Robert P. Granacher

Response validity in forensic neuropsychology: Exploratory factor analytic evidence of distinct cognitive and psychological constructs

Forensic neuropsychology studies usually address either cognitive effort or psychological response validity. Whether these are distinct constructs is unclear. In 122 participants evaluated in a compensation-seeking context, the present Exploratory Factor Analysis examined whether forced-choice cognitive effort measures (Victoria Symptom Validity Test, Test of Memory Malingering, Letter Memory Test) and Minnesota Multiphasic Personality Inventory, Second Edition (MMPI-2) validity scales (L, F, K, FBS, Fp, RBS, Md, Dsr2, S) load on independent factors. Regardless of factor rotation strategy (orthogonal or oblique), four response validity factors emerged by means of both Principal Components Analysis (82.7% total variance) and Principal-Axis Factor Analysis (74.1% total variance). The four factors were designated as follows: Factor I, with large loadings from L, K, and S--underreporting of psychological symptoms; Factor II, with large loadings from FBS, RBS, and Md-overreporting of neurotic symptoms; Factor III, with large loadings from VSVT, TOMM, and LMT--insufficient cognitive effort; and Factor IV, with the largest loadings from F, Fp, and Dsr2--overreporting of psychotic/rarely endorsed symptoms. Results reflect the heterogeneity of response validity in forensic samples referred for neuropsychological evaluation. Administration of both cognitive effort measures and psychological validity scales is imperative to accurate forensic neuropsychological assessment.

Malingering as a Categorical or Dimensional Construct : The Latent Structure of Feigned Psychopathology as Measured by the SIRS and MMPI-2

The 6 nonoverlapping primary scales of the Structured Interview of Reported Symptoms (SIRS) were subjected to taxometric analysis in a group of 1,211 criminal and civil examinees in order to investigate the latent structure of feigned psychopathology. Both taxometric procedures used in this study, mean above minus below a cut (MAMBAC) and maximum covariance (MAXCOV), produced dimensional results. A subgroup of participants (n = 711) with valid Minnesota Multiphasic Personality Inventory-2 (MMPI-2) protocols were included in a second round of analyses in which the 6 nonoverlapping primary scales of the SIRS and the Infrequency (F), Infrequency-Psychopathology (Fp), and Dissimulation (Ds) scales of the MMPI-2 served as indicators. Again, the results were more consistent with dimensional latent structure than with taxonic latent structure. On the basis of these findings, it is concluded that feigned psychopathology forms a dimension (levels of fabrication or exaggeration) rather than a taxon (malingering-honest dichotomy) and that malingering is a quantitative distinction rather than a qualitative one. The theoretical and clinical practice implications of these findings are discussed.

Use of MMPI-2 to predict cognitive effort: A hierarchically optimal classification tree analysis

Neuropsychologists routinely rely on response validity measures to evaluate the authenticity of test performances. However, the relationship between cognitive and psychological response validity measures is not clearly understood. It remains to be seen whether psychological test results can predict the outcome of response validity testing in clinical and civil forensic samples. The present analysis applied a unique statistical approach, classification tree methodology (Optimal Data Analysis: ODA), in a sample of 307 individuals who had completed the MMPI-2 and a variety of cognitive effort measures. One hundred ninety-eight participants were evaluated in a secondary gain context, and 109 had no identifiable secondary gain. Through recurrent dichotomous discriminations, ODA provided optimized linear decision trees to classify either sufficient effort (SE) or insufficient effort (IE) according to various MMPI-2 scale cutoffs. After of an initial, complex classification tree, the Response Bias Scale (RBS) took precedence in classifying cognitive effort. After removing RBS from the model, Hy took precedence in classifying IE. The present findings provide MMPI-2 scores that may be associated with SE and IE among civil litigants and claimants, in addition to illustrating the complexity with which MMPI-2 scores and effort test results are associated in the litigation context.

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

Compensation-seeking neuropsychological evaluees were classified into Honest (HON; n = 37) or Probable Cognitive Feigning (PCF; n = 53) groups based on results from the Victoria Symptom Validity Test, the Test of Memory Malingering, and the Digit Span subtest of the Wechsler Adult Intelligence Scale—3rd ed. The groups were generally comparable on demographic, background, and injury severity characteristics, although HON TBI participants were significantly more likely to have a documented loss of consciousness, whereas PCF participants were significantly more likely to be currently on disability. PCF participants scored significantly lower on many neuropsychological test, particularly of memory, as well as higher on most MMPI-2 clinical scales. The PCF group also had significantly higher scores on multiple indices of feigning of psychiatric symptoms. Results from the Letter Memory Test (LMT) were significantly lower for the PCF group, and using the recommended cutting score, specificity was .984, whereas sensitivity was .640, suggesting adequate performance on cross-validation.

Comparability of Structured Interview of Reported Symptoms (SIRS) and Structured Interview of Reported Symptoms–Second Edition (SIRS-2) Classifications With External Response Bias Criteria.

Rogers, Sewell, and Gillard (2010) released a revised version of the Structured Interview of Reported Symptoms (SIRS; Rogers, Bagby, & Dickens, 1992), the SIRS-2, which introduced several new scales, indices, and a new classification model with the overall goal of improving its classification of genuine versus feigned presentations. Since the release of the SIRS-2, several concerns have been raised regarding the quality of the SIRS-2 development and validation samples and the method used to calculate classification accuracy estimates. To further explore issues related to the clinical utility of the SIRS-2, the current study examined associations of the SIRS and SIRS-2 with the Minnesota Multiphasic Personality Inventory-2–Restructured Form (Ben-Porath & Tellegen, 2008/2011) validity scales in separate samples of disability claimants and criminal defendants. Results indicate that the SIRS-2 reduced the number of feigning classifications. Additional analyses suggest that the Modified Total Index and Supplementary Scale Index do not assess the test-taking strategy that Rogers and colleagues (2010) intended the indices to capture. External data indicates that evaluees reclassified on the SIRS-2 in nonfeigning categories exhibited feigned symptoms of psychopathology. Indeed, we found that SIRS-identified feigners showed significant evidence of overreporting on the Minnesota Multiphasic Personality Inventory-2–Restructured Form validity scales, regardless of their SIRS-2 classification. The current study highlights the overall weakness in clinical utility of the SIRS-2. Implications of these results for both clinical and forensic settings are discussed.