Assessment of Neuropsychological Malingering after Traumatic Brain Injury: Is the Word Memory Test Worth the Effort?
In evaluations of disability arising from traumatic brain injury (TBI), assessment of malingering is seen as an increasingly important aspect of evidence-based neuropsychological practice (Halligan et al., 2003). However, in the absence of a consensus criterion or so-called gold standard of malingering, scientific evaluation of cognitive effort and motivation is fraught with difficulty. Nevertheless, in many aspects of clinical science worthwhile progress has been made in the absence of specific consensus criteria (Faust, 2003).
One recently published test of cognitive effort intended for evaluation of malingering in patients suffering TBI is the Word Memory Test. Although a relatively new test, this measure of cognitive effort has attracted extraordinary attention and has had significant impact on the practice of malingering evaluation, internationally. The claims for validity advanced by the authors of this test are novel and scientifically provocative. It is suggested that effort, as measured by the Word Memory Test, (1) explains a substantial portion of variance in cognitive outcome after TBI and (2) effort interacts with injury severity to produce patterns of scores after TBI which cannot be explained by injury severity alone (Green, Lees-Haley & Allen, 2002).
In this paper, we examine the original evidence cited by the test authors and report a replication of their primary validity study in a sample of 100 Australians involved in litigation for the effects of TBI. We conclude that the scientific basis for validity of the Word Memory Test is open to question, and our independent replication does not support the assumption that WMT effort scores interact with injury severity to modify cognitive outcome after TBI.