Human factors in forensic face identification

Abstract

Facial identification by forensic examiners is a core component of criminal investigations and convictions. These identifications are often done in challenging circumstances that require experts to match identity across images and videos taken at a various distances, under different illumination conditions, and across a wide range of poses. Until recently, laboratory studies of human face identification have concentrated, almost exclusively, on face identification by untrained (naïve) observers, with only a handful of studies focusing directly on the accuracy of expert forensic facial examiners. Over the last two decades, DNA-based exonerations of convicted criminals in the United States have revealed weaknesses in the forensic identification process due to human factors. In this paper, we review and analyze the factors known to impact facial identification accuracy for both naïve participants and trained experts. Combined, these studies point to a set of challenges that impact accuracy for both groups of participants. They also lead to an understanding of the specific conditions under which forensic facial examiners can surpass naïve observers at the task of face identification. Finally, we consider the role that computer-based face recognition systems can play in the future of forensic facial identification. These systems have made remarkable strides in recent years, raising new questions about how human and machine strengths at face identification can be combined to achieve optimum accuracy.