Validity of neuropsychological test results in disability evaluations.

A group of 50 disability claimants referred by the Social Security Administration for neuropsychological screening were administered a 36-item, forced-choice, digit-recognition method of detecting malingering to assess effort and motivation to perform well. This abbreviated form of the 1989 Hiscock and Hiscock Forced-choice Procedure has been shown to be quite easy even for individuals with severe organic brain dysfunction. A perfect performance of 36 correct on this digit-recognition task is obtained by most individuals with moderate to severe brain damage. A performance of less than 90% correct is due more likely to poor effort or even malingering rather than brain damage. In this sample, 18% (n = 9) obtained scores of less than 90% correct, i.e., < 33, which calls into question the reliability and validity of test data obtained. An additional 20% (n = 10) obtained intermediate scores of 33 to 35 correct. These intermediate scores are more difficult to interpret although at least some proportion of those scores reflects poor motivation. The results over-all indicate that nearly one-fifth of potential disability claimants produced invalid and uninterpretable neuropsychological test protocols and an additional one-fifth obtained protocols that should be well scrutinized for evidence of poor effort as well. Neuropsychologists conducting disability evaluations are urged to use measures designed specifically to assess effort and motivation.