Truthiness and law: Nonprobative photos bias perceived credibility in forensic contexts

Abstract

Nonprobative but related photos can increase the perceived truth value of statements relative to when no photo is presented (truthiness). In two experiments, we tested whether truthiness generalizes to credibility judgments in a forensic context. Participants read short vignettes in which a witness viewed an offence. The vignettes were presented with or without a nonprobative, but related photo. In both experiments, participants gave higher witness credibility ratings to photo‐present vignettes compared to photo‐absent vignettes. In Experiment 2, half the vignettes included additional nonprobative information in the form of text. We replicated the photo presence effect in Experiment 2, but the nonprobative text did not significantly alter witness credibility. The results suggest that nonprobative photos can increase the perceived credibility of witnesses in legal contexts.