Known-Groups Cross-Validation of the Letter Memory Test in a Compensation-Seeking Mixed Neurologic Sample

Computerized analysis of error patterns in digit span recall

We analyzed error patterns during digit span (DS) testing in four experiments. In Experiment 1, error patterns analyzed from a community sample of 427 subjects revealed strong primacy and recency effects. Subjects with shorter DSs showed an increased incidence of transposition errors in comparison with other error types and a greater incidence of multiple errors on incorrect trials. Experiment 2 investigated 46 young subjects in three test sessions. The results replicated those of Experiment 1 and demonstrated that error patterns of individual subjects were consistent across repeated test administrations. Experiment 3 investigated 40 subjects from Experiment 2 who feigned symptoms of traumatic brain injury (TBI) with 80% of malingering subjects producing digit spans in the abnormal range. A digit span malingering index (DSMI) was developed to detect atypical error patterns in malingering subjects. Overall, 59% of malingering subjects with abnormal digit spans showed DSMIs in the abnormal range and DSMI values correlated significantly with the magnitude of malingering. Experiment 4 compared 29 patients with TBI with a new group of 38 control subjects. The TBI group showed significant reductions in digit span. Overall, 32% of the TBI patients showed DS abnormalities and 11% showed abnormal DSMIs. Computerized error-pattern analysis improves the sensitivity of DS assessment and can assist in the detection of malingering.

Use of the SIRS in compensation cases: an examination of its validity and generalizability

The Structured Interview of Reported Symptoms (SIRS; Rogers et al., Structured interview of reported symptoms (SIRS) and professional manual, 1992) is a well-validated psychological measure for the assessment of feigned mental disorders (FMD) in clinical, forensic, and correctional settings. Comparatively little work has evaluated its usefulness in compensation and disability contexts. The present study examined SIRS data from 569 individuals undergoing forensic neuropsychiatric examinations for the purposes of workers' compensation, personal injury, or disability proceedings. Using bootstrapping comparisons, three primary groups were identified: FMD, feigned cognitive impairment (FCI), genuine-both (GEN-Both) that encompasses both genuine disorders (GEN-D) and genuine-cognitive presentation (GEN-C). Consistent with the SIRS main objective, very large effect sizes (M Cohen's d = 1.94) were observed between FMD and GEN-Both groups. Although not intended for this purpose, moderate to large effect sizes (M d = 1.13) were found between FCI and GEN-Both groups. An important consideration is whether SIRS results are unduly affected by common diagnoses or clinical conditions. Systematic comparisons were performed based on common disorders (major depressive disorder, PTSD, and other anxiety disorders), presence of a cognitive disorder (dementia, amnestic disorder, or cognitive disorder NOS), or intellectual deficits (FSIQ < 80). Generally, the magnitude of differences on the SIRS primary scales was small and nonsignificant, providing evidence of the SIRS generalizability across these diagnostic categories. Finally, the usefulness of the SIRS improbable failure-revised (IF-R) scale was tested as a FCI screen. Although it has potential in ruling out genuine cases, the IF-R should not be used as a feigning screen.

Cross-Validation of a Manual form of the Letter Memory Test Using a Known-Groups Methodology

A manual form of the Letter Memory Test (LMT: Orey, Cragar, & Berry, 2000) was compared in neuropsychological evaluees classified as honest (HON: n = 39) or probable cognitive feigners (PCF: n = 10) using results from two well-validated motivational tests. With the exception of lower educational level and higher rate of compensation seeking in the PCF, the groups were equivalent on most important demographic and injury severity parameters. PCF participants scored significantly lower on most neuropsychological tests (median Cohen's d = 1.2), as well as on the manual LMT (Cohen's d = 4.2). Operating characteristics of the manual LMT in the present sample were comparable to those reported in a similar study using the computerized version of the LMT in neuropsychiatric patients (Vagnini et al., 2006).

Identification of Feigned Mental Retardation Using the New Generation of Malingering Detection Instruments: Preliminary Findings

A recent Supreme Court decision--Atkins v. Virginia, 536 U.S. 304 (2002)--prohibiting the execution of mentally retarded (MR) defendants may have raised the attractiveness of feigning this condition in the criminal justice system. Unfortunately, very few published studies have addressed the detection of feigned MR. The present report compared results from tests of intelligence, psychiatric feigning, and neurocognitive faking in a group of 26 mild MR participants (MR) and 25 demographically matched community volunteers asked to feign MR (CVM). Results showed that the CVM suppressed their IQ scores to approximate closely the level of MR participants. WAIS-III and psychiatric malingering measures were relatively ineffective at discriminating feigned from genuine MR. Although neurocognitive malingering tests were more accurate, their reduced specificity in MR participants was of potential concern. Revised cutting scores, set to maintain a Specificity rate of about .95 in MR clients, were identified, although they require cross-validation. Overall, these results suggest that new cutting scores will likely need to be validated to detect feigned MR using current malingering instruments.