Eyewitness memory holds significant sway in numerous criminal trials, and substantial psychological research has contributed to its understanding over time. This research paper delves into diverse aspects of eyewitness memory, explores the factors that impact it, discusses techniques for enhancing eyewitness memory, and elucidates the processes involved in evaluating eyewitness memory during investigations and criminal proceedings.
History of Research on Eyewitness Memory
The origins of psychological research in relation to the legal system can be traced back to 1908, when Alfred Binet revealed that the manner in which questions were posed could influence a person’s responses. While this work didn’t immediately impact the legal system significantly, it marked the beginning of empirical research into witness testimony. Shortly after, William Stern applied this research directly to eyewitness testimony, highlighting that eyewitnesses were susceptible to errors influenced by factors like their emotions during the event. Around the same period, Hugo Munsterberg published “On the Witness Stand,” addressing problems related to eyewitness memory and jurors’ challenges in accurately assessing such testimony. Munsterberg’s work faced criticism, with some arguing that psychological research wasn’t suitable for the legal system. Despite methodological limitations, Munsterberg’s contribution was significant as he was the first to systematically study issues tied to eyewitness memory in a scientific manner.
It wasn’t until the 1970s that eyewitness research regained prominence, largely due to the work of Elizabeth Loftus. Using realistic stimuli such as videotaped and live events, Loftus demonstrated that memory in general, including eyewitness memory, could be altered based on how questions were framed by interviewers. Her research, marked by rigorous methodological controls, delved into both the quantity and accuracy of eyewitness memory. This work sparked interest in the field among her students and colleagues, including Robert Buckhout, who unveiled the prevalence of errors in eyewitness identification. While skepticism persisted regarding the utility of eyewitness research in the legal context, the tide began to turn in 1978 when Gary Wells introduced the concept of estimator variables and system variables. This distinction helped critics understand how psychological research could contribute to the legal system and allowed researchers to concentrate on issues practically applicable within the legal framework.
Types of Eyewitness Memory and Factors Affecting Eyewitness Memory
In the realm of eyewitness memory, two broad categories emerge: eyewitness recall and eyewitness identification, corresponding to the traditional distinction between recall and recognition in cognitive psychological research on human memory. Eyewitness recall holds particular significance in criminal investigations. When a crime occurs, responding police officers often conduct interviews with eyewitnesses to gather information related to the crime, including details about the perpetrator(s) and the incident itself. These interviews may occur multiple times during the investigative process. Some of the information recalled by the eyewitness, such as descriptions of weapons or the attire of the perpetrator, can prove crucial later in the investigation or during a trial.
Research on eyewitness recall delves into factors influencing the accuracy of eyewitness descriptions, including the impact of stress levels experienced by the eyewitness and the presence of weapons. A highly studied factor in this context is the effect of witness questioning, focusing on the information provided to witnesses following the event and the manner in which they are questioned about it. Numerous studies have consistently shown that the wording and tone of questions can lead eyewitnesses to provide inaccurate information. In these studies, individuals who witnessed an event were questioned in ways that encouraged subsequent reports containing false details. For instance, participant witnesses were asked either, “Did you see a broken headlight?” or “Did you see the broken headlight?” Despite only one word differing between these two conditions, participants who heard the word “the” rather than “a” were more likely to claim they had seen a broken headlight. While much of the discussed research has centered on adults, it’s important to note that significant effects of post-event information have also been observed in both older adults and children. In fact, children under the age of 3 to 4 and adults over the age of 65 appear to be the groups most susceptible to post-event suggestion.
The act of questioning a witness repeatedly doesn’t just affect the way the witness recalls an event; it can also have a profound impact on the witness’s memory of the event itself. For instance, repeatedly prompting college students to reflect on plausible yet nonexistent events from their childhood (e.g., accidentally spilling punch at a party) led them to eventually accept these events as real. One particularly well-known example is the “Lost in the Mall” experiment. In this experiment, an adolescent boy was asked to recall an incident where he had been lost in a mall as a young child. Initially, the boy claimed not to remember such an event, but he was encouraged to think about it and document his recollections each night, a therapeutic technique known as journaling. After two weeks of this journaling exercise, not only did he recall the event—something that never actually happened—but he also provided specific details, such as the color of the shirt worn by the man who had found him and even the texture of the man’s hand.
Critics of false memory research contend that lab-generated false memories are plausible and relatively harmless. They question whether the findings can be applied to real-world legal and therapeutic scenarios, where recalled memories are often more traumatic and unconventional, such as in cases of childhood sexual abuse.
Eyewitness recognition of perpetrators plays a pivotal role in criminal investigations and case resolution, whether it leads to a trial or a plea bargain. Such recognition can happen spontaneously, like when a crime victim encounters their assailant in public and contacts the police. Alternatively, eyewitness identification can occur through structured identification tests such as showups, photo arrays, and live lineups. These identification procedures often hold significant sway with jurors.
Psychological research on eyewitness identification has delved into various factors believed to affect the accuracy of identifications. These factors encompass the circumstances surrounding the crime, the duration of the eyewitness’s exposure to the perpetrator, the stress experienced by the witness, the presence of weapons, disguises used by the perpetrator, and the time elapsed between the crime and the identification process.
One factor that has garnered substantial attention in psychological studies is the cross-race effect or own-race bias (ORB). This phenomenon suggests that when an eyewitness’s racial background aligns with that of the perpetrator, they are more likely to make an accurate identification. Conversely, when the eyewitness and perpetrator belong to different racial groups, identification accuracy tends to suffer. While there are variations in false identifications—specifically, White participants exhibit a more pronounced ORB effect compared to Black participants—accurate identifications show no significant differences in the ORB effect among participants. One theory regarding the ORB posits that the extent of the ORB effect is contingent on an individual’s level of interracial exposure to the target race. This theory finds support in studies showing that participants residing in areas with more interracial interactions do not exhibit the typical ORB effect observed in those with limited interracial exposure.
Methods of Improving Eyewitness Memory
Differentiating between eyewitness recall and identification accuracy provides valuable insights into how psychological research has contributed to the development of methods aimed at improving eyewitness memory. Practical recommendations stemming from research on eyewitness recall have concentrated on constructing questions that do not lead the eyewitness astray and preventing the implantation of false memories. Additionally, research has explored the potential of hypnosis to enhance eyewitness recall, although the findings from such studies have been discouraging.
One notable success story emerging from research on enhancing eyewitness recall is the cognitive interview technique. The cognitive interview method is grounded in three fundamental processes: memory and cognition, social interactions, and effective communication. The process commences by instructing the eyewitness to close their eyes and mentally reconstruct the event, or ideally, revisit the crime scene if feasible. During this phase, the interviewer should refrain from interruptions and solely pose open-ended questions. Witnesses should be encouraged to provide a multi-perspective account of the event and should respond with “I don’t know” when uncertain, rather than making guesses. Building rapport with the witness is crucial to strike a balance between authority and fostering active participation. Following the eyewitness’s account of the event, the interviewer can employ probing questions to exhaust the memory. Research has demonstrated that when this procedure is carefully and thoroughly applied, it can enhance the eyewitness’s memory of the event without leading to an increase in erroneous information.
Research focused on improving eyewitness identification has also achieved significant progress. Several tests are employed to identify a suspect, with lineups and showups being among the most common. A lineup can be conducted live, where the eyewitness views actual individuals, or through a photo spread, involving a series of photographs. Typically, a lineup includes several fillers, individuals known to be innocent, and one suspect. While it’s possible to include more than one suspect in a lineup, it is generally not recommended for various reasons.
Considerable research has delved into the various facets of lineup administration. Notably, the instructions given prior to lineup administration can significantly influence the likelihood of the witness selecting an individual from the lineup, regardless of whether the actual perpetrator is present. It is advisable to inform the witness that the perpetrator may not be among the lineup members, prompting the witness not to make an identification if they believe the culprit is not present. Equally critical in lineup instructions and administration are the selection of fillers who accompany the suspect. Fillers serve as a control for random guesses, and if a filler is chosen, it indicates a mistaken identification by the eyewitness. It is crucial to select fillers that align somewhat with the witness’s description of the suspect. By ensuring that the fillers resemble the witness’s description of the perpetrator, it helps confirm that the witness’s identification is not solely based on logical deduction.
Additionally, lineup presentation methods have been extensively researched. The two primary presentation types are the simultaneous lineup, where all lineup members are viewed at once, and the sequential lineup, where only one lineup member is shown at a time. Research consistently demonstrates that sequential lineup presentations result in fewer erroneous identifications than simultaneous lineups when the actual culprit is absent from the lineup. However, correct identification rates do not differ between the two presentation modes when the perpetrator is present. Whenever possible, employing a double-blind lineup procedure is recommended. In this procedure, the administrator is unaware of the suspect’s identity, preventing inadvertent transmission of information about the suspect’s identity to the witness.
These procedures have substantially enhanced identification accuracy. Coupled with the increasing number of DNA exonerations in recent years, many states have implemented these reforms to ensure the most impartial and equitable lineup identification procedures. For instance, New Jersey and North Carolina now mandate the use of sequential lineups by police departments and prosecutor offices. Santa Ana, California, and several Minnesota counties have also adopted sequential lineups. In Clinton, Iowa, the arresting officer is barred from the identification room. Numerous cities, including New York and Seattle, have started utilizing computerized programs for presenting photo arrays. Furthermore, committees have been established in Chicago, as well as parts of Wisconsin and Minnesota, to investigate identification procedures with the aim of reducing false identifications.
Evaluating Eyewitness Memory
In a sense, all estimator variables can be seen as postdictors of eyewitness accuracy. While research has predominantly focused on eyewitness recall, testimony, and identification, the study of postdictor variables has been largely confined to eyewitness identification. Among these variables, one of the most extensively examined is eyewitness confidence. This emphasis on confidence is likely due to the fact that jurors tend to perceive confident eyewitnesses as highly persuasive and credible. It intuitively appears that witness confidence should be strongly associated with accuracy, a belief reinforced by the court’s suggestion that jurors may use witness confidence as an indicator of reliability. Regrettably, psychological research has consistently and decisively shown that the link between confidence and eyewitness accuracy is, at best, weak. Moreover, this tenuous relationship diminishes as the time between the event and the expression of confidence lengthens. The absence of a robust connection between confidence and accuracy may be attributed to witnesses frequently relying on misleading information when gauging their confidence. For instance, it has been demonstrated that providing confirmatory feedback to a witness elevates their confidence in their identification. Merely informing a witness that they have chosen correctly boosts their confidence in the accuracy of their identification compared to participants who receive no feedback. This inflation of confidence is particularly noticeable when the participants’ identifications are inaccurate.
Similarly, eyewitness descriptions of the perpetrator serve a vital role in the investigative process, aiding investigators in locating suspects. However, these descriptions are typically incomplete and nondescript, often limited to generic details like “White male, 5 feet 9 inches to 6 feet, approximately 18 to 24 years old.” It is worth noting that while these descriptions tend to lack detail, the provided information is typically accurate, especially when witnesses are asked to describe the assailant without any prompting from investigators. The critical question, then, is whether the accuracy and thoroughness of eyewitness descriptions correlate with identification accuracy. One might assume that witnesses offering more comprehensive and detailed descriptions of the culprit would be more accurate in their identifications. In fact, the U.S. Supreme Court has considered the accuracy of witness descriptions as an indicator of witness reliability. However, research has generally shown that the quality and quantity of witness descriptions are not significantly related to identification accuracy.
Not only do witness descriptions inadequately predict accurate identifications, but they may also potentially hinder subsequent identification accuracy, a phenomenon known as verbal overshadowing. Verbal overshadowing refers to the decline in lineup identification accuracy when a witness is asked to describe the suspect’s face before the lineup is presented. While there exists a weak correlation between witness descriptions and identifications, two factors deviate from this trend. First, witnesses who excel at providing facial descriptions are more likely to benefit from this practice. Second, the link between witness description and identification accuracy becomes stronger when describing the culprit’s face is unusually straightforward, such as when there are distinctive features like facial tattoos or disfigurements.
Another estimator variable believed to predict identification accuracy is the swiftness of the identification process. The underlying logic is that witnesses who had a clear view of the culprit and possess vivid memories of the crime should be able to promptly and confidently identify the perpetrator. In most cases, research has consistently supported this reasoning. Additionally, it has been observed that witnesses who report that the suspect’s face immediately stood out to them during the lineup tend to make more accurate identifications than those who deliberated longer. Hence, there exists a robust relationship between accuracy and the speed of identification, with faster identifications generally yielding greater accuracy.
Eyewitnesses in the Courtroom
Considerable research has delved into how jurors assess eyewitness memory and whether their evaluations can be enhanced. Through trial simulation methods, research indicates that jurors frequently fail to consider factors that are known to affect eyewitness memory, such as the witness’s level of stress, the phenomenon of weapon focus, and the influence of suggestive identification procedures. Additionally, jurors often rely on factors that have a weak correlation with identification accuracy. A case in point is witness confidence, which significantly sways jurors’ assessments of eyewitness identifications. In these studies, highly confident witnesses exert considerable influence, leading jurors to convict defendants based on the testimony of confident witnesses.
The apparent challenges jurors face in evaluating eyewitness identification procedures in line with the research findings have led some psychologists to advocate for the presence of knowledgeable psychologists as expert witnesses in court. These experts do not pass judgment on the accuracy of the identification but instead aim to provide jurors with all the pertinent information to make an informed decision when assessing the reliability of the witness. However, not all participants in the legal system share a consensus on the effectiveness or necessity of eyewitness testimony during trials. Some argue that such testimony may introduce bias, while others claim it is redundant because matters related to memory are considered common knowledge (a viewpoint at odds with research findings). Although research has examined the impact of expert testimony on factors affecting eyewitness accuracy, the results are mixed regarding its influence on jurors.
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