The Discrediting Effect in Eyewitness Testimony1

Loftus (1974) had subjects read summaries of criminal trials that contained the testimony of either credible or discredited prosecution eyewitnesses, and found no effect of discrediting an eyewitness. Instead, almost as many subjects voted guilty with a discredited eyewitness as with a credible eyewitness; this led Loftus to the conclusion that jurors tend to overbelieve eyewitness testimony. Loftus's conclusion was subsequently challenged by others who reported a strong discrediting effect. A series of three experiments using college students was conducted to explore the characteristics of trial summaries that might account for the discrepancy in results, such as inclusion of judicial instructions concerning proof beyond a reasonable doubt, or an eyewitness's reaffirmation of his testimony following discrediting. In all cases, a strong discrediting effect was found. Apparently the discrediting effect appears regardless of wide variation in content of trial summaries. The present data do not support the overbelief claim.     

Change Blindness and Eyewitness Testimony

The authors explored the relevance of research on change blindness to eyewitness identification and testimony under intentional and incidental memory conditions. Participants (N = 80, 40 men and 40 women) viewed a video enactment of a burglary in which the identity of the burglar changed at the halfway point of the film. Half of participants were briefed to remember the content, and the other half were not. All were tested for the recall of the content, awareness of the change, and ability to identify either or both of the burglars. Some 61% of participants did not notice the identity change. Rates of detection were significantly higher in participants in the intentional condition, who also recalled significantly more detail from the film. Awareness of change was also significantly related to content recall scores and accuracy of identification of both burglars. The results illustrate the interrelation between the eyewitness and change blindness literatures.     

A Lay Perspective on the Accuracy of Eyewitness Testimony1

To understand more about what laypeople think they “know” about eyewitness testimony, 276 jury-eligible university students were asked to indicate what factors they believe affect the accuracy of eyewitness testimony. In contrast to the large proportion of eyewitness-memory research that concerns system variables, the lay respondents overwhelmingly generated factors related to estimator variables, while system-variable factors such as police questioning and identification procedures were rarely mentioned. Respondents also reported that their own common sense and everyday life experiences were their most important sources of information about the accuracy of eyewitness testimony. Not only do these results clarify the need for further research on the lay perspective of eyewitness testimony, but they also provide some insight into the way in which many jurors might approach cases involving eyewitness evidence.     

Judge's Instruction on Eyewitness Testimony: Evaluation and Revision1

Studies of the reliability of eyewitness identification show that such testimony may frequently be inaccurate; because of this inherent unreliability, the law has established certain safeguards to the use of eyewitness evidence. One safeguard has been the development of an instruction that a judge may use to focus jurors' attention on the eyewitness issue. The effectiveness of this instruction has never been assessed, although other studies confirm that jurors frequently misunderstand or incorrectly use instructions they get from the judge. The purpose of these studies was to evaluate comprehension of this instruction in the context of a videotaped trial and to develop a simplified instruction that would be easier for jurors to understand. Compared to jurors who heard the existing instruction, those with the revised version were more knowledgeable of the factors to consider when listening to eyewitness testimony and were less likely to convict the defendant. A sample of superior court judges in the U.S. thought the simplified instruction was more effective than the existing version at conveying the intended legal concepts to the jury, but also rated it as more strongly biased toward the defense.     

Degree of Detail of Eyewitness Testimony and Mock Juror Judgments1

The influence of the degree of detail of eyewitness testimony on two sides of a court case was investigated in two experiments. In the first experiment subject-jurors read a civil court case involving an automobile-pedestrian accident. The plaintiff and the defendant presented conflicting eyewitness accounts. Judgments of the relative credibility of the eyewitnesses on each side and the percentage of negligence of the parties were influenced by the relative degree of detail of the eyewitness testimony on each side. In the second experiment subject-jurors read a criminal court case involving robbery and murder. The prosecution and defense presented conflicting eyewitness accounts. The degree of detail of the prosecution eyewitness testimony influenced judgments of guilt and judgments of the credibility of the eyewitnesses. An examination of the reasons for verdicts and credibility judgments revealed that some subjects inferred that an eyewitness who gave testimony with a greater degree of detail had a better memory for the trivial details and the culprit than an eyewitness who gave testimony with a lesser degree of detail. Implications of these results for the legal system are discussed.     

心理学关于目击证人证言可靠性实证研究

目击证人的证词在刑事诉讼中有着极为重要的作用,但是由于证人对案件的记忆往往会受到其自身和外界各种因素的干扰,因此,对于目击证人证词可靠性的研究引起了心理学界的关注,西方心理学界自上个世纪七十年代以来,从证人的年龄性别、心理状态、对证人的询问方式以及辨认的情景等方面进行了大量的实证研究,为司法实践提供了重要的启示。本文从以上四个方面全面总结了西方心理学界关于证人证词可靠性的实证研究,并作了分析与展望。     

事件后信息影响目击证言准确性的实验研究

本研究探讨了不同案件类型、不同性别及给予不同的事件后信息对目击证言的影响,征集了男女大学生被试101名,进行了实验研究,研究结果如下:(1)以主体信息的记忆成绩为因变量,性别、案件类型和事件后信息为白变量,得出案件类型主效应显著,事件后信息的主效应显著,性别主效应以及各因素的交互作用都不显著;(2)以情境信息的记忆成绩为因变量,性别、案件类型和事件后信息为自变量,得出事件后信息主效应显著,案件类型和事件后信息之间交互作用效应显著;(3)不同性别、接受不同案件信息的被试对不同信息记忆的确信程度有所不同.     

Eyewitness Testimony: The Effects of Discussion on Recall Accuracy and Agreement

While some previous research has suggested that group discussion may facilitate eyewitness accuracy, other research has drawn attention to the potential dangers of such discussion. The present studies examine this controversy and the interaction between accuracy and agreement following group discussion. It was found that individuals tend to agree in their testimony following group discussion, and are liable to change their original replies to bring themselves into agreement with group leaders' recall. A second experiment focused upon the actual items which witnesses agreed on following discussion. Changing the mode of questioning from interrogative to narrative eliminated differences in magnitude of agreement between discussion and no-discussion groups. As narrative recall leads to reporting of "easy" items, it was suggested that only certain "difficult" items are susceptible to discussion effects. The need for caution regarding the reliance on testimony following witness discussion was stressed.     

The Psychology of Eyewitness Testimony: A Comparison of Experts and Prospective Jurors

To compare people's beliefs about eyewitness testimony with expert opinion, 79 college students and community adults filled out a questionnaire in which they reported whether they agreed or disagreed with 21 statements previously used in a survey of eyewitness experts (Kassin, Ellsworth, & Smith, 1989). The results indicated that there was a significant inter-item correlation of agreement rates but that subjects differed from the experts on 15 of these items. For courts seeking to determine the extent to which juries need assistance in their evaluations of eyewitness evidence, these findings offer a tentative list of topics worthy of either expert testimony or cautionary instructions from the judge.     

Remembrance of Eyewitness Testimony: Effects of Emotional Content,Self‐Relevance,and Emotional Tone1

This experiment concerned the effects of emotional content, self‐relevance, and emotional tone of testimony on memory. Eyewitness accounts of 4 events were constructed that systematically differed in emotionality and self‐relevance. The testimony, captured on videotape, was expressed with or without negative emotion. After viewing one of the videotaped accounts, participants were administered cued‐recall and recognition memory tests. Significant main effects indicated that participants best remembered testimony that was emotional in content, self‐relevant, and negatively expressed. Although emotional content and self‐relevance interacted to affect state anxiety, the latter did not mediate memory effects. Overall, significant gender differences in state anxiety but not memory emerged. Implications for understanding the influence of emotion on juror memory are discussed.     

儿童目击证人取证过程的玩偶辅助研究

儿童目击证人取证是司法实践的难题之一,警方的取证策略和方式被批评对儿童有一定的暗示作用,从而影响儿童证词的准确性。本项研究考察了玩偶辅助的取证模式对学龄前儿童目击证人的影响。实验显示在目击成人与儿童冲突的事件中使用玩偶辅助取证模式显著优于传统的警方提问取证模式,并且不会给学龄前儿童造成严重的误导。     

A Comparison of What U.S. Judges and Students Know and Believe About Eyewitness Testimony

We compared what 160 U.S. judges, 57 law students, and 121 undergraduates know and believe about factors affecting the accuracy of eyewitness testimony. Judges were no more knowledgeable than were undergraduates, and both groups were less knowledgeable than were law students. For all 3 groups, increased knowledge of eyewitness factors was associated with beliefs that might reduce wrongful convictions. Participants in all 3 groups underestimated what potential jurors know about eyewitness testimony. The results suggest that increasing judges' knowledge of eyewitness testimony might help them to reduce wrongful convictions and to more accurately assess when eyewitness experts are needed. The results also suggest that law schools need to do a better job of educating law students about eyewitness testimony.     

The Effects of Discussion on Eyewitness Memory1

This study investigated the effects of witness discussion on the accuracy of recall and misidentifications in eyewitness memory. Dyadic groups who discussed the crime and dyads who made joint memorial decisions about the incident were more accurate in recall than were dyads who discussed noncriminal matters, and a no-discussion group. Collaborative dyads giving joint decisions also were significantly more accurate than were the other groups in rejection of the culprit-absent lineup. The sequential lineup method proved superior to the simultaneous method, regardless of whether or not witnesses discussed the crime prior to identification. It was concluded that discussion and joint decision making by 2 eyewitnesses can improve both eyewitness recall and minimize false identifications in some circumstances.