Preliminary Evidence for How the Behavioral Immune System Predicts Juror Decision-Making

The behavioral immune system (BIS) is comprised of a variety of psychological and behavioral defenses designed to protect against pathogenic threats. These processes predict various affective and behavioral responses in myriad human contexts, including putative decisions to mitigate exposure to environmental pathogens. We investigated whether the strength of BIS responses predicted jurors’ verdicts in a sexual assault trial, wherein strength of the evidence against the defendant was manipulated (ambiguous vs. strong) to determine the extent to which chronic activation of BIS predicted derogation of the defendant. Subsequent mediation analyses indicated that dispositionally activated BIS (as indexed by perceived vulnerability to disease) predicted greater likelihood of conviction by way of affective experiences of disgust, which in turn influenced participants’ cognitive appraisals of diagnostic evidence. Furthermore, such responses also elicited greater desire for social distance with the defendant. Evidence strength, however, did not moderate these effects. Findings provide preliminary evidence for how BIS responses may influence legal proceedings