magazine issue 2 2012 / Issue 14

Would you recognize the perpetrator? What do you need to know when you have to make an identification from a lineup?

• written by Melanie Sauerland & Alana C. Krix
• edited by Ishani Banerji

Cognitive Factors

Lineup presentation

The term lineup presentation refers to the context in which the suspect is shown. While a lineup presents the suspect among several foils, a "showup" only consists of one person. Consequently, a showup instantly reveals the identity of the suspect and offers less protection to innocent suspects. A meta-analysis (Steblay, Dysart, Fulero, & Lindsay, 2003) compared identification performance in lineups vs. showups. Looking at conditions in which the perpetrator was present in the array, the hit rates of these two procedures were about the same. However, eyewitnesses were more likely to accurately state that the perpetrator was not present (thus, resulting in a higher correct rejection rate) in showups than in lineups. Despite this, the showups also produced higher false identification rates when the perpetrator was absent.

Another finding discredits the use of showups. Suspects displayed in showups are mostly arrested, merely because they were close to the crime scenes and generally matched the descriptions provided by the witnesses, including the descriptions of the clothes worn. This can have detrimental consequences in cases in which an apprehended innocent suspect happens to wear the same or similar kind of distinct clothing as the real perpetrator did (Dysart, Lindsay, & Dupuis, 2006).

Turning to lineups, there are at least two different options for their presentation: In simultaneous lineups, the lineup members are presented all at once. By contrast, in sequential lineups members are presented one after another (Lindsay & Wells, 1985). While many witnesses may be more at ease with viewing a simultaneous lineup, theoretical considerations suggest identification accuracy should be higher for sequential lineups. Specifically, Lindsay and Wells (1985) argued that simultaneous lineups enable comparisons between the different lineup members. This can lead to a so-called relative judgment in which witnesses are prone to choose the person who most resembles the perpetrator from the lineup. In sequential lineups, however, witnesses come to an absolute judgment. Here, the witness sees one person at a time and for each of them, he or she has to decide whether it is the perpetrator or not. Because of the absence of other possibilities of comparison, a comparison between the memory of the perpetrator and the lineup member is enforced. Another feature of sequential lineups is that the witness is not allowed to reconsider after a decision regarding a lineup member has been made. Indeed, modified versions of the sequential lineup that allow going back to pictures viewed earlier or comparing two pictures at a time are less effective than the original sequential procedure (Lindsay & Bellinger, 1999).

During the past decade, some researchers have argued about the assumed superiority of the sequential lineup (e.g., Lindsay, Mansour, Beaudry, Leach, & Bertrand, 2009; McQuiston-Surrett, Malpass, & Tredoux, 2006). While one camp claimed that sequential lineups lead to a significant reduction of false alarms (Lindsay, 1999; Steblay, Dysart, Fulero, & Lindsay, 2002), others argued that the effect simply went back to a reduction in choosing rates (Ebbesen & Flowe, 2002), thus leading to an increased risk of freeing actual perpetrators (Malpass, Tredoux, & McQuiston-Surrett, 2009).

A recently published meta-analysis including data from 13,143 participants sheds more light on the issue (Steblay, Dysart, & Wells, 2011). The results show that though a sequential lineup is less likely to result in a suspect identification, it is morediagnostic of guilt than a simultaneous one. More specifically, witnesses viewing a sequential lineup were 8% less likely to make a correct identification, but 22% more likely to correctly reject a lineup than witnesses who were presented with a simultaneous lineup.

Thus, even though a witness may intuitively feel like a simultaneous lineup puts him or her in a better position, a sequential lineup is more likely to require an absolute rather than a relative judgment. This, in turn, increases the likelihood of a correct decision.