Rates of below-chance performance in forced-choice symptom validity tests.

The rates of significantly below-chance results on three neuropsychological symptom validity tests (SVTs) including the Portland Digit Recognition Test (PDRT), Test of Memory Malingering (TOMM), and Word Memory Test (WMT) were compared in a private practice forensic sample of 1032 examinees with alleged mild traumatic brain injury, moderate to severe traumatic brain injury, alleged toxic exposure, and reported chronic pain. The PDRT and WMT were equivalent to one another in the rates of below-chance results, with both yielding more frequent below-chance results than the TOMM. Seemingly more difficult sections of the PDRT and WMT had higher yields than seemingly easier sections. Multiple SVTs were more likely to yield below-chance results than a single test, supporting the use of multiple SVTs in forensic neuropsychological evaluations.