Bridging the gap between neurocognitive processing theory and performance validity assessment amongst the cognitively impaired: a review, methodological approach and initial findings

Angela Leighton

    Research output: ThesisDoctoral Thesis

    138 Downloads (Pure)

    Abstract

    [Truncated] Neurocognitive symptoms remain a common, yet difficult, complaint for clinicians to navigate, as some individuals can purposely distort their symptomology for external gain (e.g., compensation, competency to stand trial, etc.). Such feigning or exaggeration of cognitive deficits, and the increasing demands for legally admissible measures of performance validity has necessitated the need for a clinically objective manner with which to assess the level of effort being supplied in a neurocognitive evaluation. The development of both free-standing and “embedded” performance validity tests (PVTs; Larrabee, 2012; also known as symptom validity tests, or SVTs)has been successful, with a large body of research supporting their validity in many clinical groups, and relevant professional societies endorsing their use as a practice standard (Bush et al., 2005). However, some characteristics of PVTs and their use insignificantly impaired individuals, including the problem of potential “false positive” errors (PVT classification inaccurately indicative of poor performance validity)remain controversial and inadequately researched. The application of neurocognitive theoretical research findings represents a promising approach to evaluate the methodological and psychometric properties of current PVTs (Bigler, 2012), and develop future measures.
    For example, individual PVTs have implemented the simultaneous forced-choice methodology (i.e., generally a learning phase followed by the item(s) learned,or ‘target’ being simultaneously paired with a distractor, or ‘foil’ for selection, whereby over-selection of the foil may indicate responding bias) using a variety of test characteristics (e.g., word vs. picture stimuli) with known neurocognitive processing implications (e.g., the “picture superiority effect”). However, the influence of such variations on the subsequent classification accuracy of examinees has been inadequately evaluated, particularly amongst cognitively impaired individuals. The current thesis places the PVT literature in the context of neurocognitive processing theory, and identifies potential methodological factors to account for the significant variability that have been identified in classification accuracy across current PVTs. A systematic evaluation of both the current PVT and cognitive processing literature was completed and presented in Chapter 1. This led to the subsequent evaluation of the utility of a well-known cognitive manipulation (based in cognitive load theory) to provide a Clinical Analogue Methodology (CAM); that is an experimental technique to alter the performance of healthy individuals on PVTs to levels more similar to cognitively impaired individuals. In the empirical study reported in in Chapter 2, an initial validation of the CAM in healthy individuals was completed. Chapter 3 further validated the CAM suggesting that it may be useful alongside other approaches(analogue malingering methodology) for the systematic evaluation of new and existing PVTs, as well as provided further support for a phenomenon called the ‘picture superiority effect’ (Paivio, 1991) in the PVT paradigm. Two exemplar PVTs(the Word Memory Test; WMT, and Test of Memory Malingering; TOMM) provided the basis for subsequent evaluations of the influence of specific neurocognitive processing components on performance.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - Sep 2015

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