Jury Decision Making and Eyewitness Testimony Research Paper

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Jurors are assigned the arduous task of examining and processing copious amounts of evidence – in light of their legal instructions – to determine an appropriate verdict. While jurors do a relatively good job at sorting through the evidence and the law, the complex nature of evidence may lie outside jurors’ “common knowledge,” and additional education may aid jurors as they process such information. This is especially true in the domain of eyewitness testimony. Eyewitness testimony is extremely influential despite its potential to be unreliable. Eyewitnesses may appear very confident in their identification of the perpetrator, yet be completely mistaken. Indeed, over 75 % of wrongful convictions overturned due to DNA testing have been linked to faulty eyewitness identifications. Unfortunately, traditional safeguards, such as cross-examination of eyewitnesses, result in little improvement in jurors’ ability to discriminate between accurate and inaccurate eyewitness identifications. This has led the courts to establish additional safeguards against wrongful convictions based on faulty eyewitness identifications including the use of expert testimony and detailed instructions on how to evaluate eyewitness testimony.

Jury Decision-Making Research

Understanding how jurors make decisions has been a topic that has interested social scientists for the better part of a century. Legal decision making has been studied by examining both group-level deliberations and individual juror decisions. At the group level, deliberation styles have been characterized as either evidence or verdict driven. Evidence-driven deliberations typically entail reconstructing the chain of events and focusing on the evidence presented before determining a verdict. On the other hand, deliberations that are verdict driven tend to be shorter and involve an immediate vote followed by discussion that is centered on how the evidence supports the verdict options. Unfortunately, deliberations in general do little to remedy mistakes or improve evidence and instruction comprehension. However, 12 member juries (as opposed to six) appear to result in more diverse jury composition, more accurate recall of trial testimony, and increased satisfaction among jury members (Saks and Marti 1997).

Because of the cost and time required to conduct research involving juries, the bulk of legal decision-making research focuses on individual jurors. One of the most popular cognitive theories is the Story Model, which takes into account individual jurors’ attitudes and beliefs. Jurors proceed through three stages during the course of a trial. First, jurors develop one or more stories based on evidence presented during the trial that are supplemented by personal knowledge of similar events and individual beliefs and attitudes. Second, jurors are provided with judge’s instructions that explain the verdict options available to them and the required elements for a finding of each verdict. Finally, a categorical decision is made based on the best match between a chosen story and verdict options available. Story construction is the focal point of this theory and is what will determine one’s verdict choice.

Broader cognitive theories have also been applied to juror decision making. For example, dual process theories propose that people process information more or less thoroughly depending upon an individual’s motivation and ability to understand such information. Jurors may be overwhelmed by large amounts of information. For example, expert testimony often entails complex information that is difficult to understand. When jurors defer to heuristic cues when evaluating the testimony. Heuristic cues, such as source attractiveness or length of testimony, do not directly contribute to the overall quality of the argument. Jurors should be relying on the clarity and strength of the experts’ argument, but if they are unable to assess these features, they may rely on more superficial factors. An eyewitness expert, for example, may present scientific research to the jury outlining what factors may increase or decrease the reliability of eyewitness identifications. If this research is too difficult for jurors to understand, or so lengthy that they lose motivation to process the information, they may not absorb the message the expert is trying to present. However, if the expert presents information in a way that is understandable and interesting to the jurors, they will be more likely to systematically process the information and use it to assist with their evaluation of the eyewitness testimony presented at trial.

Eyewitness Research

Eyewitness testimony can be powerfully persuasive evidence. To the detriment of innocent defendants, such testimony is often damning. Extensive research has determined a variety of factors that may explain how misidentifications can occur.

Research on factors influencing the accuracy of eyewitness identifications has examined two types of variables: estimator variables and system variables. Estimator variables are situational variables associated with the crime, eyewitnesses, and perpetrators that can only be considered after the fact to evaluate the quality of the identification. System variables are variables related to police procedures dealing with lineup administration. Both system and estimator variables can impact the reliability and quality of eyewitness identifications and their accuracy.

Estimator variables are outside the control of the criminal justice system. For example, the viewing conditions experienced by the witness when they saw the perpetrator can influence the ability of the witness to later make an accurate identification. Conditions include lighting at the time of the witness’ viewing, the witness’ distance from the culprit, and the length of time the witness had to view the culprit.

A number of witness characteristics can impact the reliability of eyewitness testimony aside from any situational factors. For example, young children and the elderly appear more likely to make a mistaken identification compared to young adults. In addition, cross-race identifications are less accurate than identifications of culprits who are members of the same race as the witness (Meissner and Brigham 2001). People who witness crimes under high stress are less likely to make accurate identifications than witnesses who are not under stress (Deffenbacher et al. 2004). Furthermore, memory for an event may be limited when a weapon is present as attention is focused on the weapon and shifted away from the perpetrator (Steblay 1992). Lastly, the amount of time between witnessing the event and identifying the individuals is another important consideration in the accuracy of eyewitness testimony as memory deteriorates quickly for details of the event and perpetrator.

During the identification procedure, there are several important factors that can act as indicators of accuracy. For example, the speed at which a witness makes an identification is associated with witness reliability. Quicker identifications tend to be more accurate (Wells and Olson 2003). Perhaps the most important research regarding estimator variables is on eyewitness confidence. Although people commonly use the confidence level of an eyewitness to evaluate the reliability of eyewitness testimony, confidence is not highly correlated with accuracy (Sporer et al. 1995). In some situations the confidence of a witness can be a better predictor of accuracy, as when the confidence rating is taken directly after an identification. However, the most important manner in which the confidence-accuracy relationship is of concern is in relation to how confidence can be impacted by confirmatory feedback (Bradfield et al. 2002) or by a biased lineup (Charman et al. 2011). Confidence is malleable and susceptible to suggestive procedures used by lineup administrators. For instance, witnesses express higher levels of confidence when they receive feedback that they have correctly identified the suspect than when they do not receive this feedback (Bradfield et al. 2002). This occurs regardless of whether the witnesses’ identification was accurate or not. Thus, if an identification is inaccurate and the witness receives positive feedback, they will appear more confident to a jury, but actually be mistaken about the identification.

System variables are typically under the control of the criminal justice system. Most often, these variables refer to procedures employed by the police when administering a lineup. There are a variety of biases related to lineup administration, specifically lineup composition, instructions, and presentation method in addition to the behavioral influence of the administrator that has the potential to cause suggestive lineups.

Foil bias occurs when the “foils” or the members of the lineup that are not the suspect (also known as “fillers”) do not match the original description provided by the eyewitness (Charman et al. 2011). A distinction must be made between choosing foils that are similar to the suspect and those that are similar to the description provided by the eyewitness. In order to create a fair lineup, the police will often choose foils that look similar to the suspect. While this seems like a reasonable way to make sure that witnesses do not disproportionately identify suspects because they “stand out” in an array, there are several reasons why this matching strategy may be a problem. If foils are chosen based on their similarity to the suspect, the question arises about how similar the foils should be. If a witness is presented with a lineup consisting of almost identical individuals, the lineup task will be too hard, and there is the potential for a large number of false rejections or errors. When a witness provides the police with a description, they are not providing the police with an exact picture of the suspect. The witness may mention the suspects’ hair color, eye color, height, weight, or distinctive tattoos or scars. If foils are chosen based on this short list of characteristics, the members of the lineup will differ from each other on a variety of characteristics the witness did not describe to the police. This raises the chances that the eyewitness can correctly identify the perpetrator – but not as a result of suggestiveness created by the police. According to a survey of experts in eyewitness research, 71 % felt that research on foil bias was consistent enough to present in court (Kassin et al. 2001).

Instruction bias is another type of bias that can occur with lineup administration. When using biased instructions, the lineup administrator does not explicitly instruct the witness that the suspect may or may not be in the lineup. Failing to provide this information implies that the suspect is present in the lineup, which has the potential to put pressure on the witness to make a choice from the lineup. Unbiased instructions, on the other hand, inform the witness that the suspect may or may not be present in the lineup. They also inform the witness explicitly that if they are uncertain about the identity of the suspect, they have the ability to reject the lineup. These instructions have been demonstrated to result in more accurate identifications (and particularly reduce mistaken identifications) as compared to biased instructions (Steblay 1997).

Presentation bias in lineup administration deals with how the various photographs in a lineup are displayed to the witness. In simultaneous lineups, all the photographs are displayed to the witness at the same time. The witness may be inclined to compare the photographs and choose the person who most closely resembles their memory of the culprit. However, this “relative judgment” procedure increases the likelihood of a false identification when the perpetrator is not in the lineup. Sequential lineups involve showing the witness one photograph at a time. This forces the witness to compare each face to their memory and use an “absolute judgment” when deciding each time whether the photograph is the culprit they remember or not. The sequential lineup presentation procedure results in fewer false identifications with only a modest reduction in the number of suspect identifications – and those lost identifications are likely the result of reduced guessing by witnesses (Wells et al. 2011).

Double-blind administration of lineups is another important method for reducing inaccurate eyewitness identifications. A number of researchers have recommended this method for improving the accuracy and eliminating biases associated with lineup administration (Greathouse and Kovera 2009). Double-blind administration of a lineup means that the person administering the lineup to the witness does not know who the suspect is. If the administrator is aware of the identity of the suspect, they may communicate this information unconsciously to the witness through subtle means (i.e., hesitations, pauses, smiles). They also may provide biased feedback to the witness that can affect confidence judgments of that witness going forward. If they are aware of the suspects’ identity, they may inform the witness they were correct in their identification, which has the potential to increase future confidence assessments of that witness. Double-blind procedures can eliminate these biases and prevent the possibility that the lineup administrator intentionally or unintentionally communicated their belief in the suspects’ guilt during the identification procedure.

How familiar are jurors with the factors that influence eyewitness performance? In order to answer questions about how much lay jurors know and understand about factors that affect the reliability of eyewitness identifications, Desmarais and Read (2011) performed a metaanalysis of various surveys concerning lay knowledge of eyewitness issues. Although laypeople understood more about factors affecting the accuracy of identifications than expected, the authors still concluded that “75 % of the eyewitness factors reviewed herein are ‘beyond the ken’ of potential jurors” (Desmarais and Read 2011, p. 209). They then concluded that jurors would be assisted in their decision making by expert testimony on these factors. These findings suggest that one way to improve the evaluation of eyewitness testimony by jurors should be to educate them about factors affecting the reliability of eyewitness testimony.

The Efficacy Of Traditional Safeguards

Given the various issues with eyewitness identifications, there are obvious concerns about the impact eyewitness testimony will have on jurors in court. To help jurors make sound verdict decisions when eyewitness testimony is involved, the courts have devised a number of methods for sensitizing jurors to factors affecting eyewitness identification accuracy. There has been some debate about the respective efficacy of these various safeguards, but overall it appears these safeguards are not as effective as the courts intended.

Some potential safeguards that occur before a trial begins are jury selection and voir dire. Before a trial, both the defense and the prosecution have the opportunity to remove jurors from the courtroom that may be hostile to their case or biased on some issue relevant to the trial. This procedure typically involves the judge, prosecutor, and defense attorney interviewing potential jurors to determine whether they are biased. If a potential juror is biased on an issue relevant to the trial, the defense or prosecutor may bring this to the attention of the judge. It is then up to the judge to determine whether they will remove the juror from participating in the jury by exercising a for-cause challenge or whether they will attempt to rehabilitate that juror and remove their biases. The judge in the case may then ask the juror if they can make a decision about the outcome of the case putting aside their particular biases. The judge will then determine, based on that juror’s response, whether they believe that a juror can be rehabilitated. If the judge thinks that juror cannot put aside their biases and decide the case in an unbiased manner, the juror will be dismissed. If the judge does not dismiss a juror, the defense or prosecution may excuse the juror using one of their limited number of peremptory challenges.

Another potential safeguard against erroneous convictions is cross-examination of witnesses. Cross-examination is considered the traditional method to prevent unreliable evidence from impacting jurors. It is expected that whatever weaknesses exist in the prosecutor’s case will be exposed by the defense attorney through cross-examination (and vice versa). Eyewitnesses are like other witnesses in that they can be questioned by the opposing counsel. In order for cross-examination to be effective, both attorneys and jurors need to possess some degree of knowledge about eyewitness issues. An attorney must know what factors impact the reliability of eyewitness identifications in order to identify such weaknesses in the witness’ testimony. Yet describing eyewitness problems for the jury is fruitless if jurors are not sensitive to these issues. Jurors may have difficulty believing information that is contrary to beliefs they have already developed about eyewitnesses, especially if that information is provided to them by a potentially biased defense attorney.

The adversarial nature of cross-examination renders it ineffective as an educational tool for jurors, thus creating a need for some other way to disseminate information about eyewitness issues to jurors. The final two safeguards – judicial instruction and expert testimony – involve expert advice. Judicial instruction is typically used to inform jurors about what evidence they should and should not use when making a decision. Often, a judge will issue an instruction informing jurors to ignore any media coverage of the trial and to avoid using information from media sources when making a decision. Judicial instruction may also be used to instruct jurors to ignore any inadmissible evidence from entering verdict decisions. Judicial instructions are largely ineffective in persuading jurors to disregard inadmissible evidence (Steblay et al. 2006). However, one study found that jurors were more likely to disregard inadmissible evidence if told that the evidence was inadmissible because it was unreliable, rather than if its inadmissibility was due to the fact that it was obtained illegally (Kassin and Sommers 1997). The results of this study suggest that judicial instructions informing jurors about reliability issues with eyewitness identifications could cause them to question the reliability of identifications.

Although standard pattern judicial instructions are regularly used in all cases, recently courts have been supporting the use of case-specific instructions on eyewitness testimony. These instructions would be in place to educate jurors on factors affecting the reliability of eyewitness identifications in a specific case. General eyewitness instructions have existed for 40 years – US v. Telfaire (1979). The Telfaire instruction was created by the courts to address the problems with eyewitness identifications, but this instruction has not been particularly effective in sensitizing jurors to factors affecting the reliability of eyewitness identifications. Revised instructions may be more effective in educating jurors. Whether such instructions will work is an open question – most research has found judicial instruction to have little to no effect on jurors’ verdict responses. Furthermore, it is reasonable to predict judicial instructions may, for the most part, have a skepticism effect on potential jurors. If jurors are informed by the judge about the unreliability of eyewitness evidence, they may assume that the judge believes the identification to be unreliable. Despite these caveats, some courts (e.g., New Jersey v. Henderson 2011) are advocating for case-specific instructions that will focus on reliability issues at play in a given identification. It is possible that the proposed judicial instructions will assist jurors in evaluating the reliability of eyewitness evidence, but as yet, none have demonstrated success in sensitizing jurors to the differences between reliable and unreliable identifications.

The most strongly supported safeguard against eyewitness misidentifications affecting jury verdicts is expert testimony. Expert testimony can increase jurors’ sensitivity to eyewitness issues. Experts on eyewitness research and human memory are most often hired by the defense to speak to the court and jury about the factors that impact the accuracy of eyewitness identifications. Expert testimony typically focuses on specific system and estimator variables relevant to the case at hand. Support for juror sensitivity has been mixed. However, given the low level of lay knowledge about eyewitness issues, as outlined in Desmarais and Read (2011), expert testimony may serve as a useful educational tool to help jurors understand eyewitness issues. Those authors recommend expert testimony as the most effective safeguard, highlighting that the educational component may make up for the relative lack of knowledge jurors have about eyewitness issues.

Current Controversies And Issues With Eyewitness Research

Research on juror decision making, particularly experimental jury simulations, has been criticized for a variety of reasons. These reasons include the low stakes involved in mock jurors’ decisions, the lack of ecological validity, use of college samples, and the lack of deliberating groups. Of course, it is simply unethical and impractical to manipulate variables in actual court cases that could impact the outcome for research purposes. However, the quality and verisimilitude of trial materials used when conducting stimulation studies has continued to improve. Additionally, in a review of the existing literature, Bornstein (1999) found few differences between college student and community samples serving as mock jurors. Overall, the results of post-trial surveys of actual jurors tend to corroborate the findings of stimulation studies, thereby increasing its validity. Still, the courts have been slow to embrace the research despite much consensus among experts regarding the findings.

While most courts have been slow to rely on psychological findings, the New Jersey Supreme Court in New Jersey v. Henderson goes as far as any court ever has in embracing psychological research regarding eyewitness identification. The court in Henderson appointed a Special Master to hear testimony from experts on human memory and eyewitness identification. Drawing on the Special Master Report, the court exhaustively reviewed eyewitness identification research and the general acceptance of this research among experts.

The Henderson court decided to modify the existing criteria used to determine eyewitness identification admissibility in pretrial hearings. These criteria were based on Manson v. Brathwaite (1977) which resulted in a two-pronged test. First, courts determine whether suggestive police procedures were used to secure an identification. If suggestive action was taken, the reliability of the identification must be assessed by reviewing the opportunity of the witness to view the criminal at the time of the crime, the witness’ degree of attention, the accuracy of his prior description of the criminal, the witness’ certainty, and the time between the crime and the identification – criteria initially outlined in Neil v. Biggers (1972). Manson made it clear that identifications can still be admissible despite the presence of suggestive procedures when the identification is deemed reliable according to the five criteria. The defendant has the burden of demonstrating the identification was made under suggestive circumstances that the police improperly created and is unreliable based on the totality of the circumstances.

Extensive research conducted since 1977 has demonstrated that the criteria are incomplete and inadequate measures of reliability. In addition, three of the five reliability criteria in Manson are, themselves, influenced by the presence of suggestion (i.e., the witness’ certainty, witness reports about opportunity to view, and witness reports about degree of attention). Recognizing these deficiencies, the New Jersey Supreme Court ruled that when an identification is challenged by a defendant, all relevant system and estimator variables should be reviewed, including suggestive factors that may not involve police action, such as lightning and distance. If the defendant is unable to demonstrate a strong likelihood of misidentification, the jury will be charged with the task of determining whether the identification was reliable based on the evidence presented in court. Because juries tend to overestimate the accuracy of eyewitnesses and are unfamiliar with the literature establishing the influence of multiple factors on identification accuracy, the court directed a committee to develop new jury instructions addressing case-specific eyewitness identification factors. Unfortunately, as noted above, the effectiveness of these instructions has not been empirically demonstrated.

Relative to New Jersey, the US Supreme Court in its review of Perry v. New Hampshire (2011) was not as receptive to eyewitness research. This was the first case involving eyewitness identification before the US Supreme Court since Manson v. Brathwaite in 1977. The Supreme Court affirmed the state court’s decision that due process protection against unreliable identification evidence applies only to identifications made under suggestive circumstances that are caused by the police. In this instance, the suggestive circumstances were happenstance, involving a woman looking out of her window into a dark parking lot and identifying a single black male among a group of police officers from 100 ft away. Despite research that demonstrates jurors are unable to determine the reliability of eyewitness testimony, the Court ruled that eyewitness evidence is like any other evidence and is therefore at the discretion of the jury to determine its reliability.

Future Directions

As demonstrated by the large number of people who have been wrongfully convicted, the traditional safeguards used by the courts to prevent wrongful convictions based on eyewitness misidentifications have not fully sensitized jurors to factors affecting eyewitness identification accuracy. The recommendation of the court in Henderson to develop case-specific instructions regarding eyewitness factors is a step in the right direction, but it may not be enough.

The Innocence Project has made recommendations focused on improving system variables, including double-blind administration, improving lineup composition, recording confidence statements immediately after an identification, videotaping the entire lineup and identification procedure, and using sequential lineups. Law enforcement agencies across the countries are heeding these recommendations. In addition, the Henderson Special Master made several recommendations not accepted by the New Jersey Supreme Court, but worthy of future attention by the courts. First, the Special Master recommended mandatory pretrial hearings for all cases involving eyewitness identifications. Second, it was recommended that the initial burden be shifted from the defendant, who now needs to establish that suggestive procedures were present during an identification, to the prosecution – the party seeking to introduce identifications into evidence. The prosecution would then have the initial burden to prove an identification was reliable. This in essence treats eyewitness evidence like physical trace evidence.

Focusing the majority of recommendations on improving system as opposed to improving the decision-making ability of jurors leaves open the possibility that a confident eyewitness may outweigh any efforts to understand the circumstances that led to the identification. Yet, some jury reforms have been proposed. For example, researchers have called for a return to 12 member juries and requiring unanimity of verdicts to ensure more thorough decision making. In addition, expert testimony may be the best option in court for sensitizing jurors to factors affecting eyewitness identification accuracy. Future research should focus on how these experts can improve the decision-making ability of jurors.


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