Introduction
This paper presents preliminary data exploring the effects of expert testimony (present/absent), timing of this testimony (before/after the defendant's testimony), and how strongly the case facts support prospective memory failure (PMF; weak/strong) in a case of vehicular heatstroke involving the death of a child by his mother. Importantly, there are disparities in the handling and outcomes of such cases in the criminal justice system (Breitfeld, 2020). Decision makers (e.g., State, triers of fact) need to understand the cognitive mechanisms involved in PMF to appropriately evaluate evidence as it pertains to the standard of proof for aggravated manslaughter. Specifically, the emotional, physiological, and cognitive processes that could lead to PMF including forgetting to do something you planned to do (e.g., dropping a child off). Thus, expert testimony on PMF is needed to educate jurors on how such memory failures could occur.


Method, Results, and Conclusion
Jury-eligible participants (N = 247) read trial transcripts, provided verdicts, and completed an anger measure. While there was no effect of case strength of PMF, findings revealed that mock-jurors exposed to expert testimony were less likely to find the defendant guilty of aggravated manslaughter (22% vs. 35% guilty). Additionally, the timing of the expert testimony affected the proposed sentence length. Mock-jurors who received the expert testimony before (vs. after) the defendant testified provided shorter sentences. Expert testimony also led to lower ratings of mock-juror anger. Finally, PROCESS Model 4 (Hayes, 2021) was used to test the following mediation model: Expert Testimony (X)  Anger (M)  Aggravated Manslaughter Verdict (Y). Anger mediated the effect of expert testimony on verdicts: anger was greatest when expert testimony was absent, contributing to a greater likelihood of guilt. Findings suggest that juror education through expert testimony could result in better decision-making in such cases by reducing juror anger.