Results From Three Performance Validity Tests (PVTs) in Adults With Intellectual Deficits.

Previous studies of performance on the Word Memory Test (WMT; Green, 2003 ; Green & Astner, 1995 ) in adults with very low intelligence have provided conflicting evidence. Most studies suggest that a Full-Scale IQ (FSIQ) less than 70 cannot explain failure on the WMT, but Shandera et al. ( 2010 ) suggest that many adults with mental retardation (MR) cannot pass the WMT. If so, we would expect adults with such low intelligence to fail the WMT at a high rate, even if they were motivated to perform well. In the current study, parents with an FSIQ of 70 or less, who were seeking custody of their children, rarely failed the WMT or the Medical Symptom Validity Test (MSVT; Green, 2004 ). They did not fail the WMT or MSVT any more often than adults of higher intelligence. On the other hand, adults with an external incentive to appear impaired scored significantly lower on the WMT and MSVT than did parents with an incentive to look good. The data strongly suggest that MR with an FSIQ in the range of 46 to 70 is not sufficient to explain failure on these performance validity tests by adults.