Objective: Social Security Disability is a common external incentive in neuropsychological evaluations. This study determined base rates of invalidity when patients referred for routine clinical evaluations have Social Security Disability as an external incentive. Method: Patients (n = 242) were grouped as validly or invalidly performing based on the use of multiple performance validity tests. Frequency analyses were then conducted. Results: As a whole, 46.0% of clinically referred patients with Social Security Disability as an external incentive produced invalid data. When divided by disability pursuit status, 58.6% of individuals already receiving Social Security Disability, 44.6% of individuals actively seeking Social Security Disability, and 39.3% of individuals considering seeking Social Security Disability produced invalid data. By comparison, only 8.5% of clinically referred patients without known external incentives produced invalid data. Conclusions: Beyond establishing base rates, these data indicate that the external incentive, not necessarily the evaluation setting, increases the rate of invalidity, as obtained base rates mirror those observed in independent medical examinations. In addition, this study highlights that even patients who report that they are considering but have not committed themselves to pursuing an external incentive frequently invalidate testing.
Keywords: Social security disability; base rate; clinical evaluations; external incentive; invalidity.