Ecological validity of the WMS-III rarely missed index in personal injury litigation

The purpose of this study was to evaluate the clinical utility of the Rarely Missed Index (RMI) to detect cognitive exaggeration in 78 nonlitigant patients (i.e., Mixed Clinical group) and 158 personal injury litigants (i.e., 20 Suspected Exaggerators, 12 Borderline Exaggerators, 126 Genuine Responders). The base rate for probable malingered neurocognitive dysfunction in the litigant sample was 12.7%. The false positive error rate of the RMI in the Genuine Responder and Mixed Clinical group ranged from 5.4% to 8.6%. Positive RMI scores were found in 25% and 41.7% of the Suspected Exaggerator and Borderline Exaggerator groups respectively. The clinical utility of the RMI to identify Suspected Exaggerators versus individuals in the Genuine Responder and Mixed Clinical groups revealed low sensitivity (sensitivity = .25), very high specificity (range = .91 to .95), moderate positive predictive power (range = .50 to .71), and moderate to high negative predictive power (range = .68 to .83). These results do not support the use of the RMI as a reliable predictor of cognitive exaggeration.     

Using the WMS-III to Detect Malingering: Empirical Validation of the Rarely Missed Index (RMI)

To detect malingering during memory assessment, we evaluated item response biases to the Logical Memory Delayed Recognition (LMDR) subtest of the WMS-III. In a sample of 50 healthy volunteers who were completely naïve to the content of the Logical Memory stories, 6 LMDR items were correctly endorsed above chance probabilities. These 6 rarely missed items significantly discriminated 51 patients with neurological impairment from 36 volunteers who attempted to feign head injury and poor cognitive performance. A weighted combination of the 6 items was summed to form a single Rarely Missed Index (RMI). The RMI accurately classified over 98% of participants and demonstrated high sensitivity (97%) and specificity (100%) in discriminating between analog malingerers and patients. Because the RMI is calculated directly from the LMDR items, it has the advantage of requiring no additional administration time or materials, and thus may serve as a quick screen for dissimulation that can be obtained without additional testing.     

Using the WMS-III faces subtest to detect malingered memory impairment

The current study evaluated the utility of the WMS-III Faces I subtest (Faces) for the assessment of malingering. Thirty nonlitigating traumatic brain injury patients and 30 control participants were administered Faces under standard administration and instructed malingering conditions. Although the two groups obtained similar scores when taking the test under standard instructions, both groups produced significantly lower performances when instructed to malinger, indicating that Faces is sensitive to malingering, but less sensitive to traumatic brain injury. The total raw score provided stronger classification accuracy than an empirically weighted combination of the five easiest items (i.e., floor effect items). A raw score cutoff of 31 yielded the maximum classification accuracy with 93.3% sensitivity and 80.0% specificity.     

Using intraindividual variability to detect malingering in cognitive performance

The utility of measures for detecting malingering was evaluated using a simulation design in which half the participants were encouraged to do their best and half were asked to feign head injury. Particular attention was focused on the utility of repeated assessment (intraindividual variability) in discriminating the groups. Participants were tested on three occasions on measures commonly used to detect malingering including a specific symptom validity test (SVT). The results indicated that multiple measures of malingering obtained in single assessment (occasion one) discriminated the groups effectively. In addition, however, intraindividual variability in performance, particularly of indicators from the SVT, provided unique information beyond level of performance. The results suggest that response inconsistency across testing sessions may be a clinically useful measure for the detection of malingering.     

Using the Wechsler Memory Scale-III to detect malingering in mild traumatic brain injury

This study examined the classification accuracy of the WMS-III primary indices in the detection of Malingered Neurocognitive Dysfunction (MND) in Traumatic Brain Injury (TBI) using a known-groups design. Sensitivity, specificity, and positive predictive power are presented for a range of index scores comparing mild TBI non-malingering (n = 34) and mild TBI malingering (n = 31) groups. A moderate/severe TBI non-malingering (n = 28) and general clinical group (n = 93) are presented to examine specificity in these samples. In mild TBI, sensitivities for the primary indices ranged from 26% to 68% at 97% specificity. Three systems used to combine all eight index scores were also examined and all achieved at least 58% sensitivity at 97% specificity in mild TBI. Specificity was generally lower in the moderate/severe TBI and clinical comparison groups. This study indicates that the WMS-III primary indices can accurately identify malingered neurocognitive dysfunction in mild TBI when used as part of a comprehensive classification system.     

Using the Wisconsin card sorting test to detect malingering: an analysis of the specificity of two methods in nonmalingering normal and patient samples

This study sought to examine the specificity of two sets of equations designed to differentiate honest from malingered performance on the WCST. Data were provided by several samples of nonmalingering normal college students and neurological patients. High false positive error rates were observed in most samples. It was argued that these equations performed poorly because they reflect valid WCST response profiles. The importance of learning to identify malingering on standard neuropsychological tests is recognized, and an alternative approach to identifying such patterns of malingered performance is proposed.     

Brief screening indexes for malingering: A confirmation of Vocabulary minus Digit Span from the WAIS-III and the Rarely Missed Index from the WMS-III

This study investigated the specificity of empirically derived screening measures for the detection of symptom exaggeration in persons with a diagnosis of alcohol abuse (n = 30), polysubstance abuse (n = 43), or head trauma (n = 27). The first measure evaluated was Vocabulary (V) minus Digit Span (DS) (Mittenberg, Theroux-Fichera, Zielinski, & Heilbronner, 1995); the second measure was the Rarely Missed Index (RMI) for the WMS-III Logical Memory subtest (Killgore & Della-Pietra, 2000). V-DS misclassified 0% of individuals in the alcohol abuse group, 2% of those in the polysubstance abuse group, and 0% of head injury cases. RMI misclassification rates were 3%, 5%, and 7% for the alcohol abuse, polysubstance abuse, and head injury groups, respectively. Overall accuracy rates were 99% for V-DS and 95% for RMI.     

Detecting poor effort and malingering with an expanded version of the Auditory Verbal Learning Test (AVLTX): validation with clinical samples

Three studies describe the development and validation of a new procedure (AVLTX) to detect inadequate effort or malingering by adding 60-min delayed recall/recognition trials and identifying "impaired" memory performances that are highly inconsistent with performances of brain-damaged (BD) individuals. In Study I, AVLTX performances of 25 probable malingerers (PMs) were compared with those of 43BD and 40 psychiatric patients (PSYs). Seven inconsistencies were identified and converted to scaled inconsistency scores, yielding the exaggeration index (EI). Study II reported cross-validation in an independent sample of 34 PM, 70BD and 89 PSY, showing sensitivity of 0.59 and specificities of 0.97 (BD) and 0.92 (PSY). Study III compared the diagnostic accuracy of the EI with two well-established effort assessment paradigms, exemplified by the RMTand DRT (a symptom validity test). The RMT showed excellent sensitivity and poor specificity; the DRT showed poor sensitivity and excellent specificity; the EI showed good sensitivity and excellent specificity. Adding a second delayed trial to list-learning tests can be a time-efficient procedure to detect inadequate effort.     

Comparability of the expanded WMS-III standardization protocol to the published WMS-III among right and left temporal lobectomy patients

We examined whether differences between the expanded standardization protocol (SP) used to derive norms for the final published version (PB) of the Wechsler Memory Scale - Third Edition (WMS-III; Wechsler, 1997a) would result in differences on the Primary Indexes in a neurologic sample. Specifically, we examined the comparability of the performances of 63 patients with temporal lobectomy (TL) who were administered either the expanded SP protocol (n = 33: 22 left TL and 11 right TL) or the PB battery (n = 30: 11 left TL and 19 right TL). Patients who were administered the SP or PB were comparable in terms of age, sex, education, seizure duration, postsurgical seizure status, and Full Scale IQ. Postoperative intervals were significantly longer for the SP group, although correlational analyses demonstrated no significant relationship between postoperative follow-up interval and WMS-III performance. A series of t tests revealed no significant differences on any of the eight Primary Index scores between patients taking the two versions of the WMS-III for either left or right TL groups. Furthermore, repeated measures analyses of variance failed to show significant differences on modality-specific memory scores between the SP and PB for the left and right TL groups. The current study indicates that temporal lobectomy patients obtained comparable scores on the two versions of the WMS-III.     

A validation of the test of memory malingering in a forensic psychiatric setting

The Test of Memory Malingering (TOMM) has not been adequately validated in a forensic psychiatric setting. Dissimulation of cognitive impairment, as assessed by the TOMM, was evaluated in a group of 25 forensic inpatients admitted for evaluation of Competency to Stand Trial (CST/MSO group), and hypothesized to be at higher risk for feigning cognitive impairment. A comparison group of 36 patients, who were either civilly committed or adjudicated Not Guilty by Reason of Insanity (CIVIL/NGRI group), were hypothesized to be less likely to feign cognitive impairment. Groups were comparable in age, education, premorbid intelligence, and psychiatric symptom severity. Significantly more CST/MSO patients (36%) scored below a recommended TOMM cutoff score relative to CIVIL/NGRI patients (6%). Findings indicate excellent specificity and modest sensitivity, and generally support the validity of the TOMM in a forensic psychiatric population. The utility of different cutoff scores and need for multiple indicators of effort are discussed.     

Comparison of Wechsler Memory Scale-Fourth Edition (WMS-IV) and Third Edition (WMS-III) dimensional structures: improved ability to evaluate auditory and visual constructs

Dimensional structures underlying the Wechsler Memory Scale-Fourth Edition (WMS-IV) and Wechsler Memory Scale-Third Edition (WMS-III) were compared to determine whether the revised measure has a more coherent and clinically relevant factor structure. Principal component analyses were conducted in normative samples reported in the respective technical manuals. Empirically supported procedures guided retention of dimensions. An invariant two-dimensional WMS-IV structure reflecting constructs of auditory learning/memory and visual attention/memory (C1 = .97; C2 = .96) is more theoretically coherent than the replicable, heterogeneous WMS-III dimension (C1 = .97). This research suggests that the WMS-IV may have greater utility in identifying lateralized memory dysfunction.     

A new look at the WMS-III: new research to guide clinical practice

The Wechsler Memory Scale, Third Edition (WMS-III) was published in 1997 and marked an ambitious and substantial revision of the traditional memory scale. Since publication, however, clinical experience has led many practitioners to raise questions about the validity and clinical utility of the new subtests and new index scores. The impetus of this special issue was to address some of the questions with which clinicians have been struggling. The articles contained in this special issue present new empirical research on the WMS-III, and several include new methods and scoring techniques that go beyond what has been published in the WAIS-III-WMS-III Technical Manual (The Psychological Corporation, 1997, 2002). It is hoped that the new scores and techniques will prove useful in clinical practice and that this research will benefit future revisions of the Wechsler Memory Scale.     

Exploratory factor analysis and validation study of the lifetime severity index for cocaine, Spanish version (LSI-C-Spanish)

The purpose of the study was to do an exploratory factor analysis and to examine the criterion-related and discriminant validity of the Lifetime Severity Index for Cocaine (LSI-C), Spanish version. A sample of 171 outpatients from 10 drug centers in Spain participated in the study. We conducted the factor analysis with orthogonal rotation and examined correlations between the LSI-C total score and criterion variables as well as the score obtained by a quality of life measure. The factor analysis revealed 2 principal factors that explain 65.8% of the variance. Lower LSI-C scores were associated with taking medication, receiving social help, using cocaine fewer than 30 times during the previous 6 months, and with better scores on quality of life measures. Higher LSI-C scores were associated with unstable housing, overdose, hospitalization, cocaine consumption more than 100 times during the previous 6 months, and more years of drug consumption. The LSI-C Spanish version shows acceptable criterion-related and discriminant validity.     

The influence of IQ stratification on WAIS-III/WMS-III FSIQ-general memory index discrepancy base-rates in the standardization sample.

Since memory performance expectations may be IQ-based, unidirectional base rate data for IQ-Memory Score discrepancies are provided in the WAIS-III/WMS-III Technical Manual. The utility of these data partially rests on the assumption that discrepancy base rates do not vary across ability levels. FSIQ stratified base rate data generated from the standardization sample, however, demonstrate substantial variability across the IQ spectrum. A superiority of memory score over FSIQ is typical at lower IQ levels, whereas the converse is true at higher IQ levels. These data indicate that the use of IQ-memory score unstratified "simple difference" tables could lead to erroneous conclusions for clients with low or high IQ. IQ stratified standardization base rate data are provided as a complement to the "predicted difference" method detailed in the Technical Manual.