College of Psychology: Faculty Proceedings, Presentations, Speeches and Lectures

Title

Identification of Malingered Head Injury with WAIS-3 Vocabulary and Digit Span

Event Location / Date(s)

Tampa, FL / October 19-22, 2005

Document Type

Conference Proceeding

Presentation Date

10-19-2005

Conference Name / Publication Title

25th Annual Meeting of the National Academy of Neuropsychology

Description

Abstract

Objective: Prior research documents that exaggeration is common in compensable head trauma, and can be identified by intelligence test performance pattern. This study derived a WAIS-3 Vocabulary-Digit Span discriminant function to identify malingering by comparing clinical malingerers and head trauma patients.

Method: Fifty-nine malingering litigants were identified by scores on the TOMM, PDRT, WMT, or VSVT that were lower than obtained by any TBI patients in validation studies. Fifty-nine nonlitigants were matched to litigants onWAIS-3 FSIQ (85.53 vs. 85.54). Nonlitigants had a median GCS of 9 and 18 h post-injury coma. Litigants had a median GCS of 15 and median coma less than 1 h. Litigants and nonlitigants obtained FSIQ’s that were lower than demographically estimated premorbid IQ (M= 19 and 12 points) at 30 months versus 9 months post-injury. Vocabulary and Digit Span scores were entered in a stepwise discriminant analysis to determine if groups could be accurately identified.

Results: Seventy-five percent of TBI and 76% of malingerers were correctly classified. Discrimination was unrelated to coma length, GCS, CT results, or obtained FSIQ in either group. Discriminant score was significantly correlated with TOMM (r > .47) and VSVT (r > .44) scores in malingerers. Crossvalidation in independent groups of 68 nonlitigating TBI and 108 normals instructed to malinger impairment produced 71% and 77% diagnostic accuracy rates, respectively.

Conclusions: Vocabulary and Digit Span performance pattern continues to be useful in identifying malingered head injury. This study was supported by the NAN Clinical Research Grant and an NSU President’s Grant.

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