Juror Reactions to DNA Evidence: Errors and Expectancies

Authors: Schklar J.¹; Diamond S.S.²

Source: Law and Human Behavior, Volume 23, Number 2, April 1999 , pp. 159-184(26)

Publisher: Springer

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Abstract:

In this paper we examine evidence for two potential descriptions of juror reactions to probabilistic DNA evidence. The error-based description posits that jurors commit systematic logical or mathematical errors when they are called upon to evaluate quantitative evidence. The expectancy-based description posits that jurors use their background knowledge and beliefs in evaluating results from scientific tests. Consistent with the error-based description, participants in our study incorrectly aggregated separately presented probabilities and afforded probabilistic evidence less weight than would be expected by applying Bayesian norms. Consistent with the expectancy-based description, participants' background beliefs about the possibility of laboratory errors and intentional tampering affected the weight participants afforded a DNA match report. We discuss potential implications of these findings for the legal system and suggest directions for future research.

Language: English

Document Type: Research article

Affiliations: 1: Department of Psychology, University of Illinois at Chicago, and American Bar Foundation. Jason Schklar, Department of Psychology (MC 285), University of Illinois at Chicago, Chicago, IL 60607-7137. jschklar@uic.edu 2: Department of Psychology, University of Illinois at Chicago, and American Bar Foundation

Publication date: 1999-04-01