Neuroimages as Evidence in a Mens Rea Defense: No Impact
Psychology, Public Policy, and Law, Vol. 17, No. 3, pp. 357–393, 2011
Posted: 8 Mar 2012
Date Written: August 1, 2011
Recent developments in the neuropsychology of criminal behavior have given rise to concerns that neuroimaging evidence (such as MRI and functional MRI [fMRI] images) could unduly influence jurors. Across four experiments, a nationally representative sample of 1,476 jury-eligible participants evaluated written summaries of criminal cases in which expert testimony was presented in support of a mental disorder as exculpatory. The evidence varied in the extent to which it presented neuroscientific explanations and neuroimages in support of the expert’s conclusion. Despite suggestive findings from previous research, we found no evidence that neuroimagery affected jurors’ judgments (verdicts, sentence recom-mendations, judgments of the defendant’s culpability) over and above verbal neuroscience - based testimony. A meta-analysis of our four experiments confirmed these findings. In addition, we found that neuroscientific evidence was more effective than clinical psycho- logical evidence in persuading jurors that the defendant’s disorder reduced his capacity to control his actions, although this effect did not translate into differences in verdicts.
Keywords: neuroimage, scientific evidence, mens rea, juror decisionmaking
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