Estimating the reliability of eyewitness identifications from police lineups

Abstract

Laboratory-based mock crime studies have often been interpreted to mean that (i) eyewitness confidence in an identification made from a lineup is a weak indicator of accuracy and (ii) sequential lineups are diagnostically superior to traditional simultaneous lineups. Largely as a result, juries are increasingly encouraged to disregard eyewitness confidence, and up to 30% of law enforcement agencies in the United States have adopted the sequential procedure. We conducted a field study of actual eyewitnesses who were assigned to simultaneous or sequential photo lineups in the Houston Police Department over a 1-y period. Identifications were made using a three-point confidence scale, and a signal detection model was used to analyze and interpret the results. Our findings suggest that (i) confidence in an eyewitness identification from a fair lineup is a highly reliable indicator of accuracy and (ii) if there is any difference in diagnostic accuracy between the two lineup formats, it likely favors the simultaneous procedure.eyewitness identification | confidence-accuracy relationship | simultaneous vs. sequential lineups E yewitnesses to a crime are often called upon by police investigators to identify a suspected perpetrator from a lineup. A traditional police lineup in the United States consists of the simultaneous presentation of six people, one of whom is the suspect (who is either guilty or innocent) and five of whom are fillers who resemble the suspect but who are known to be innocent. Live lineups were once the norm, but, nowadays, photo lineups are much more commonly used (1). When presented with a photo lineup, an eyewitness can identify someone-either the suspect (a suspect ID) or one of the fillers (a filler ID)-or can reject the lineup (no ID). A filler ID is a known error that does not imperil the identified individual, but a suspect ID (including a misidentification of an innocent suspect) does. According to the Innocence Project, eyewitness misidentification is the single greatest cause of wrongful convictions in the United States, having played a role in over 70% of the 333 wrongful convictions that have been overturned by DNA evidence since 1989 (2).In an effort to reduce eyewitness misidentifications, several reforms based largely on the results of mock crime studies have been proposed. In a typical mock crime study, participants become witnesses to a staged crime (e.g., a purse snatching) and then later attempt to identify the perpetrator from a targetpresent lineup (containing a photo of the perpetrator) or a target-absent lineup (in which the photo of the perpetrator is replaced by a photo of the "innocent suspect"). The results of mock crime studies have often been interpreted to mean that (i) eyewitness confidence is an unreliable indicator of accuracy (3, 4) and (ii) suspect ID accuracy is enhanced-and the risk to innocent suspects is reduced-when the lineup members are presented sequentially (i.e., one at a time) rather than simultaneously (5-7). In light of such findings, the state of New J...

Individual differences in eyewitness identification accuracy between sequential and simultaneous line-ups: consequences for police practice and jury decisions

“…The results revealed no significant relationship between the type of line-up procedure undertaken and identification accuracy for either simultaneous or sequential line-ups; participants in the sequential line-up condition were no more accurate in their identifications than those in the simultaneous line-up condition. Such findings are consistent with previous literature, which suggested that, when examining procedural difference effects between simultaneous and sequential techniques, utilising genuine or more realistic line-up procedures to those used within real police identifications, rates of accurate and inaccurate identifications remain similar (Wells et al, 2015;Wixted et al, 2016). Corresponding with Malpass et al (2009) and Meissner et al (2005), the present results suggest that when removing the memory component in line with the mock witness paradigm, sequential line-up procedures provide little superior effects upon eyewitness identifications than those obtained within traditional simultaneous line-ups.…”

“…Alongside acknowledging the need for inclusion of personality assessments, the need to replicate the present findings within a more formal policing environment is required. Despite using an array of images derived from a genuine police investigation alongside an attempt to simulate the layout of a police interview room, the conditions under which participants observed photographs were more akin to laboratory settings than a police station -a factor which some research has shown to impact the strength and direction of results (Wixted et al, 2016). Furthermore, participants were not actual witnesses to the crime in which they were asked to make line-up identifications about and based selections wholly upon standardised descriptions provided to them.…”

“…Similarity of mistakenly identified individuals to the actual perpetrator responsible, strength of the initial memory trace, and distinctions between those who choose to make an identification versus those who did not, have all been found to negate non-significant confidence-accuracy findings (Deffenbacher, 1980;Lindsay, 1986;Sporer, Penrod, Read, & Cutler, 1995). Recent research also obtained evidence that, when examining the relationship between confidence and identification accuracy in genuine police line-up situations, confidence becomes a highly significant and reliable indicator of correct identification (Wixted et al, 2016).…”

“…Some factors have been shown to be related to individual differences in characteristics of the eyewitnesses themselves, including demographic estimators, and the perceived confidence of witnesses in their identifications (Cutler et al, 1990;Meissner & Brigham, 2001;Semmler et al, 2011;Wells & Bradfield, 1999;Wright & Stroud, 2002;Yarmey, 1993). However, predominately, research findings and debate have centred on the police line-up procedure itself, with differences between procedural techniques found to elicit varying levels of accurate identifications and, more importantly, lower rates of false identifications (Brewer & Wells, 2006;Lindsay & Bellinger, 1999;Malpass, Tredoux, & McQuistonSurrett, 2009;Wells, Steblay, & Dysart, 2015;Wixted, Mickes, Dunn, Clark, & Wells, 2016).…”

Why eyewitnesses fail

“…Subsequent studies using a more sophisticated statistical approach based on receiver operating characteristics indicate, however, that the primary effect of the sequential procedure is the elicitation of more conservative responses on the part of the eyewitness: witnesses simply make fewer lineup picks (17). Furthermore, several reports now suggest that witnesses are better able to optimize sensitivity to their memories-that is, they manifest better discriminability-when simultaneous lineups are used (17,(22)(23)(24). Future research may identify how variations of these or other lineup procedures can further improve performance, but the NAS committee on eyewitness identification concluded that there was not sufficient evidence to warrant a change from the traditional simultaneous procedure.…”