Prevalence estimates as priors: Juror characteristics, perceived base rates, and verdicts in cases reliant on complainant and defendant testimony

Abstract

Jurors often have to make decisions about whether they believe a complainant's or defendant's account of an event. However, the relative ambiguity of cues in testimony creates a situation where juror evaluations can vary significantly. As a result, in cases heavily reliant on testimony there is a particular likelihood that juror characteristics will be associated with verdicts, and it is important to understand these associations. This research investigates the relationships between two juror characteristics-gender and cultural worldviews-and verdicts in two such cases, and the potential for those relationships to be explained by differences in perceived prevalence of alleged events acting as prior probability judgements. As predicted, results show significant relationships between gender and cultural worldview and verdicts and show that these relationships are mediated by differences in underlying prevalence estimates. These findings have important implications for understanding associations between juror characteristics and verdicts, and related policy.

Adaptive lie detection and perceived prevalence of false reports in evaluation of sexual offense allegations.

“…Note that the estimate of the prevalence of false allegations in the control condition is higher than the same prevalence rating in Study 1, which was 13.73 (95% CI [11.61, 15.85], SD = 15.13; and participants in our true framing condition gave estimates similar to this rating). This suggests that, consistent with prior work (Helm & Growns, 2022), seeing case facts involving an alleged false allegation can lead to increased ratings of the prevalence of false allegations. This effect likely led to estimates across conditions being higher than they would have been if asked for prior to rather than after viewing case facts.…”

“…This potential lack of individuating cues creates a situation in which the ALIED Framework suggests that people’s evaluations will be influenced by their perceptions of the prevalence of truths versus lies, specifically in the relevant legal context (e.g., in the context of sexual offense allegations). This influence of perceived prevalence is consistent with theory underlying jury decision-making more generally (see e.g., the role of plausibility in Pennington & Hastie’s Story Model, Pennington & Hastie, 1991, 1992) and previous work that has provided support for the idea that perceptions of prevalence impact legal lie detection judgements (Domagalski et al, 2020; Helm & Growns, 2022; Kassin et al, 2005).…”

“…Participants then read case materials in a vignette involving a girl accusing her teacher of child sexual assault (these case materials were taken from existing work in this area; Helm & Growns, 2022). Participants first saw some brief information introducing the task, and then read a summary of each side’s position, and testimony from the complainant and defendant in the case in the form of responses to direct examination questions.…”

“…Perhaps as a result of these difficulties, estimates of the rates of false allegations vary widely—one review of 20 studies reported estimates ranging from 1.5% of allegations being false to 90% of allegations being false (Rumney, 2006)—and statements relating to prevalence are often made in the absence of any data (e.g., MacDonald, 2008). This lack of clarity creates a situation in which different groups can easily form different conclusions as to prevalence (e.g., Helm & Growns, 2022; Ortiz & Smith, 2022).…”