That's my teacher! Children's ability to recognize personally familiar and unfamiliar faces improves with age

Adults’ ability to recognize unfamiliar faces across images that capture within-person variability is poor, whereas their familiar face recognition is extremely good (Jenkins, White, Van Montford & Burton, 2011). Very little is known about children’s ability to recognize personally familiar faces and most of what we know about unfamiliar face recognition comes from studies measuring recognition of only one or two highly controlled images of an identity. Therefore the purpose of the present study was to examine the effect of within-person variability on identity perception across childhood. Children aged between 6 – 11 years were presented with a teacher's house (either their teacher [n = 27] or an unfamiliar teacher [n = 21]) and a pile of pictures. Half of the pictures were of the teacher and the other half were of a physically similar unfamiliar identity, and all the pictures captured natural within-person variability in appearance. Children were asked to put all of the pictures of the teacher, but not the other woman, into the house. Children familiar with the teacher were highly accurate (M d’ = 3.10) with no improvement with age (r(25) = -.001, p = .995). However, children unfamiliar with the teacher were less accurate (M d’ = 1.15), their performance (d’) improved with age (r(19) = .62, p = .002), with most errors comprising misses (failing to put a teachers’ photo into the house). In an ongoing study, data-to-date (n = 19) show a familiar face recognition advantage for younger children (4-5 years), although the younger children made more errors (M d’ = 2.51) than older children. These findings suggest that children’s familiar face recognition is adult-like at age 6, whereas unfamiliar face recognition continues to improve across childhood. Understanding within-person variability is essential for understanding the development of expertise in face recognition