-601.

Ross, C. A., & Norton, G. R. (1989). Effects of hypnosis on the features of multiple personality disorder. Dissociation, 3, 99-106.

Ross, C. A. ., Norton, G. R., & Wozney, K. (19 8 9). Multiple personality disorder: An analysis of 236 cases. Canadian Journal of Psychiatry, 34, 413-418.

Sapolsky, R. M. (2000). Glucocorticoids and hippocampal atrophy in neuropsychiatric disorders. Archives of General Psychiatry, 57, 925-935.

Sarbin, T. R. (1995). On the belief that one body may be host to two or more personalities. International journal of Clinical and Experimental Hypnosis, 43, 163183.

Schreiber, F. R. (1973). Sybil. New York: Warner.

Schultz, R., Braun, B. G., & Kluft, R. P. (1989). Multiple personality disorder: Phenomenology of selected variables in comparison to major depression. Dissociation, 2, 45-51.

Scroppo, J. C., Drob, S. L., Weinbergerj. L., & Eagle, P. (1998). Identifying dissociative identity disorder: A self-report and projective study. Journal of Abnormal Psychology, 107, 272-284.

Shermer, M. (1997). Why people believe weird things: Pseudoscience, superstition, and other confusions of our time. New York: Freeman.

Shermer, M. (2001). The borderlands of science: Where sense meets nonsense. New York: Oxford University Press.

Showalter, E. (1997). Hystories: Hysterical epidemics and modern culture. New York: Columbia University Press.

Slovenko, F. (1999). The production of multiple personalities. Journal of Psychiatry and Law, 27, 215-253.

Sno, H. N., & Schalken, H. F. (1999). Dissociative identity disorder Diagnosis and treatment in the Netherlands. European Psychiatry, S, 270-277.

Southwick, S., Morgan, A. C., Nicolaou, A. L., & Charney, D. S. (1997). Consistency of memory for combat-related traumatic events in veterans of Operation Desert Storm. American journal of Psychiatry, 154, 173-177.

Spanos, N. P. (1994). Multiple identity enactments and multiple personality disorder: A sociocognitive perspective. Psychological Bulletin, 116, 143-165.

Spanos, N. P. (1996). Multiple identities and false memories: A sociocognitive perspective. Washington, DC: American Psychological Association.

Spanos, N. P., & Chaves, J. F. (1989). Hypnosis: The cognitive-behavioral perspective. Buffalo, NY: Prometheus.

Spanos,N. P., Menary, E., Gabora, M.J., DuBreuil, S. C., & Dewhirst, B. (1991). Secondary identity enactments during hypnotic past-life regression: A sociocognitive perspective. Journal of Personality and Social Psychology, 61, 308320.

Spanos, N. P., Weekes, J. R., & Bertrand, L. D. (19 85). Multiple personality: A social psychological perspective. Journal of Abnormal Psychology, 94, 362-376,

Spanos, N. P., Weekes, J. R., Menary, E., & Bertrand, L. D. (1986). Hypnotic interview and age regression procedures in the elicitation of multiple personality symptoms. Psychiatry, 49, 298-311.

Spiegel, D. (1993, May 20). Letter to the Executive Council, International Study for the Study of Multiple Personality and Dissociation. News, International Society of the Study of Multiple Personality and Dissociation, 11, 15.

Stafford, J., & Lynn, S. J. (1998). Cultural scripts, childhood abuse, and multiple identities: A study of role-played enactments. Manuscript submitted for publication.

Stein, M. B., Koverola, C., Hanna, C., & Torchia, M. G. (1997). Hippocampal volume in women victimized by childhood sexual abuse. Psychological Medicine, 27,951-959.

Takahashi, Y. (1990). Is multiple personality really rare in Japan? Dissociation, 3, 57-59.

Tellegen, A., & Atkinson, G. (1974). Openness to absorbing and self-altering experiences ("absorption"), a trait related to hypnotic susceptibility. Journal of Abnormal Psychology, 83, 268-277.

Thigpen, C. H., & Cleckley, H. M. (1957). The three faces of Eve. New York: McGraw Hill.

Tsai, G. E., Condie, D., Wu, M-T., & Chang, L-W. (1999). Functional magnetic resonance imaging of personality switches in a woman with dissociative identity disorder. Harvard Review of Psychiatry, 72, 119-122.

van der Hart, 0. (1993). Multiple personality disorder in Europe: Impressions. Dissociation, 6, 102-118.

van der Kolk, B. A., van der Hart, 0., & Marmar, C. R. (1996). Dissociation and information processing in posttraurnatic stress disorder. In B. A. van der Kolk, A. C. McFarlane, & L. Weisaeth (Eds.), Traumatic stress: The effects of overwhelming experience on mind, body, and society (pp. 303-327). New York: Guilford Press.

Widorn, C. S. (1988). Does violence beget violence? A critical examination of the literature. Psychological Bulletin, 106, 3-28.

Zohar, J. (1998). Post-traumatic stress disorder: The hidden epidemic of modern times. CNS Spectrums, 3(7, Suppl. 2), 4-51.
 

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