Sensitivity and specificity of finger tapping test scores for the detection of suspect effort

Abstract

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 </=35 for men yielded 50% sensitivity, while a score of </=28 yielded 61% sensitivity for women. Specificity values for specific cutoff scores varied significantly across the comparison groups, indicating that cutoffs should be adjusted for the particular differential diagnosis. In conclusion, results indicate that when using finger tapping scores to detect noncredible performance: (a) Dominant hand performance is more sensitive, and (b) cutoffs should be selected based on gender and claimed diagnosis.