Digit Span Age-Corrected Scaled Score (ACSS) and Reliable Digit Span (RDS) have been suggested as effective in assessing credibility. The purpose of this study was to confirm the efficacy of suggested cutoffs for ACSS and RDS and to explore the utility of other Digit Span variables in a large sample (N = 66) of "real-world" > or = suspect effort patients versus clinic patients with no motive to feign (N = 56) and controls (N = 32). With specificity at > or = 90%, sensitivity of ACSS increased from 32% to 42% when a < or = 5 cutoff was used instead of the recommended < or = 4. The RDS recommended cutoff of < or = 7 resulted in a sensitivity of 62% but with an unacceptably high false positive rate (23%); dropping the cutoff to < or = 6 raised the specificity to 93% but sensitivity fell to 45%. Cutoffs for other Digit Span scores did not exceed 45% sensitivity with the exception of 50% sensitivity (11% false positive rate) for average time per digit for all attempted items > 1.0 second. A criterion of ACSS < or = 5 or RDS < or = 6 was associated with 51% sensitivity (91% specificity) while RDS < or = 6 or longest string with at least one item correct < or = 4 was associated with 54% sensitivity (88% specificity). While only moderately sensitive, Digit Span scores, including new time variables, may have a unique and effective role in the detection of suspect effort.

Past studies indicate that patients with incentive to fake neuropsychological symptoms are likely to have lower finger tapping scores than credible patients. The present study builds upon past research by investigating finger tapping performance for seven groups: (a) noncredible patients (as determined by failed psychometric and behavioral criteria), and patients with (b) closed head injury, (c) dementia, (d) mental retardation, (e) psychosis, or (f) depression, and (g) healthy older controls. Results showed that men tapped faster than women, requiring that groups be divided by gender. Noncredible male and female patients tapped slower than their comparison group counterparts. Dominant hand score proved to be more sensitive to noncredible performance than other scores (nondominant, sum of both hands, difference between dominant and nondominant), especially for women. Sensitivity, specificity, and positive and negative predictive value tables are presented. With specificity set at 90% for the comparison groups combined, a dominant hand cutoff score of

The relationship between IQ and nine effort indicators was examined in a sample of 189 neuropsychology clinic outpatients who were not in litigation or attempting to obtain disability. Participants with the lowest IQ (50-59) failed approximately 60% of the effort tests, while patients with an IQ of 60 to 69 failed 44% of effort indicators, and individuals with borderline IQ (70 to 79) exhibited a 17% failure rate. All patients with IQ < 70 failed at least one effort test. Cutoffs for the Warrington Recognition Memory Test (Words) and Finger Tapping maintained the highest specificities in low IQ samples.