Validation of reliable digits for detection of malingering

This study is a cross validation of the previous work by Greffenstein, Baker, and Gola (1994) and Greiffenstein, Gola, and Baker (1995) on the Reliable Digits (RD) method of detecting possible malingering. This study consisted of 47 mild brain-injured litigating and 49 mild brain-injured non-litigating participants. The result of this study was that only 4.1% of the non-litigating participants were classified as malingering by RD, while 48.9% of the litigating participants were classified as malingering by RD. Comparing litigating participants' performance on a forced choice task with their RD revealed that 77.8% (7/9) who failed the forced choice task also failed RD. RD classified more litigating patients as malingering than did the forced choice task and none of the non-litigating participants failed forced choice. These findings underscore the previous recommendations of Greiffenstein et al. (1994, 1995), that it is important to assess motivation on specific neuropsychological tests and that motivation on neuropsychological tests is not an all or none phenomenon.