Dekel, D. J., (2006). Viewing composite sketches: Lineups and showups compared. Applied Cognitive Psychology, 20, 383 – 395.
One tool used frequently in the investigation of crimes is the composite sketch. In many cases eyewitnesses to crimes view and/or help in the creation of these composites. But do these composites have an effect on the identifications (or lack thereof) in showups and lineups?
Perpetrator Showup
Lineup
Method
581 individuals participated in the study (244 were used in pilot research). The study was conducted in three phases, with each phase taking place on separate but consecutive days. The first phase consisted of viewing a mock crime slide show depicting the theft of a camera in a picnic setting. After viewing the crime each participant was asked to write a description of the perpetrator.
Phase two of the experiment (day 2) consisted of approximately two thirds of the participant viewing one of two composite drawings of the perpetrator. Half of those participants viewed a biased composite (one that more closely resembled a foil), and the other half of the participants viewed an unbiased composite (one was an equal match to all individuals in the photo lineup). Additionally, the participants were asked to rate the composite on similarity to their memory for the perpetrator on a percentage scale. They were also asked for any changes to the composite that might increase these similarity ratings.
For the final phase (day 3) all participants returned for free recall and recognition tests of their memory for the mock crime. All of the individuals were assigned to one of five identification task conditions (target-absent lineup, target-present lineup, target-absent showup, target-present showup, and target-absent biased showup).
Results
Free recall and recognition questions
Analyses of the written descriptions provided on day one did not show any differences when group designation was based on the composite viewed during phase two. Thus there were no differences in memory before viewing composites.
The similarity ratings obtained on day two were significantly higher for those that viewed the unbiased composite than those that viewed the biased composite.
During phase three the participants completed recognition questions for memory about the mock crime. No significant differences were found based on composite type viewed.
Photo identification task
See Tables 1 & 2
Folks in the no composite condition were more likely to respond don’t know (DK) versus identifying (ID) a photo than those individuals in either composite group.
Ps in the showup conditions were more likely to give a DK response than an ID.
For both target-absent showups and lineups, DK responses were more likely than ID.
Ps in the showup condition were more likely to reject than ID.
For both target-absent showups and lineups, rejection responses were more likely than ID.
Table 3
Ps in the target-absent showups were more accurate than those in the other conditions.
Discussion
Viewing composites (biased or unbiased) facilitated the participants memory of the target. The authors proffer Deffenbacher, Carr, and Leu’s (1981) enhancement effect as an explanation. Overall, showups lead to equal or better accuracy than do lineups. This is contrary to popular belief in the legal realm.
Important Legal
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