Impact of Gruesome Photographic Evidence on Legal Decisions: A Meta-Analysis.

Gruesome crime scene and autopsy photographs are admissible evidence under the Federal Rules of Evidence (FRE) if their probative value substantially outweighs their prejudicial impact. Despite important methodological differences and mixed results from past studies, recommendations from the psychological literature have been made about the prejudicial impact of gruesome photographs perhaps prematurely. This meta-analysis investigates whether there is sufficient empirical evidence that presenting gruesome photographs in a trial affects legal decisions. The analysis of 23 studies and 4868 participants shows a small but statistically significant effect of gruesome photographs increasing guilty/liable verdicts or punishments, Hedge's g = 0.143, 95% CI: [0.055, 0.232]. However, this effect is significantly, Q(1) = 8.086, p = .004, and substantially moderated by an important methodological distinction: the effect is much larger when studies compare gruesome photographs with no photographs (g = 0.450) than when they are compared with neutral photographs (g = 0.077). These results suggest that gruesome photographs do increase affirmative verdicts, both through a small effect of gruesome content as well as a larger additive of having visual material. These findings help shed light on the mixed empirical results and suggest that important additional research is needed.