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.     

The Impact of Regulatory Fit on Performance in an Inattentional Blindness Paradigm

The influence of timing and frequency of instructions on the reasoning of jurors in a simulated grand larceny trial was investigated. Mock jurors were given definitions of grand larceny before and after the testimony, only before, only after, or not at all. Although timing of instructions was not significantly related to reasoning or to verdicts, frequency of instructions influenced the aspects of testimony deemed relevant and increased juror use of legal rules in making verdicts. Selective encoding of testimony could not account for the instruction effect.     

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.     

The effects of rational and experiential information processing of expert testimony in death penalty cases

Past research examining the effects of actuarial and clinical expert testimony on defendants' dangerousness in Texas death penalty sentencing has found that jurors are more influenced by less scientific pure clinical expert testimony and less influenced by more scientific actuarial expert testimony (Krauss & Lee, 2003; Krauss & Sales, 2001). By applying cognitive-experiential self-theory (CEST) to juror decision-making, the present study was undertaken in an attempt to offer a theoretical rationale for these findings. Based on past CEST research, 163 mock jurors were either directed into a rational mode or experiential mode of processing. Consistent with CEST and inconsistent with previous research using the same stimulus materials, results demonstrate that jurors in a rational mode of processing more heavily weighted actuarial expert testimony in their dangerousness assessments, while those jurors in the experiential condition were more influenced by clinical expert testimony. The policy implications of these findings are discussed.     

Effects of Mental Health and Neuroscience Evidence on Juror Perceptions of a Criminal Defendant: the Moderating Role of Political Orientation

Several recent studies have examined the effects of mental health and neuroscientific evidence on attitudes toward criminal defendants, suggesting that these factors may influence juror decision‐making in meaningful ways. Few studies to date have manipulated both of these variables while also considering theoretically important individual difference variables (e.g., political orientation). Using a criminal case simulation, this study manipulated the presence of evidence concerning mental disorders (psychopathy and schizophrenia) and increasing levels of neuroscientific detail regarding a defendant's brain injury, and examined verdicts and sentencing recommendations in over 400 persons attending jury duty. Main effects were detected for mental health testimony and political orientation, although interactions were noted as well. More negative reactions to defendants labeled as psychopaths were relatively consistent, whereas participants who identified as liberal generally were less punitive towards a defendant identified as schizophrenic than were more conservative jurors. Consistent with other recent research, juror perceptions of the defendant's level of psychopathic traits (independent of the effects of the experimental manipulations) predicted guilty verdicts and longer sentencing recommendations. Copyright © 2016 John Wiley & Sons, Ltd.     

Information Integration Theory,Juror Bias,and Sentence Recommendations Captured Over Time in a Capital Trial

Initial juror verdicts have been shown to predict final verdicts, leading researchers to conclude that jurors seek confirmatory information during trial (confirmation bias) or distort information to fit pre‐existing biases (pre‐decisional distortion). However, Information Integration Theory suggests that individuals are not distorting/ignoring this information, and instead, information influences judgments in the direction of the message. The current study sought to test these competing theories in a juror setting. Mock jurors were presented with the sentencing phase of a capital trial and were asked to give sentence recommendations at eight different time points. Additionally, they were grouped by their pretrial bias as being pro‐defense, neutral, or pro‐prosecution. Results showed support for Information Integration Theory; although jurors' pretrial bias predicted final sentence, sentence recommendations were affected in the direction of the testimony presented throughout the trial (e.g., pro‐defense testimony lowered death penalty decisions across all groups). Implications and future directions are discussed. Copyright © 2015 John Wiley & Sons, Ltd.     

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.     

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.     

Expert testimony in child sexual abuse cases: The effects of evidence,coherence and credentials on juror decision making

Psychological experts have been used increasingly to testify in child sexual abuse cases, yet little research has investigated what specific factors make experts effective. This study examined the potential effects that credentials, evidence strength and coherence may have on juror decision making. Sixty‐four mock jurors read cases of child sexual abuse, followed by experts' testimony and rated guilt of the defendant, effectiveness of the expert testimony and credibility of the victim. Evidence strength and coherence of the testimony affected all dependent variables, and the interaction was significant. Guilt ratings of the defendant were lower and the victim was rated as less credible when both evidence strength and coherence were low. The credentials of the expert, however, had negligible impact. These findings indicate that experts can be effective and impact jurors when testimony is either high in coherence or high in evidence. Copyright © 2009 John Wiley & Sons, Ltd.     

Improving the Credibility of Child Sexual Assault Victims in Court: The Impact of a Sexual Assault Nurse Examiner

The present study investigated the influence of a sexual assault nurse examiner's (SANE's) testimony on mock juror perceptions of a child or adolescent victim of child sexual assault. Community members (N = 252, 156 females) read a fictional criminal trial summary of a child sexual assault case in which the victim was 6 or 15 years old and the prosecution presented medical testimony from a SANE or a traditional registered nurse (RN), or did not present medical testimony. Mock jurors were more likely to render guilty verdicts when a SANE testified compared with the other two testimony conditions. In addition, pro-victim judgments (e.g., sympathy toward the victim) and negative defendant judgments (e.g., anger toward the defendant) mediated this relation. Finally, cognitive network representations of the case demonstrated that the RN and no-medical-testimony groups were similar and the SANE group was distinct from the other two conditions. We discuss these results in terms of the implications of SANE testimony in child sexual assault court cases. Copyright © 2015 John Wiley & Sons, Ltd.     

Alice-in-Wonderland terminological usage in,and communicational concerns about,that peculiarly American flight of technological fancy

Alice-in-Wonderland (AW) terminological usage employs basic terms in a systematically misleading and taxonomically anarchic way. The so-called “control” question “test” (CQT) polygraph procedure, which enjoys a controversial but nevertheless scientific status in North America, involves such AW terminological usage. The basic concepts of “test,” “control,” and “quantification” are loosely employed. There is loose talk about the “detection ofdeception,” which generates the paradox that in the CQT it is in the innocent that deception should be detected. Moreover, deception is not really assessed either in the CQT or in the more scientifically-based Guilty Knowledge Test (GKT). Finally, there is loose practice in evaluating the CQT, which should not be primarily assessed in terms of its overall accuracy, but in terms of its specific effects in improving accuracy through the provision of physiological information to the examiner. Such an assessment has not been carried out even in laboratory analogues of polygraphy. The treatment of the CQT exemplifies most psychophysiologists’ reluctance to treat basic definitional issues seriously, and also means that opponents of the CQT are unable to communicate clearly about it with non-psychophysiologist professionals and with the lay community.     

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).     

Alice-in-Wonderland terminological usage in, and communicational concerns about, that peculiarly American flight of technological fancy. The CQT polygraph

Alice-in-Wonderland (AW) terminological usage employs basic terms in a systematically misleading and taxonomically anarchic way. The so-called "control" question "test" (CQT) polygraph procedure, which enjoys a controversial but nevertheless scientific status in North America, involves such AW terminological usage. The basic concepts of "test," "control," and "quantification" are loosely employed. There is loose talk about the "detection of deception," which generates the paradox that in the CQT it is in the innocent that deception should be detected. Moreover, deception is not really assessed either in the CQT or in the more scientically-based Guilty Knowledge Test (GKT). Finally, there is loose practice in evaluating the CQT, which should not be primarily assessed in terms of its overall accuracy, but in terms of its specific effects in improving accuracy through the provision of physiological information to the examiner. Such as assessment has not been carried out even in laboratory analogues of polygraphy. The treatment of the CQT exemplifies most psychophysiologists' reluctance to treat basic definitional issues seriously, and also means that opponents of the CQT are unable to communicate clearly about it with non-psychophysiologist professionals and with the lay community.     

The Effect of Acknowledging Mock Jurors' Feelings on Affective and Cognitive Biases: It Depends on the Sample

An intervention designed to correct affective and cognitive biases was tested in the context of a civil commitment hearing of a sexually violent predator. Potential differences between a college student mock jury sample and a more representative, juror venire sample in reaction to these bias correction interventions were explored. In the first of two experiments, undergraduate mock jurors (n = 130) demonstrated a leniency effect when the sex offender's attorney acknowledged jurors' emotional reactions and motivated them to thoughtfully weigh the evidence. The second experiment failed to replicate these findings with a more ecologically valid sample (n = 300). Several differences between samples were found: representative jurors, as opposed to undergraduates, were sensitive to differences between pure clinical and actuarial expert testimony; and measures of intrinsic cognitive effort predicted verdicts for undergraduates, but not for representative jurors. Copyright © 2011 John Wiley & Sons, Ltd.     

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.     

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.     

An Aiibi Witness' Influence on Mock Jurors' Verdicts1

The impact of alibi testimony on juror decision making is not yet clear because it has been examined empirically infrequently. This study was designed to determine the impact of alibi witness' testimony, the impact of an alibi witness with a relationship in comparison to one without a relationship to the defendant, and the impact of an eyewitness' confidence on juror decision making. Results indicated that mock jurors acquit a defendant more often when an alibi witness with no relationship to the defendant testified on his behalf. Participants did not believe an alibi witness who had a relationship with the defendant even though the witness was not a family member. Implications for these results are discussed.     

How jurors use and misuse character evidence

The Federal Rules of Evidence allow defendants to offer testimony about their good character, but that testimony can be impeached with cross-examination or a rebuttal witness. It is assumed that jurors use the defense's character evidence (CE) to form guilt and conviction judgments but use impeachment evidence only to assess the character witness's credibility. Two experiments tested these assumptions by presenting mock jurors with various forms of CE and impeachment. Participants made trait ratings for the character witness and defendant and guilt and conviction judgments. Positive CE did not affect guilt or conviction judgments, but cross-examination caused a backlash in which judgments were harsher than when no CE was given. Using path analysis, the authors tested a model of the process by which CE and impeachment affect defendant and witness impressions and guilt and conviction judgments. Implications for juror decision making are discussed.     

"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.