Recognition of age-different facial images of unfamiliar children: what are the influential factors?

Abstract

Background: Each year 8 million children go missing worldwide. As time passes, physical changes associated with growth and development may be detrimental for a potential recognition by third parties. The objective of this study was to identify observer- and image-related factors that influence recognition of age-different unfamiliar faces of children. Methods: Sixty frontal photographs of European males and females aged between 10 and 21 years were selected from a large data set of longitudinal images, along with one matching and three non-matching images and randomly ordered in a face recognition test catalogue. The image comparisons were equally distributed into three age gaps: 1-2 years, 3-5 years, and 6+ years. Twenty one observers (10 experienced and 11 non-experienced with facial identification) were asked to match the images, and to specify which facial features prompted their decision. Results: Experts were more likely to correctly match child faces on age-different images compared with non-experts (82% v. 72%). The frequency of correct recognition decreased with an increasing age gap between the images. Conclusion: Experience with facial identification facilitated correct matches of unfamiliar faces of children on age-different images, partly due to the difference in the type of features noted as useful for recognition. Age gaps of six and more years between images rendered recognition more difficult regardless of the expert status. By identifying the factors that facilitate facial recognition on age-different images, the results of this study provide useful information for management of cases of missing children.