Visual Decision Aids: Improving Laypeople’s Understanding of Forensic Science Evidence

Abstract

Forensic science plays an important role in the criminal justice system, however research and miscarriages of justice have demonstrated that laypeople can easily misunderstand the results of forensic tests. Given the importance of these test results, interdisciplinary oversight groups have called for clearer expression of forensic tests’ corresponding error rates. Meanwhile, a large body of research in the medical domain suggests that visual decision aids can improve understanding of statistical information. Seeking to apply decision aids to the forensic domain, we present three preregistered experiments (N = 879) demonstrating that visual decision aids may indeed improve understanding of forensic science evidence. A mini meta-analysis across the three experiments comparing control conditions to visual aids demonstrated a medium effect size of g = 0.35. Therefore, decision aids represent a promising, easy-to-implement way to improve laypeople’s understanding of forensic science evidence, thereby potentially preventing associated miscarriages of justice.

Keywords: forensic science; forensic evidence; decision aids; error rates; communicating science

JEL Classification: K10, K14, K42