B – 123 Excluded from the Norms: Forensic Neuropsychological Test Data from Murder Defendants

Abstract Objective Neuropsychological testing is important in legal decision making but normative data may not reflect the functioning of criminal defendants with histories that may exclude them from standardization samples. This study examines whether performance on neuropsychological measures in a forensic sample differs from published norms, hypothesizing significant deviations from normative expectations. Method Data from 228 male criminal defendants (primarily capital murder offenses) were obtained from a private practice. Participants were excluded only if they failed more than one of three performance validity measures: TOMM (Trial 2 45), Word Choice (raw 45), and Dot Counting (E-Score 18). This poster presents a subset of data from a larger retrospective study, focusing on Wisconsin Card Sort Test perseverative errors, FAS, Animal Fluency, Rey Complex Figure Test immediate and delayed recall, and Digit Vigilance Test time and errors T-scores. Results Using one-sample t-tests (Bonferroni adjusted α = .0071), participants scored significantly lower than the normative mean (T = 50) on the FAS (t(216) = -5.98, p .001, d = -0.41), RCFT immediate recall (t(190) = -5.54, p .001, d = -0.41), and RCFT delayed recall (t(189) = -6.49, p .001, d = -0.47). WCST perseverative errors differed but did not remain significant after correction. All other tests were not significantly different from norms. Conclusion Criminal defendants demonstrated significant weaknesses in verbal fluency and visual memory. These findings highlight potential limitations in applying standard neuropsychological norms to forensic populations and support the need for more representative norming samples to improve clinical and legal interpretation.