The face of guilt: bias in perceptions of guilt and innocence

This study examined whether facial appearance influences judgements of guilt and innocence in a legal decision-making context. Drawing on research on impression formation, implicit stereotyping, and Signal Detection Theory (SDT), participants completed a randomized photo-classification task involving United Nations/WHO officials (control), exonerees documented by the US Innocence Project, and convicted offenders. Participants made binary judgements and selected up to three facial or social cues informing each decision. They correctly classified UN officials as innocent and convicted offenders as guilty in 83% and 82% of cases, respectively, but attributed guilt to 61% of exonerees on average. Perceived untrustworthiness and emotionless appearance were associated with guilt, whereas perceived trustworthiness was associated with innocence, especially for exoneree profiles. The findings suggest that facial impressions may shift decision criteria under evidentiary uncertainty and increase false-positive judgements. Implications include witness education, photo-array design that de-emphasizes non-diagnostic cues, and courtroom guidance limiting reliance on surface-level impressions.