Results From Three Performance Validity Tests in Children With Intellectual Disability.

If we wish to conclude that failure on a performance validity test (PVT) is a false positive for poor effort, we must have evidence that the person is truly incapable of passing the test because of cognitive impairment. We must show that they have a diagnostic condition that is sufficient to account fully for failure on that test. The purpose of the current study was to evaluate the performance of children with a primary diagnosis of intellectual disability (ID) on the Word Memory Test (WMT), the Medical Symptom Validity Test (MSVT), and the Nonverbal Medical Symptom Validity Test (Green, 2003 , 2004 , 2008b ; Green & Astner, 1995 ). If a Full-Scale IQ (FSIQ) less than 70 could account for failure on these tests in adults, then children with ID would also fail them. In fact, the children with ID in the current study did not fail the WMT or MSVT as long as they had at least a Grade 3 reading level. Also, the children with ID did not fail these tests any more often than did children of significantly higher intelligence. The data suggest that an FSIQ in the range of 48 to 70 is not sufficient to explain failure on these PVTs by children or adults.