Does Trial Presentation Medium Matter in Jury Simulation Research? Evaluating the Effectiveness of Eyewitness Expert Testimony

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1 APPLIED COGNITIVE PSYCHOLOGY Appl. Cognit. Psychol. 24: (2010) Published online 15 May 2009 in Wiley InterScience ( Does Trial Presentation Medium Matter in Jury Simulation Research? Evaluating the Effectiveness of Eyewitness Expert Testimony KATHY PEZDEK*, ELIZABETH AVILA-MORA and KATHRYN SPERRY Claremont Graduate University, USA SUMMARY This study assesses whether mock jurors perceptions of eyewitness expert testimony vary based on the level of ecological validity video or transcript trial presentation medium. In Experiment 1, 496 jury-eligible mock jurors were presented a simulated trial. Each served in one condition in a 3 (no expert or eyewitness expert either with or without prosecution rebuttal witness) 2 (trial presentation medium: Video or transcript) design. Participants were generally less certain of the defendant s guilt after the eyewitness expert testimony, and affective and cognitive ratings of the expert testimony were higher in the transcript than video condition. However, there were no significant interactions of modality with expert conditions, thus reducing concerns that jury simulation research must be conducted with live or video trials to be externally valid. Findings were replicated in Experiment 2 using the testimony of a different eyewitness expert rated to have a more dynamic communication style. Copyright # 2009 John Wiley & Sons, Ltd. The medium is the message. Marshall McLuhan (1964, p. 7) The best current evidence is that media are mere vehicles that deliver instruction but do not influence student achievement any more than the truck that delivers our groceries causes changes in our nutrition. Richard Clark (1983, p. 445) Eyewitness evidence is critical for solving crimes, and it is often the sole source of evidence for determining who the perpetrator is. However, it has been estimated that each year in the United States, approximately 4500 wrongful convictions occur based on mistaken eyewitness identifications (Penrod & Cutler, 1999). Studies consistently report that eyewitness misidentifications are the leading cause of erroneous convictions (Huff, *Correspondence to: Kathy Pezdek, Department of Psychology, Claremont Graduate University Claremont, CA , USA. Kathy.Pezdek@cgu.edu Copyright # 2009 John Wiley & Sons, Ltd.

2 674 K. Pezdek et al. 1987; Huff, Rattner, & Sagarin, 1996), and eyewitness evidence has been the major source of evidence used to convict innocent people who were later exonerated based on forensic DNA (Scheck, Neufeld, & Dwyer, 2000; Wells, Small, Penrod, Malpass, Fulero, & Brimacombe, 1998). Yet ironically, jurors tend to find eyewitness testimony especially compelling (Lindsay, Wells, & O Connor, 1989; O Toole, Cox, Easterly, & Schmechel, 2005). During a trial, using an expert witness on eyewitness identification and memory is one way to safeguard against jurors over-reliance on eyewitness testimony. But how effective is an eyewitness expert witness in sensitizing jurors to eyewitness evidence? This study addresses this question and specifically tests whether the results of research evaluating the effectiveness of eyewitness expert testimony differ as a function of the trial presentation medium trial transcript or trial video. In the early studies assessing the impact of eyewitness expert testimony (see for example Blonstein & Geiselman, 1990; Loftus, 1980; Maass, Brigham, & West, 1985), mock jurors read a brief (only several pages) description of a criminal case, including a summary of the prosecution s case and the defence case. They then either read a brief summary of the testimony of an eyewitness expert or not. It was generally reported that providing a summary of the eyewitness expert testimony tended to decrease guilty verdicts. In other studies there were richer assessments of the effectiveness of eyewitness expert testimony. This work has been thoroughly reviewed by Leippe (1995) and discussed by Pezdek (2007). For example, Hosch, Beck, and McIntyre (1980) presented a live or video-taped staged trial to jury-eligible community residents or college students. The trial concerned a fictitious burglary that involved the testimony of an eyewitness that was either followed by eyewitness expert testimony or not. Mock juries deliberated after the trial, and all acquitted the defendant. However, juries that heard the eyewitness expert spent more time deliberating, and rated the eyewitness testimony as less reliable and less important. Cutler, Dexter, and Penrod (1989) and Cutler, Penrod, and Dexter (1989) presented over 500 college students and 100 experienced jurors with a video of an armed robbery trial that included the testimony of an eyewitness to the robbery. The testimony of an eyewitness expert was either included in the video or not. Although there was not a significant main effect of expert condition either on verdicts or ratings of eyewitness accuracy, the eyewitness expert testimony did increase jurors sensitivity to the reliability of eyewitness evidence. That is, the eyewitness expert testimony was more likely to reduce the weight given by jurors to eyewitness evidence when they were presented weak rather than strong eyewitness evidence. Similar results were reported by Devenport, Stinson, Cutler, and Kravitz (2002) using a video of a simulated trial that either included eyewitness expert testimony or not. More recently, Devenport and Cutler (2004) assessed whether the inclusion of a prosecution rebuttal witness affected ratings of mock jurors who watched a video of a simulated trial. Although overall the expert witness conditions did not affect culpability ratings or verdicts, participants who heard a prosecution rebuttal witness in addition to the eyewitness expert perceived the testimony of the eyewitness expert to be significantly less credible, less influential and less useful. Although the research evaluating the effectiveness of eyewitness expert testimony is promising, it is not conclusive; the findings are mixed. One experimental factor that likely affects the effectiveness of mock trial testimony in general, and eyewitness expert testimony more specifically, is the ecological validity of the experimental context. One of the ways this has been varied across mock trial studies is in terms of trial presentation medium, that is, whether the trial and the expert testimony were presented as a trial

3 Eyewitness expert testimony 675 transcript or trial video. The ecological validity would be lower in the transcript than the video presentation condition because relative to the trial video, the trial transcript does not avail the full audio/visual presentation of the expert. The question of interest in this study is whether this difference in ecological validity of trial presentation medium affects the external validity of the findings regarding the effectiveness of eyewitness expert testimony. The major purpose of this study is to assess the effects of varying levels of the trial presentation medium on jurors judgments of culpability and their perceptions of expert testimony and eyewitness evidence. This study was not designed to assess if showing a persuasive message in a video versus a written format makes a difference, but rather tests whether research findings regarding the effectiveness of eyewitness expert testimony, and likely other matters as well, differ as a function of the trial presentation medium. Concerns about the ecological validity of jury simulation research was first systematically raised in a special issue of Law and Human Behaviour published in 1979 (Diamond, 1979) and were reiterated almost 20 years later by Diamond (1997) and more recently by Penrod and Bornstein, (2006). Almost a decade ago, Bornstein (1999) reviewed the research on this topic and reported that of the 11 published studies in which the trial presentation medium had been varied, in all but three of these studies there was no main effect of medium. Further, only six of these studies specifically compared a trial video with a trial transcript, and none of these six studies assessed the impact of expert witness testimony on mock jurors. The salience of the concern about the effect of trial presentation medium on mock jury research outcomes is highlighted by the fact that the Social Science Citation Index for the Bornstein (1999) study is high, 1 currently 111. It is also interesting to note that presenting research participants with written transcripts has gained ecological validity in that courts can now require parties to submit direct testimony in writing (Longan, 1995). Written testimony is often employed to shorten trials (Phonetel v. AT & T, 1989, upholding the use of written testimony), although more commonly in civil rather than criminal cases. Also, written expert testimony is also sometimes preferred because it improves mock jurors comprehension of complex expert testimony (ForsterLee, Horowitz, Athaide-Voctor, & Brown, 2000). In Experiment 1, mock jurors were presented a simulated trial either as a video or a written transcript. The trial video was that used in the previous studies by Devenport and Cutler (2004) and Devenport et al. (2002), and most of the questions that were included in these studies were included in the present study as well. The testimony of the eyewitness expert was varied to produce three conditions: No expert, eyewitness expert, and eyewitness expert plus prosecution rebuttal witness. These three conditions were included to provide a more extensive test of the effect of trial presentation medium on perceptions of eyewitness expert testimony. The transcripts were verbatim transcripts of each trial video. We specifically tested whether the impact of the eyewitness expert testimony varied across these three expert conditions as a function of whether the mock jurors were presented the trial video or the trial transcript. In this study, we are most interested in determining if there are statistical interactions with presentation medium; it is the interactions of conditions with medium that assess the extent to which the pattern of results across conditions is consistent with a trial video and a trail transcript. Two predictions can be made regarding the effect of eyewitness expert testimony on mock jurors as a function of trial presentation modality. First, if verisimilitude trumps all other variables, then it would be predicted that the eyewitness expert testimony would have 1 Many but not all of the citations to the Bornstein (1999) study concern trial presentation medium.

4 676 K. Pezdek et al. more impact if viewed in a trial video than if read in a transcript of that trial. Accordingly, the impact of the eyewitness expert would be affected by the content of his or her testimony as well as his or her communication style, and only in the video trial condition are the mock jurors exposed to both of these dimensions of the expert testimony. Alternatively, if regardless of verisimilitude, it is the content of the eyewitness expert testimony that is relatively more important, then there should be less difference between presenting mock jurors with a video trial or a transcript of that same trial as the content is the same in both of these trial conditions. If this resulted, it would suggest that mock jury research could be conducted with trial transcripts rather than live or video trials without sacrificing external validity. Although there are some studies that have presented mock jurors with trial transcripts and other studies that have presented mock jurors with trial videos, few studies have compared the relative impact of trial presentation modality on mock jurors using two otherwise identical versions of the same simulated trial, and none of these has assessed the impact of expert witness testimony on mock jurors. EXPERIMENT 1 Method Participants and design The participants were 496 jury-eligible students, all from one of two state universities in Southern California. In California, the eligibility requirements for serving on a jury are the following: (a) must be a citizen of the United States, (b) must be at least 18 years of age, (c) must be able to understand the English language, (d) must be a resident of California and (e) must not have been convicted of a felony. We included in this experiment, only the 496 respondents who indicated that they satisfied these five requirements. The sample included 370 females, 113 males and 13 gender unspecified (age: M ¼ 23, SD ¼ 6.65). The race/ethnicity distribution of the sample was 43% Caucasian (non-latino), 36% Latino, 8% African-American, 8% Asian, 5% other. Although using community participants is more ecologically valid than using college participants, this was not practical given the very large number of participants required. Also, in Bornstein s (1999) meta-analysis, 21 of the 26 jury decision-making studies sampling both undergraduates and community representative mock jurors found no main effect of participant sample; and, of the five studies that did show an effect, the differences were inconsistent. Respondents volunteered to participate during a regular class session with their classmates. Classes were randomly assigned to one of the six conditions in this experiment, defined by a 3 (expert condition: No expert, eyewitness expert or eyewitness expert testimony plus prosecution rebuttal witness) 2 (trial presentation medium: Video or transcript) independent groups design. At least two different classes participated in each condition, and there were at least 59 participants in each condition (see top of Table 1 for the N per condition). The sample size in each of the six conditions exceeded what was required by power analyses conducted using methods suggested by Faul, Erdfelder, Lang, and Buchner, (2007). To detect meaningful differences, the power analysis was conducted assuming a small effect size (h 2 ¼.03, effect size ¼.17), an a level of.05, and a desired power level of.90. Accordingly, the required target N was 282 (47 per cell). The size of each sample in both experiments of this study exceeded this lower limit.

5 Eyewitness expert testimony 677 Table 1. Post-trial questionnaire used in this study (anchor for each question specified) with the mean (and standard deviation) indicated for each condition for Experiments 1 and 2 Experiment 1 Experiment 2 No expert Expert no. 1 Expert no. 1 with rebuttal Expert no. 2 Questions Transcript N ¼ 59 Video N ¼ 106 Transcript N ¼ 74 Video N ¼ 96 Transcript N ¼ 101 Video N ¼ 60 Video N ¼ At the end of the trial, how certain were you of the defendant s guilt or innocence? (l ¼ certainly innocent, 9 ¼ certainly guilty) 2. How convincing was the testimony of the alibi witness in this case, Diane Reyes? (1 ¼ not at all, 9 ¼ highly) 3. How convincing was the identification by the eyewitness in this case, Barbara Dunn? (1 ¼ not at all, 9 ¼ highly) 4. Was the line-up procedure suggestive in this case? (l ¼ not at all suggestive, 9 ¼ highly suggestive) 5. What was your impression of the defendant in this case, Mr Peter Brown? (l ¼ not at all like me, 9 ¼ very similar to me) 6. How easy or difficult was it for you to identify with the defendant s situation in this case? (l ¼ very difficult to identify with, 9 ¼ very easy to identify with) 7. Prior to the testimony of the eyewitness expert witness, Dr Foster, how certain were you of the defendant s guilt or innocence? (l ¼ certainly innocent, 9 ¼ certainly guilty) 4.68 (1.78) 5.31 (1.86) 4.80 (1.89) 4.70 (2.03) 4.96 (1.93) 5.18 (1.47) 5.08 (2.04) 4.66 (1.69) 4.35 (1.95) 4.16 (1.87) 4.70 (1.85) 4.30 (1.85) 4.60 (1.80) 3.98 (1.87) 5.15 (1.82) 5.50 (2.20) 5.16 (2.05) 4.83 (2.05) 5.08 (2.13) 5.53 (1.97) 5.43 (2.18) 5.93 (1.85) 5.38 (2.12) 6.43 (1.98) 6.53 (2.07) 6.19 (2.16) 5.85 (1.96) 5.96 (2.13) 3.66 (2.03) 3.50 (2.05) 3.23 (1.85) 3.93 (1.72) 3.63 (1.84) 3.72 (1.80) 3.53 (2.08) 4.61 (1.68) 4.29 (2.23) 4.73 (2.47) 4.01 (2.17) 4.75 (2.09) 3.75 (2.08) 4.57 (2.20) NA NA 5.18 (1.61) 5.13 (1.87) 5.25 (1.70) 5.63 (1.38) 5.33 (2.06) (Continues)

6 678 K. Pezdek et al. Table 1. (Continued) Questions 8. What impact did the testimony of the eyewitness expert witness have on your decision regarding the defendant s guilt or innocence? (l ¼ minimal impact, 9 ¼ significant impact) 9. How understandable was the testimony of the eyewitness expert witness? (l ¼ not at all, 9 ¼ highly) 10. How useful was the testimony of the eyewitness expert witness? (1 ¼ not at all, 9 ¼ highly) 11. How informative was the testimony of the eyewitness expert witness? (l ¼ not at all, 9 ¼ highly) 12. How influential was the testimony of the eyewitness expert witness? (l ¼ not at all, 9 ¼ highly) 13. How confusing was the testimony of the eyewitness expert witness? (l ¼ highly, 9 ¼ not at all) 14. How did the testimony of the eyewitness expert witness impact your sense of the credibility of Psychology as a Science? (l ¼ greatly reduced, 9 ¼ greatly enhanced) 15. How did the testimony of the eyewitness expert witness impact your sense of the credibility of the eyewitness identifications in general? (l ¼ greatly reduced, 9 ¼ greatly enhanced) Experiment 1 Experiment 2 No expert Expert no. 1 Expert no. 1 with rebuttal Expert no. 2 Transcript N ¼ 59 Video N ¼ 106 Transcript N ¼ 74 Video N ¼ 96 Transcript N ¼ 101 Video N ¼ 60 Video N ¼ 51 NA NA 5.92 (1.98) 5.40 (2.21) 6.03 (1.84) 5.25 (1.56) 5.47 (1.74) NA NA 6.95 (2.03) 6.79 (1.92) 7.16 (1.64) 6.02 (1.81) 6.71 (1.93) NA NA 6.64 (1.93) 6.18 (1.95) 7.04 (1.50) 5.78 (1.49) 5.69 (2.16) NA NA 7.38 (1.76) 6.94 (1.61) 7.26 (1.43) 6.57 (1.51) 6.82 (1.91) NA NA 6.14 (2.20) 5.74 (2.09) 6.53 (1.49) 5.73 (1.56) 5.65 (2.12) NA NA 7.01 (2.18) 6.72 (2.12) 6.73 (2.12) 6.12 (2.02) 6.33 (2.49) NA NA 6.31 (1.30) 6.10 (1.34) 6.42 (1.24) 5.70 (1.33) 5.84 (1.61) NA NA 5.41 (1.88) 5.16 (1.64) 5.49 (1.74) 5.08 (1.29) 5.39 (1.78)

7 Eyewitness expert testimony 679 Procedure and materials Participants were instructed to assume the role of a juror and attend to the case as if you were actually serving as a juror. Like a real juror, you should pay careful attention as you will later have to deliver a verdict concerning the guilt or innocence of the defendant. The videos ranged in length from 32 minutes (the no expert condition) to 60 minutes (eyewitness expert with rebuttal witness condition). Within each of the three expert conditions, participants in the video and transcript conditions were presented the trial for the same amount of time, that is, the duration of the video. All participants completed reading the transcript in this period of time. There were no restrictions regarding whether participants could re-read portions of the transcript. Trial video. The trial video was that used in the previous studies by Devenport and Cutler (2004) and Devenport et al. (2002) (see this latter reference for details of the trial). The trial involved an armed robbery that resulted in a murder. The trial video included opening statements by the prosecution and the defence followed by testimony of an eyewitness, the police officer in charge of the identification procedure, and an alibi witness who testified for the defence. The trial ended with closing statements by both attorneys and jury instructions presented by the Judge. The eyewitness evidence presented in this case was dubious because of the eyewitness s opportunity to see the perpetrator and the line-up procedures used by the police. The video was edited such that when the eyewitness expert testified, his testimony was inserted at the beginning of the defence case, right after the police officer. In the condition specified as eyewitness expert with prosecution rebuttal witness, the testimony of a rebuttal witness was added after the alibi witness, during the prosecution s redirect. In the no expert condition, participants saw or read all other aspects of the trial except there was no eyewitness expert testimony on rebuttal witness. Trial transcript. Each of the three versions of the trial, defined by the three expert conditions, was transcribed word-for-word to produce the three trial transcripts used in the transcript conditions. The formatting of the trial transcripts followed that used for transcriptions of real trials including a cover page with the case details indicated. Eyewitness expert testimony. The eyewitness expert was a Ph.D. psychologist who is a faculty member and occasionally testifies in this capacity in court cases. The direct testimony of this eyewitness expert included a description of the encoding, storage and retrieval stages of memory and discussed various factors that influence eyewitness accuracy (e.g. viewing time, weapon focus, eyewitness confidence). The eyewitness expert also talked about the potential role of systems variables such as line-up construction and line-up instructions. The duration of the expert testimony in the video condition was 21 minutes, including direct testimony and cross-examination. Although the duration of the testimony of the eyewitness expert represented a significant proportion of the whole trial, this is consistent with the treatment in previous relevant studies by Devenport and Cutler (2004) and Devenport et al. (2002). In the condition specified as eyewitness expert with prosecution rebuttal witness, the rebuttal witness was also a Ph.D. psychologist. He criticized the research presented by the eyewitness expert for its reliance on crime simulations rather than actual crimes, for using college students as participants, and for the lack of real-world implications of the decisions made by typical research participants. The rebuttal witness also opined that the line-up procedures used in this case were not unduly suggestive. The duration of his testimony in the video condition was 7.6 minutes including direct testimony and cross-examination.

8 680 K. Pezdek et al. Post-trial questionnaire. Immediately after reading or watching the trial, each participant completed the post-trial questionnaire. Prior to conducting the post-trial questionnaire, the trial transcripts were collected; thus the transcripts were not available to participants while they completed their responses. The post-trial questionnaire included the 15 questions presented in Table 1 with a 1 9 rating response for each. The anchors for each question are provided in Table 1. These questions probed jurors judgments regarding trial testimony and defendant culpability (questions 1 7), 2 affective and cognitive perceptions of the eyewitness expert (questions 8 13), and two general credibility questions (questions 14 and 15). Participants in the no expert condition only received the first six questions; questions 7 15 specifically asked about the testimony of the eyewitness expert and these individuals did not read or hear this testimony. The questions regarding the trial were followed by nine demographic questions including a question regarding the jury eligibility of each participant. Results and discussion Analyses were first conducted to assess if there were differences across conditions in age or gender. None of these affects approached significance, thus minimizing concern that differences among conditions resulted from differences in the demographics of the participants. Jurors judgments To assess the effects of conditions on juror judgments, first, separate 3 (expert testimony condition) 2 (modality) Analyses of Variance (ANOVAs) were conducted on responses to each of the first six questions (see results in Table 1). It is important to note that there were no significant main effects or interactions in the analyses of the responses to questions about the eyewitness (question 3), the defendant (question 5) or the alibi witness (question 2). It is possible that any differences in results obtained between the video and the transcript conditions could simply result from the opportunity to see the appearance of the witnesses and the defendant in the video but not the transcript condition. In other words, does the defendant look like most people s stereotype of a bad guy or not? Does the eyewitness look like most people s stereotype of a good citizen or not? The absence of significant effects on these three questions suggests that this interpretation is not likely to account for any effects of modality in this experiment. In the analysis of question 6 about the defendant s situation, there was a significant main effect of modality; the defendant s situation was rated as easier to identify with in the transcript (M ¼ 4.71, SD ¼ 2.12) than the video (M ¼ 4.06, SD ¼ 2.19) condition, F(1, 490) ¼ 11.63, p <.01, h 2 ¼.02. Perhaps being convicted of a crime seems more real, and thus less easy to identify with when participants actually see the situation than just read about it. The major question concerns whether the conditions in this experiment affected jurors responses regarding the defendant s guilt. The 3 2 ANOVA conducted on responses to question 1 ( At the end of the trial, how certain were you of the defendant s guilt or innocence? ) yielded no significant effects. To examine further, jurors judgments of guilt, a 2 (expert testimony condition) 2 (modality) ANOVA was conducted on responses to question 7 ( Prior to the testimony of the eyewitness expert witness, Dr Foster, how certain 2 It is true that a dichotomous measure of culpability is more ecological valid, however it is less sensitive to change than a 1 9 rating scale. We decided to use a 1 9 rating scale to assess culpability in this study to reduce the risk of Type II error.

9 Eyewitness expert testimony 681 were you of the defendant s guilt or innocence? ). Participants in the no expert condition were not presented this question. Neither the main effects nor the interaction approached significance in this analysis either. The next analysis was conducted to assess jurors judgments of guilt between the two conditions that included the eyewitness expert testimony. 3 In this analysis, we compared the mean ratings for questions 1 and 7 for each participant to assess whether their judgments of guilt changed from the point in time just before the eyewitness expert testified to the end of the trial, and if the magnitude of this change was consistent in the video and transcript condition. A 2 (question 1 versus question 7) 2 (expert testimony condition) 2 (modality) ANOVA was conducted on respondents ratings. Overall, participants were less certain of the defendant s guilt after the testimony of the eyewitness expert (question 7: M ¼ 4.89, SD ¼ 1.88) than before (question 1: M ¼ 5.27, SD ¼ 1.68), F(1, 326) ¼ 14.09, p <.001, h 2 ¼.04. However, no other main effects or interactions were significant. Thus, overall the testimony of the eyewitness expert significantly reduced respondents certainty of the defendant s guilt (which is a good thing, given that the eyewitness testimony in this trial was dubious), but the degree to which this occurred did not vary as a function of the expert condition or trial presentation modality. Further, we tested the correlation between (a) the difference in each respondent s response to questions 1 and 7 and (b) their response to question 8 ( What impact did the testimony of the eyewitness expert witness have on your decision regarding the defendant s guilt or innocence? ). This correlation was modest (r ¼.14) but significant ( p <.01), suggesting that jurors who reported larger changes in their certainty of the defendant s guilt from just prior to the eyewitness expert testimony to the end of the trial were slightly more likely to report a greater impact of the eyewitness expert s testimony. These analyses should be considered with caution, however, because it is unclear how accurately individuals can introspect about their past judgments at different points in time (cf. Nisbett & Wilson, 1977). However, in many research contexts, analyses of difference scores within individuals reveal findings that are not apparent when analysing mean pre-test scores or mean post-test scores alone. In the present study, analysing jurors judgments at two points in time allowed for this comparison, and the fact that findings with difference scores were significant suggests that subjects can differentially assess their past judgments at two different points in time. Nonetheless, the accuracy of such assessments cannot be verified. Question 4 ( Was the line-up procedure suggestive in this case? ) was included to assess the extent to which the expert condition affected jurors perceptions regarding the fairness of the lineup that was described in the investigating officer s testimony (the lineup described was suggestive). A 3 (expert condition) 2 (modality) ANOVA was performed on responses to question 4. The only significant effect was the main effect of expert condition, F(2, 488) ¼ 6.50, p <.01, h 2 ¼.03. Post hoc analyses confirmed that respondents rated the line-up procedure as more suggestive when the expert testified (M ¼ 6.49, SD ¼ 2.03) then there was no expert testimony (M ¼ 5.58, SD ¼ 2.04). Ratings in the expert with rebuttal testimony condition (M ¼ 6.06, SD ¼ 2.09) did not differ from the other two conditions. Thus, presenting the eyewitness expert testimony effectively influenced jurors perceptions regarding the fairness of the lineup, and this effect was consistent in the video and transcript conditions. 3 Note that participants in the no expert condition are not included in this analysis because clearly they could not have been questioned about the testimony of the eyewitness expert witness.

10 682 K. Pezdek et al. Question 15 ( How did the testimony of the eyewitness expert witness impact your sense of the credibility of eyewitness identification in general? ) assessed whether the eyewitness expert testimony affected general scepticism regarding the credibility of eyewitness identifications or whether the influence of the testimony was more case-specific. In the 2 (expert condition) 2 (modality) ANOVA on the mean responses to question 15, neither the main effects nor the interaction were significant. Also, across all four conditions in which this question was posed, the mean response was M ¼ 5.30 (SD ¼ 1.67), which is slightly above the middle of the 1 9 credibility scale. These results suggest that the eyewitness expert testimony did not affect respondents scepticism regarding the credibility of eyewitness evidence in general. Perceptions of the eyewitness expert testimony Several analyses were conducted on questions 8 13 pertaining to the participants perceptions of the eyewitness expert testimony. The mean response for each of these questions is presented in Table 1. These questions were categorized as assessing cognitive dimensions (question 9: Understandable ; question 11: Informative ; and question 13: Confusing ; Cronbach s a ¼.70) or global/affective dimensions (question 8: Impact ; question 10: Useful ; and question 12: Influential ; Cronbach s a ¼.83) of the eyewitness expert testimony. We analysed these responses in categories to minimize the extent to which we were capitalizing on chance when analysing the results of each question separately. Within each of these two categories, the responses to the relevant questions were averaged and a 2 (expert testimony condition) 2 (modality) ANOVA was conducted on these means. For the cognitive questions, there was a significant main effect of modality, F(1, 325) ¼ 11.35, p <.001, h 2 ¼.03. Participants found the testimony of the eyewitness expert to be more understandable, informative and less confusing in the transcript (M ¼ 7.08, SD ¼ 1.48) than the video (M ¼ 6.60, SD ¼ 1.45) condition. There was also a significant main effect of expert condition, F(1, 325) ¼ 4.18, p <.05, h 2 ¼.01; the mean response was higher in the expert after eyewitness condition (M ¼ 6.96, SD ¼ 1.54) than in the expert with rebuttal testimony condition (M ¼ 6.75, SD ¼ 1.43). The interaction was not significant. In the 2 (expert condition) 2 (modality) ANOVA conducted on the global/affective questions, only the effect of modality was significant, F(1, 327) ¼ 15.67, p <.001, h 2 ¼.05. Consistent with the results with the cognitive measures reported above, participants found the testimony of the eyewitness expert to have greater impact and be more useful and influential in the transcript (M ¼ 6.41, SD ¼ 1.53) than the video (M ¼ 5.70, SD ¼ 1.63) condition. This is consistent with the results of question 14, ( How did the testimony of the eyewitness expert witness impact your sense of the credibility of Psychology as a Science? ). Respondents were more likely to indicate that the eyewitness expert testimony enhanced the credibility of Psychology as a Science if they had read the trial transcript (M ¼ 6.37, SD ¼ 1.27) than watched the trial video (M ¼ 5.90, SD ¼ 1.35), F(1, 326) ¼ 10.03, p <.01, h 2 ¼.03. No other results involving question 14 were significant. Conclusions In this experiment, we were most interested in determining if there are statistical interactions with modality; the interactions assess the extent to which the pattern of results is consistent in the trial video versus transcript conditions. The major finding in Experiment 1 was that few main effects of modality and no interactions involving modality resulted. The

11 Eyewitness expert testimony 683 pattern of results was consistent across the trial video and transcript conditions. The conclusions from Experiment 1 may be restricted to the testimony of the specific eyewitness expert used in that trial. Simply put, it is possible that the communication style of this eyewitness expert may not have enhanced the effectiveness of his testimony above and beyond what was available to those who read the transcript. After all, the presentation style of this eyewitness expert was serious and not very animated. It is important to note, however, that this simulated trial with the same testimony of this eyewitness expert was used in previous studies where it was effective in elevating participants sensitivity to eyewitness evidence (Devenport & Cutler, 2004; Devenport et al., 2002). Each of these previous studies was conducted using only one simulated trial, and it was the same one used in Experiment 1. Nonetheless, Experiment 2 was conducted to test the generalizability of the results of Experiment 1. In Experiment 2 the testimony of a different eyewitness expert was recorded and edited into the trial video from the eyewitness expert (no rebuttal witness) condition in Experiment 1. The eyewitness expert used in Experiment 2 was also a Ph.D. psychologist who is a faculty member and frequently testifies in this capacity in court cases. This eyewitness expert was selected because the testimony of this expert was considered to reflect a more dynamic communication style than that used in Experiment 1, and this was verified in a pilot study, the results of which are reported below. The eyewitness expert in Experiment 2 presented the same verbatim testimony presented by the expert in Experiment 1. This was done specifically to hold content constant while varying communication style. Participants responses to this new video were then compared to responses of participants in Experiment 1 who read the transcript of the trial in the eyewitness expert condition with no rebuttal witness. Experiment 2 thus includes one condition from Experiment 1 as the control condition. This comparison tests if the testimony of an eyewitness expert with a more dynamic communication style yields differences between the trial video versus transcript conditions, differences that did not result in Experiment 1 when the trial video included a less dynamic expert testimony. EXPERIMENT 2 Method Participants and design Experiment 2 consists of two conditions a new experimental condition and a control condition from Experiment 1. There were 51 participants in the new experimental condition in Experiment 2. These were 51 jury-eligible students from two psychology classes at one of the state universities used in Experiment 1. This sample included 33 females,12 males, and 6 gender unspecified (age: M ¼ 26, SD ¼ 8.08). The race/ethnicity distribution of the sample was 31% Caucasian (non-latino), 37% Latino, 16% African- American, 10% Asian, and 6% other. The performance of participants in this condition was compared to that of the 59 participants from Experiment 1 who read the transcript of the trial in the eyewitness expert condition with no rebuttal witness. All respondents volunteered to participate during a regular class session with their classmates. Procedure and materials All participants in the new experimental condition in Experiment 2 viewed the same trial video. This trial video was the same video presented in Experiment 1 in the eyewitness

12 684 K. Pezdek et al. expert (no rebuttal witness) condition, with the exception that a different eyewitness expert testified in the video condition in Experiment 2. The eyewitness expert used in the video condition in Experiment 2 was a female Ph.D. psychologist, who is a faculty member and frequently testifies in this capacity in court cases. The testimony of this expert was selected because it was considered to reflect a more dynamic communication style than that used in Experiment 1. However, to hold content constant while varying communication style, the expert in the video condition in Experiment 2 presented the same verbatim testimony as was presented by the expert in Experiment 1. The testimony of the new eyewitness expert was edited into the video from Experiment 1 by a professional video editor. Participants in the pilot study indicated no significant difference in the quality of these two videos. Participants in Experiment 2 received the same instructions and post-trial questionnaire that was used in Experiment 1. Pilot test comparing the eyewitness expert testimony in Experiments 1 and 2 Two different psychology classes at one of the state universities used in Experiment 1 were each randomly assigned to view the video of either the eyewitness expert testimony from Experiment 1 (N ¼ 54) or that from Experiment 2 (N ¼ 92). Immediately after viewing the video of the expert testimony, participants rated the presentation using a 1 (not at all) 7 (highly) scale for each of eight dimensions associated with a more dynamic communication style: Engaging, assertive, credible, persuasive, confident, attractive, competent and convincing. A factor analysis of the ratings identified two components, and seven of the eight dimensions loaded more heavily on one component than the other. Only the dimension, attractive, did not load more heavily on this component. This dimension was then dropped from the analyses. The association among the other seven dimensions was strong, Chronbach s a ¼.84. Pooling across these seven dimensions, the mean rating was significantly higher for the eyewitness expert in Experiment 2 (M ¼ 5.47, SD ¼.92) than in Experiment 1 (M ¼ 4.84, SD ¼ 1.03), t(144) ¼ 3.85, p <.01, d ¼ These pilot data verified that the communication style of the eyewitness expert testimony in Experiment 2 was more dynamic than that used in Experiment 1. Experiment 2 thus presents a stronger test of whether differences are likely to result from mock jury research conducted with a trial video versus transcript. Results and discussion Analyses were first conducted to assess if there were differences across conditions in age or gender. As in Experiment 2, none of these affects approached significance, thus minimizing concern that differences among conditions resulted from differences in the demographics of the participants. Jurors judgments Experiment 2 tests the generalizability of the results of Experiment 1. The primary purpose of Experiment 2 was to see if the minimal effects of modality in Experiment 1 replicated with a different video that included an eyewitness expert with a more dynamic communication style. The critical comparisons are between the video condition in 4 The mean ratings for these two eyewitness experts also significantly differed when ratings were pooled across all eight dimensions, t(144) ¼ 3.22, p <.01.

13 Eyewitness expert testimony 685 Experiment 2 (these data are presented in the right column of Table 1) and the transcript of this testimony from the eyewitness expert (no rebuttal witness) condition in Experiment 1. Independent groups t-tests were conducted to compare these two groups on the mean response to each of the first seven questions in Table 1. None of these mean differences approached significance. An additional analysis was conducted to assess if jurors judgments of culpability changed from the point in time just before the eyewitness expert testified to the end of the trial, and if the magnitude of this change was consistent in the video and transcript condition. A 2 (question 1 versus question 7) 2 (video versus transcript) ANOVA was conducted. Only the main effect of question was significant. Participants were less certain of the defendant s guilt after the testimony of the eyewitness expert (question 7: M ¼ 4.74, SD ¼ 1.97), than before (question 1: M ¼ 5.15, SD ¼ 1.76), F(1, 168) ¼ 8.68, p ¼.01, h 2 ¼.05). However, this main effect did not interact with the modality condition. This finding is consistent with the comparable results of Experiment 1 from a 2 (question 1 versus question 7) 2 (video versus transcript) ANOVA conducted on the mean responses in the two expert after the eyewitness (no rebuttal testimony) conditions. Perceptions of the eyewitness expert testimony Several analyses were conducted on questions 8 13 pertaining to the participants perceptions of the eyewitness expert testimony. The mean response for each of these questions is presented in Table 1. These questions were categorized as assessing cognitive dimensions (question 9: Understandable ; question 11: Informative ; and question 13: Confusing ; Cronbach s a for responses in Experiment 2 ¼.75) or global/affective dimensions (question 8: Impact ; question 10: Useful ; and question 12: Influential ; Cronbach s a for responses in Experiment 2 ¼.77) of the eyewitness expert testimony. As in Experiment 1, we analysed these responses in categories to minimize the extent to which we were capitalizing on chance when analysing the results of each question separately. Within each of these two categories, the responses to the relevant questions were averaged and a t-test was conducted to compare mean ratings in the video versus transcript conditions. The between groups differences were not significant on ratings of the cognitive dimensions. However, participants who read the transcript (M ¼ 6.23, SD ¼ 1.73) rated it higher on global/affective dimensions than did those who viewed the video (M ¼ 5.60, SD ¼ 1.66), t(123) ¼ 2.03, p <.05, d ¼.37. In comparable comparisons in Experiment 1, of the mean ratings of the expert in the video versus transcript conditions in the expert after the eyewitness (no rebuttal testimony) conditions, the differences were not significant for either the cognitive or the global/affective dimensions. Further, in Experiment 2 there was no significant difference in the mean ratings for question 14 ( How did the testimony of the eyewitness expert witness impact your sense of the credibility of Psychology as a Science? ) between the trial video and transcript conditions. Question 15 ( How did the testimony of the eyewitness expert witness impact your sense of the credibility of eyewitness identification in general? ) assessed whether the eyewitness expert testimony affected general scepticism regarding the credibility of eyewitness identifications or whether the influence of the testimony was more case-specific. Mean response to this question did not significantly differ between the video and transcript conditions. As can be seen in Table 1, in both of these conditions, the mean response was slightly above the middle of the 1 9 credibility scale, suggesting that the eyewitness expert testimony did not affect respondents scepticism regarding the credibility of eyewitness evidence in general.

14 686 K. Pezdek et al. Conclusions The major results of Experiment 1 were replicated in Experiment 2, using a trial video that included an eyewitness expert rated to have a more dynamic communication style. In terms of jurors judgments, none of the main effects of modality were significant, and although judgments of guilt significantly decreased from the point in time just before the eyewitness expert testified to the end of the trial, the magnitude of this change was consistent in the video and transcript condition. In terms of jurors perceptions of the eyewitness expert, the only difference as a function of the modality condition was that jurors actually found the testimony of the eyewitness expert to have more impact, and to be more useful and influential in the transcript than the video. Interestingly, however, this finding was not corroborated by the finding reported above that the magnitude of the decrease in culpability judgments from just before the eyewitness expert testified (question 7) to the end of the trial (question 1) was similar in the video and transcript condition. Further, we tested the correlation between (a) the difference in each respondent s response to questions 1 and 7 and (b) their response to question 8 ( What impact did the testimony of the eyewitness expert witness have on your decision regarding the defendant s guilt or innocence? ). This correlation, computed for the video and transcript conditions together, was not significant. This suggests that jurors who reported larger changes in their certainty of the defendant s guilt from just prior to the eyewitness expert testimony to the end of the trial were not more likely to have reported a greater impact of the eyewitness expert s testimony in their response to question 8. GENERAL DISCUSSION Was there a consistent effect of eyewitness expert condition? Several findings suggest that providing eyewitness expert testimony generally affected mock jurors perceptions of the reliability of the dubious eyewitness testimony that was included in this simulated trial. First, in both experiments, participants were less certain of the defendant s guilt after the trail (question 7) than before the testimony of the eyewitness expert (question 1). However, these difference scores did not vary as a function of the expert condition or trial presentation modality. Second, the pattern of responses to question 4 regarding whether the line-up procedure was suggestive in this case is also revealing. In Experiment 1, presenting the eyewitness expert testimony effectively influenced jurors perceptions regarding the fairness of the lineup relative to both the no expert condition and the expert with rebuttal witness condition. Generally, however, on few measures was the main effect of expert condition significant, and on no measures was the interaction of this variable with trial presentation modality significant. These findings essentially replicated the results involving similar eyewitness expert conditions reported by Devenport and Cutler (2004). Was the effect of eyewitness expert condition affected by trial presentation modality? The major purpose of this study was to assess the effects of varying levels of ecological validity of the trial presentation medium on jurors perceptions of trial evidence and expert testimony. It is the interactions that are most important in any test of external validity. That

15 Eyewitness expert testimony 687 is, we want to know if the results of any study are consistent across levels of the independent variable that is assessing the external validity condition, in this case, trial presentation modality. Together, the results of both experiments suggest that although there are some advantages to the transcript over the video trial presentation modality, presentation modality did not affect judgments of culpability and did not vary the effects of expert conditions on either judgments of culpability or perceptions of the eyewitness expert testimony. The effects of expert condition were consistent in the trial video and trial transcript conditions; in other words, there were no significant interactions of modality with the expert condition. The primary effects of presentation modality were on perceptions of the eyewitness expert testimony and not judgments of culpability. Respondents in the transcript compared to the video condition rated the eyewitness expert testimony higher on global/affective dimensions in both experiments, and higher on cognitive dimensions in Experiment 1. One interpretation of this effect is that participants do more systematic processing of information in a transcript than a video. The heuristic-systematic model of persuasion is a message-based model of persuasion that maps onto cognitive processes that are applicable to information processing of mock trials (Chaiken, Wood & Eagly, 1996). Systematic processing occurs when an individual focuses on message- and issue-relevant thinking in forming their opinions. Heuristic processing involves little detailed processing of the message content. Although both systematic and heuristic processing typically co-occur, judgments that result from systematic processing are more likely to persist than those that result from heuristic processing alone (Chaiken & Eagly, 1983). Chaiken and Eagly (1976) reported that with difficult to understand material, material similar to the mock trial presented in the current study, greater changes in opinion resulted in a text than a video condition. More systematic processing of information in the transcript than the video condition is one explanation for why perceptions of the eyewitness expert testimony were generally higher in the transcript than video condition in the current study. CONCLUSIONS In any test of external validity, it is the interactions that are most important. The absence of any significant interactions between trial presentation modality and expert condition in this study suggests it is likely that mock jury research at least mock jury research on the role of an eyewitness expert testimony can be conducted with trial transcripts rather than live or video trials without sacrificing external validity. One interpretation of these findings is that it is the content of the expert testimony that is relatively more important than the communication style of the presenter in determining culpability. By communication style in this case, we refer to how dynamic the presentation style is, communicated, for example by mannerisms, use of gestures, eye contact, vocal quality, etc. These are dimensions that are apparent in the video but not the transcript version of the trial. The content was the same in each pair of trial video and transcript conditions. The results of this study suggest that the extra information pertaining to the communication style of the presenter that was available in the trial video but not the transcript, did not have an advantageous effect on respondents ratings of culpability, nor did it produce an interaction with the effect of expert condition on any measure. Thus, it appears that regardless of verisimilitude, it is the content of the expert testimony that is relatively more important than the communication style of the presenter.