The Effect of Jury Instructions on Juror Perceptions of Anxious Nonverbal Behavior

Abstract

This study examined the degree to which jury instructions could modulate juror perceptions of anxious nonverbal behavior. More specifically, our experiment explored the relationship between the perceived nervousness of a defendant, assessments of credibility, and trial outcomes. The results of the study revealed that instructions had no statistically significant effect on verdicts or ratings of credibility. Affect appeared to influence trial outcomes regardless of jury instruction type. In addition, the credibility of the defendant mediates the relationship between perceived nervousness of the defendant and verdicts (ACME = 0.049, p < 0.001). A nervous defendant was perceived as less credible, resulting in more guilty verdicts. Moreover, for each one-unit increase in defendant credibility, the probability of a guilty verdict decreased by approximately 6.19 percentage points, holding other factors constant (p < 0.05). Despite being instructed to not consider nonverbal behavior, jurors failed to follow the instructions or overcome their cognitive bias as it relates to nonverbal cues typically associated with deception.