Detection of inadequate effort on neuropsychological testing: a meta-analytic review of selected procedures

Thirty-two studies of commonly researched neuropsychological malingering tests were meta-analytically reviewed to evaluate their effectiveness in discriminating between honest responders and dissimulators. Overall, studies using the Digit Memory Test (DMT), Portland Digit Recognition Test (PDRT), 15-Item Test, 21-Item Test, and the Dot Counting Test had average effect sizes indicating that dissimulators obtain scores that are approximately 1.1 standard deviations below those of honest responders. The DMT separated the means of groups of honest and dissimulating responders by approximately 2 standard deviations, whereas the 21-Item Test and the PDRT separated the groups by nearly 1.5 and 1.25 standard deviations, respectively. The 15-Item Test and the Dot Counting Test were less effective, separating group means by approximately 3/4 of a standard deviation. Although the DMT, PDRT, 15-, and 21-Item Tests all demonstrated very high specificity rates, at the level of individual classification, the DMT had the highest sensitivity and overall hit-rate parameters. The PDRT and 15-Item Test demonstrated moderate sensitivity, whereas the 21-Item Test demonstrated poor sensitivity. The less than perfect sensitivities of all the measures included in this review argue against their use in isolation as malingering screening devices.