Individual Differences in Eyewitness Identification Accuracy between Sequential and Simultaneous Line-ups: Consequences for Police Practice and Jury Decisions.

Background- Although previous research indicated sequential line-up procedures result in fewer mistaken identifications, findings revealed this is at the expense of accurate identifications more typical within simultaneous procedures. As such, a lack of agreement remains surrounding which procedure is superior, and the interaction such procedures have upon eyewitness confidence. The interaction witness demographics have upon identification accuracy also remains unclear.
Participants and Procedure- The opportunistic sample, consisting of 60 people from the general population, was divided evenly into two experimental conditions; Simultaneous (SIM) and Sequential (SEQ). Participants in the sequential procedure observed 12 photographs, one at a time, deciding if they believed the suspect to be the person shown in the current photograph and unable to return to a given picture once they decided the individual shown was not the suspect described. Participants in the simultaneous condition were shown all 12 photographs concurrently and asked to determine which, if any, of the photographs was the suspect described.
Results- Findings displayed no significant differences in identification accuracy between line-up procedures, however significant differences in confidence levels between the two line-up procedures. Additionally, analysis of demographic features showed previous line-up experience to be significantly associated with identification accuracy.
Conclusions- The present research provides new insight into the interaction of eyewitness confidence between line-up techniques offering an alternative explanation of witness confidence as well as procedural fairness. Evidence of practice effects increasing the accuracy of identifications provides beneficial future implications for police line-up procedures and safer jury decisions, often reliant upon identification evidence.