The impact of magnetic resonance imaging on juror perceptions of guilt

iv Introduction 1 Method 11 Results 15 Discussion 19 References 29 List of Tables 35 Appendices 39 The Impact of Forensic Evidence on Juror Perceptions of Guilt Forensic evidence includes polygraph evidence, fingerprint matching, deoxyribonucleic acid (DNA) analysis, and a variety of neuroimaging techniques [e.g., magnetic resonance imaging (MRI)]. In its courtroom application, forensic evidence is circumstantial—it requires a juror to make a decision regarding the connection between the evidence and the facts. Forensic evidence forms the basis for two types of arguments: characterand location-based arguments. Attorneys may use the evidence to suggest the defendant is lying (character-based; e.g., polygraph evidence) or use it to suggest the defendant was present at the scene of the crime (location-based; e.g., fingerprint matching, DNA analysis). Empirical research examining the effect of forensic evidence on juror perceptions of guilt often involve presenting mock jurors with a trial summary that differs in the types of evidence presented (McAllister & Bregman, 1986; McCabe, Castel, & Rhodes, 2011; Myers & Arbuthnot, 1997; Myers, Rosol, & Boelter, 2003). Participants are asked to render a verdict as if they were present at the trial. If the proportion of guilty verdicts in all conditions is similar, then it is assumed that the forensic evidence does not influence juror verdicts. Using this aforementioned methodology, this study assesses the impact of MRI on juror perceptions of guilt. Independent of empirical research, courtroom judges maintain the belief that forensic evidence may improperly [emphasis added] influence the jury. Court decisions reflect the concerns that forensic evidence may usurp the role of jurors as triers of facts (U.S. v. Scheffer, 1998), may cause juror confusion and prejudice, and may not be accepted in the relevant scientific communities (U.S. v. Alexander, 1975). Of particular concern to the 2 judicial system is the question, “How much does forensic evidence influence a juror’s decision?” Legal Precedent for Forensic Evidence United States (US) courts have different rules regarding the admissibility of forensic evidence. These rules regarding forensic evidence are changeable. Historically, US courts have deemed polygraph evidence, fingerprint matching, and DNA analysis both admissible and inadmissible at some point in time. For example, US courts traditionally accepted the results of a polygraph test as evidence. In the past few decades, however, courts have consistently abandoned the use of polygraph evidence. The US Supreme Court has determined that polygraph testing does not meet the Daubert standards of evidence admissibility (refer to Daubert v. Merrell Dow Pharmaceuticals, 1993). Specifically, the conclusions drawn from polygraph examiners are plagued with doubt, considered subjective, and neither verifiable nor falsifiable. Additionally, the polygraph test can be manipulated by various countermeasures (U.S. v. Scheffer, 1998). Fingerprint matching is more readily accepted as evidence in US courts. Recently, however, several courts have ruled that the Analysis, Comparison, Evaluation, and Verification (ACE-V) method of latent fingerprint identification is unreliable (Cooper v. Dupnik, 1992; Maryland v. Rose, 2007; U.S. v. Plaza, Acosta, & Rodriguez, 2002). The presiding judge in Maryland v. Rose noted several shortcoming of fingerprint analysis. Specifically, there is no objective criterion for determining a match, and the fingerprint analyst is not required to document the process of analysis, so there is no meaningful peer review process. Consequently, the error rate of fingerprint analysis is unknown.