The Impact of the Illusory Truth Effect and Location of Testimony in Juror Deliberations

The illusory truth effect (ITE) is the tendency to believe false information as being accurate after it has been presented repeatedly over time. ITE has been shown to hold true in many different contexts; however, there have been no studies that examine the influence of ITE in jurors’ deliberation. Given the importance of weighing legally relevant facts in the decision-making process, and the potential influence of ITE, this study examined whether the repetition of key evidence in testimony matters in this context. This study also examined whether critical information would be influenced by the location of ITE. In that context, jurors may process critical information differently when introducing ITE early (i.e., primacy effect) or later (i.e., recency effect) in the vignette of a murder case. To examine this effect, 100 participants were recruited and asked to read a vignette where pertinent evidence related to a murder was strategically repeated throughout the case narrative. Participants were assigned to one of four groups: control; ITE throughout vignette; ITE at the beginning of vignette; and ITE at the end of vignette. After reading the vignette, participants were asked to complete a short questionnaire and provide a final decision about various aspects of the case. Results revealed that repetition of pertinent evidence matters. The placement of evidence also has the potential to influence jurors’ perceptions of certain case relevant details. These findings suggest that within a sensitive legal context, such as jurors weighing evidence of an accused’s culpability, ITE could alter one’s perception of the facts.

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