Fair Forensic-Object Lineups Are Superior to Forensic-Object Showups

• Published in: Journal of applied research in memory and cognition Vol. 9; no. 1; pp. 68 - 82
• Main Authors: Smith, Andrew M., Mackovichova, Simona, Jalava, Shaela T., Pozzulo, Joanna
• Format: Journal Article
• Language: English
• Published: Washigton Elsevier Science 01.03.2020; Society for Applied Research in Memory and Cognition
• Subjects: Face Perception; Female; Human; Male; Theft; Witnesses; Lineups; Showups; Eyewitness identification; Forensic-object identification; Differential-filler siphoning
• ISSN: 2211-3681; 2211-369X
• DOI: 10.1037/h0101843

When presenting a suspect to a witness for an identification attempt, fair lineups are superior to one-person showups. Relative to showups, fair lineups decrease innocent-suspect identifications to a greater extent than culprit identifications (Steblay et al., 2003). We examined whether the lineup advantage extends from facial identification to forensic-object identification. Participants (N = 1906) watched a short video of a car theft and then completed two culprit-present or culprit-absent showups or lineups. Participants first attempted to identify the culprit from the video and then attempted to identify the vehicle from the video. Forensic-object lineups were superior to forensic-object showups to the extent that the cost of an innocent-suspect identification exceeded the cost of a missed culprit identification or to the extent that the base rate of culprit presence was low. Importantly, we are referring to actual costs and base rates in the real world rather than to methods of manipulating witness decision criteria (see Clark, 2012 for a similar approach). Finally, confidence discriminated between accurate and inaccurate suspect identifications for forensic-object lineups, but not for forensic-object showups. General Audience Summary When it comes to presenting a suspect to a witness for an identification attempt, it is better to first surround that suspect with high-similarity known-innocent persons (to use a "fair" lineup) than it is to present the suspect to the witness in isolation (to use a showup). The rationale is that if the suspect is innocent, these known-innocent persons (called fillers) offer the suspect protection from mistaken identification as many witnesses will mistakenly identify a known-innocent filler rather than the innocent suspect. But, because police officers know these fillers are innocent, a mistaken identification of one of these persons will not result in an arrest and potential conviction as it might for the innocent suspect. Critically, relative to showups, the known-innocent fillers in lineups draw more picks away from innocent-suspects than they do from guilty suspects. The result is that lineups lead to a better trade-off between culprit and innocent-suspect identifications than do showups (e.g., Smith, Wells, Lindsay, & Penrod, 2017). We examined whether this lineup advantage extends from facial identification procedures to what we call forensic-object identification procedures. Participants (N = 1906) watched a video of a car theft and then attempted to identify both the culprit and the vehicle from separate showup or lineup procedures. For half of the participants, both the culprit and the target vehicle were present in their respective identification procedures and for the remaining participants neither the culprit nor the vehicle was present in their respective identification procedures. For both the facial and forensic-object identification procedures, we found evidence that lineups were superior to showups. In addition, confidence was helpful at discriminating between accurate and inaccurate suspect identifications for forensic-object lineups, but not for forensic-object showups.