Expert testimony and jury decision making: An empirical analysis

This experiment examines the influence of expert psychological testimony on juror decision making in eyewitness identification cases. Experienced jurors and undergraduate mock jurors viewed versions of a videotaped trial, rated the credibility of the eyewitness and the strength of the prosecution's and defense's cases, and rendered verdicts. In the absence of expert testimony jurors were insensitive to eyewitness evidence. Expert testimony improved juror sensitivity to eyewitness evidence without making them more skeptical about the accuracy of the eyewitness identification. Few differences emerged between the experienced jurors and undergraduate mock jurors.     

Testifying on Eyewitness Reliability: Expert Advice Is Not Always Persuasive1

This study investigates the impact of different types of expert testimony regarding the unreliability of eyewitness identification. In two hypothetical court cases involving eyewitnesses, expert testimony was presented that was either sample-based (presenting the results of a research program on eyewitness identification) or person-based (presenting information about the particular eyewitness under consideration); the expert either offered causal explanations for his unreliability claim or failed to do so. Two additional control groups (with and without eye-witness identification) were not presented with any expert testimony. The results indicate that subjects who had been confronted with an expert statement made more lenient judgments about the offender but did not discount the eyewitness identification completely. Sample-based information had a moderate impact on the subjects' judgments, regardless of whether or not causal explanations were given. Person-based testimony was the most influential type of expert advice when a causal explanation was provided but the least influential one when no reasons were given. The practical (international differences in admissibility of expert testimony) and theoretical implications (processing of base-rate information) of these findings are discussed.     

How effective are the cross-examination and expert testimony safeguards? Jurors' perceptions of the suggestiveness and fairness of biased lineup procedures

Mock jurors (N = 800) viewed a videotaped trial that included information about a lineup identification procedure. Suggestiveness of the eyewitness identification procedure varied in terms of foil, instruction, and presentation biases. Expert testimony regarding the factors that influence lineup suggestiveness was also manipulated. Criteria included juror ratings of lineup suggestiveness and fairness, ratings of defendant culpability, and verdicts. Jurors were sensitive to foil bias but only minimally sensitive to instruction and presentation biases. Expert testimony enhanced juror sensitivity only to instruction bias. These results have implications for the effectiveness of cross-examination and expert testimony as safeguards against erroneous convictions resulting from mistaken identifications.     

The Psychology of Eyewitness Testimony: A Comparison of Experts and Prospective Jurors

To compare people's beliefs about eyewitness testimony with expert opinion, 79 college students and community adults filled out a questionnaire in which they reported whether they agreed or disagreed with 21 statements previously used in a survey of eyewitness experts (Kassin, Ellsworth, & Smith, 1989). The results indicated that there was a significant inter-item correlation of agreement rates but that subjects differed from the experts on 15 of these items. For courts seeking to determine the extent to which juries need assistance in their evaluations of eyewitness evidence, these findings offer a tentative list of topics worthy of either expert testimony or cautionary instructions from the judge.     

Beliefs about factors affecting the Reliability of eyewitness testimony: A Comparison of judges,jurors and the general public

We surveyed 164 members of the juror pool of the Court of Appeal and a representative sample of 1000 adult Norwegians without juror experience, about their knowledge and beliefs about eyewitness testimony, and compared their answers to a prior survey of Norwegian judges. Although the judges were somewhat more knowledgeable than jurors and the general public, all groups had limited knowledge of eyewitness testimony. Juror experience, in terms of number of times serving as juror, did not correlate with eyewitness knowledge. Consistent with this finding, the knowledge scores of the jurors were similar to the scores of the general public, tested with an abridged seven‐item version of the questionnaire. Comparisons with the results of surveys conducted in the US, indicate similar levels of knowledge among law professionals and jurors in the two countries. Increasing the knowledge of eyewitness testimony among the principal participants in the judiciary system may be an important component of the solution to eyewitness error. Copyright © 2009 John Wiley & Sons, Ltd.     

Polygraph Testimony and Juror Judgments: A Comparison of the Guilty Knowledge Test and the Control Question Test1

The present experiment investigated the impact of the Control Question Test (CQT) and the Guilty Knowledge Test (GKT) on the verdicts of mock jurors. Although studies have indicated that polygraph evidence has little influence on jurors' verdicts (Cavoukian & Heselgrave, 1980; Spanos, Myers, Dubreuil, & Pawlak, 1992–1993), no research has previously distinguished between the different types of polygraph tests and their impact on juror verdicts. In the present study, jurors were shown a videotape of a simulated rape-murder trial that contained either CQT polygraph evidence, GKT polygraph evidence, or no polygraph evidence. No differences were found among the 3 conditions for either jury verdicts or individual juror verdicts, and jurors tended to rate both forms of polygraph testimony below other forms of equally suspect evidence, such as eyewitness testimony, in its influence on their decision-making process.     

Perspectives on the role of the eyewitness expert

Extensive controversy over the appropriate application of expert knowledge regarding issues of eyewitness accuracy led to a conference and a special issue of taw and Human Behavior in 1986. Arguments were presented both in support of and against the eyewitness researcher as expert testifier. The current research explored the views of the general public (N = 50), defense attorneys (N = 14), and prosecutors (N = 10) with regard to the use of eyewitness expertise in each of four roles (court-appointed expert, consultant, researcher, expert tesdfier for the defense). Extensive differences of opinion were found across both samples and expert roles. In general, prosecutors held significantly more negative views of the usefulness of expert witnesses for the defense than did the public or defense attorneys. The role of court-appointed expert was viewed positively by all three groups and may present a useful alternative to the battles of experts that may result from current practices.     

Solving the eyewitness problem

Faulty eyewitness testimony is a major source of wrongful convictions. Four solutions are examined to safeguard against mistaken testimony having undue impact: (1) to overturn any conviction based solely on the uncorroborated testimony of a single eyewitness, (2) to require that an attorney be present at any pretrial identification procedure, (3) to allow an expert to testify during the trial about factors of perception and memory that could affect a witness's accuracy, and (4) to have the judge deliver a cautionary instruction to the jury, admonishing them to carefully scrutinize eyewitness testimony, or to educate them about such testimony. Each alternative is discussed within the context of psychological research and legal cases.     

Child‐Witness and Defendant Credibility: Child Evidence Presentation Mode and Judicial Instructions1

Child‐witness presentation mode, judicial instructions, and deliberation stage effects on juror ratings of child witness and defendant were investigated Perceptions of the impact of presentation mode on witnesses, juror task, and justice also were explored. Participants (N= 108) viewed a simulated child sexual abuse trial videotape. Overall child‐witness credibility was significantly more positive with videodeposition or court‐given child evidence than with videolink. The defendant was seen as more definitely guilty when child testimony was court given than by videodeposition or videolink. Presentation mode also significantly influenced perceived impact on child witness, defendant case, and juror task. Judicial instructions interacted with presentation mode to affect perceptions of impact on child witness and juror task. Findings are discussed in relation to previous research, and implications for future research and practice are outlined.     

Reasoning about scientific evidence: effects of juror gender and evidence quality on juror decisions in a hostile work environment case.

This study examined whether participants were sensitive to variations in the quality of an experiment discussed by an expert witness and whether they used heuristic cues when evaluating the expert evidence. In the context of a hostile work environment case, different versions of the expert testimony varied the presence of heuristic cues (i.e., whether the expert's research was generally accepted or ecologically valid) and evidence quality (i.e., the construct validity of the expert's research). Men who heard expert testimony were more likely to find that the plaintiff's workplace was hostile than were men who did not hear the expert testimony; expert testimony did not influence women's liability judgments. Heuristic cues influenced participant evaluations of the expert testimony validity, but evidence quality did not. Cross-examination did not increase juror sensitivity to evidence quality. Implications for science in the legal system are discussed.     

Effects of Eyewitness Evidence on Plea-Bargain Decisions by Prosecutors and Defense Attorneys1

The present experiment tested the relative impact of two types of eyewitness evidence (identification and non identification) on plea-bargain decisions by prosecutors and defense attorneys. A hypothetical case involving a robbery was mailed to three prosecutors and three defense attorneys in each of 47 states. The subjects were randomly assigned to receive a case in which an eyewitness claimed: (a) the defendant was the criminal (identification), (b) the defendant was not the criminal (non identification), or (c) it was not possible to tell whether the defendant was the criminal (control). Similar to findings with jurors, both prosecutors and defense attorneys underutilized the non identification information in making their plea-bargain decisions. In the case of the prosecutors, there was evidence that the underutilization of eyewitness non identification was at least partially mediated by the prosecutors' predictions of juror reaction to the evidence.     

Rape myth acceptance: A case for providing educational expert testimony in rape jury trials

The prevalence and content of rape myth acceptance indicate a need for educational expert testimony in rape jury trials. It is proposed that expert testimony regarding common misconceptions about rape and rape victim behavior, conceptualized in terms of a social framework, would help to compensate for societal bias against the complainant in a rape trial. Rape trauma syndrome, eyewitness identification, and general educational testimony concerning rape are discussed. Evidence is presented that suggests inclusion of such testimony serves the purpose of expert testimony according to the Federal Rules of Evidence.     

Sensitizing Potential Jurors to Variations in Eyewitness Evidence Quality Using Counterfactual Thinking

Jurors often have difficulty evaluating eyewitness testimony. Counterfactual thinking is a type of mental simulation that informs causal inference. Encouraging jurors to think counterfactually about eyewitness factors may sensitize them to these factors' causal influence on eyewitness identification and testimony accuracy, improving their overall judgments (such as verdicts). One hundred twenty‐one undergraduate participants were randomly assigned to read a scenario containing either high‐quality or low‐quality eyewitness evidence and to evaluate eyewitness factors adopting either their default or a counterfactual mindset via a question‐order manipulation. Logistic regressions and analyses of variance revealed that a counterfactual mindset lowered perceptions of eyewitness accuracy and guilty verdicts (compared with the default mindset) when the evidence was poor; a counterfactual mindset, however, did not increase perceptions of accuracy and guilty verdicts when evidence was strong. We discuss possible mechanisms underlying these effects and identify several potential avenues for future research.Copyright © 2016 John Wiley & Sons, Ltd.     

Judge's Instruction on Eyewitness Testimony: Evaluation and Revision1

Studies of the reliability of eyewitness identification show that such testimony may frequently be inaccurate; because of this inherent unreliability, the law has established certain safeguards to the use of eyewitness evidence. One safeguard has been the development of an instruction that a judge may use to focus jurors' attention on the eyewitness issue. The effectiveness of this instruction has never been assessed, although other studies confirm that jurors frequently misunderstand or incorrectly use instructions they get from the judge. The purpose of these studies was to evaluate comprehension of this instruction in the context of a videotaped trial and to develop a simplified instruction that would be easier for jurors to understand. Compared to jurors who heard the existing instruction, those with the revised version were more knowledgeable of the factors to consider when listening to eyewitness testimony and were less likely to convict the defendant. A sample of superior court judges in the U.S. thought the simplified instruction was more effective than the existing version at conveying the intended legal concepts to the jury, but also rated it as more strongly biased toward the defense.     

Expert psychological testimony on eyewitness reliability before and after Daubert: the state of the law and the science

This article examines the legal and scientific issues inherent in the use of expert psychological testimony on the factors that affect eyewitness reliability. First, the history of the use of such expert testimony is traced. Next, we look at the criteria that state and federal courts have used in determining whether to admit such testimony, as well as the grounds upon which the testimony has been excluded. We then examine the Daubert decision and discuss its implications for the use of expert eyewitness testimony. We conclude by reviewing eyewitness research and research on jury decision-making that is likely to assume new importance in the post-Daubert era.