When evidence is technical or difficult to understand, experts may provide testimony that assists jurors in evaluating the evidence. However, experts may become biased toward the side that has hired them and attorneys may seek experts who will deliberately bias their testimony or may make experts seem untrustworthy through cross-examination. Concurrent testimony is a practice that is presumed to remedy expert partisanship: experts for both sides in a case meet to discuss the case and generate a joint report, they testify together during trial, and are cross-examined by one another and the attorney for the opposing side.
Relying on theories of attitude-behavior relationships and persuasion, the PI proposes three studies to examine the effects of this concurrent testimony technique on the behavior of experts, jurors, and attorneys. In the first study, experts will generate forensic reports and testify under adversarial or concurrent procedures. The experts' products will be coded for indications of extremity and bias. In the second study, community members will act as mock jurors in a trial simulation containing adversarial or concurrent expert testimony to examine whether concurrent expert testimony reduces jurors' reliance on heuristic cues (e.g., source credibility) and increases sensitivity to variation in the strength of the evidence supporting a particular verdict. In a third study, the PI will investigate whether attorneys select different (perhaps less impartial) experts or change their examination strategies when using concurrent rather than adversarial expert procedures.
The results of these studies will provide valuable information about effectiveness of the concurrent expert remedy for expert partisanship and elucidate the psychological mechanisms underlying the reduction in expert bias and the improvement of fact-finder decision making when this remedy is implemented. These studies will evaluate the effectiveness of a remedy for expert partisanship and provide evidence on which future policy decisions could be made.
Adversarial allegiance is the tendency for experts’ evaluations of evidence to be biased toward the party that hired them. One alternative method of presenting expert evidence, concurrent expert testimony, might reduce the effects of adversarial allegiance on experts’ opinions. Concurrent expert testimony requires that experts from each side work together to develop a joint report prior to trial that outlines points of agreement and disagreement. The judge stipulates at trial the issues on which the experts agree. The experts testify together during trial only on those issues on which they disagree, detailing their opinions, asking each other questions, and taking questions from the judge and the attorneys. Concurrent expert testimony is intended to reduce expert partisanship, decrease the likelihood that attorneys will hire extremely biased experts, and assist jurors in their evaluations of the expert and other trial evidence. We conducted three studies to examine the effects of concurrent expert testimony on experts’ evaluations of case facts, attorneys' hiring decisions, and jurors' sensitivity to variations in evidence strength. In the first study, pro-prosecution and pro-defense participants with training in clinical psychology were randomly assigned to act as concurrent, adversarial, or court-appointed experts. Participants reviewed case materials to evaluate whether a mock defendant was criminally responsible for his involvement in a bank robbery and provided ratings of his mental state. After writing a report and providing additional ratings about the defendant’s mental state, participants testified about the defendant’s mental state in a mock courtroom and again rated the defendant’s mental state. Having experts testify under concurrent expert conditions did not reduce the effects of adversarial allegiance; in both of adversarial and concurrent conditions, experts hired by the prosecution found the defendant more responsible than did experts hired by the defense. In contrast, pre-study variations in allegiance toward the prosecution or the defense did not influence court-appointed expert’s ratings of defendant responsibility. In a second study, jury-eligible community members viewed a one-hour reenacted robbery trial in which the defendant was claiming insanity. Within the trial, we varied whether experts testified under adversarial or concurrent conditions, their testimony was delivered using complex language filled with jargon or simple languge, the prosecution or the defense expert had better credentials, and the strength of the evidence supporting a finding of insanity. Jurors showed sensitivity to evidence strength in both their verdicts and evidence ratings. Jurors’ verdict decisions and evidence ratings were also affected by expert testimony presentation and the relative credibility of the experts. When experts testified under adversarial conditions, they relied on heuristic cues (i.e., cognitive shortcuts) about the relative credentials of the experts, with judgments about criminal responsibility that were consistent with the opinion of the more credible expert, irrespective of the strength of the evidence. The relative credentials of the expert did not affect mock jurors’ judgments when the experts testified using the concurrent procedure. In a third study, attorneys were randomly assigned to whether they were litigating an adversarial trial or one with the concurrent presentation of expert evidence and read materials that provided information about the defendant’s mental state. After reviewing the materials, participants evaluated the professional resumes of six experts, which varied in their expertise (high vs. low) and bias (high vs. ambiguous vs. low). Attorneys rated each expert’s perceived desirability, competence, trustworthiness, experience, and credibility. For adversarial experts, attorneys rated high bias experts as more desirable than low bias experts and ambiguous bias experts. Attorneys rated low bias experts as more desirable than ambiguous bias experts. For concurrent experts, although attorneys still rated high bias experts as more desirable than low bias experts and ambiguous bias experts, attorneys did not rate low bias and ambiguous bias experts differently. Despite attorneys rating high bias experts as more desirable than low or ambiguous bias experts, most (56 percent) chose to hire the high credibility, low bias expert, and there was no difference in expert selection due to attorney side or testimony type. This research evaluated a specific procedural reform touted as a remedy for expert partisanship and adversarial allegiance. Although it has been suggested that concurrent presentation of experts will cause attorneys to hire less biased experts, attorneys' hiring decisions did not vary depending upon whether experts are testifying under adversarial or concurrent conditions. And although concurrent presentation of evidence did not interfere with systematic processing of evidence and did reduce jurors’ reliance on heuristic cues when evaluating expert evidence, concurrent expert testimony did not remedy the effects of expert partisanship. Experts testifying under adversarial and concurrent conditions were equally biased in their evaluations of case materials. In contrast, court-appointed experts were less biased in their evaluations of the case materials than were the other two types of experts. Thus, the use of court-appointed experts may be one method of increasing fairness in U.S. courts.
