Potentially Mitigating and Aggravating: The Influence of Neurological Evidence in Capital Sentencing Hearings

Abstract

Advances in neuroscience research are continuing to provide more of a complete understanding of human behavior, including behavior that may bring an individual in contact with the criminal justice system. This study primarily examined whether neurological evidence in the form of expert testimony is predictive of a life sentence if presented by a defense expert as a mitigating factor or a death sentence if presented by a prosecution expert as an aggravating factor. The current study is the first to assess how neurological evidence is viewed in a capital sentencing context. A total of 394 participants were administered a vignette in which either a defense or prosecution expert presented neurological evidence. Facts and testimony included in the vignettes also reflected a crime consistent with reactive aggression or instrumental aggression. Participants were asked to provide either a life imprisonment or death sentence and then were asked to rate how influenced they were by neurological testimony. Results provided some support that participants who more influenced by neurological evidence presented by a defense expert were more likely to provide a life imprisonment sentence when facts reflected reactive aggression. Due to the majority of participants in prosecution groups incorrectly identifying that it was a defense expert who testified, it could not be determined whether neurological evidence from the prosecution would increase the probability of a death sentence. This study is consistent with prior research that suggests neurological evidence is viewed as decreasing defendant culpability.%%%%Ph.D., Clinical Psychology – Drexel University, 2013