Distinct brain mechanisms linked to evidence accumulation and crime-type bias in juror decisions

Efforts to explain jury decisions have focused on competing models emphasizing utility, narrative, and social-affective mechanisms, but these are difficult to distinguish using behavior alone. Here, we use patterns of brain activation derived from large neuroimaging databases to look for signatures of the cognitive processes associated with models of juror decision making. We asked jury-eligible subjects to rate the strength of a series of criminal cases while recording the resulting patterns of brain activation. When subjects considered evidence, utility and narrative processes were both active, but cognitive processes associated with narrative models better explain the patterns of brain activation. In contrast, a biasing effect of crime type on perceived strength of the case was best explained by brain patterns associated with social cognition.