The impact of different types of expert scientific testimony on mock jurors’ liability verdicts

Participants in two experiments acted as jurors for a personal-injury case containing different types of expert testimony. In both experiments, the defendant was more likely to obtain a verdict in his favor when his expert presented anecdotal case histories than when the expert presented experimental data. Participants’ liability judgments were correlated with their perceptions of the experts’ credibility (experiments 1 and 2) and were moderated somewhat by their need for cognition and preference for numerical information (experiment 2). The results are discussed in terms of reasoning heuristics such as the base-rate fallacy.