Biased interpretation of evidence by mock jurors

Predecisional distortion is jurors' biased interpretation of new evidence to support whichever verdict is tentatively favored as a trial progresses. In 2 experiments, students and prospective jurors distorted evidence from a mock trial. Further, the magnitude of prospective jurors' distortion was twice that of students. Consistent with previous research, distortion increased with juror confidence in whichever verdict was currently leading. In spite of clear instructions to ignore prior beliefs, general proplaintiff or prodefendant attitudes influenced the verdicts of prospective jurors, but not of students. These findings suggest that jury instructions should warn against not only premature decisions but also any tentative judgments, lest such opinions influence jurors' evaluations of subsequent evidence. Predecisional distortion in jury trials may lead to biased outcomes resulting from evidence order effects.     

The Impact of Case Characteristics and Prior Jury Experience on Jury Verdicts1

An archival analysis of records from 206 criminal cases was used to evaluate the impact of personal and situational factors on jury verdicts. In particular, we evaluated whether repeated jury service produced bias in jurors that was sufficient to affect jury decisions. A variety of case characteristics and indices of prior jury experience was examined for their relative impact on trial outcomes. Several of the case characteristics were related to verdicts, but the personal characteristics were not. Although more than half of the juries contained experienced jurors, juror experience had little influence on verdicts in either major or subsidiary analyses. However, there was a slight tendency for small juries with large proportions of experienced jurors to convict. This result is consistent with data from Kentucky; a meta-analysis across the two data sets indicates that it is a reliable finding. The results have implications for the determination of jury size. We suggest that future research examine the possibility that increasing jury size may reduce the influence of an individual's bias by providing a balance of other jurors with no or offsetting biases.     

Deciding the Fate of Others: The Cognitive Underpinnings of Racially Biased Juror Decision Making

In criminal law, jurors are supposed to ignore defendant race when considering factual matters of culpability. However, when judging the merits of a criminal case, jurors’ ability (or inability) to avoid bias may affect verdicts. Fact-based decision making expend cognitive resources, while heuristic-based decisions (e.g., using criminal stereotypes) conserve resources. Here, we investigated whether differences in cognitive resources and prejudice attitudes about Blacks influenced trial outcomes. We tested the impact of working memory capacity (WMC), cognitive load, prejudice, and target race (Black, White) on penalties ascribed to fictional criminal defendants in ambiguous-fact cases. Results showed that when “loaded,” prejudiced-low-WMC persons supported guilty verdicts with higher confidence more often for Black than White defendants. Conversely, regardless of WMC or prejudice attitude, participants penalized White defendants more often when not loaded. We suggest that cognitive resources and prejudice attitude influence fact-based decisions. Links to juror judgments and potential trial outcomes are discussed.     

Independence of Multiple Verdicts by Jurors and Juries1

An assumption underlying the common practice of permitting a juror to serve on more than one jury is that jurors can and will reach multiple verdicts independently. Two studies were carried out to examine this assumption. The first experiment had mock jurors consider several cases in succession. Subjects exhibited a clear contrast effect on the strength of evidence; those subjects who initially saw strong prosecution cases were less likely to convict in a moderate test case than those who had initially seen wcak prosecution cases. In the second study, the contrast hypothesis was tested for actual juries' verdicts through archival analyses. The results of this field study paralleled those obtained in the experimental study. The discussion focused upon alternative theoretical explanations for these results, implications for trial practice, and the strengths and weak-nesses of the methodologies applied in these studies.     

Effects of pre‐trial publicity and jury deliberation on juror bias and source memory errors

We examined the effects of exposure to pre‐trial publicity (PTP) and jury deliberation on juror memory and decision making. Mock jurors either read news articles containing negative PTP or articles unrelated to the trial. They later viewed a videotaped murder trial, after which they either made collaborative group decisions about guilt or individual decisions. Finally, all participants independently attributed specific information as having been presented during the trial or in the news articles. Exposure to PTP significantly affected guilty verdicts, sentence length, perceptions of defendant credibility, and misattributions of PTP as having been presented as trial evidence. Jury deliberation had significant effects on jury verdicts, perceptions of defendant credibility, source memory for trial items, and confidence in source memory judgements, but did not affect sentences or critical source memory errors. Copyright © 2006 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.     

The Role of Declarative and Procedural Knowledge in Capital Murder Sentencing1

This paper identifies rational orderliness and moral appropriateness as 2 norms that the United States Constitution requires for sentencing in capital murder trials. The courts convey these norms directly to jurors through jury instructions in the penalty phase of capital murder trials. To follow the instructions, jurors require accurate declarative knowledge (rules of law) and procedural knowledge (processes required to execute the rules) of state and federal sentencing law. Undergraduate mock jurors showed low accuracy for both types of knowledge after reviewing and listening to pattern jury instructions. Participants failed to offset aggravating factors with mitigating circumstances as the Missouri Approved Jury Instructions direct. The less knowledge that participants mastered about mitigation, the more certain they were of invoking the death penalty.     

The Effects of Opening Statements on Mock Jurors' Verdicts in a Simulated Criminal Trial1

Twenty-nine male and 37 female adults served as mock jurors in a simulated criminal trial in which the amount of preview offered in both the prosecution's and defense's opening statements was factorially varied. It was found that the effects upon verdicts of guilt of the amount of preview in either side's opening statement depended on that in the other side's opening statement. Extensive prosecution opening statements led to more guilty verdicts only when the de fense's opening statement was also extensive; when the defense's opening statement was brief, participants tended to find the defendant guilty regardless of the amount of preview in the prosecution's opening statement. Extensive opening statements from the defense led to more not-guilty verdicts only when the prosecution's opening statement was brief. Results from a series of mid-trial measures indicated that opening statements predisposed jurors to favor one side or the other very early in the trial, and that jurors tended to maintain this predisposition throughout the course of the trial. It was suggested that opening statements serve to create thematic frameworks which the jurors use to assist them in their processing of trial information. Implications for legal practice were also discussed.     

Enhancing Juror Competence in a Complex Trial

This study examined the effects of providing substantive, case-related, judicial instructions before presentation of evidence and permitting jurors to take notes, on verdicts and cognitive performance in a complex civil trial. Jurors made compensatory awards when the evidence either strongly or modestly favored the plaintiffs. One hundred and twenty jury-eligible participants saw a videotape of a cognitively dense trial involving multiple plaintiffs. Notetakers, while showing superior cognitive performance over non-notetakers, were more effective decision makers when pre-instructed and facing less ambiguous evidence. Results indicated that notetaking when jurors are pre-instructed enhanced recall of probative evidence and resulted in fewer non-probabitive intrusions, which facilitated decision making on legally appropriate grounds. © 1997 John Wiley & Sons, Ltd.     

Victim Impact Testimony and Juror Judgments: The Effects of Harm Information and Witness Demeanor1

Victim impact testimony (i.e., testimony concerning the harmful consequences on the victim's surviving family) was examined to determine its effect on the sentencing judgments of mock jurors. Undergraduate students (N= 293) watched a videotaped murder trial simulation, rendered verdicts, and made sentencing judgments. During the penalty phase of the trial, participants were either given no victim impact testimony, or they were given victim impact testimony that varied both the severity of the harm information (mild harm/ severe harm) and the demeanor of the witness (low affect/high affect). The results indicate that information concerning the harm experienced by the victim's relatives, not the affective demeanor of the witness, influenced sentencing judgments. Implications for the U.S. Supreme Court decision in Payne v. Tennessee (1991) are discussed.     

The Effect of Capital Punishment on Jurors' Willingness to Convict

Decision-making theory suggests that jurors will tend to choose the verdict that maximizes the expected gains minus the expected losses of each decision. Capital punishment (as compared to a maximum sentence of life imprisonment) would seem to increase the perceived negative consequences of a guilty verdict without affecting the consequences of a non-guilty verdict. This should make guilty decisions less likely. To test this prediction, questionnaires were sent to all jurors who had served on 32 first degree murder trials in which capital punishment was not in effect and who reached guilty verdicts. They were asked whether their verdicts in the murder trial would have been affected if capital punishment had been a possible sentence. Thirty percent of the respondents replied that they would have been less likely to vote guilty, whereas only 3% said they would have been more likely to vote guilty. Of the 32 separate jury panels, 30 had at least one person who indicated that he or she would have been less likely to vote guilty; and in 7 trials, 50% or more of those who responded gave this answer. The results appear to indicate that the possibility of a death sentence reduces the likelihood of a guilty verdict.     

Does jury deliberation really improve jurors' memories?

The courts assume that jury deliberation corrects errors in jurors' memories, so that the verdict is based on accurate memory for the trial. We evaluated the validity of this assumption by examining jurors' memories and verdicts both before and after deliberation. Unlike previous studies, we tracked how event memories changed as a function of how they were discussed in deliberation. Overall, deliberation resulted in only a slight memory improvement. Deliberation corrected errors and did not introduce distortions. Reasons for such slight memory improvement are that jurors did not think they had memory gaps and thus did not use the deliberation process to improve their memory, and jurors who controlled deliberation were not always the most accurate in their memories. Finally, those most likely to change their verdict as a result of deliberation were not those who had the least accurate memories, but rather those who had the least confidence in their memories. Copyright © 2002 John Wiley & Sons, Ltd.     

Individual and Group Decisions in Response to a Mock Trial: A Methodological Note1

An audiovisual slide-show presentation of a murder trial was used to examine the effects of group deliberations on juror's responses. Sex of defense attorney and race of defendant were systematically varied in the mock trial. Verdicts were assessed immediately following the trial presentation (before group deliberations) and immediately following group deliberations. Neither sex nor race significantly affected distributions of individual juror's predeliberation verdicts. Following group deliberations, however, an effect of attorney's sex emerged in both jury (group) verdicts and in individual, postdeliberation verdicts. Jurors in the male defense attorney conditions were more likely to vote not guilty following deliberations than were jurors in the female defense attorney conditions. This effect is discussed in terms of group shift.     

Reducing racial bias in the penalty phase of capital trials

Past research (e.g. Lynch & Haney, 2000) has shown that race plays a significant role in juror decision making in the penalty phase of capital murder trials. This study investigates the possibility of reducing juror bias towards Blacks by altering the content of jury instructions. White and non-White participants received trial information and jury instructions in which the defendant's race (Black or White) and the instruction type (standard or simplified) were manipulated. Participants rendered a sentence recommendation, identified factors they considered to be aggravating or mitigating, and responded to instruction comprehension questions. Bias against the Black defendant was significantly reduced when simplified instructions were used and when the defendant was judged by racially diverse jurors. Simplification also led to better comprehension of sentencing instructions. Implications for capital trials are discussed.     

The effect of jury deliberations on jurors' propensity to disregard inadmissible evidence

The goal of this research was to examine the effect of jury deliberations on juror's propensity to disregard inadmissible evidence. Extant research is inconclusive; some research indicates that jurors do follow judicial instructions to ignore inadmissible evidence, but other research suggests that jurors do not. Two experiments examined whether jurors were affected by inadmissible evidence. The results revealed that although mock jurors were biased by inadmissible evidence prior to deliberations, the bias was tempered following deliberations. In Experiment 1, post deliberation jurors disregarded incriminating evidence that was ruled inadmissible because of due-process concerns. Experiment 2 replicated these results with less incriminating inadmissible evidence and also revealed that jurors did not accurately gauge the impact that the inadmissible evidence had on their verdicts. Theoretical and judicial policy implications are discussed.     

Effects of Victim,Defendant, and Juror Gender on Decisions in Child Sexual Assault Cases1

We examined the combined influence of juror, victim, and defendant gender on jurors’ decisions in child sexual abuse cases. Mock jurors read scenarios of an assault case involving a man or woman defendant accused of molesting a 15‐year‐old boy or girl. Jurors then rendered verdicts and rated the defendant's and victim's believability and responsibility for the abuse. Female jurors were generally more pro‐victim in case judgments than were male jurors. Additionally, a woman perpetrator was evaluated more leniently than was a man perpetrator, especially by male jurors when the victim was a boy. Case judgments were unrelated to jurors’ social conservatism, sexism, or attitudes toward homosexuality. Results have implications for understanding social perceptions of mixed‐ and same‐gender abuse involving adolescent victims, and juror decision making in man‐ and woman‐perpetrated child sexual assault cases.     

Gender effects on individual verdicts and on mock jury verdicts in a Simulated Acquaintance Rape Trial

Since more women than men college students vote guilty in a simulated acquaintance rape trial [e.g., G. J. Fischer (1991) “Cognitive predictors of not-guilty verdicts in a Simulated Acquaintance Rape Trial,”Psychological Reports, Vol. 68, pp. 1199–1206], guilty mock jury verdicts were expected to increase as a function of the number of women on the jury (i.e., 0, 2, 4, 6, 8, 10, and 12). However, guilty verdicts did not increase significantly until either females were an overwhelming majority (i.e., 10 women to 2 men) or the jury was all female. Even in the latter conditions, guilty verdicts were fewer than would be expected based on the 86% of women and 66% of men voting guilty on a survey completed after reading about the trial, but before serving on a jury. Although a very large majority of females were needed to increase guilty verdicts, a majority appeared to lessen the likelihood of not guilty verdicts. For example, when a majority of jurors were female, 0/18 hung juries leaned toward a not guilty verdict vs. 11/34 juries leaning toward a not guilty verdict when less than or equal to one half of the jurors were female. Most of the students were White (85%), with 4% Asian, 3.2% Black, 3.2% Hispanic, and 4% “Other.”     

Jurors' Decisions in Trials of Battered Women Who Kill: The Role of Prior Beliefs and Expert Testimony1

The present research explored the influence of four factors on mock jurors' decisions in a homicide trial involving a battered woman who killed her abusive husband: (a) jurors' preexisting beliefs about wife abuse, (b) the presence of expert testimony on the battered woman syndrome, (c) jurors' beliefs in a just world, and (d) gender. Mock jurors listened to a trial involving a woman who had killed her abuser, which either contained expert testimony or did not, and then rendered various judgments about the case. Results indicated that those individuals who were more informed about the dynamics of abuse and those exposed to the expert testimony, compared to their respective counterparts, were more believing of the battered woman's account of what occurred. In general, weak believers in a just world were more lenient in their judgments, with verdicts of not guilty being associated with weaker beliefs in a just world than guilty verdicts. Weak believers in a just world also felt that the expert testimony applied more to the defendant than did strong believers. Finally, women who were weak believers in a just world were less likely to hold the defendant responsible for the events and to be more informed about the dynamics of abuse following the experiment.     

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.