Effects of incentive and preparation time on performance and classification accuracy of standard and malingering-specific memory tests

The effects of incentive and preparation on performance and classification accuracy of standard and malingering-specific tests were investigated in a simulation study using a 2 (no incentive vs. a $20 incentive) × 2 (immediate vs. delayed preparation) factorial design. Eighty undergraduate students and 15 individuals with traumatic brain injury were administered standard (viz., Digit Span and Visual Memory Span from the WMS-R) and malingering-specific (viz., the Rey 15-Item Memory Test and the Multi-Digit Memory Test) memory tests. Preparation time was found to have a significant effect on performance and classification accuracy on a number of these tests, but incentive was found to have a significant effect on the performance but not the classification accuracy of one test (viz., the Multi-Digit Memory Test). These findings suggest that extra-test variables such as incentive and preparation time should be taken into consideration in evaluating the utility of standard and malingering-specific memory tests in detecting malingering.