Forensic science and juror decision making: can jurors be taught to recognise bias?

Abstract

Forensic science plays a central role in the administration of judicial and legal processes, and crime scene investigations. Fingerprint, bite-mark, and DNA comparisons, as well as analyses of audio and video recordings, have proven invaluable to investigators and legal practitioners. Yet research has indicated that forensic science is not infallible, and that the strength and validity of forensic evidence is often overstated. Studies have found that a range of cognitive biases, including contextual and motivational biases, may substantially influence forensic procedure. Authors of the 2016 President’s Council of Advisors on Science and Technology (PCAST) report on forensic comparison evidence argue that issues affecting forensic science are considerable, and will likely continue to influence forensic evidence admitted into courts. Technological advances have not served to reduce incidents of error attributable to bias as outcomes of analyses still rely on human judgement. Recommendations for strategies to reduce bias in forensic labs have been identified; however, researchers have stressed that implementing these may only gradually reduce instances of questionable forensic evidence entering courtrooms. Judges have been assigned a gatekeeper role in determining the admittance of forensic evidence into court; however, research has found that they are ill-equipped to reliably do so. This leaves jurors with the responsibility to identify and critique weak or flawed forensic evidence. However, studies have shown that jurors are prone to erroneous decision making. In light of this, it is troubling that literature has paid limited attention to the impact of forensic bias on court proceedings. Jurors are often influenced by extraneous information such as demographic characteristics of a defendant and victim, and the nature of a crime. They have also been found to overestimate their comprehension of forensic evidence. Attempts to improve juror decision making have included the introduction of supplementary materials such as juror instructions and forensic reports. However, such tools have not been empirically supported. Found and Edmond (2012) proposed a forensic report format to address the limitations of traditional forensic reports for effectively conveying information to jurors. Claims about the efficacy of their proposed format have not been substantiated, and cognitive psychology literature and current juror decision making research do not support Found and Edmond’s (2012) conclusions. The pervasive use of forensic evidence in court proceedings has implications for strategies to address the effects of cognitive biases on judicial outcomes. Unfortunately, current materials have not been shown to improve jurors’ evaluations of evidence, pointing to a critical gap in literature on juror information processing and decision making. This thesis will therefore attempt to empirically evaluate Found and Edmond’s (2012) proposed report format. It will also explore research on juror decision making in the context of forensic and other evidence. Differences between current juror information processing paradigms will be investigated in order to determine whether they effectively account for the complexities of juror behaviour. Furthermore this thesis will contribute new perspectives to the field of juror research by exploring alternative approaches to improving the accuracy and reliability of juror information processing and decision making outcomes.