Refining the Blank Lineup Procedure: How Should We Instruct Eyewitnesses?

Presenting a blank lineup—containing only fillers—to witnesses prior to showing a reallineup might be useful for screening out those who pick from the blank lineup as unreliablewitnesses. We show that the effectiveness of this procedure varies depending on instructionsgiven to witnesses. Participants (N = 462) viewed a simulated crime and attempted to identifythe perpetrator from a lineup approximately one week later. Rejecting a blank lineup wasassociated with greater identification accuracy and greater diagnosticity of suspectidentifications, but only when witnesses were instructed prior to the blank lineup that theywould view a series of lineups; the procedure was ineffective for screening when witnesseswere advised they would view two lineups or received no instruction. These results highlightthe importance of instructions used in the blank lineup procedure, and the need for betterunderstanding of how to interpret choosing patterns in this paradigm.