Standardized Assessment of Malingering: Validation of the Structured Interview of Reported Symptoms

Transcription

1 Psychological Assessment: A Journal of Consulting and Clinical Psychology 1991, Vo!.3 No. I, $9-96 Copyright 1991 by the American Psychological Association, Inc /91/$3.00 Standardized Assessment of Malingering: Validation of the Structured Interview of Reported Symptoms Richard Rogers and J. Roy Gillis Clarke Institute of Psychiatry Toronto, Ontario, Canada Susan E. Dickens Surrey Place Toronto, Ontario, Canada R. Michael Bagby Clarke Institute of Psychiatry Toronto, Ontario, Canada The Structured Interview of Reported Symptoms (SI) was constructed to assess specific strategies identified in the clinical literature for the evaluation of malingering. Two studies were conducted to evaluate the discriminant and concurrent validity of the SI. Study 1, with a simulation design, compared 40 simulators with 34 outpatient and 41 community controls using the SI, Minnesota Multiphasic Personality Inventory (MMPI), and M test. Test results established (a) a high level of discriminability between simulators and controls, and (b) general support for hypothesized relationships of SI with MMPI validity indicators and M Test scales. Study 2, with a known-groups comparison design, compared 25 suspected malingerers with 26 psychiatric inpatients from the same assessment unit. Nine of the 13 SI scales effectively discriminated between the two groups in the expected direction with excellent interrater reliability. In general, suspected malingerers in Study 2 endorsed similar response patterns as simulators in Study 1. Research has led to a serious questioning of clinicians' ability to accurately identify individuals who are deliberately exaggerating or fabricating symptoms associated with a mental disorder. For example, Rosenhan (1973) found that pseudopatients were not identified as malingerers, despite their deliberately atypical presentation. In addition, when staff were alerted to the possibility of malingering, many false positives were likely to occur (Rosenhan, 1975). Use of psychological test data to identify malingerers has yielded, at best, a mixed array of findings (for reviews, see Greene, 1988; Pankratz, 1988; Schretlen, 1988; Stermac, 1988). Many strategies have been advocated for the successful detection of malingering. These include watching for a clownish or fantastic presentation (Davidson, 1949; Ossipov, 1944), eagerness to discuss symptoms (Ritson & Forrest, 1970), inconsistency in self-report (Rogers, 1986a, Wachspress, Berenberg, & Jacobson, 1953), and presentations incompatible with psychiatric diagnoses (Resnick, 1984,1988; Rogers, 1987; Sadow & Suslick, 1961). In addition, strategies have been developed (Greene, 1980,1988) to assess dissimulation on the Minnesota Multiphasic Personality Inventory, (MMPI) including response consis- We gratefully acknowledge a grant from the Clarke Research Fund and the active cooperation of administrative staff, both of which made this study possible. Susan E. Dickens is now at Clarke Institute of Psychiatry, Toronto, Ontario, Canada. Correspondence concerning this article should be addressed to Richard Rogers, Metfors/Clarke Institute of Psychiatry, 1001 Queen Street West, Toronto, Ontario M6J 1H4. tency (Test-Retest index [TR], Buechley & Ball, 1952;Carelessness scale [CLS], Greene, 1978), rare symptoms (Fscale, Hathaway & McKinley, 1940), obvious and subtle symptoms (Ovs; Wiener & Harmon, 1946), neurotic stereotypes (Dissimulation scale-revised [Dsr] Gough, 1957) and indiscriminant symptom endorsement (Lachar & Wrobel, 1979). This study was designed to examine 13 strategies that have been identified in the available literature as potentially useful for detecting malingering. To date, many of these methods are supported only by clinical folklore and very little empirical research (Rogers, 1984,1987). To improve the clinical assessment of malingering, we sought to build a research program to investigate these strategies. In the development of a scale to measure strategies to detect malingering, an important methodological consideration was whether to construct a self-report measure or a structured interview. We selected the structured interview approach for the following reasons: First, several strategies for the detection of malingering were difficult to adapt to a pencil-and-paper measure because they required either a wide array of responses or clinical judgement in scoring those responses. Second, the clinical literature (Rogers, 1988) as well as social psychological studies of self-presentation (Tesser & Paulhus, 1983; Tetlock & Manstead, 1985) suggested that individuals may respond differently to different modes of presentation. For example, Johnston, Klingler, and Williams (1977) found virtually no relationship between judgements of malingering in clinical interviews and indices on the MMPI (i.e., r =. 14). Third, a multimethod approach in clinical diagnosis, generally, (Garfield, 1978) and for malingering, specifically (Grisso, 1986), was likely to im-

2 90 GE, GILLIS, DICKENS, AND BAGBY prove our evaluation of malingering by reducing measurement error attributable to method variance. Because the MMPI already offered a reasonably accurate self-report method, a standardized interview would provide a different avenue for the clinical assessment of malingering. The Structured Interview of Reported Symptoms' (SI; Rogers, 1986b) was originally developed as an experimental measure (see Rogers, 1988, for a description of its item development). After several revisions, 120 items were refined and retained, reflecting different clinical strategies to detect malingering. In addition, 30 items indicating defensive symptoms were subsequently added to reduce the overall transparency of the measure and provide some index of how willing subjects would be to endorse everyday problems. Operational definitions of the SI strategies were a critical element in its scale development. A listing of the strategies and definitions follows. Direct Appraisal of Honesty (). These items ask patients about the honesty and completeness of their self-reports. In addition, items about their level of self-disclosure to mental health professionals and their concomitant concern for being truthful with these professionals are included. A sample item would be, Do you hold back telling people everything... keep name things to yourself? Defensive Symptoms (). These symptoms represent a variety of everyday problems, worries, and situations that most individuals experience to some degree. This strategy is designed to measure common, though negative, experiences; psychometric research (Greene, 1988) has shown that the denial of such symptoms may be an index of defensiveness. A sample item would be, Do you find it difficult to say "no" to a friend? Self-Management of Symptoms (SM). This strategy asks subjects if they have been able to modify or in some way alleviate their psychological problems. Even severely impaired psychiatric patients generally have some control over their symptoms (Resniek, 1984). A sample item would be, Have you learned to manage any of your psychological problems? Rare Symptoms (). This strategy uses bona fide symptoms that are seen infrequently in psychiatric patients. Thus, the only criterion for this classification is the infrequency with which the symptoms are reported in clinical populations. A sample item would be, Are your thoughts sometimes broadcasted so that large numbers of people know what you are thinking? Improbable or Absurd Symptoms (1A). These are symptoms that have a fantastic or preposterous quality to them. Their preposterousness distinguishes them from rare symptoms and makes it unlikely, by definition, that such symptoms could possibly be true. A sample item would be, Does the furniture where you live seem to change its shape and color from day to day? Symptom Combination (SC). This strategy consists of asking about the existence of bona fide psychiatric symptoms that rarely occur simultaneously: These items are identified by the unusual pairingofsymptoms. They are distinguished from rare symptoms in that the symptoms themselves are not infrequent, only their combination. A sample item would be, Do you have severe headaches at the same time you have abnormal sexual thoughts? Overly Specified Symptoms (). This strategy is composed of symptoms that are endorsed with an unrealistic degree of precision. Such endorsements typically involve an attempt to quantify a problem either in terms of duration, day of the week, or some other dimension. Overly specified symptoms are distinguished from rare symptoms in that the symptoms themselves are commonly found in clinical populations, but not to this degree of specification. They are distinguished from improbable or absurd symptoms in that they are not preposterous, except possibly in their degree of precision. A sample item would be, Do you have exactly two nightmares every evening? Symptom Onset and Resolution (SO). These symptoms are characterized by a sudden or otherwise uncharacteristic onset and resolution that is atypical of most mental disorders. A sample item would be, Do most of your problems suddenly appear without any warning? Blatant Symptoms (). This strategy is based on the consistent findings of MMPI research (Greene, 1980) that malingerers overendorse symptoms that are obvious signs of a mental disorder. Blatant symptoms are defined as those that untrained individuals would identify as indicative of major mental illness. A sample item would be, Do you have any major problems with thoughts about suicide? Subtle Symptoms (SU). This strategy is based on symptoms that untrained individuals would see as everyday problems and not indicative of mental illness. A sample item would be, Do vou have any major difficulties with feelings of self-doubt? Severity of Symptoms (SEV). This strategy is based on the observations that malingerers often endorse an unlikely number of symptoms with extreme or unbearable severity. Within a subset of 32 symptoms, subjects are asked which of these are "unbearable" or "too painful to stand." Selectivity of Symptoms (SEL). Clinical experience has suggested that some malingering individuals are nonselective or indiscriminant in their endorsement of psychiatric problems. This strategy is simply an overall measurement of symptom endorsement on a subset of 32 symptoms. Inconsistency of Symptoms (INC). Malingerers often have difficulty remembering which symptoms they endorsed and are inconsistent in their responses. By repeating a set of 32 clinical inquiries, this strategy provides a measure of the stability of the patient's self-report. Reported Versus Observed Symptoms (). This strategy asks patients about observable behavior that is then compared with clinical observations. These symptoms typically focus on speech and physical movements that may be directly assessed by the clinician. A sample item would be, Do you always gesture or move your hands when you are talking? The first task in establishing the clinical strategies was to employ eight experts on malingering as judges in order to verify subsets of "pure" strategies. Experts were identified primarily by their contributions to the study of malingering (publications or presentations), although two were included because of their extensive experience with dissimulation in forensic evaluations. Because the 14 strategies are nonexclusive, it was essential that a small sample of clinical inquiries be identified on which consensus was reached regarding the single strategy used. The items were randomly given to these experts, along with the strategy descriptions just presented here. The minimum level 1 Copies of the SI may be obtained for research purposes only at a nominal cost from Richard Rogers.

3 STANRDIZED ASSESSMENT 91 of agreement for an item to be included in a particular scale was its endorsement by at least five experts in agreement with Rogers' original classification. On items designated as pure strategies, the actual concordance rate for individual scales ranged from 67% to 95%, with an overall level of agreement of 88.2%. As a result of this analysis, insufficient agreement was found on SM; it was therefore dropped as a SI scale. The SI was originally developed as two parallel forms (A and B). The refinement of scales resulted in these forms being combined into a single measure, although it is still possible to administer the SI in two separate sections with more "impaired" populations. Rogers, Gillis, and Bagby (1990) used a simulation design to examine the discriminability of the SI scales for a correctional sample in a treatment-oriented setting. Subjects were randomly divided into simulating («= 26) and honest (n = 25) responders. Simulators were offered a financial incentive for a convincing portrayal of a major mental illness. The study found that simulators were significantly more elevated on all scales except SEL. The goal of the present research was to investigate the usefulness of the SI for the identification of dissimulators when compared with psychiatric outpatients and inpatients. Previously cited methodological problems with both simulation and known-group-comparison designs (Haynes, 1978) argued against the exclusive reliance on either design in the validation of the SI. Because of their respective limitations, we incorporated both design methodologies in two closely related studies. Before any analysis of these two studies, it was essential to establish the internal consistency of the individual SI scales. Although this could have been accomplished on Study 1 alone, we felt that the most rigorous test of internal consistency would be to compute alpha coefficients and item-to-scale correlations on all available samples (i.e., data from Rogers, Gillis, & Bagby, 1990 and Study 1 and Study 2, described here next) so as to reflect the potential range of clinical applications for the SI. In Study 1, we examined the discriminant validity of the SI and its concurrent validity with the MMPI, using a simulated research design. In Study 2, we addressed the discriminability of the SI with suspected malingerers and psychiatric inpatients and evaluated its interrater reliability usinga knowngroups-comparison design. Finally, to examine the relationships among the SI scales, data from Studies 1 and 2 and the correctional sample (Rogers, Gillis, & Bagby, 1990) were combined and subjected to a principal-components analysis. Refinement of SI Scales The first task in the validation of the SI was to evaluate its internal consistency. As just mentioned, we combined previous test data (Rogers, Gillis, & Bagby, 1990) with the current two studies (see description that follows) to ensure a broad range of clinical applications. Alpha coefficients and item-scale correlations were computed for each scale (see Table 1). Individual test items whose item-to-scale correlations were below.20 were dropped. This resulted in only three items being deleted from the SI (le, one each from,, and SO). Alphas were recomputed for these three scales. The resulting alpha coeffi- Table 1 Internal Consistency of SI Scales Scales SC SO su Items Alphas Mean item-scale correlations Note. Scales SEV (Severity of Symptoms), SEL (Selectivity of Symptoms), and INC (Inconsistency of Symptoms) consist of arithmetic summing for which measures of internal consistency are inappropriate. SI = Structured Interview of Reported Symptoms; = Direct Appraisal of Honesty; = Defensive Symptoms; = Rare Symptoms; = Improbable or Absurd Symptoms; SC = Symptom Combination; = Overly Specified Symptoms; SO = Symptom Onset and Resolution; = Blatant Symptoms; SU = Subtle Symptoms; = Reported Versus Observed Symptoms. cients and item-scale correlations were acceptable and were used as the basis for the subsequent studies. Method Study 1 Subjects. A community sample (N = 81) was recruited through advertisements placed in employment centers and local shopping malls. This sample was randomly assigned to either honest (N= 41) or simulation (N= 40) conditions. Subjects were screened to ensure that they had the equivalent of a high school education, never had a psychiatric hosp i- talization, and had not been involved in outpatient psychiatric treatment during the last 24 months. The outpatient sample («= 34) was recruited from the Clarke Institute of Psychiatry as a psychiatric control group. Subjects were solicited from individual psychiatrists and a work adjustment program (a reimegration project for previously hospitalized patients). Subjects in the outpatient group were screened to ensure that they had a high school education, were currently involved in outpatient treatment, and had not had a psychiatric hospitalization in the last 12 months. To keep clinical groups context-specific (i.e., outpatients vs. inpatients) and because of practical problems in arranging for their participation, inpatients were not included in Study 1. Procedure. Subjects that fulfilled the criteria for either the community or outpatient samples were given appointments by research assistants and were randomly assigned to one of four interviewers. Interviewers were unaware of group assignment and instructional set. They were trained in the administration of the SI, and all of them were staff members of the psychology/research department of Clark Institute of Psychiatry (2 Ph.D.-level psychologists and 2 graduate psychology students, employed full-time). On arrival at the clinic, subjects were introduced to the study and informed consent was obtained in accordance with American Psychological Association ethical principles. The simulation group was instructed to pretend to have a serious mental illness and, as an incentive, its members were offered an additional remuneration of$5 if they were able to portray this disorder in a realistic and convincing manner. Subjects in the simulation groups were not instructed specifically on how to malinger because this might

4 92 GE, GILLIS, DICKENS, AND BAGBY have biased the results. Two control groups (honest-community and outpatient) were given instructions to respond honestly to experimental measures. AH subjects were administered three experimental measures. The SI was divided into two sections (A and B) and administered in a counterbalanced format. In addition, the subjects were administered the MMPI and the M test (Beaber, Marston, Michelli, & Mills, 1985; a brief screening measure for malingered schizophrenia). All three protocols were administered under the same instructions. After completion of the measures, subjects were debriefed. All subjects were paid $20 for their participation; in addition, subjects in the simulation group were offered a bonus of $5 for a convincing presentation. Given the preliminary nature of the research, however, all simulating subjects were awarded the additional $5, without us attempting to establish a criterion for being "convincing." Results and Discussion Most of the subjects were single and had never been married (71.3%), with relatively few having been married (either formally or by common law; 14.8%), divorced (13.0%), or widowed (0.9%). Men were slightly more represented than women (58.3% vs. 41.7%). The results of an analysis of variance (ANOVA) with Duncan's multiple range test (a =.05) showed that outpatients were older (M = 40.44, SD = 9.28) than both the honest (M = 32.05, SD = 10.96) and simulating (M = 30.45, SD = 10.38) community subjects, F(2,112) = 9.78, p <.001. The large majority of subjects were White (100% of the outpatients and 81.5% of the community sample); within the community sample 4.9% were Black, 7.4% were Oriental, and 6.2% were of other ethnic origins. As a result of the inclusion criterion requiring a high school education (typically, Grade 13 in Ontario), subjects were well educated, with outpatients showing a higher academic level (i.e., years of education) on an ANOVA with Duncan's multiple range test (a =.05) than community samples: outpatient, M = 16.35, SD = 3.49; honest community, M = 14.39, SD = 3.03; simulating community, M= 14.43, SD= 3.33; F(2,112) = 4.23, p =.02. The diversity of referral sources as well as protection of patient anonymity did not allow us to confirm the specific diagnoses of many patients; based on existing data, common diagnostic groupings would be mood, anxiety, and schizophrenic disorders. The discriminability of the SI scales was tested through a series of ANOVAS with Duncan's multiple range tests < =.05). The results, as reported in Table 2, were highly significant in the hypothesized direction, with as the only exception. In examining the proportion of the variance accounted for by each scale, the largest eta squared values were associated with SEL (48), (.47), (46), SC (), (), SU (.40) and (.37). Within a simulation design, the SI appears to have excellent discriminability. As a measure of concurrent validity, a Pearson product-moment correlational matrix was generated between SI scales and both MMPI indicators of dissimulation and M-test scales. Three hypotheses were considered for the SI scales (with the exception of the, which was not intended to detect malingering): (a) They would show moderate positive correlations with indicators of malingering; (b) they would have negative or nonsignificant correlations on measures of defensiveness; and (c) they would evidence modest correlations with scales assessing item consistency. As reported in Table 3, the first hypothesis was amply supported, with 78.2% of the scales having correlations between MMPI fake-bad indicators and SI scales (excluding as a defensiveness measure) of.60 or greater in the predicted direction. The second hypothesis yielded mixed results. Although AT scale correlations with SI scales were consistently in the predicted direction, this was not the case with the L scale, which manifested modest positive correlations (mean r =.21) with the SI scales. The third hypothesis with respect to item consistency was generally supported, with low correlations between TR and CLS and the SI scales. Of the three correlations exceeding.40, two were correlations of the TR and CLS with the SI measure of symptom inconsistency (INC); these scales are logically associated with each other. Correlations in the predicted direction were also found between the M test and the SI scales. Mean correlations between M-test scales and the SI scales (with the exception of ) were.72 for the malingering scale (M),.67 for the confusion scale (C), and.65 for the schizophrenia scale (S). As expected, showed no correlation with M and C scales (rs were -.01 and -.10, respectively) and a modest correlation with S scale (r=.26). Results from Study 1 indicated a high level of discriminability for the SI scales between simulators and community and outpatient control subjects with the exception of, which was not intended as a measure of malingering. The question remains, of course, whether these findings will remain constant when applied to suspected malingerers in contrast to psychiatric inpatients (i.e., the focus of Study 2). Results also provided empirical support for the concurrent validity of the scales, with aprioristic hypotheses being (a) supported with M-test results, (b) confirmed for indices of malingering and item consistency on the MMPI, and (c) partially supported by the MMPI measures of defensiveness. Method Study 2 Subjects. Patients in a 23-bed forensic assessment unit (M ETFO, Clarke Institute of Psychiatry) were thoroughly assessed with respect to diagnosis (including malingering) and psycholegal issues. These clinical evaluations were conducted independent of the research program; evaluations typically were composed of (a) diagnostic interviews; (b) corroborative data from prior hospitalizations, social work contacts with family and friends, and police investigative reports; and (c) psychological testing for those patients willing to participate. In the course of evaluating approximately 700 inpatients, psychological and psychiatric staff of METFO were able to identify 25 individuals who presented with probable or definite malingering. 2 The prevalence rate of 3.5% is slightly less than the rates reported in other forensic settings (Cornell & Hawk, 1988; Rogers, 1986a). A second sample of 26 psychiatric inpatients from the same assessment unit were collected consecutively. Inclusion criteria were (a) no evidence of malingering as noted by patient's assessment team, (b) presence of an Axis 1 disorder, and (c) ability to tolerate the interviews. 3 2 In all cases, probable or definite malingering was established. In an additional nine cases, the diagnosis of factitious disorder was given. These were excluded from further analysis despite the difficulties in differential diagnosis (see Rogers, Bagby, & Rector, 1989). 3 Only grossly psychotic patients who could not tolerate the 30 to 40 min required for the interview were excluded; this limitation was minimal, with several actively hallucinating patients having been allowed to participate.

5 STANRDIZED ASSESSMENT 93 Table 2 Differences Among Simulators, Community, and Outpatient Samples on SI Scales SI scales Simulators Honest Community samples Outpatients F* eta 2 SC SO SU SEL SEV INC ,, 21.37, 1.02, 0.22, 0.39 b 0.24 b 0.74 b 0.^ 2.55 b 2.85 b 0.54 b 1.17, 1.23, 1.74, , 0.21, 1.33, 0.34, 1.00, 1.82, 6.68 e 6.91, 1.59, 2.32, 1.39, Note. Scales are scored, with the exception of, so that higher elevations are indicative of malingering. Groups with common subscripts are not significantly different at the.05 level. SI = Structured Interview of Reported Symptoms; = Direct Appraisal of Honesty; = Defensive Symptoms; = Rare Symptoms; = Improbable or Absurd Symptoms; SC = Symptom Combination; = Overly Specified Symptoms; SO = Symptom Onset and Resolution; = Blatant Symptoms; SU = Subtle Symptoms; = Reported Versus Observed Symptoms; SEL = Selectivity of Symptoms; SEV = Severity of Symptoms; INC = Inconsistency of Symptoms; = Reported Versus Observed Symptoms. * For all F values, p <.0001 Procedure. Suspected malingerers were referred to the research the professional staff. All subjects were asked to participate in a study staff for possible inclusion in the study on the basis of evaluations by of psychiatric symptoms and were assured that results would not be the assessment team. Although interviewers were sometimes com- shared with the assessment team. Both suspected malingerers and inpletely unaware of group assignment, the nature of the setting (i.e., a patients were given instructions to respond to the protocols in an honsmall assessment unit with a high level of sharing of clinical data), est and self-disclosing manner. All subjects were also asked to complete meant that highly atypical patients would often be well known by all of the M test as part of the research project. Table 3 Correlations of SI Scales and Minnesota Multiphasic Personality Inventory Indicators of Dissimulation MMPI indicators (MMPI) Scales L F K F~K Dsr Ovs CR TR CLS SC so SU SEL SEV INC Note. The Dunn-Bonferroni procedure was used to hold familywise (FW) Type I error to an alpha of.05 and.01. Correcting for 117 correlations (ap,, =.05/117 or.00043), rs :>.36, p <.05 and (apw =.01/117 or ), rs a;, p <.01. Dsr = Cough's Dissimulation scale-revised; Ovs = Weiman-Harmon Obvious Versus Subtle scales; CR = Critical Items Endorsed; TR = Test-Retest index; CLS = Carelessness scale; SI = Structured Interview of Reported Symptoms; = Direct Appraisal of Honesty; = Defensive Symptoms; = Rare Symptoms; = Improbable or Absurd Symptoms; SC = Symptom Combination; = Overly Specified Symptoms; SO = Symptom Onset and Resolution; = Blatant Symptoms; SU = Subtle Symptoms; = Reported Versus Observed Symptoms; SEL = Selectivity of Symptoms; SEV = Severity of Symptoms; INC = Inconsistency of Symptoms; = Reported Versus Observed Symptoms.

6 94 GE, GILLIS, DICKENS, AND BAGBY A second component of the study was to test the interrater reliability of the SI. A previous study of the SI examined its interrater reliability on a consecutive sample of 23 forensic inpatients (Rogers, 1988); Rogers found a mean correlation of.83 (range =.48-99). As a result of that study, a general set of instructions was developed for more uniform scoring of the SI. The reliability of the scales was re-examined, using a subsample of 27 suspected malingerers and inpatients who were seen jointly by two raters. Selection of subjects was made solely on the availability of research staff. Altogether, four psychology staff members took part in the reliability study. Results and Discussion Consistent with the census of the forensic unit, nearly all subjects were men (90.2%), and the large majority were White (84.3%). There were small representations of Black (7.8%), Oriental (5.9%), and other ethnic groups (2.0%). More than one half (59.2%) of the subjects had never been married; 24.5% were married (either formally or by common law), 14.3% were divorced, and 2.0% were widowed. Age differences between the two groups were unremarkable: suspected malingerers, M , SD = 7.51; inpatients, M= 32.79, SD = 10.18; F(l, 49) = 3.04, p =.09. The two groups differed with respect to educational level, F(l, 49) = 15.02, p <.001; Duncan's multiple range test Ift =.05) found suspected malingerers to be less educated (M= 9.20, SD= 2.65) than inpatients (M = 12.00, SD= 2.51). Primary diagnoses for the inpatient group were mostly Axis I: schizophrenic disorders in (46.2%), bipolar-mood disorders (19.2%), schizoaffective disorders (7.7%), other psychotic disorders (7.7%), substance-abuse disorders (7.7%), and borderline and other personality disorders (11.5%). The first objective of Study 2 was to examine whether suspected malingerers responded differently to the SI than did nonmalingering psychiatric inpatients. To test for such differences, ANOVAS with Duncan's multiple range tests (a =.05) were computed for the SI scales. As noted in Table 4, significant differences were found on 9 of the 13 scales in the expected direction. In examination of eta squared, the following scales appeared to account for much of the variance in making this discrimination: (.43), (.39), SEL (.38), SC (.30), SEV (.29), SU (.24), (.20), and 1A (.19). These findings are highly consistent with those reported here in Study 1. Product-moment correlations were calculated to estimate the reliability of the individual SI scales (see Table 4). The resulting correlations were considerably higher (i.e, mean r =.96, range = ) than in the earlier study (i.e., mean r =.83, range =.48-99), which suggests that the instructions were useful in improving reliability. The results of Study 2 indicated that suspected malingerers do not appear to differ from nonmalingering inpatients in the extent that they admit to everyday problems () and less-thanhonest interactions with others (), or in the frequency with which they endorse overly specified symptoms () and atypical symptom onset (SO). On all other scales, however, they endorsed significantly more symptoms than nonmalingering inpatients. Supplementary Analyses An important question for the SI is, How comparable were the response patterns for simulators in Study 1 to suspected malingerers in Study 2? To address this question, a series of; tests were conducted between the two groups. Even using a very liberal standard (a =.20), no significant differences were Table 4 Differences Between Suspected Malingerers and Psychiatric Inpatients on SI Scales and Interrater Reliability SIKS scales SC SO SU SEL SEV INC M Malingerers Group differences SD M Inpatients SD F *** 10.45" 20.67*** *** 14.34*** 29.60*** 20.04*" 5.05* 10.03** eta Reliability r Note. Scales are scored, with the exception of, so that higher elevations are indicative of malingering. SI = Structured Interview of Reported Symptoms; = Direct Appraisal of Honesty; = Defensive Symptoms; = Rare Symptoms; = Improbable or Absurd Symptoms; SC = Symptom Combination; = Overly Specified Symptoms; SO = Symptom Onset and Resolution; = Blatant Symptoms; SU = Subtle Symptoms; = Reported Versus Observed Symptoms; SEL = Selectivity of Symptoms; SEV = Severity of Symptoms; INC = Inconsistency of Symptoms; = Reported Versus Observed Symptoms. *p<.05. **/i<.01 ***p<m\.

7 STANRDIZED ASSESSMENT 95 found between the two groups, with the exception of. Interestingly, suspected malingerers were less likely to endorse items (M= 3.24) than were simulators (M= 5.64, t = 2.25, p =.03). Further inspection of the nonmalingering groups revealed a gradual increase in symptom endorsement on the SI among those patients with greater psychopathology; some scales appeared less effective when used with more disturbed populations (i.e,,, and SO with inpatients). To explore the interrelationships among the various strategies for the detection of feigned mental illness, we subjected the SI scales to a principal-components analysis. To this end, all available data from community, psychiatric, and correctional settings (i.e., the data from the 217 subjects of Studies 1 and 2 and from Rogers, Gillis, & Bagby, 1990) were combined, with means substituted for missing values. Scree test and eigenvalue > 1.0 criteria (Cattell, 1978) indicated a two-factor solution that was rotated to a varimax solution, with means substituted for missing values. Table 5 summarizes the results for these two factors, which account for 72.1% of the variance. Factor 1, a measure of general malingering, had significant loadings (i.e., >0.40) on all scales but and had shared loadings for, SO, SEL, SEX and SU Factor 2 accounted for only 9.8% of the variance, with its only unique loading being on (defensiveness). In the light of the shared loadings and proportion of variance explained by Factor 1, we interpret this as essentially a single-factor solution suggesting that all scales, with the exception of, are measuring the same underlying construct, namely, malingering. Table5 Principal-Components Analysis of SI Scales Scales sc so SEL SU INC SEV Factor 1 Varimax factor loadings Eigenvalues 8.09 % of variance 62.2 Factor Note. SI = Structured Interview of Reported Symptoms; = Improbable or Absurd Symptoms; = Overly Specified Symptoms; = Reported Versus Observed Symptoms; = Rare Symptoms; SC = Symptom Combination; SO = Symptom Onset and Resolution; = Blatant Symptoms; SU = Subtle Symptoms; INC = Inconsistency of Symptoms; SEV - Severity of Symptoms; = Defensive Symptoms. 9.8 General Discussion The SI appears to be a reliable and valid measure in the assessment of malingering. The results of these two studies support its usefulness in identifying specific dissimulative styles found in psychiatric patients. Acknowledging the heterogeneity of individuals and symptoms subsumed under malingering, perhaps its most fruitful contribution will be in providing a meaningful organization or typology for the further study of malingerers in different assessment settings. It is, however, of considerable interest that the factor analysis of community, clinical, and correctional samples appeared unidimensional in the detection of feigned mental illness. This finding does not suggest that malingerers are uniform in fabrication of psychological symptoms; rather, it suggests that those faking mental illness may be effectively detected by the same SI strategies. SI scales were not equally effective at differentiating feigners from clinical subjects. For example, neither nor SO discriminated between suspected malingerers and inpatients. At this early stage in test development, these scales have been retained. However, we envision that subsequent studies will reduce the number of SI scales on the basis of the robustness of their psychometric properties. In this regard, the principalcomponents analysis suggested that nearly all of the scales are measuring a single dimension of malingering. It seems premature, however, to combine individual scales into one scale, because these rationally based strategies may be clinically useful in describing the dissimulative style of a particular patient. In addition, further research is planned for other diagnostic groupings, including factitious disorders for which these individual scales may be helpful. One unexpected finding was that feigners (simulators and suspected malingerers) endorsed a greater number of subtle symptoms (SU) than did patients responding honestly. We had hypothesized, on the basis of MMPI studies, that feigners would endorse relatively fewer SU items than would others. One possible explanation for this contrary finding is that the MMPI only examined /"scores for differences between obvious and subtle items. Given the fact that obvious items are much less frequently endorsed than subtle items (i.e., extrapolating from normative data in Greene, 1980, subjects need only endorse an average of 45.6% of obvious items vs. 70.9% of subtle items to achieve a 7" score of 70 on the MMPI-1), a malingerer could easily endorse a high number of subtle items, which would be obscured by the successive data transformations. It appears that many feigners adopted the principle that "more is better" and were equally willing to endorse everyday problems as symptoms associated with severe psychopathology. On a more practical level, the SI may be used to supplement, but not supplant, the MMPI in the determination of malingering. Given the importance of differential diagnosis between actual disorders and malingering, the use of a standardized, multimethod approach should be strongly encouraged. This is particularly true with the adoption of a descriptive approach to diagnosis (American Psychiatric Association, 1980, 1987), in which clinical interviews have become the primary method for establishing the necessary inclusion and exclusion criteria. The SI may be useful in cases where suspected malingerers, for whatever reason, have declined to complete the MMPI

8 96 GE, GILLIS, DICKENS, AND BAGBY and other psychological testing. In such cases, the SI would provide a standardized alternative to an otherwise invalidated and highly idiosyncratic process (Rogers, 1987). In addition, it sidesteps "bizarre nonresponding," observed clinically with some suspected malingerers. Individuals have been known to complete the MMPI by endorsing all categories (both true and false), drawing apparently random lines connecting different responses and writing cryptic phrases (e.g., "Wrath of God"), which seemingly reflect psychotic states. Further test validation will include the effects of coaching on the ability to feign mental illness as well as differences in motivation (for a discussion, see Rogers, in press). In addition, crossvalidated discriminant models may provide a particularly useful tool in the accurate classification of suspected malingerers. References American Psychiatric Association. (1980). 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