The effects of explicit “Not Present” and “Don't Know” response options on identification decisions in computer-administered lineups

Eyewitness researchers recommend that “not present” and “don't know” response options should be presented with police lineups. Although it is important that witnesses—most of whom are unlikely to be familiar with the identification task—are fully cognizant of all response options available to them, an understanding of how explicit non-identification options affect performance is lacking. Across four experiments, including 3,633 participants and 8 different stimulus sets, we tested the effects of including non-identification options in computer-administered lineups. When explicit non-identification options were presented, target-present and -absent choosing decreased. This decrease in choosing was characterized by a shift from filler identifications to lineup rejections. ROC analyses revealed that there was no overall difference in discriminability between guilty and innocent suspects depending on response option condition. On balance, the findings suggest that, in addition to informing witnesses about acceptable responses, displaying non-identification response options does not undermine identification performance.