Base rates of negative response bias and malingered neurocognitive dysfunction among criminal defendants referred for neuropsychological evaluation.

Several studies reveal the prevalence of negative response bias (NRB) in civil forensic settings, but little NRB base rate information is available for criminal forensic neuropsychological settings. We reviewed the published literature on neuropsychological NRB in the civil setting. We then present data from 105 criminal defendants serially referred for neuropsychological assessment to determine the prevalence of NRB. The rate of NRB using one positive indicator was 89.5%. The rate was 70.5% when using two or more positive indicators and 53.3% for three or more indicators. Based on the Slick, Sherman, and Iverson (1999) classification for malingered neurocognitive dysfunction (MND), 19% were Valid, 26.7% were Possible MND, 32.4% were Probable MND, and 21.9% were Definite MND. The combined rate of probable and definite MND was 54.3%. Results suggest rates of neuropsychological NRB and malingering in criminal forensic settings are higher than in civil forensic settings.