You can believe your eyes: measuring implicit recognition in a lineup with pupillometry

As pupil size is affected by cognitive processes, we investigated whether it could serve as an independent indicator of target recognition in lineups. Participants saw a simulated crime video, followed by two viewings of either a target-present or target-absent video lineup while pupil size was measured with an eye-tracker. Participants who made correct identifications showed significangtly larger pupil sizes when viewing the target compared with distractors. Some participants were uncertain about their choice of face freom the lineup, but nevertheless showed pupillary changes when bvewing the target, suggesting covert recognition of the target face had occurred. The results suggest that pupillometry might be a useful aid in assessing the accuracy of an eyewitness' identiication.