A Comparison of Eyewitness and Physical Evidence on Mock-Juror Decision Making

Abstract

Two studies compared the effectiveness of eyewitness testimony and physical evidence on mock-juror decision making. Jury-eligible participants were randomly assigned to read one of eight versions of a hypothetical murder scenario and were each asked to render a verdict, to recommend a sentencing option, and to make other evaluative judgments of the defendant. In Study 1, either eyewitness testimony or physical evidence was presented, whereas in Study 2, both types of evidence were presented together. Also, in both studies, the strength of evidence varied. Log linear analysis confirmed that mock jurors’ verdicts and evaluative judgments were influenced to a greater extent by physical evidence than by eyewitness testimony. Strong evidence produced more guilty verdicts than weak evidence. However, combining strong evidence of both types was no more effective than presenting strong evidence of either type. Implications of these factors for prosecutors and defense attorneys in criminal proceedings are discussed.