Psychological Trauma: Theory, Research, Practice, and Policy 2015, Vol. 7, No. 1, 93–101

© 2014 American Psychological Association 1942-9681/15/$12.00 http://dx.doi.org/10.1037/a0035181

Distinguishing Simulated From Genuine Dissociative Identity Disorder on the MMPI-2 Bethany L. Brand and Gregory S. Chasson

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Towson University Due to high elevations on validity and clinical scales on personality and forensic measures, it is challenging to determine if individuals presenting with symptoms of dissociative identity disorder (DID) are genuine or not. Little research has focused on malingering DID, or on the broader issue of the profiles these patients obtain on the Minnesota Multiphasic Personality Inventory (MMPI-2), despite increasing awareness of dissociation. This study sought to characterize the MMPI-2 profiles of DID patients and to determine the utility of the MMPI-2 in distinguishing DID patients from uncoached and coached DID simulators. The analyses revealed that Infrequency, Back Infrequency, and Infrequency-Psychopathology (Fp) distinguished simulators from genuine DID patients. Fp was best able to discriminate simulated DID. Utility statistics and classification functions are provided for classifying individual profiles as indicative of genuine or simulated DID. Despite exposure to information about DID, the simulators were not able to accurately feign DID, which is inconsistent with the iatrogenic/sociocultural model of DID. Given that dissociation was strongly associated with elevations in validity, as well as clinical scales, including Scale 8 (i.e., Schizophrenia), considerable caution should be used in interpreting validity scales as indicative of feigning, and Scale 8 as indicative of schizophrenia, among highly dissociative individuals. Keywords: dissociative identity disorder, malingering, iatrongenic, sociocultural, MMPI-2

(Brand et al., 2009). Detecting feigned PTSD can be challenging due to genuine patients sometimes producing elevations on validity scales on the MMPI-2 that are indistinguishable from those of feigners (Bury & Bagby, 2002; Butcher et al., 2001; Elhai, Gold, Sellers, & Dorfman, 2001; Marshall & Bagby, 2006). A metaanalysis found extreme elevations on Back Infrequency (Fb), Infrequency (F), and Infrequency-Psychopathology (Fp) for patients with PTSD (Rogers, Sewell, Martin, & Vitacco, 2003). Fp is often found the most effective for assessing feigned PTSD, particularly among child sexual abuse (CSA) samples (Elhai et al., 2004; Klotz Flitter, Elhai, & Gold, 2003; Rogers et al., 2003). Childhood trauma survivors also have numerous elevated MMPI-2 clinical scales (Elhai, Gold, Mateus, & Astaphan, 2001; Engels, Moisan, & Harris, 1994; Klotz Flitter et al., 2003; Korbanka & McKay, 2000). Eleven items from Scale 8 (schizophrenia) correctly distinguished 81% of adults abused in childhood from nonabused controls (Wolf, Reinhard, Cozolino, Caldwell, & Asamen, 2009), leading the authors to conclude that the items reflected difficulty regulating affect, impulses, and cognitive process—including dissociation— directly related to trauma. Trauma, forensic, and assessment experts agree that the extreme elevations on validity and clinical scales often reflect the array of symptoms, impairment, and distress common among those who experienced complex childhood trauma (Caldwell, 2001; Rogers, Payne, Correa, Gillard, & Ross, 2009). Dissociation also contributes to F scale elevations (Dunn, Paolo, Ryan, & van Fleet, 1993; Klotz Flitter et al., 2003). Dissociation was the strongest and only unique predictor of F scores among women who experienced CSA; combined with PTSD, depression and family environment, dissociation accounted for 40% of the variance in F (Klotz Flitter et al., 2003). Dissociation also influ-

Trauma has been linked as a causal factor in posttraumatic stress disorder (PTSD) as well as severe dissociative reactions, including dissociative identity disorder (DID; e.g., Brand et al., 2009; Dalenberg et al., 2012). Dissociation is defined in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5; American Psychiatric Association, 2013) as “a disruption of and/or discontinuity in the normal integration of consciousness, memory, identity, emotion, perception, body representation, motor control, and behavior” American Psychiatric Association, 2013. Increased interest and awareness of dissociation led to the addition of a dissociative subtype of PTSD in DSM-5. As dissociative reactions garner greater recognition, it is important to be able to accurately assess dissociative reactions and to distinguish genuine DID from feigned DID. The current study sought to determine the utility of the Minnesota Multiphasic Personality Inventory (MMPI-2; Butcher, Graham, Ben-Porath, Tellegan, & Dahlstrom, 2001) in detecting simulated from genuine DID. Individuals with DID usually are also diagnosed with PTSD, so research about feigned PTSD informs the detection of feigned DID

This article was published Online First March 17, 2014. Bethany L. Brand and Gregory S. Chasson, Psychology Department, Towson University. We thank the DID patients and simulators, as well as the research assistants who made this study possible. They would also like to thank Steve Gold for helpful comments on a draft of this article. This study was funded by a grant from Towson University’s Faculty Development and Research Committee to the first author. Correspondence concerning this article should be addressed to Bethany L. Brand, Psychology Department, Towson University, 8000 York Rd., Towson, MD 21252. E-mail: [email protected] 93

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ences scores on clinical scales. It correlates strongly with Scale 8 in child abuse survivors (between .48 and .59 in Allen & Coyne, 1995), who commonly have 8 (Schizophrenia)– 4 (Psychopathic Deviate) or 8 –2 (Depression) profiles (Elhai, Gold, Mateus, et al., 2001; Engels et al., 1994; Korbanka & McKay, 2000; Wolf et al., 2009), with additional elevations on 6 (Paranoia) and 7 (Psychasthenia) (Klotz Flitter et al., 2003). Similarly, individuals with dissociative disorders have high elevations on clinical and validity scales, making correct classification challenging (Bliss, 1984; Coons & Sterne, 1986; Solomon, 1983). On the MMPI, approximately one third of DID patients’ profiles were technically invalid due to high F scores, with extremely high clinical scale elevations occurring on Scale 8 (91 in Coons & Sterne, 1986), typically followed by lower elevations on Scales 2, 4, 6, and 7, and common profiles of 8 –2, 8 – 4, and 8 – 6 (Coons & Sterne, 1986; Solomon, 1983; Welburn et al., 2003). The only MMPI-2 study of DID found very extreme F (M ⬎ 100T) along with extreme elevations (Ms ⬎ 80T) on 2, 4, 6, 7, and 8 in genuine DID patients (Welburn et al., 2003). Other tests, including the Structured Interview of Reported Symptoms and the Personality Assessment Inventory, have been found to overclassify highly dissociative patients as feigners on scales that include items associated with trauma such as dissociation (Brand, McNary, Loewenstein, Kolos, & Barr, 2006; Stadnik, Brand, & Savoca, 2013; Brand, Tursich, Tzall, & Loewenstein, 2014; Rogers et al., 2009). Although studies have examined feigned PTSD on the MMPI-2 (Rogers et al., 2003), there have only been two studies of feigning DID, and, unfortunately, both used small samples (Coons & Milstein, 1994; Welburn et al., 2003). The MMPI did not differentiate 11 patients with factitious or malingered DID compared with 50 clinically diagnosed DID cases (Coons & Milstein, 1994), nor could the MMPI-2 distinguish 10 simulators from 12 DID patients (Welburn et al., 2003). Whereas the Welburn et al. study used the gold-standard interview for diagnosing dissociative disorders, the Structured Clinical Interview for DSM–IV Dissociative Disorders–Revised (SCID-D-R; Steinberg, 1994), it was underpowered. Thus, it remains unknown if it is possible to reliably differentiate those with SCID-D-R diagnosed DID from feigned DID. Given the high stakes in forensic, clinical, and disability cases, it is crucial to have empirically supported methods to discriminate malingered from genuine DID. The goals of this study were to characterize the MMPI-2 profiles of an adequate sample of SCID-D-R-diagnosed DID patients, as well as DID feigners, and distinguish genuine from feigned DID in a two-step procedure. In the first step, we tested differences in the MMPI-2 profiles for coached and uncoached DID simulators, as well as those of genuine DID patients. In the second step, those MMPI-2 scales that reliably differentiated coached, uncoached, and DID participants in the first step were evaluated in a classification model to determine the degree to which group membership (DID vs. non-DID) was predicted with accuracy. The scales included in the first step were selected because they were previously used in research with DID or PTSD (i.e., F, Fb, Fp, 2, Familial Discord Subscale (Pd1), Social Alienation Subscale (Pd4), Self-Alienation Subscale (Pd5), 7, and 8). Additional validity (e.g., Variable Response Inconsistency Scale, True Response Inconsistency Scale, and Dissimulation Scale Revised) and clinical scales (e.g., 1, 3, 6,

Hypomania (9), and Social Introversion (0)) were included, given the limited research on DID and the MMPI-2. Our hypotheses were that Fp would be the most effective scale for correct classification, and that DID patients would produce extreme F elevations, with the highest clinical elevation on Scale 8, followed by elevations ⬎70T on Scales 2, 4, 6, and 7.

Method Participants DID participants. DID patients (n ⫽ 53) were recruited from an inpatient unit treating severely traumatized patients (n ⫽ 18; 34%) as well as from outpatient practices of therapists in the community known to treat dissociative patients. Patients were paid $20. They ranged in age from 22 to 62 years (mean age ⫽ 41.21, SD ⫽ 9.95), and most (n ⫽ 47) were female. Forty-four (83%) identified as Caucasian, five as African American (9%), one as Asian (2%), none as Latino, one as Biracial (2%), and two (4%) did not specify an ethnic background. Coached simulating participants. Undergraduate students (n ⫽ 77) who had taken Abnormal Psychology were recruited from the psychology research pool. They ranged in age from 18 to 27 years (mean age ⫽ 21.97, SD ⫽ 3.73), and most (n ⫽ 64) were female. Sixty-two (80%) identified as Caucasian, six as African American (8%), one as Asian (1%), two as Latino (3%), one as Biracial (1%), and five (7%) did not specify an ethnic background. The coached simulators were required to read accurate material about DID obtained from the Internet and provided by the researchers, read the book Sybil (Schreiber, 1989), and/or watch the movie Sybil, and pass a knowledge test showing they could identify the symptoms of DID. Uncoached simulating participants. Undergraduate students (n ⫽ 67) who had not taken Abnormal Psychology were recruited from the psychology research pool. They were primarily female (n ⫽ 46) and ranged from 18 to 21 years old (mean age ⫽ 19.43, SD ⫽ 2.09). Forty-six (69%) identified as Caucasian, 11 as African American (16%), five as Asian (7.5%), one as Latino (1.5%), one as Biracial (1.5%), and three (4.5%) did not specify an ethnic background. This group was asked to simulate DID, although they were not provided with any information about DID.

Materials and Procedure DID Knowledge Test. This is a 10-item true–false quiz that described eight accurate (e.g., hear voices; have amnesia; call themselves different names; act very differently at different times; have trance states; have different personality states; typically have PTSD; experienced severe childhood abuse) and two inaccurate symptoms (e.g., individuals are so out of touch with reality that they are psychotic; compulsively wash hands) associated with DID. Sources of knowledge about DID. Participants indicated which types of sources of information they had been exposed to about DID from a list of eight options, including movies, books, chapters in psychology textbooks, the Internet, and “other.”

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DISTINGUISHING SIMULATED DID

MMPI-2 (Butcher et al., 2001). The MMPI-2 is a widely used 567 true–false self-report inventory for assessing psychopathy. Dissociative Experiences Scale (DES; Bernstein & Putnam, 1986). The DES is a 28-item self-report measure of dissociative symptoms, with good reliability and validity (Carlson & Putnam, 1993). The alphas for this sample were .92 DID, .84 uncoached, and .87 coached. Posttraumatic Stress Checklist-Civilian. The PCL-C (Weathers, Litz, Huska, & Keane, 1994) is a 17-item measure of PTSD symptomatology experienced in the past month, with ratings from 1 (not at all) to 5 (extremely). Total scores, calculated by summing the responses, of 50 points or more are suggestive of PTSD (e.g., Weathers & Ford, 1996). SCID-D-R (Steinberg, 1994). The SCID-D-R is a 277-item semistructured interview that is considered the gold standard for diagnosing dissociative disorders. The SCID-D-R has good to excellent reliability and good discriminant validity (Steinberg, 1994, 2000).

Procedure This study was part of a larger study investigating the assessment of DID and its simulation. The simulators in both groups (i.e., coached and uncoached) were told they did not need to behaviorally act as if they had DID; rather, they answered tests as if they had the disorder. DID patients were diagnosed using the SCID-D-R interview, which were conducted by the first author, an expert in dissociative disorders, or a psychology postdoctoral fellow or psychologist from the hospital’s trauma disorders program, under the supervision of the first author. Simulators earned course credit, and a $50 incentive was provided for the best simulation each semester. Both groups of simulators truthfully completed the DES; those with scores above 30 were removed to ensure simulators did not have DID. Only the DID group completed the PCL-C.

Data Analysis The data were analyzed in two steps: (a) profile analysis comparing the three groups on MMPI indices while controlling for age, sex, and ethnicity, and (b) discriminant function analysis (DFA) predicting group membership from a linear combination of covariates. In the first step, emphasis was placed on the interaction between group and MMPI index, which, if significant, would suggest dissimilar MMPI profiles across the groups. In the second step, variables that significantly differed between participants with DID and those without DID (i.e., regardless if uncoached or coached) were then included in a DFA to predict DID status (present or absent). The DFA was selected instead of logistic regression because the study would be underpowered with the latter. For a multiple logistic regression, well over 1,000 participants would be needed to ensure sufficient power (⬎.80; Hsieh, Bloch, & Larsen, 1998). Missing data were rare and were handled using case-wise deletion within a given statistical test, explaining minor fluctuations in sample size.

95 Results

Preliminary Analyses We evaluated whether participants recruited from the inpatient setting versus noninpatient settings presented with different levels of dissociative symptom severity. The participants with DID who were recruited from the inpatient treatment setting endorsed statistically significantly higher severity of dissociative symptoms on the DES, t(40) ⫽ 2.40, p ⬍ .05, d ⫽ .75 (inpatient, M [SD] ⫽ 55.48 [20.61]; noninpatient M [SD] ⫽ 41.28 [17.03]). However, based on the direction of the effect, it was a conservative decision to retain inpatient participants with DID, as the higher symptom severity would make it harder to detect differences between the DID group and feigning group on the MMPI scales (higher symptom severity, as well as feigning psychopathology, increases MMPI validity indicators; Rogers et al., 2003). We carried out analyses as a manipulation check. The coached group reported exposure to significantly more sources of knowledge about DID than did the uncoached group (M ⫽ 4.32, SD ⫽ 1.17 vs. M ⫽ 0.73, SD ⫽ 0.89, respectively), t(156) ⫽ 21.66, p ⬍ 001, and accurately identified more DID symptoms on the knowledge test than did the uncoached group (M ⫽ 9.49, SD ⫽ .60 vs. M ⫽ 8.40, SD ⫽ 1.14), t(110.44) ⫽ 7.41, p ⬍ .001.

Descriptive Results The DID group scored above the PCL-C cutoff suggestive of PTSD (M ⫽ 59.16, SD ⫽ 12.22; Weathers & Ford, 1996). MMPI-2 and DES data for each group are presented in Table 1. Based on a criterion of Z ⬎ 3.29 (Tabachnick & Fidell, 2001), five outlier scores were identified within the TRIN index. Results that included and excluded the outlier scores were virtually identical. In the spirit of not altering data unnecessarily, results with outliers are provided herein. The ethnicity variable could not be analyzed for group differences because 67% of cells had an expected frequency below five (using chi-square analysis). Thus, the variable was dichotomized into “Caucasian” and “not Caucasian,” which differed across groups, ␹2(2) ⫽ 6.50, p ⬍ .05, and was therefore included in the profile analysis as a covariate. Age differed across groups, F(2, 192) ⫽ 242.74, p ⬍ .0001, as did sex ratio, ␹2(2) ⫽ 8.246, p ⬍ .05, so both were included as covariates. The DID group had a female to male ratio of more than 7:1 (vs. approximately 4.5:1 and 2:1 in the coached and uncoached groups, respectively). Consequently, sex was also included as a covariate. The age, ethnicity, and sex variables also correlated with dependent variables within each group, further suggesting a need for their control in the profile analysis.

Profile Analysis The data conformed to assumptions of profile analysis. MMPI indices were assessed as dependent variables in a mixed-design ANOVA with study group as the between-groups predictor (i.e., DID, coached, and uncoached), a within-subject MMPI index (18 levels representing the 18 predictor variables), and age, sex, and ethnicity as covariates. The sphericity assumption was violated, as Mauchly’s W approached zero (p ⬍ .001). With GreenhouseGeisser ε ⫽ .426, findings were interpreted using the Greenhouse-

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Table 1 Descriptive Data for DES and MMPI-2 Scores by Group

DES (item average) F Fb Fp VRIN TRIN Ds2 Hs D Hy Pd Pa Pt Sc Ma Si Pd1 Pd4 Pd5

DID M (SD)

Uncoached M (SD)

Coached M (SD)

Total M (SD)

DES r DID (non-DID)

46.79 (19.57) 90.99 (19.69) 93.24 (21.74) 72.01 (19.46) 55.27 (9.75) 57.40 (6.81) 75.62 (16.10) 72.66 (13.12) 82.53 (11.25) 73.53 (14.31) 78.06 (12.59) 76.19 (14.66) 76.45 (10.28) 84.11 (13.06) 58.64 (10.04) 66.79 (9.94) 69.92 (10.93) 69.85 (12.38) 75.26 (11.48)

11.49 (6.27) 112.97 (17.09) 110.40 (18.24) 110.46 (18.39) 72.88 (17.97) 62.64 (10.72) 86.98 (15.46) 74.45 (11.16) 73.01 (12.76) 66.61 (13.22) 78.87 (13.42) 89.88 (21.15) 77.06 (11.25) 91.73 (15.56) 72.78 (12.96) 64.94 (10.59) 72.39 (12.22) 73.43 (12.66) 73.38 (10.54)

7.42 (4.94) 112.11 (14.81) 114.21 (13.34) 105.10 (20.07) 61.29 (15.34) 60.61 (9.38) 89.16 (15.23) 74.99 (11.81) 81.68 (15.80) 68.59 (13.13) 84.41 (12.83) 89.53 (19.93) 81.44 (11.08) 95.99 (14.79) 66.79 (13.59) 71.18 (10.28) 78.33 (11.52) 75.99 (13.29) 77.76 (10.56)

19.53 (20.20) 106.64 (19.48) 107.20 (19.59) 97.95 (25.06) 63.64 (16.61) 60.44 (9.45) 84.73 (16.47) 74.17 (11.94) 78.93 (14.25) 69.25 (13.70) 80.78 (13.22) 86.03 (19.94) 78.58 (11.11) 91.30 (15.31) 66.63 (13.61) 67.84 (10.61) 74.01 (12.09) 73.44 (13.00) 75.57 (10.92)

— .49ⴱⴱ (⫺.12) .49ⴱⴱ (⫺.11) .37ⴱⴱ (⫺.07) ⫺.27 (.17ⴱ) .04 (.09) .27 (⫺.07) .33ⴱ (⫺.14) .16 (⫺.25ⴱⴱ) .46ⴱⴱ (⫺.24ⴱ) .39ⴱⴱ (⫺.19ⴱ) .50ⴱⴱ (⫺.07) .37ⴱⴱ (⫺.06) .47ⴱⴱ (⫺.15) .32ⴱ (.14) ⫺.01 (⫺.16) .28ⴱ (⫺.21ⴱ) .16 (⫺.06) .26 (⫺.16)

Note. DID, n ⫽ 53; coached, n ⫽ 75; uncoached n ⫽ 67. DES ⫽ Dissociative Experiences Scale; MMPI-2 ⫽ Minnesota Multiphasic Personality Inventory; DID ⫽ dissociative identity disorder; F ⫽ MMPI-2 Infrequency Scale; Fb ⫽ MMPI-2 Back Infrequency Scale; Fp ⫽ MMPI-2 Infrequency Psychopathology Scale; VRIN ⫽ MMPI-2 Variable Response Inconsistency Scale; TRIN ⫽ MMPI-2 True Response Inconsistency Scale; Ds2 ⫽ MMPI-2 Dissimulation Scale Revised; Hs ⫽ MMPI-2 Hypochondriasis scale; D ⫽ MMPI-2 Depression Scale; Hy ⫽ MMPI-2 Hysteria Scale; Pd ⫽ MMPI-2 Psychopathic Deviate Scale; Pa ⫽ MMPI-2 Paranoia Scale; Pt ⫽ MMPI-2 Psychasthenia Scale; Sc ⫽ MMPI-2 Schizophrenia Scale; Ma ⫽ MMPI-2 Hypomania Scale; Si ⫽ MMPI-2 Social Introversion Scale; Pd1 ⫽ MMPI-2 Familial Discord Subscale; Pd4 ⫽ MMPI-2 Social Alienation Subscale; Pd5 ⫽ MMPI-2 Self-Alienation Subscale. ⴱ p ⬍ .05. ⴱⴱ p ⬍ .01.

Geisser corrected test (Field, 2009). The within-subjects effect for MMPI index was significant, F(7.24, 1338.90) ⫽ 7.12, p ⬍ .001, ␩p2 ⫽ .037. The between-subjects effect for group was nonsignificant, F(2, 185) ⫽ 1.55, p ⫽ .216, ␩p2 ⫽ .016. The age covariate was significant, F(1, 185) ⫽ 4.81, p ⬍ .05, but the sex covariate, F(1, 185) ⫽ 0.25, p ⫽ .621, and the dichotomized ethnicity covariate were nonsignificant, F(1, 185) ⫽ 0.58, p ⫽ .449. The interaction between group and MMPI index was significant, F(14.48, 1338.90) ⫽ 4.73, p ⬍ .001, ␩p2 ⫽ .049, indicating statistically different MMPI profiles across the groups. Figure 1 illustrates the groups’ profiles. To follow up the significant interaction, post hoc one-way ANOVAs were performed on the MMPI indices included in the profile analysis. To protect against Type I error, alpha was set at .0028 (i.e., ␣ ⫽ .05 divided by 18 tests). Significant post hoc one-way ANOVAs were followed up with a test of marginal means using Tukey’s Honestly Significant Difference corrections. Results are in Table 2. Variables that demonstrated significant differences between DID and both the uncoached and coached groups were considered the most promising variables for the subsequent DFA. Based on this criterion, the following seven MMPI indices were analyzed in the DFA: F, Fb, Fp, Ds2, 5, 7, and 8. The DID profiles were similar to the means for PTSD samples in the Rogers et al. (2003) meta-analysis: PTSD F 86.31 versus 90.99 for DID patients, PTSD Fb of 92.31 versus 93.2 DID, and PTSD Fp ⫽ 69.02 versus 72.0 DID. DID participants’ scores were lower than or similar to that obtained by treatment-seeking PTSD patients who had experienced CSA (Ds2 75.62 in DID vs. 82.17 CSA found by Elhai, Gold, Sellers, et al., 2001).

Discriminant Function Analysis The grouping variable was collapsed into DID versus non-DID (i.e., coached and uncoached were merged) for three reasons. First, univariate post hoc tests revealed that all but one of the predictors demonstrated a pattern in which coached and uncoached responses were statistically identical (i.e., Ma), and in all cases, both nonclinical groups scored significantly higher than the DID group. Thus, the few potentially meaningful statistical differences between coached and uncoached participants did not outweigh the advantage of enhancing statistical power by using two groups instead of three. Second, DFA is highly related to MANOVA; indeed, DFA has been called MANOVA “turned around” (Tabachnick & Fidell, 2001, p. 456). Thus, following up the profile analysis (i.e., MANOVA) using the same groups and many of the same predictors would be partially redundant. Finally, collapsing the non-DID participants into one group allows exploration of a second research question, and one that seems highly relevant. Forensic and clinical experts are not informed about who is coached or uncoached. Thus, uncovering meaningful ways of predicting DID versus non-DID, regardless if coached or not, seems important and more generalizable outside of academic labs. All data analytic assumptions of DFA were met. The model was statistically significant, ␹2(7) ⫽ 116.36, p ⬍ .001, canonical r ⫽ .68. This significant DFA model was subsequently followed up with univariate analyses of individual predictors, which indicated that all MMPI indices significantly differed between the DID versus non-DID groups; however, only those predictors with a standardized correlation with the discriminant function ⬎.5 were

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DISTINGUISHING SIMULATED DID

Figure 1.

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MMPI profiles for DID patients and coached and uncoached simulators.

considered robust (Tabachnick & Fidell, 2001). Results from the DFA are in Table 2 and indicate that Fp, F, and Fb were the only robust predictors for differentiating DID from non-DID MMPI profiles. The DFA did not include age as a covariate, even though it was a significant covariate in the profile analysis. As an alternative, we could have carried out a logistic regression model that included age as a covariate. However, the DFA was elected because the sample size would have resulted in a considerably underpowered logistic regression analysis. Nonetheless, as an exploratory analysis, we carried out a logistic regression in which the dichotomous group membership was regressed on the same predictors from the DFA, plus age as a covariate. The model was significant, ␹2(8, N ⫽ 195) ⫽ 181.67, p ⬍ .001. The only significant main effect was Fp, ␹2(1, N ⫽ 195) ⫽ 6.86, p ⬍ .01. The F and Fb variables— which were deemed robust predictors in the DFA model—were not significant in the logistic regression model, ␹2(1, N ⫽ 195) ⫽ 0.11, p ⫽ .74, and ␹2(1, N ⫽ 195) ⫽ 0.19, p ⫽ .66, respectively. Unfortunately, because the logistic regression analysis was substantially underpowered, the null effects for Fb and F (and the other predictors in the model) cannot be easily interpreted. Incidentally, age was a statistically significant covariate in the logistic regression, ␹2(1, N ⫽ 195) ⫽ 21.58, p ⬍ .001.

Exploratory Cut Scores Validity scales were evaluated to suggest optimal cut scores for classifying DID versus non-DID. Utility statistics are in Table 3 for cut scores within plus or minus one-half standard deviation of the sample mean for each validity scale. To derive classification results, one classification model was tested for each combination of group (i.e., DID vs. non-DID) and one validity scale. Ds2 did not achieve adequate sensitivity or specificity. Cut scores of .5Z

(116.38) for F, ⫺.5Z (97.41) for Fb, and ⫺.5Z (85.42) for Fp were the optimal cut scores and resulted in overall diagnostic power (ODP) of .78, .78, and .83, respectively. None of the validity scales achieved a positive predictive power (PPP) higher than .66, indicating these validity scales may exhibit less than adequate predictive accuracy for differentiating true positives (i.e., DID cases classified as DID) from false positives. Using the DFA combination of predictors, 85.3% of all cases were classified, with a sensitivity of 83.0%, specificity of 86.0%, PPP of 68.8%, and ODP of 85.3%. These percentages outperform the single validity scale percentages listed in Table 3. For the highest classification accuracy, it may be useful to use the DFA model instead of single MMPI indices, although the model requires replication in a new clinical sample for corroboration. The DFA model could be applied to an individual’s test scores to determine classification using the classification equation, C j ⫽ c j0 ⫹ c j1X1 ⫹ c j2X2 ⫹ c j3X3 ⫹ c j4X4 ⫹ c j5X5 ⫹ c j6X6 ⫹ c j7X7 in which Cj represents a classification score for a given group (i.e., DID or non-DID), cj0 represents a group’s constant, cj1 through cj7 represent the classification coefficients for each of the seven MMPI indices for a given group, and X1 through X7 represent an individual’s scores on each of the seven MMPI indices (Tabachnick & Fidell, 2001). The DID and non-DID group constants and coefficients can be located in Table 2; the group constants are in the footnote. To determine classification for a given individual, plug the individual’s scores into the DID version of the equation and separately for the non-DID version of the equation. The individual should be classified into the group with the largest classification score (Cj).

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Table 2 Profile Analysis and Discriminant Function Analysis Results

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Profile analysis

F Fb Fp VRIN TRIN Ds2 Hs D Hy Pd Pa Pt Sc Ma Si Pd1 Pd4 Pd5

Discriminant function analysis

Univariate F

Post-hoc group differencesa

Standardized canonical correlations

31.54ⴱ 24.27ⴱ 67.81ⴱ 21.91ⴱ 4.53 13.18ⴱ .652 9.31ⴱ 4.03 4.63 9.53ⴱ 4.25 10.29ⴱ 18.95ⴱ 6.73 8.61ⴱ 3.44 2.79

(Uncoach ⫽ Coach) ⬎ DID (Uncoach ⫽ Coach) ⬎ DID (Uncoach ⫽ Coach) ⬎ DID Uncoach ⬎ Coach ⫽ DID DID ⫽ Coach ⫽ Uncoach (Uncoach ⫽ Coach) ⬎ DID DID ⫽ Coach ⫽ Uncoach (Coach ⫽ DID) ⬎ Uncoach DID ⫽ Coach ⫽ Uncoach DID ⫽ Coach ⫽ Uncoach (Uncoach ⫽ Coach) ⬎ DID DID ⫽ Coach ⫽ Uncoach (Uncoach ⫽ Coach) ⬎ DID Uncoach ⬎ Coach ⬎ DID DID ⫽ Coach ⫽ Uncoach Coached ⬎ (Uncoach ⫽ DID) DID ⫽ Coach ⫽ Uncoach DID ⫽ Coach ⫽ Uncoach

.62d .53d .90d — — .40 — — — — .34 — .33 .42 — — — —

Standardized canonical coefficients

DID classification coefficientsb

Non-DID classification coefficientsc

.24 ⫺.02 1.03 — — .44 — — — — .04 — ⫺.93 .12 — — — —

.16 .13 ⫺.13 — — ⫺.10 — — — — ⬍.01 — .24 .26 — — — —

.19 .13 ⫺.02 — — ⫺.04 — — — — ⬍.01 — .11 .28 — — — —

Note. DID, n ⫽ 53; coached, n ⫽ 75; uncoached, n ⫽ 67; Non-DID, n ⫽ 144. DID ⫽ dissociative identity disorder; F ⫽ MMPI-2 Infrequency Scale; Fb ⫽ MMPI-2 Back Infrequency Scale; Fp ⫽ MMPI-2 Infrequency Psychopathology Scale; VRIN ⫽ MMPI-2 Variable Response Inconsistency Scale; TRIN ⫽ MMPI-2 True Response Inconsistency Scale; Ds2 ⫽ MMPI-2 Dissimulation Scale Revised; Hs ⫽ MMPI-2 Hypochondriasis scale; D ⫽ MMPI-2 Depression Scale; Hy ⫽ MMPI-2 Hysteria Scale; Pd ⫽ MMPI-2 Psychopathic Deviate Scale; Pa ⫽ MMPI-2 Paranoia Scale; Pt ⫽ MMPI-2 Psychasthenia Scale; Sc ⫽ MMPI-2 Schizophrenia Scale; Ma ⫽ MMPI-2 Hypomania Scale; Si ⫽ MMPI-2 Social Introversion Scale; Pd1 ⫽ MMPI-2 Familial Discord Subscale; Pd4 ⫽ MMPI-2 Social Alienation Subscale; Pd5 ⫽ MMPI-2 Self-Alienation Subscale. a Tukey’s Honestly Significant Difference correction applied. b Constant ⫽ ⫺23.83. c Constant ⫽ ⫺30.12. d Robust predictor based on standardized canonical coefficients ⬎ .50 (Tabchnick & Fidell, 2011). ⴱ p ⬍ .0028 (Bonferroni correction).

Discussion We sought to characterize the MMPI-2 profiles of DID patients and to determine if they could be distinguished from the MMPI-2 profiles from uncoached and coached DID simulators. Fb was the

highest scale, followed by F, among the DID patients (93T and 90T, respectively). Fb items emphasize suicidal ideation and problems with relationships, difficulties common among DID patients (Brand et al., 2009; Foote, Smolin, Neft, & Lipschitz, 2008). As

Table 3 DID Versus Non-DID Classification Results for Scores Within a Range of Z ⫽ ⫾ .5 on Common MMPI-2 Validity Scales

F Fb Fp Ds2 DFA

Z

Cut score

True positives

False positives

False negatives

True negatives

Sensitivity

Specificity

PPP

NPP

ODP

⫺.5 0 .5 ⫺.5 0 .5 ⫺.5 0 .5 ⫺.5 0 .5 —

96.90 106.64 116.38 97.41 107.20 117.00 85.42 97.95 110.48 76.50 84.73 92.97 —

31 40 44 28 37 41 42 47 51 28 38 43 —

23 30 35 18 29 43 22 38 49 29 58 85 —

22 13 9 25 16 12 11 6 2 25 15 10 —

121 114 109 126 115 101 122 106 95 115 86 59 —

.58 .75 .83 .53 .70 .77 .79 .89 .96 .53 .72 .81 .83

.84 .79 .76 .88 .80 .70 .85 .74 .66 .80 .60 .41 .86

.57 .57 .56 .61 .56 .49 .66 .55 .51 .49 .40 .34 .69

.85 .90 .92 .83 .88 .89 .92 .95 .98 .82 .85 .86 .93

.77 .78 .78 .78 .77 .72 .83 .78 .74 .73 .63 .52 .85

Note. F model characteristics: DIDConstant ⫽ ⫺15.772, non-DIDConstant ⫽ ⫺22.466; DIDb-weight ⫽ .318; non-DIDb-weight ⫽ .393; Fb model characteristics: DIDConstant ⫽ ⫺15.359, non-DIDConstant ⫽ ⫺20.768; DIDb-weight ⫽ .301, non-DIDb-weight ⫽ .364; Fp model characteristics: DIDConstant ⫽ ⫺8.224, non-DIDConstant ⫽ ⫺15.803; DIDb-weight ⫽ .192, non-DIDb-weight ⫽ .287; Ds2 model characteristics: DIDConstant ⫽ ⫺13.273, non-DIDConstant ⫽ ⫺16.582; DIDb-weight ⫽ .316, non-DIDb-weight ⫽ .369. DID ⫽ dissociative identity disorder; MMPI-2 ⫽ Minnesota Multiphasic Personality Inventory; PPP ⫽ positive predictive power; NPP ⫽ negative predictive power; ODP ⫽ overall diagnostic power; F ⫽ MMPI-2 Infrequency Scale; Fb ⫽ MMPI-2 Back Infrequency Scale; Fp ⫽ MMPI-2 Infrequency Psychopathology Scale; Ds2 ⫽ MMPI-2 Dissimulation Scale Revised; True positive ⫽ DID cases classified as DID; False positives ⫽ non-DID cases classified as DID; False negatives ⫽ DID cases classified as non-DID; True negatives ⫽ non-DID cases classified as non-DID.

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DISTINGUISHING SIMULATED DID

many as 15% of the DID patients had F and Fb scores higher than 100T, which could lead to DID patients being misclassified as feigning. Despite the validity scores being extremely elevated, the DID group’s mean scores were not unusual for PTSD samples (Rogers et al., 2003). The DID scores were similar, or even somewhat less elevated, than those found in CSA survivors without DID (Elhai, Gold, Mateus, et al., 2001). As predicted, DID patients’ mean Scale 8 exceeded all other clinical scale means, with additional marked elevations (⬎70T) on Scales 2, 4, 6, and 7, and slight elevations on Scales 1 and 3. The DID 8 –2 code type has been found in DID (Bliss, 1984), although 8 – 4 and 8 – 6 are also common (Coons, 1984; Coons & Milstein, 1994; Coons & Sterne, 1986; Welburn et al., 2003). Elevations in Scale 8 among interpersonally traumatized individuals are frequent (Elhai, Gold, Mateus, et al., 2001; Engels et al., 1994; Korbanka & McKay, 2000; Wolf et al., 2009). Several items on Scale 8 are dissociative in nature (e.g., daydreaming; feeling numb; gaps in memory; feeling unreal), so it is not surprising that Scale 8 strongly correlated with dissociation among the DID group (r ⫽ .47), although the relationship was not significant and in the opposite direction for feigners (r ⫽ ⫺.15). These results support Wolf et al.’s (2009) conclusion that many Scale 8 items detect characteristics of dissociative trauma survivors, including difficulties regulating affect, dissociation, somatization, and personality changes. Dissociation was strongly associated with F, Fb, and Fp in this study as well as others (Dunn et al., 1993; Klotz Flitter et al., 2003). The magnitude of the relationship between F and dissociation was similar in this DID sample to that found in females with CSA (r ⫽ .49 vs. .51 in Klotz Flitter et al., 2003). Due to the growing evidence linking elevations in fake-bad scales to dissociation, childhood abuse, and PTSD, considerable caution should be used in interpreting validity scales as indicative of feigning and Scale 8 as indicative of schizophrenia among traumatized individuals, particularly those who experienced childhood trauma and/or who are highly dissociative (Elhai, Gold, Mateus, et al., 2001; Elhai, Gold, Sellers, et al., 2001; Wolf et al., 2009). This is the first study to examine how dissociation relates to Fb and Fp. The positive correlation between Fp and dissociation was somewhat weaker than that between dissociation and F and Fb. Given that Fp is relatively uninfluenced by psychopathology (Rothke et al., 2000), it makes sense that it was less strongly linked with dissociation compared with F and Fb. In fact, the weaker association between Fp and dissociation might explain why it is the best validity scale for severely dissociative samples. Further research is needed to further clarify this possibility. With respect to distinguishing simulated from genuine DID, the DID group was different from at least one of the simulating groups on 10 out of 18 scores in the profile analysis. Consistent with the malingering literature (Rogers et al., 2003), the simulating groups scored higher than the DID group. In these samples, F, Fb, and Fp were significantly higher among the coached and uncoached groups than in the DID group. However, none of these validity scales achieved adequate PPP. Using the DFA prediction model, in which seven promising MMPI indices were combined, the model correctly classified 85.3% of all cases and 86.0% of the DID cases (i.e., specificity). It is important to note that group differences emerged despite the DID group including many (34%) inpatients who were expected to have high elevations on the MMPI-2, due to

99

increased severity, making it less likely to detect differences between simulators and patients. That is, future research with less severe groups of patients may find that MMPI-2 differences are even more robust than current findings. The exploratory analysis of cutoff scores provided support for some, but not all, of the MMPI-2 validity scales. Ds2 was not effective in distinguishing feigned DID. The F cutoffs that were required to achieve acceptable utility statistics were extreme (T ⬎ 100). This and other studies show that F (and Fb) is not a highly effective validity indicator for childhood trauma survivors (Elhai et al., 2004; Elhai, Gold, Mateus, et al., 2001). As predicted, and as consistent with studies among child trauma survivors as well as meta-analytic research, the Fp scale obtained the highest specificity and sensitivity (Elhai et al., 2004; Rogers et al., 2003). The Fp cutoffs showed sufficient sensitivity—false negatives among DID participants were minimized. Similarly, the Fp cutoffs showed sufficient specificity—false positives among non-DID participants were minimized. This study adds to the growing evidence that Fp is a useful validity indicator across diagnostic groups (Rogers et al., 2003). However, future research is needed to identify factors that increase the PPP of these MMPI scales. For example, Fp was insufficient for identifying true DID cases among all those who were classified as DID. This is a pertinent differentiation, particularly in clinical and forensic settings. Fp items can be further analyzed to clarify what item content—specific to correlates of dissociation (e.g., family betrayal; Friedman, Lewak, Nichols, & Webb, 2001)—was endorsed by individuals with DID. Validity scales that minimize dissociation yet assess symptoms that are typically elevated in DID (e.g., depression, anxiety), as well as less well-known correlates (e.g., family difficulties), are more likely to be effective with this population, such as the new Trauma Index in the Structured Interview of Reported Symptoms (Brand, Armstrong, & Loewenstein, 2006; Brand, Tursich, et al., 2014; Rogers et al., 2009). The training that we provided on DID resulted in the coached group reporting significantly more sources of exposure to information about DID, as well as having greater knowledge about its symptoms. However, despite having been exposed to hours of information about DID, the coached feigners were only slightly more successful in feigning DID than the uncoached group. Specifically, the coached group did not exaggerate being inconsistent (i.e., VRIN) to the extent found in the uncoached group. The coached group was able to portray themselves as being as depressed as the DID group, and more depressed than the uncoached group. Thus, extremely well-coached simulators appear to be able to provide a somewhat better imitation of DID than uncoached simulators, although neither group accurately portrayed the range of difficulties associated with DID. Furthermore, the uncoached group’s performance conforms to widely known facts and myths about DID. That is, they overestimated the extent to which someone with DID would give contradictory, inconsistent responses, yet they did not understand that depression is a common comorbidity of DID. Thus, assessing for subtle, less known, and common comorbid conditions, and/or an exaggerated presentation of stereotypic symptoms of DID, may prove useful in making accurate distinctions between genuine versus feigned DID. Regardless of the amount of knowledge they had about DID, neither group was successful in fully imitating DID on the MMPI-2, which has important implications. The iatrogenic or

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BRAND AND CHASSON

sociocognitive model of DID suggests that DID is created iatrogenically by media and other cultural cues about DID, as critically evaluated in Dalenberg et al. (2012). Proponents of this model would predict that those who simulate DID are not distinguishable from individuals diagnosed with DID. The present findings challenge the iatrogenic/sociocultural theory: DID patients can be distinguished from uncoached, and even well-coached, DID simulators. Furthermore, the direction of the correlations between dissociation and MMPI-2 scales were in the opposite direction for the feigners compared with the DID group for 15 out of the 18 correlations examined. Portrayals of DID based on sociocultural influences are simply not the same phenomena as genuine dissociation that arises from prolonged childhood trauma. This study provides evidence for the construct validity of DID as a disorder that is not merely created by influential media portrayals, nor possible to be feigned by even well-coached, motivated feigners. Although coached feigners knew enough about the illness to endorse occasional dissociative items, they were unable to accurately portray the full clinical presentation of this disorder, including common clinical correlates. Imitators did not convey the sense of betrayal and fear in relationships with family, the unsettling worry that something was terribly wrong with one’s memory and/or mind, and unspeakably painful thoughts mixed with inexplicable feelings of terror, loneliness, and depression. This is the first adequately powered study to investigate the utility of the MMPI-2 in detecting feigned DID using welldiagnosed DID patients. These strengths are balanced by our reliance on students simulating DID and DID patients who were predominantly middle-aged, well educated, Caucasian women. However, age, gender, and ethnicity were statistically controlled in the profile analyses; thus, the current findings seem to extend beyond group differences attributable to demographics. Nonetheless, future research should compare more diverse DID patients with known malingerers and/or factitious patients, as well as develop MMPI-2 validity scales that do not overclassify severely dissociative individuals. In conclusion, this study has several findings. First, DID patients had extreme elevations on most clinical and validity scales, with the highest elevations on Fb and F, as well as Scales 8 and 2. Second, the DID group’s elevations were not more extreme than those found in PTSD and CSA samples, indicating that the elevations are not due to feigning but rather to the enduring difficulties that are associated with trauma. This study and others suggest that the MMPI-2 validity scales likely detect dissociation and the lingering impact of trauma among traumatized and dissociative samples, rather than feigning. Third, if uninformed about these findings and similar results in the literature, assessors may misclassify genuinely dissociative individuals as feigners. Fourth, Fp was the best predictor of malingered DID, although its PPP was not optimal. Fifth, dissociation was strongly associated with elevations in validity scales as well as Scale 8. Sixth, feigners, even thoroughly coached and motivated feigners, could not produce the range of symptoms and difficulties that are associated with genuine DID. Rather, they endorsed the occasional dissociative item but missed the more subtle accompanying problems. Thus, this study provides support for the construct validity of DID and challenges the sociocognitive/iatrogenic hypothesis that media and cultural influences, rather than severe childhood trauma, create DID. Research is needed to develop validity scales that are useful indicators of

feigning among traumatized individuals. Considerable caution should be used when interpreting validity scales as indicative of feigning, and Scale 8 as indicative of schizophrenia, among individuals who are highly dissociative.

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Received October 11, 2012 Revision received June 12, 2013 Accepted June 24, 2013 䡲