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.

Stable truthiness effect across the lifespan.

“…For the bivariate correlations, BF 10 denotes the evidence for the effect of interest compared to the null model. The data used in all analyses are on OSF (Derksen et al, 2018−2020a).…”

“…Additionally, for the lab-based sample, instead of using Latin Square counterbalancing, we used a semirandomized trial order while maintaining an equal proportion of each trial type. All stimuli are on OSF (Derksen et al, 2018−2020b).…”

“…Truthiness is not exclusive to trivia claims. Nonprobative but related photos also increase perceived credibility of both expert and nonexpert witnesses in forensic contexts (Derksen et al, 2020;Sanson et al, 2020), increase the propensity for people to misremember past events (Cardwell et al, 2016;Wade et al, 2002), and increase 'likes' and mistake the ease with which they process the trivia claim as evidence that the claim is true rather than correctly attributing that ease to the presence of the nonprobative but related photograph (Newman et al, 2015;Schwarz & Newman, 2017; see also fluency misattribution, Jacoby & Whitehouse, 1989).…”

“…Truthiness is not exclusive to trivia claims. Nonprobative but related photos also increase perceived credibility of both expert and nonexpert witnesses in forensic contexts (Derksen et al, 2020; Sanson et al, 2020), increase the propensity for people to misremember past events (Cardwell et al, 2016; Wade et al, 2002), and increase ‘likes’ and ‘shares’ in a social media environment (Fenn et al, 2019). The existing empirical research suggests that truthiness occurs throughout a variety of judgment contexts because nonprobative but related photos make claims feel subjectively easier to process (i.e., increase processing fluency ) compared to when no photo is present (e.g., Jacoby & Dallas, 1981; Whittlesea, 1993).…”

Introduction to the special issue. Answering questions raised by a well‐known Italian collective child abuse case

“…I also, along with others, claim that one needs to be careful when using the term credibility, as this is a subjective judgment, prone to strong biases. The paper in this special issue (Derksen, Giroux, Connolly, Newman, & Bernstein, 2020) examines one of such biases, that is, the introduction of visual information with a content that is irrelevant to the proceedings, but that leaves nonetheless a trace and has an effect in the perceived credibility. The authors focus their interest in the effect of photos on the credibility of witnesses, finding that photos with contents related to a scene, but containing information that is not probative, increase the perceived credibility of witnesses, whereas non-probative information provided in text had no effect on the Going back to the Italian case, the children involved in the case are now young adults.…”