Eyewitness Identification Is a Visual Search Task

The simultaneous six-pack photo lineup is a standard eyewitness identification procedure, consisting of one police suspect plus five physically similar fillers. The photo lineup is either a target-present array (the suspect is guilty) or a target-absent array (the suspect is innocent). The eyewitness is asked to search the six photos in the array with respect to a target template stored in memory (namely, the memory of the perpetrator's face). If the witness determines that the perpetrator is in fact in the lineup (detection), then the next step is to specify the position of the perpetrator's face in the lineup (localization). The witness may also determine that the perpetrator is not present and reject the lineup. In other words, a police lineup is a detection-plus-localization visual search task. Signal detection concepts that have long guided thinking about visual search have recently had a significant impact on our understanding of police lineups. Expected final online publication date for the Annual Review of Vision Science, Volume 7 is September 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Digital Detectives: Websleuthing Reduces Eyewitness Identification Accuracy in Police Lineups

Eyewitnesses to crimes sometimes search for a culprit on social media before viewing a police lineup, but it is not known whether this affects subsequent lineup identification accuracy. The present online study was conducted to address this. Two hundred and eighty-five participants viewed a mock crime video, and after a 15–20 min delay either (i) viewed a mock social media site including the culprit, (ii) viewed a mock social media site including a lookalike, or (iii) completed a filler task. A week later, participants made an identification from a photo lineup. It was predicted that searching for a culprit on social media containing the lookalike (rather than the culprit) would reduce lineup identification accuracy. There was a significant association between social media exposure and lineup accuracy for the Target Present lineup (30% more of the participants who saw the lookalike on social media failed to positively identify the culprit than participants in the other conditions), but for the Target Absent lineup (which also included the lookalike) there was no significant association with lineup identification accuracy. The results suggest that if an eyewitness sees a lookalike (where they are expecting to see the culprit) when conducting a self-directed search on social media, they are less likely to subsequently identify the culprit in the formal ID procedure.

Optimizing the selection of fillers in police lineups

A typical police lineup contains a photo of one suspect (who is innocent in a target-absent lineup and guilty in a target-present lineup) plus photos of five or more fillers who are known to be innocent. To create a fair lineup in which the suspect does not stand out, two filler selection methods are commonly used. In the first, fillers are selected if they are similar in appearance to the suspect. In the second, fillers are selected if they possess facial features included in the witness’s description of the culprit (e.g., “20-y-old white male”). The police sometimes use a combination of the two methods by selecting description-matched fillers whose appearance is also similar to that of the suspect in the lineup. Decades of research on which approach is better remains unsettled. Here, we tested a counterintuitive prediction made by a formal model based on signal detection theory: From a pool of acceptable description-matched photos, selecting fillers whose appearance is otherwise dissimilar to the suspect should increase the hit rate without affecting the false-alarm rate (increasing discriminability). In Experiment 1, we confirmed this prediction using a standard mock-crime paradigm. In Experiment 2, the effect on discriminability was reversed (as also predicted by the model) when fillers were matched on similarity to the perpetrator in both target-present and target-absent lineups. These findings suggest that signal-detection theory offers a useful theoretical framework for understanding eyewitness identification decisions made from a police lineup.

Active exploration of faces in police lineups increases discrimination accuracy

Eyewitness identifications play a key role in the justice system, but eyewitnesses make errors, often with profound consequences. Errors are more likely when the witness is of a different race to the suspect, due to a phenomenon called the Own Race Bias (ORB). ORB is characterized as an encoding-based deficit, but has been predominantly tested using static photographs of people facing the camera. We used findings from basic science and innovative technologies to develop and test whether a novel interactive lineup procedure, wherein witnesses can rotate and dynamically view the lineup faces from different angles, improves witness discrimination accuracy and attenuates the ORB, compared to the most widely used procedure in laboratories and police forces around the world—the static frontal-pose photo lineup. No novel procedure has previously been shown to improve witness discrimination accuracy. In Experiment 1, participants (N=220) identified own-race or other-race culprits from sequentially presented interactive lineups or static frontal-pose photo lineups. In Experiment 2, participants (N=8,507) identified own-race or other-race culprits from interactive lineups that were either presented sequentially, simultaneously wherein the faces could be moved independently, or simultaneously wherein the faces moved jointly into the same angle. Interactive lineups enhanced witnesses’ discriminability compared to static lineups, especially when they were presented simultaneously, for both own-race and other-race identifications. Our findings suggest that ORB is an encoding-based phenomenon, and exemplify how basic science can be used to address the important applied policy issue on how best to conduct a police lineup and reduce eyewitness errors.

Child Witness Expressions of Certainty are Informative

Children are frequently witnesses of crime. In the witness literature and legal systems, children are often deemed to have unreliable memories. Yet, in the basic developmental literature, young children can monitor their memory. To address these contradictory conclusions, we reanalysed the confidence-accuracy relationship in basic and applied research. Confidence provided considerable information about memory accuracy, from at least age 8, but possibly younger. We also conducted an experiment where children in young- (4–6 years), middle- (7–9 years), and late- (10–17 years) childhood (N=2,205) watched a person in a video, and then identified that person from a police lineup. Children provided a confidence rating (an explicit judgement), and used an interactive lineup—in which the lineup faces can be rotated—and we analyzed children’s viewing behavior (an implicit measure of metacognition). A strong confidence-accuracy relationship was observed from age 10, and an emerging relationship from age 7. A constant likelihood ratio signal-detection model can be used to understand these findings. Moreover, in all ages, interactive viewing behavior differed in children who made correct versus incorrect suspect identifications. Our research reconciles the apparent divide between applied and basic research findings and suggests that the fundamental architecture of metacognition that has previously been evidenced in basic list-learning paradigms also underlies performance on complex applied tasks. Contrary to what is believed by legal practitioners, but similar to what has been found in the basic literature, identifications made by children can be reliable when appropriate metacognitive measures are used to estimate accuracy.

Rethinking the Reliability of Eyewitness Memory

Although certain pockets within the broad field of academic psychology have come to appreciate that eyewitness memory is more reliable than was once believed, the prevailing view, by far, is that eyewitness memory is unreliable—a blanket assessment that increasingly pervades the legal system. On the surface, this verdict seems unavoidable: Research convincingly shows that memory is malleable, and eyewitness misidentifications are known to have played a role in most of the DNA exonerations of the innocent. However, we argue here that, like DNA evidence and other kinds of scientifically validated forensic evidence, eyewitness memory is reliable if it is not contaminated and if proper testing procedures are used. This conclusion applies to eyewitness memory broadly conceived, whether the test involves recognition (from a police lineup) or recall (during a police interview). From this perspective, eyewitness memory has been wrongfully convicted of mistakes that are better construed as having been committed by other actors in the legal system, not by the eyewitnesses themselves. Eyewitnesses typically provide reliable evidence on an initial, uncontaminated memory test, and this is true even for most of the wrongful convictions that were later reversed by DNA evidence.

The Police Lineup

Police lineups are an essential tool of justice but remain dangerous. Six problems still to be dealt with sufficiently are (a) the overbelief in lineup “identifications,” (b) the all-or-none nature of the lineup, (c) similarity of the foils to the suspect, (d) similarity of innocent suspects to the offender, (e) failures to choose the offender, and (f) the small size of the lineup. This article discusses these problems and suggests a radical departure in procedure. The proposed method would have witnesses view more than a hundred foils, have them choose foils by their own judgment of similarity to the offender, and allow multiple choices from the lineup.