Juror Sensitivity to the Cross-Race Effect

Black and White mock jurors' sensitivity to the cross-race effect was investigated by varying the race of the eyewitness in a simulated murder trial of a Black defendant. Participants heard an audiotape of a trial after which they rendered a verdict and rated the credibility of the witnesses. White participants found the prosecution witnesses (including the eyewitness) more credible, and the defense witness less credible, than did Black participants; they were also more likely to find the defendant guilty. The Black eyewitness was perceived as more credible than was the White eyewitness, but eyewitness race had no effect on verdict. These results are consistent with the literature indicating that jurors of different races reach different verdicts, and also that jurors are relatively insensitive to factors that affect eyewitness testimony, such as the cross-race effect.     

Considering forensic science: individual differences,opposing expert testimony and juror decision making

Two experimental studies examined the effect of opposing expert testimony on perceptions of the reliability of unvalidated forensic evidence (anthropometric facial comparison). In the first study argument skill and epistemological sophistication were included as measures of individual differences, whereas study two included scores on the Forensic Evidence Evaluation Bias Scale. In both studies participants were assigned to groups who heard: (1) no expert testimony, (2) prosecution expert testimony, or (3) prosecution and opposing expert testimony. Opposing expert testimony affected verdict choice, but this effect was mediated by perceptions of reliability of the initial forensic expert's method. There was no evidence for an effect on verdict or reliability ratings by argument skill or epistemology. In the second experiment, the same mediation effect was found, however scores on one subscale from the FEEBS and age also affected both verdict and methodological reliability. It was concluded that opposing expert testimony may inform jurors, but perceptions of the reliability of forensic evidence affect verdict, and age and bias towards forensic science influence perceptions of forensic evidence. Future research should investigate individual differences that may affect perception or bias towards forensic sciences under varying conditions of scientific reliability.     

The relationship between verdict, defendant characteristics, and type of crime in sex-related criminal cases

In an earlier study, we unexpectedly found that defendants charged with sex crimes were four times less likely to be convicted than were all other defendants. We now report that failure to convict for rape was associated with failure to come to trial and that minor sex crimes were tried, but often continued without a finding, even when the judge found sufficient facts to make a guilty finding. Whether a minor crime involved a victim and whether the defendant has a criminal record both relate to verdict, but psychiatric history did not. The implications for understanding "acquittal of the guilty" are discussed.     

Public beliefs about the accuracy and importance of forensic evidence in the United States

Recent advances in forensic science, especially the use of DNA technology, have revealed that faulty forensic analyses may have contributed to miscarriages of justice. In this study we build on recent research on the general public’s perceptions of the accuracy of 10 forensic science techniques and of each stage in the investigation process. We find that individuals in the United States hold a pessimistic view of the forensic science investigation process, believing that an error can occur about half of the time at each stage of the process. We find that respondents believe that forensics are far from perfect, with accuracy rates ranging from a low of 55% for voice analysis to a high of 83% for DNA analysis, with most techniques being considered between 65% and 75% accurate. Nevertheless, respondents still believe that forensic evidence is a key part of a criminal case, with nearly 30% of respondents believing that the absence of forensic evidence is sufficient for a prosecutor to drop the case and nearly 40% believing that the presence of forensic evidence – even if other forms of evidence suggest that the defendant is not guilty – is enough to convict the defendant.     

Error Rates,Likelihood Ratios,and Jury Evaluation of Forensic Evidence

Forensic examiners regularly testify in criminal cases, informing the jurors whether crime scene evidence likely came from a source. In this study, we examine the impact of providing jurors with testimony further qualified by error rates and likelihood ratios, for expert testimony concerning two forensic disciplines: commonly used fingerprint comparison evidence and a novel technique involving voice comparison. Our method involved surveying mock jurors in Amazon Mechanical Turk (N = 897 laypeople) using written testimony and judicial instructions. Participants were more skeptical of voice analysis and generated fewer “guilty” decisions than for fingerprint analysis (B = 2.00, OR = 7.06, p = <0.000). We found that error rate information most strongly decreased “guilty” votes relative to no qualifying information for participants who heard fingerprint evidence (but not those that heard voice analysis evidence; B = −1.16, OR = 0.32, p = 0.007). We also found that error rates and conclusion types led to a greater decrease on “guilty” votes for fingerprint evidence than voice evidence (B = 1.44, OR = 4.23, p = 0.021). We conclude that these results suggest jurors adjust the weight placed on forensic evidence depending on their prior views about its reliability. Future research should develop testimony and judicial instructions that can better inform jurors of the strengths and limitations of forensic evidence.     

On the Power of Confession Evidence: An Experimental Test of the Fundamental Difference Hypothesis

In Arizona v. Fulminante (1991), a U.S. Supreme Court majority stated that confessions are similar to, not fundamentally different from, other types of evidence. To evaluate this claim, three mock juror studies compared the impact of confessions to other common forms of evidence. In Experiment 1, participants read summaries of four criminal trials (murder, rape, assault, theft), each of which contained a confession, an eyewitness identification, character testimony, or none of the above. Significantly, the confessions produced the highest conviction rates. In Experiments 2 and 3, participants read a murder or assault trial containing all three types of evidence and made a series of midtrial judgments. Results indicated that the confession was seen as the most incriminating, followed by the eyewitness and character testimony. Although the comparisons we made are limited in certain respects, our findings suggest that confessions are uniquely potent.     

Racial prejudice in the canadian legal system

The effects of defendant and victim race and the impact of judicial instructions on defendant verdict were examined using a simulated videotaped rape trial. Subjects were 243 Canadian university students randomly assigned to one of eight conditions. Subjects were asked to assume the role of juror and to view a videotape of a simulated rape trial. The results indicated that the defendant's overall attractiveness or “positive appeal” was the best predictor of defendant guilt, above and beyond defendant race. Neither victim characteristics nor the presence of judicial instructions was found to have predictive utility. Results are contrasted with findings from simulation studies in the United States.     

Measuring the effects of the guilty but mentally Ill (GBMI) verdict

We studied effects of guilty but mentally ill (GBMI) legislation on use of the insanity defense in Georgia using data on all defendants entering an insanity plea before (1976–1981) and after (1982–1985) the introduction of the GBMI verdict. In contrast to earlier studies, our results indicated that GBMI did decrease the likelihood of an insanity verdict and affected the composition of those found not guilty by reason of insanity. Defendants pleading insanity and found GBMI were typically white males with a serious mental disorder, charged with murder or robbery in which an unrelated female victim was involved. The data also indicated that defendants who pleaded insanity and were found GBMI received harsher sentences than their guilty counterparts. We conclude that the GBMI verdict will make the insanity plea a less appealing option for mentally ill defendants.     

The Effect of Gender in the Perception of Elder Physical Abuse in Court

Two experiments investigated mock jurors' perceptions of elder abuse (EA) in a physical assault case. In Experiment 1, participants read a fictional criminal trial summary of a physical assault case in which the alleged victim was 66, 76, or 86 years old. In Experiment 2, the age of the alleged victim was 76 years old, but the gender of the alleged victim and the gender of the defendant were crossed. The results of the experiments showed that women believed the alleged victim more and rendered a guilty verdict more often than men. Overall, the alleged victim was believed more than the defendant regardless of the age of the alleged victim, and most verdicts were guilty. These results are discussed in terms of the factors that affect perceptions of alleged victims of EA in court.     

Educating Jurors about Forensic Evidence: Using an Expert Witness and Judicial Instructions to Mitigate the Impact of Invalid Forensic Science Testimony

Invalid expert witness testimony that overstated the precision and accuracy of forensic science procedures has been highlighted as a common factor in many wrongful conviction cases. This study assessed the ability of an opposing expert witness and judicial instructions to mitigate the impact of invalid forensic science testimony. Participants (N = 155) acted as mock jurors in a sexual assault trial that contained both invalid forensic testimony regarding hair comparison evidence, and countering testimony from either a defense expert witness or judicial instructions. Results showed that the defense expert witness was successful in educating jurors regarding limitations in the initial expert's conclusions, leading to a greater number of not-guilty verdicts. The judicial instructions were shown to have no impact on verdict decisions. These findings suggest that providing opposing expert witnesses may be an effective safeguard against invalid forensic testimony in criminal trials.     

Expert Testimony Regarding Child Witnesses: Does It Sensitize Jurors to Forensic Interview Quality?

Does expert testimony on forensic interviews with children help adults distinguish between poorly conducted and well-conducted interviews? This study evaluates the effects of social framework expert testimony regarding child witnesses in a case involving allegations of child sexual abuse. A 2 (Expert Testimony: present or absent) × 3 (Child Forensic Interview Quality: poor, typical, or good) × 2 (Child’s Age: 4- or 10-year-old) factorial design was used to examine whether expert testimony is prejudicial or beneficial to jurors (N = 463). The results revealed that, without expert testimony, mock jurors did not consider the forensic interview quality when reaching a verdict. However, with expert testimony, mock jurors were more likely to render guilty verdicts if the interview quality was good versus poor. Further expert testimony increased mock jurors’ knowledge about child witnesses. These findings suggest that expert testimony related to the impact of interview techniques on the reliability of children’s reports may assist fact-finders in evaluating child abuse cases.     

The impact of general versus specific expert testimonyand eyewitness confidence upon mock juror judgment

Subjects (n=128) initially viewed an eyewitness of high or low confidence. Subsequently, participants viewed a psychologist who gave either espert testimony on the unreliability of eyewitness identification, specific expert testimony, or no expert (control) testimony. Subjects viewing expert testimony believed the eyewitness identified the gunman significantly less often, gave the defendant lower guilt ratings, estimated a lower general percentage of correct identifications under similar circumstances, estimated a lower percentage of general accurate eyewitness testimony, and gave significantly lower ratings to the belief that one can generally tell from eyewitness confidence whether an eyewitness is accurate than subjects in control conditions. Significant differences were also obtained between general and specific expert testimony. Participants viewing specific expert testimony estimated lower general percentages of correct identifications under the circumstances of the crime and reported relying more upon the psychologist's testimony than subjects viewing general expert testimony. Additionally, subjects viewing general expert testimony had significantly less confidence in their gunman vs. innocent person decision than subjects in specific testimony or control conditions. Subjects who viewed the high confidence eyewitness decided that the eyewitness correctly identified the gunman more often, gave the defendant higher guilt ratings, and estimated the general percentage of accurate eyewitness testimony to be significantly higher than jurors in low eyewitness confidence groups. The finding that jurors may continue to rely on eyewitness confidence to gauge the accuracy of the witness even after viewing expert testimony is discussed.