The Victoria Symptom validity test: development of a new clinical measure of response bias




Slick, Daniel Joseph

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This dissertation describes the development of the Victoria Symptom Validity Test (VSVT). The VSVT was designed to assist in screening for non-optimal performance during neuropsychological evaluation due to malingering, psychiatric disturbance, or other environmental or dispositional factors. Specifically, the VSVT is a test of recognition memory that uses the forced-choice paradigm for detecting biased or random responding. Response latency is also recorded. Results from pilot and follow-up normative studies with experimental and clinical populations are presented. The VSVT was found to have excellent divergent and adequate convergent validity in samples of compensation-seeking and noncompensation-seeking patients. Classifications of experimental participants using below chance performance as a cutoff were consistent with the majority of previous studies in finding 100% specificity but poor sensitivity. A new system wherein a third category is added for questionable (at chance) performance showed greatly increased sensitivity, with no decrement in specificity. Although scores in the questionable range are not unequivocal indicators of malingering, findings suggest good utility for screening or corroborative purposes. A Bayesian diagnostic probability matrix that takes base-rates into account was also provided as a more flexible alternative to absolute cutoff scores. Response latency as a measure of symptom validity was shown to have adequate sensitivity for screening, but less acceptable discriminant validity and lower specificity. Limitations of experimental results and clinical applications of symptom validity tests are discussed.



Malingering, Diagnosis, Symptoms