Law enforcement should take into account estimator variables--factors that influence eyewtiness testimony and are under the control of the criminal justice system--and system variables--factors that influence eyewitness testimony and are under the control of the criminal justice system and should put forth preventative measures to reduce wrongful convictions due to eyewitness identification errors.
The Issue of Memory
Post-Event Factors That May Affect Eyewitness Identification
Interviews with Witnesses
Situational Factors That May Affect Eyewitness Identification
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Estimator Variables that Affect Eyewitness Identification Accuracy
Safeguards and Protections
Section's Main Idea: “Before we can understand the complexity of eyewitness memory, we must discuss some basic principles of memory. The most common model postulates three stages in memory processing: encoding, storage, and retrieval. Memory errors can occur at one, two, or all three stages” (BCampus, 2013).
Section’s Main Idea: “To this point, we have discussed many of the factors that contribute to mistaken identifications. We now turn to some of the safeguards or protections that can be used to decrease the chances that innocent people will be mistakenly identified, and if they are identified, that they will not be convicted of a crime. These safeguards or protections fall into two main categories: those that can be implemented during police investigation procedures, especially lineups, and those that can be implemented within the courtroom” (BCampus, 2013).
Section’s Main Idea: “The process of interviewing a witness so as to maximize the amount of accurate information and minimize the amount of inaccurate information retrieved has been the subject of a considerable amount of research. In this section, we describe six general principles of interviewing witnesses and introduce one particular protocol that has been very successful, the Enhanced Cognitive Interview (ECI)” (BCampus, 2013).
Section’s Main Idea: "Situational factors may play a role in mistaken eyewitness memory. The following sections review the research on various situational factors" (BCampus, 2013).
Section’s Main Idea: “There are many factors that can affect the accuracy of identifications, including passage of time, the environment and duration of the event, the race of individuals involved, and unconscious transference. We will look at each of these factors in the following sections” (BCampus, 2013).
Claim: “At the encoding stage, we don’t simply passively encode stimuli in the environment; we actively interpret our experiences. Expectations that are formed long before an event occurs may predispose us to remember the event in certain ways” (BCampus).
Evidence: “In Connolly and Price (2013), a former bank teller described her recollection of a particularly violent robbery that she witnessed. Immediately after the robbery when she described what had happened, she reported with absolute certainty that the robbers were dressed in black. When she saw the videotape of the robbery, she discovered that they were dressed in plaid shirts! In Greenwald, Oakes, and Hoffman (2003), participants played a timed video game in which they were to “shoot” a suspect if he carried a gun but not if he carried a harmless object (e.g., a camera). The object was sometimes held by a black man and sometimes by a white man. Participants had more trouble distinguishing a gun from a harmless object when the man was black than when he was white, and they were faster to shoot when a gun was held by a black man than by a white man. In both of these studies, the pre-experimental expectations affected the way the event was encoded in the first place. From the very beginning, memory of a complex event may be an incomplete record of that past event. It may even be a biased record of the event.”
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Claim: “Information about a past event is not stored in a veridical videotape-like manner that we can access whenever we need to; it is a compilation of information from a variety of sources that combines to allow us to “know” what occurred at some past time” (BCampus).
Evidence: “Accordingly, information acquired before and after the event influences what we report remembering about the target event (Bartlett, 1932; Rubin, Schrauf, & Greenberg, 2004). In terms of the effect of post-event information, the classic Loftus studies launched extensive research on eyewitness’s suggestibility (e.g., Loftus, 1975, 1979, 2000). Using a variety of stimuli and methodologies, Loftus demonstrated that a sizable minority of participants report that they perceived details during a past event when in fact they were only told about the details after the event. The topic of suggestibility is discussed in more detail below” (BCampus).
Claim: “When we encounter an event, we selectively attend to and encode a subset of event details. Selective attention is particularly relevant when the event is complex and extensive, as more details are selected out of attention, resulting in a memory trace that is incomplete” (BCampus).
Evidence: “To illustrate the impact of selective attention, Powers, Andriks, and Loftus (1979) conducted a study in which male and female witnesses to a purse snatching described what they had seen. Relative to females, males reported more details about the culprit, suggesting they paid more attention to the culprit. On the other hand, females appeared to have paid more attention to the victim” (BCampus).
Selective attention can leave out important details regarding a criminal offense because we tend to focus on what matters to us rather than the grand scheme of things, as illustrated in the Powers, Andriks, and Loftus 1979 study.
Our own biases and misconceptions can provide a false report of an event.
Instead of memory being recorded in a videotape-esque manner, it is instead recorded using a hodgepodge of information from before and after an event.
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Courtroom: Safeguards and Protections
Police Investigation: Safeguards and Protections
Claim: “Research on facial recognition suggests a positive relationship between time and accuracy such that the longer witnesses are exposed to a perpetrator, the more accurate their eyewitness testimony will be (Memon, Hope, & Bull, 2003). There is, however, a tendency for people to overestimate the duration of brief events and underestimate the duration of lengthy events” (Bcampus, 2013).
Evidence: “Penrod and Cutler (1999) have indicated that these overestimates tend to be about three or four times the actual length of the event. Therefore, witnesses who see a perpetrator for only 30 seconds may estimate that they were exposed to the perpetrator for two minutes. An exposure time of 30 seconds does not allow witnesses much time to pay attention to, and note facial and other physical features of, the perpetrator. Of course, as discussed previously, if the perpetrator has a weapon, witnesses will spend even less time observing facial and physical features” (Bcampus, 2013).
Claim: “Several environmental factors can affect the accuracy of eyewitness identification (Figure 8.2). The amount and type of light available at the crime scene affect how well eyewitnesses are able to see and, therefore, how well they are able to perceive the events as they unfold” (Bcampus, 2013).
Evidence: “Research has indicated that it is difficult to accurately detect colours in monochromic lighting, such as that given off by a streetlight. Fog, as well as the presence of rain, snow, or other precipitation, also affects visibility and thus serves to lower the potential for accurate eyewitness information. The distance between the witness and the observed event is a factor, as is the presence of additional simultaneous activity or other distractors” (Bcampus, 2013).
Claim: “As with any memory, recall drops off as time passes” (BCampus).
Evidence: “Shepard (1983) exposed witnesses to an irate stranger for 45 seconds and then asked the witnesses to pick the stranger out of a video lineup after varying lengths of time. After a one-week delay, 65 percent of the witnesses were able to make an accurate identification, but after an 11-month delay, only 10 percent of the witnesses made an accurate identification. Thus, the rate of accurate identifications decreased over time. Cutler, Penrod, and Martens (1987) also found this to be true: that false identifications increase over time” (BCampus).
Memory and accurate identifications of a culprit diminishes as time elapses.
Environmental factors (i.e., lighting, fog, precipitation) can influence the accuracy of eyewitness identification negatively.
The more time one views a perpetrator, the more likely one is to correctly identify the perpetrator, but individuals tend to overestimate or underestimate the time in which an event occurred
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Section’s Main Idea: “Aside from situational factors that occur at the time of the event, post-event factors may also play a role in mistaken eyewitness reports. Let’s consider some of the more common post-event factors that may account for mistaken eyewitness testimony” (BCampus).
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Claim: “The passage of time affects memory for events and eyewitness identification. A more complete discussion of this factor is presented in the section on eyewitness identification” (Bcampus, 2013).
Evidence: NA
Claim: “Loftus and her colleagues showed that the way in which questions are worded could also influence eyewitness recall” (Bcampus, 2013).
Evidence: “Participants were asked to estimate the speed of two cars when they “contacted,” “hit,” or “smashed” each other. The estimated speeds varied significantly as a function of the wording used. Participants estimated the cars to be traveling at a slower speed when the word “contacted” was used than when the word “smashed” was used in the question. In addition, participants were much more likely to recall seeing a broken headlight when they were asked whether they saw “the” broken headlight than when they were asked whether they saw “a” broken headlight. Thus, subtle variations in wording or subtle suggestions implanted in a question or statement about an event can result in substantial variation in the eyewitness’s recall of the event” (Bcampus, 2013).
Claim: “Suggestions implanted within questions can influence the recall of eyewitnesses” (Bcampus, 2013).
Evidence: “In one series of studies, Loftus and Palmer (1974) showed participants a film of a car crash. Half of the participants were asked about the speed of the car when it “turned right,” and half were asked to estimate the speed when the car “ran the stop sign.” Later, participants were asked whether they saw a stop sign; 35 percent of the group who were asked about the speed of the car when it turned right indicated that they saw a stop sign, whereas 53 percent of the group who had been asked about the speed of the car when it ran the stop sign reported seeing a stop sign. When a suggestion about the presence of a barn was included in the questioning, 17 percent of participants reported seeing a barn when, in fact, there was no barn in the film” (Bcampus, 2013).
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Claim: “There is an interaction between passage of time and suggestion. The more time that passes between a witnessed event and a misleading question or other attempt to implant a suggestion, the more effective the suggestion will be in distorting the accuracy of the eyewitness’s report (Hoffman, Loftus, Greenmun, & Dashiell, 1992)” (Bcampus, 2013).
Evidence: “Three explanations for the suggestibility effect have been offered (e.g., Zaragoza, Belli, & Payment, 2007):
“Misinformation Acceptance: This is the process in which participants guess or respond in a way they think the questioner wants them to respond. Because the questioner presented the misinformation or otherwise expressed a desire to hear the misinformation, it seems reasonable to participants that the suggestion is the desired response” (Bcampus, 2013).
“Source Misattributions: Participants recall both the experienced detail and the suggested detail but cannot remember how each detail was learned, and sometimes inaccurately attribute the suggested detail to the experience” (Bcampus, 2013).
“Memory Impairment: The misinformation impairs participants’ ability to remember the experienced details (that is, it either renders the experienced detail inaccessible or destroys/alters it)” (Bcampus, 2013).
Suggestive questioning can cause people to believe implanted suggestions had occurred when, in fact, it did not.
The wording of questions also can play a role in how witnesses recall an instance.
As more time passes, one becomes more vulnerable to incorporating misleading information into their original report.
Time has a direct association with memory retention of events.
Claim: “Generally, we recall the gist and central elements of emotional events more accurately than we do the gist and central features of non-emotional events” (Bcampus, 2013).
Evidence: “There are at least four possible reasons for this: (1) events are emotional because they relate to things or include details that we care about, and this leads to better memory for those details; (2) we tend to rehearse arousing events more than neutral events, and rehearsal enhances memory; (3) arousing events may activate amygdala-based processing that leads to particularly vivid memories (not necessarily accurate, but memories that are experienced as vivid); and (4) there is a narrowing of attention to the central details of events that are arousing, leading to good memory for the central details at the expense of memory for peripheral details” (Bcampus, 2013).
In comparison to mundane events, stressful or arousing events are more easily retained.
Claim: “This last point is known as the Easterbrook hypothesis, which states that as arousal increases, attention to the most salient elements of the event is sharpened at the expense of attention to the less central elements of the event” (BCampus, 2013).
Evidence: “Thus, compared to memory for a neutral event, memory for the central details of a negative event is superior but memory for peripheral details is poorer. Reisberg and Heuer (2007) suggest that the narrowing of attention may not be entirely due to arousal. Part of the effect could be explained because the central details of emotionally arousing events are typically unusual in some way, and unusual details command attention. Because we have limited attentional resources, some attention is diverted from peripheral details to the central details, leading to improved memory for the central details and impoverished memory for peripheral details” (BCampus, 2013).
Stress can help us remember the most important details of an unusual event, but in the process of evaluating the event, we neglect the peripheral details of said event.
Claim: “As a final and essential gloss on all research on memory for arousing and stressful events, much depends on how the individual experiences the event. The effects of arousal and stress will only take place if the event is experienced as such” (Bcampus, 2013).
Evidence: “Some events are inherently stressful and will be experienced as such by most people. However, in the “normal” course of the day, some events may be experienced as highly stressful for some and moderately upsetting or even benign for others (Hervé, Cooper, & Yuille, 2007; Reisberg & Heuer, 2007). As an example, think about beginner swimming lessons—fun for some and terrifying for others!” (Bcampus, 2013).
The levels of stress one experiences during a inherently stressful event are highly suggestive because what may be very arousing for someone can be moderately upsetting for others (e.g., swimming lessons).
Claim: “Research has shown that eyewitnesses are significantly influenced by the visual presence of a weapon" (BCampus, 2013).
Evidence: "When a weapon, such as a knife or gun, is present, witnesses’ memory for other details is impaired (Kramer, Buckhout, & Eugenio, 1990). It appears that eyewitnesses narrow their attention, spending more time focusing on the weapon and less time on other aspects of the situation, including the physical characteristics of the event and the perpetrator (Figure 8.1). This weapon focus effect has been demonstrated even when people watch a film of a crime being committed (Tooley, Brigham, Maass, & Bothwell, 1987)” (Bcampus, 2013).
When a culprit is brandishing a firearm, witnesses tend to gravitate their attention to the weapon which results in witnesses' memory being impaired.
General Principles for Interviewing Witnesses
Enhanced Cognitive Interview (ECI)
Claim: “Remain neutral and objective” (Bcampus, 2013).
Evidence: “Interviewers must not direct the dialogue or reveal their biases. There are a number of ways interviewers can inadvertently introduce their beliefs about the event to the witness: by selectively reinforcing responses that are consistent with their hypothesis, verbally and non-verbally; by ignoring or otherwise discounting statements that are inconsistent with their biases; by asking leading questions; and by taking control of the interview” (Bcampus, 2013).
Claim: “Begin the interview by developing rapport with the witness” (Bcampus, 2013).
Evidence: “This serves two important goals. First, the witness is being asked to work hard to provide a detailed description of an unpleasant experience to a stranger (the police officer) who is assumed to be an expert on crime. This request will be more successful if the police officer can reduce some of the stress by developing rapport. Second, rapport building is also a first step in transferring control of the interview to the witness” (Bcampus, 2013).
By having more of an intimate dynamic with a witness, this allows the witness to feel more comfortable and willing to provide the investigator with more detailed information about an event, and this also allows the interviewee to have more control of the interview.
By not introducing your own bias and prejudices, you can achieve the most accurate witness report as an interviewer.
Claim: “Avoid the use of leading (or misleading) questions” (Bcampus, 2013).
Evidence: “Recall the suggestibility research discussed earlier. Closed questions are more likely than open questions to contain misleading information, and this could contaminate and compromise subsequent testimony. Wright and Alison (2004) found that 9 percent of the questions asked by the police officers were leading questions” (Bcampus, 2013).
Leading questions can diminish the credibility of a subsequent witness testimony.
Claim: “Now let’s look at a specific interviewing technique. The original Cognitive Interview (CI) was developed in response to request made to two psychologists to help in training and guiding police interviews (Fisher, 2010; Geiselman, Fisher, MacKinnon, & Holland, 1985)...It has all the characteristics of a good interview, including beginning with rapport building and transferring control to the interview to the witness” (Bcampus, 2013).
Evidence: “In several studies that compared the amount and accuracy of details obtained from the ECI to those obtained from standard police interviews, the results were startling. Some researchers reported a 35 percent increase in correct information reported with the ECI compared to a standard police interview. Based on meta-analyses, Kohnken, Milne, Memon, & Bull (1999) and Memon, Meissner, and Fraser (2010) concluded that the majority of the research has found that the cognitive interview elicits more correct information compared to a control interview; however, there is also a small increase in the amount of incorrect information reported” (Bcampus, 2013).
The Enhanced Cognitive Interview, which includes all of the general principles for interviewing witnesses, is a significantly better alternative than traditional interviews, resulting in a 35 percent increase in correct information reported. However, there is a small increase in false information reported.
Claim: The second rule proposed by Wells and colleagues (1998) is that “eyewitnesses should be told explicitly that the person in question might not be in the lineup or photo spread and therefore should not feel that they must make an identification. They should also be told that the person administering the lineup does not know which person is the suspect in the case (p. 629)” (Bcampus, 2013).
Evidence: “As discussed earlier in this chapter, eyewitnesses find it difficult not to select someone from a lineup or photo spread; instead of indicating that the perpetrator is not present, they will most often select the person from the lineup or photo spread who most closely resembles the perpetrator. Instructing the eyewitnesses that the suspect might not be in the lineup or photo spread reduces the chances that they will make a false identification” (BCampus, 2013).
Claim: “The third rule that Wells and colleagues (1998) recommended was that “the suspect should not stand out of the lineup or photo spread as being different from the distractors based on the eyewitness’ previous description of the culprit or based on other factors that would draw extra attention to the suspect” (Bcampus, 2013).
Evidence: “The critical issue here is to ensure that an innocent suspect in the lineup or photo spread does not stand out from the foils in any significant way that would cause this person to be selected more than would be expected on the basis of chance. One way to test whether this rule has been met with any particular lineup is through the use of a mock witness procedure. Mock witnesses (people who have never seen the perpetrator) are given the eyewitness’s description of the perpetrator and then shown the lineup and asked to select the person they believe is the perpetrator. If the mock witnesses are able to figure out who the suspect is, this suggests a problem with the lineup. In theory, if there are six members of a lineup or photo spread, each member should be selected by one-sixth of the mock witnesses” (Bcampus, 2013).
Claim: “Wells and his colleagues (1998) recommended that the first rule be that “the person who conducts the lineup or photo spread should not be aware of which member of the lineup or photo spread is the suspect” (p. 627)” (Bcampus, 2013).
Evidence: “The lead detective or investigator on a case is most often the person who assembles and conducts the lineup or photo spread. Thus, as in the experimenter situation, it is possible that the lead investigator will convey verbal and non-verbal cues to the eyewitness regarding which member of the lineup is the suspect. For these reasons, it has been recommended that the person who conducts the lineup or photo spread should be blind as to which member is the suspect” (Bcampus, 2013).
Claim: “It appears that jurors are so swayed by eyewitness evidence that even testimony indicating that an eyewitness did not view the perpetrator under adequate conditions does not change the chances of conviction significantly” (BCampus, 2013).
Evidence: “In a classic study, Loftus (1979) presented three groups of mock jurors with evidence from a criminal case… Thus, one of the challenges for the defence in any trial is to attempt to educate the jury about the factors that may impact the accuracy of an eyewitness’s testimony. Aside from cross-examining eyewitnesses in an attempt to bring to light possible weaknesses in their testimony, the defence can educate the jury about some of these factors in two other ways: expert testimony about eyewitness testimony and judicial instructions” (BCampus, 2013).
Claim: “Psychologists may be called as experts to testify about eyewitness testimony. In general, this type of testimony focuses on the factors that may impact the accuracy of eyewitness testimony in an attempt to educate the jury about the possibility of false or mistaken testimony. The psychologist will explain the research on eyewitness testimony to the judge or to the jury but will not comment on the accuracy of the particular witness” (Bcampus, 2013).
Evidence: “Cutler and his colleagues (1990b) conducted a series of studies to examine the impact of expert testimony…Thus, it seems that the presentation of expert testimony at trial can serve to educate jurors about the relevant factors for evaluating eyewitness testimony” (Bcampus, 2013).
Claim: “The fourth rule recommended by Wells and colleagues (1998) is that “a clear statement should be taken from the eyewitness at the time of the identification and prior to any feedback as to his or her confidence that the identified person is the actual culprit (p. 635)” (Bcampus, 2013).
Evidence: “As discussed earlier in this chapter, an eyewitness’s confidence tends to increase over time, with successive identifications, and with post-identification information provided to the eyewitness. In addition, we know that jurors can be strongly persuaded by a witness’s level of confidence. If eyewitnesses are given feedback that they identified the person the police suspected, their confidence in the identification will be raised. In addition, asking eyewitnesses to recall the level of confidence they had at the time of the identification is not reliable, especially when they have been given feedback about the identification. Thus, the only way to accurately assess eyewitnesses’ confidence in the identification is to ask for their confidence level at the time of the identification. This way, any significant discrepancy between the level of confidence indicated by the eyewitness at the time of the identification and during testimony at trial can be noted by the jury and considered accordingly” (Bcampus, 2013).
Even when it is presented to a jury that the eyewitness evidence in question has flaws, it does not have any notable change in the rate at which defendants are falsely convicted.
The presentation of expert testimony regarding the limitations of eyewitness identifications caused participants to place less emphasis on eyewitness testimony and eyewitness confidence.
With successive identifications, the confidence of the witness increases, so a clear statement about the eyewitness' confidence prior to any feedback regarding whether or not an individual is a culprit can counter this during testimony.
Because lead detectives or investigators may give off verbal or non-verbal cues that insinuate that an individual is a culprit, Wells recommends that the lineup conductor should not know who the suspect is.
When you instruct the witness that the suspect may or may not be present in the lineup, it prevents the witness from feeling pressured to select someone who may closely resemble a description of a suspect and lessens the chances that they will make a false identification.
Wells and his colleagues advise police officials to not make the suspect ostracized from other foils because this can cause the eyewitness to select an innocent individual, and this error can be identified with a mock witness procedure.
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Claim: “There is no evidence that members of one race are better or worse at eyewitness identification than members of another race. However, there is evidence to suggest that people are better at recognizing the faces of members of their own race than they are at recognizing the faces of members of other races” (Bcampus, 2013).
Evidence: “Meissner and Brigham (2001) conducted a meta-analysis of 39 studies and found that within-race identifications were significantly more likely to be accurate than cross-race identifications (also known as own-race bias). Various reasons have been proposed for why people are better at identifying others from their own race more accurately. Some researchers have suggested that we classify the facial features of someone from our own race in more detail, and less superficially, than we do the facial features of someone from another race (Fiske & Taylor, 1991; Malpass & Kravitz, 1969). This may be a result of a greater familiarity with those from our own race. Meissner and Brigham (2001) found that as our contact with members of different racial groups increases, our ability to recognize faces from those racial groups improves” (Bcampus, 2013).
Backed by numerous studies, individuals are less accurate at identifying members of another race.
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Claim: “Another potential source of error that can affect information stored in memory concerns repeated reporting. Often, witnesses are asked to recount what they remember several times” (BCampus, 2013).
Evidence: “Often, witnesses are asked to recount what they remember several times. Each time the experience is recounted, a memory trace of the recollection is formed and stored. Memory traces of what was reported may become confused with details that were perceived during the event. In other words, we have trouble remembering what we actually perceived versus what we reported having perceived. This could lead to inaccuracies if the prior reports contain errors ( Johnson, Hashtroudi, & Lindsay, 1993)” (BCampus, 2013).
If a witness is asked to recount an occurrence several times, s/he is more likely to find it difficult to distinguish what we reported perceiving versus what we actually perceived.