Juror Need for Cognition and Sensitivity to Methodological Flaws in Expert Evidence1

This study examined whether need for cognition (NC) moderated jurors' sensitivity to methodological flaws in expert evidence. Jurors read a sexual harassment trial summary in which the plaintiff's expert presented a study that varied in ecological validity, general acceptance, and internal validity. High NC jurors found the defendant liable more often and evaluated expert evidence quality more favorably when the expert's study was internally valid vs. missing a control group; low NC jurors did not. Ecological validity and general acceptance did not affect jurors' judgments. Ratings of expert and plaintiff credibility, plaintiff trustworthiness, and expert evidence quality were positively correlated with verdict. Theoretical implications for the scientific reasoning literature and practical implications for trials containing psychological science are discussed.     

Negative and positive pretrial publicity affect juror memory and decision making

The experiment examined the effects of exposure to pretrial publicity (PTP) and delay on juror memory and decision-making. Mock jurors read news articles containing negative PTP, positive PTP, or unrelated articles. Five days later, they viewed a videotaped murder trial, after which they made decisions about guilt. Finally, all participants independently attributed specific information as having been presented during the trial or in the news articles. Half of the jurors rendered their verdicts and completed the source-memory test immediately after the trial, while the other half did so after a 2-day delay. Exposure to PTP significantly affected guilty verdicts, perceptions of defendant credibility, juror ratings of the prosecuting and defense attorneys, and misattributions of PTP as having been presented as trial evidence. Similar effects were obtained for negative and positive PTP. Delay significantly increased source-memory errors but did not influence guilt ratings. Defendant's credibility and juror ratings of prosecuting and defense attorneys significantly mediated the effect of PTP on guilt ratings. (PsycINFO Database Record (c) 2008 APA, all rights reserved).     

"Recipe for a Jury" Revisited: A Balance Theory Prediction

This study examined the relationship of three variables to verdict confidence in an experimental simulation of the jury deliberation process. The three variables were: sex of juror, verdict (guilty or innocent), and the similarity or dissimilarity between juror and confederate verdicts (congruence or incongruence). The subjects were 35 male and 37 female college students. They deliberated in groups containing a male confederate who role-played an obnoxious anti-White or anti-Black juror. Results indicated that before deliberation, male and guilt verdict jurors were more confident than females and innocent verdict jurors. After deliberation, however, sex differences in verdict confidence were absent while innocent verdicts jurors were more confident than guilt verdict jurors. Most important, as predicted from Heider's Balance Theory, males who deliberated with a confederate whose verdict was congruent with theirs' became less confident in their verdicts. Unexpectedly, females became more confident. The study's major hypothesis, then, that it may be advantageous for the defense to accept a juror who zealously advocates a guilty verdict, was only supported for males.     

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.     

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.     

Disjunction Between Probability and Verdict in Juror Decision Making

Although the law assumes a close relation between the probability that a defendant committed the act in question and the ensuing verdict of the jurors, prior research has shown this assumption to be often violated. We present five experiments designed to show that factors that influence probability also influence verdict, but other factors are capable of directly producing changes in verdict without affecting probability. In Experiment 1, we replicated the Wells Effect; scenarios generating the same probability that the Blue Bus Company was to blame for the same accident, nevertheless, generated significantly different likelihoods of finding the defendant liable. In Experiment 2, we showed that equally diagnostic affirmative and negative evidence had differential effects on mock jurors' probability estimates and verdicts. In Experiment 3, we showed that a completely nondiagnostic witness, who either implicates the same bus company or a different bus company as did a diagnostic witness, significantly influenced mock jurors' verdicts. However, the nondiagnostic witness did not change the probability that the Blue Bus Company was responsible for the accident. In Experiment 4, we demonstrated that base rate and witness reliability information resulted in very similar probability estimates but radically different verdicts. In Experiment 5, we showed that a change in the diagnosticity of the evidence influenced both probability and verdict with the former mediating differences in the later. Because probability is only one of the several determinants of the verdict, the two dependent variables are not as closely related as the law presumes. Copyright © 2011 John Wiley & Sons, Ltd.     

Plea bargaining recommendations by criminal defense attorneys: evidence strength, potential sentence, and defendant preference

Although most criminal cases are disposed of through the process of plea bargaining, little research has focused on this process, and that research has focused on two variables: probability of conviction and potential sentence. This study examined the plea bargaining process from the perspective of the criminal defense attorney and expands prior research by including a third variable: defendant preference regarding plea. Attorney participants (N = 186) responded to a survey containing a vignette presented in a 2 x 2 x 2 between-subjects design, in which there was systematic manipulation of the following three variables in the context of criminal litigation: likelihood of conviction based on the strength of evidence, defendant preference regarding plea, and potential sentence if convicted. All of these variables were considered important to criminal defense attorneys, and how these variables significantly interacted with each other is explained. We discuss these findings in light of past research and theory that suggested attorneys make plea recommendations according only to probability of conviction and potential sentence, and we discuss implications and directions for future research.     

Effects of physical attractiveness on evaluations of a male employee's allegation of sexual harassment by his female employer

College students (N = 324) served as mock jurors in a simulated civil case in which a male plaintiff accused a female defendant of sexual harassment. The authors experimentally manipulated the physical attractiveness of the litigants. The authors asked mock jurors to decide whether the defendant was guilty and to rate their certainty of belief in the defendant's guilt (or lack of guilt). Jurors were more certain of the guilt of the defendant when the plaintiff was attractive than when he was unattractive. Plaintiff attractiveness significantly affected female jurors' individual recommended verdicts when the defendant was unattractive but not when she was attractive. With male jurors, plaintiff attractiveness significantly affected their verdicts when the defendant was attractive but not when she was unattractive. Female jurors were more likely than male jurors to conclude that sexual harassment had taken place but only when the litigants were different in attractiveness.     

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.     

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.”     

Understanding pretrial publicity: predecisional distortion of evidence by mock jurors

Prejudicial pretrial publicity (PTP) constitutes a serious source of juror bias. The current study examined differences in predecisional distortion for mock jurors exposed to negative PTP (N-PTP) versus nonexposed control participants. According to work by K. A. Carlson and J. E. Russo (2001), predecisional distortion occurs when jurors bias new evidence in favor of their current leading party (prosecution or defense) rather than evaluating this information for its actual probative properties. Jury-eligible university students (N=116) acted as jurors in a mock trial. Elevated rates of guilty verdicts were observed in the N-PTP condition. Predecisional distortion scores were significantly higher in the N-PTP condition and reflected a proprosecution bias. The effect of prejudicial PTP on verdict outcomes was mediated by predecisional distortion in the evaluation of testimony. Results are discussed in relation to motivated decision making and confirmation biases.     

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.     

Pretrial Publicity, the Timing of the Trial, and Mock Jurors' Decision Processes

Pretrial publicity and a temporal interval between the news and trial were explored for their effects upon the jury's deliberation process and verdict. Publicity (neutral, negative) and trial timing (immediate, delayed) were manipulated in a 2 × 2 design. Twenty 12-person simulated juries were exposed either to neutral or negative publicity and viewed a videotaped criminal trial immediately following news exposure or after a one-week delay between news and trial. Dichotomous pre-and postdeliberation verdicts, probability of guilt scales, trial recall, ratings of companion jurors, perceptions of attorneys, assessments of the news article, and recall of news facts were measured. Deliberations were tape recorded and content analyzed. Juries exposed to neutral and negative publicity did not significantly differ on conviction rate, deliberation length, or on quality of deliberations. Prejudicial news elicited counter remarks about the threatening nature of the publicity to the defendant's right to a fair trial. Individual juror data revealed that while the news manipulation did not significantly affect predeliberation verdicts or attention to trial events, negative news lowered jurors' probability estimates of guilt and facilitated their recall of news facts. A discriminant analysis predicting jury verdict indicated a lack of support for prior research showing damaging effects from prejudicial pretrial publicity. Findings are explored for methodological implications and for usefulness of theoretical notions of reactance, and "sleeper effects".     

Well…ah…: Hesitations and Hedges as an Influence on Jurors' Decisions1

Hispanic jurors' verdicts and whether these decisions were related to jurors' judgments of the credibility of the witness were the focus of this experiment. A prosecution witness testified in English or in Spanish with interpretation in English. Witnesses' speaking style systematically included hedges and hesitations or did not. Guilty verdicts were independent of language of testimony. Within Spanish‐interpreted conditions, jurors convicted the defendant 47% of the time in the absence of hedges and hesitations. When he hedged and hesitated, they convicted 34% of the time. This effect was complicated by a reliable Witness Hesitation × Juror Language Dominance interaction. These results are interpreted in the context of the courtroom impact of non‐English‐speaking witnesses and the impact of interpretation.     

Mock Juror Attribution of Criminal Responsibility: Effects of Race and the Guilty But Mentally III (GBMI) Verdict Option1

The present study examined three questions relevant to the insanity defense: Does the availability of the alternative verdict “Guilty But Mentally III” affect juror assessment of criminal responsibility? Does race of defendant significantly affect juror decision-making about who should be acquitted under the insanity defense? And does race of victim significantly influence how jurors decide their final insanity defense verdicts? Race of defendant (black or white), race of victim (black or white), and verdict choice set [(Not Guilty by Reason of Insanity (NGRI), Guilty, and Not Guilty) vs. (Guilty but Mentally III (GBMI), NGRI, Guilty, and Not Guilty)] were systematically varied. The mock-trial was presented to 197 college student subjects by means of an audiotape and slide show. Following the re-enacted trial, subjects answered a series of questions regarding the case. The main dependent variable was the rendered verdict. Both χ²loglinear analyses revealed a significant relationship between race of defendant and verdict such that the defendant, when presented as black, was acquitted NGRI significantly more often than when the defendant was presented as white. No significant effects were found for race of victim. The availability of the GBMI verdict option resulted in a twofold effect: There was a two-thirds reduction in both NGRI and straight guilty verdicts when the GBMI verdict option was made available. The implications for legal policy and future research are discussed.     

Juror Preference for Curative Alternative Verdicts for Veterans With PTSD

Two studies examined mock juror verdicts for veterans with PTSD in the criminal justice system. Mock jurors demonstrated a leniency toward treatment bias for veterans with PTSD who committed a violent crime, compared to a nonviolent crime. This leniency toward treatment bias occurred only when alternative verdict options, beyond guilty or not guilty, were available. In fact, a guilt bias was demonstrated by mock jurors when the only verdict options were guilty or not guilty, and a bias toward treatment was demonstrated when curative alternative verdicts were available. Implications for efforts to address the growing national problem of veterans with PTSD in the criminal justice system are discussed.