Four-to-six-year-old children use norm-based coding in face-space

Children's performance on face perception tests does not reach adult levels until adolescence, a result which, a priori, could be due to qualitative change in face mechanisms with age, quantitative change in these mechanisms, or improvements in general cognitive abilities that are not face-specific (e.g., memory, attention). In adults, the major functional mechanisms of face recognition include holistic/configural processing and face-space coding. Previous research has established that holistic/configural processing is present by 4-6 years of age. Very little, however, is known about face-space coding in children. Here, we demonstrate that 4-6-year-old children show adaptation aftereffects for figural distortions (expanded/contracted, eyes up/down), providing the first evidence of aftereffects for identity-relevant information in children younger than 8 years. We also show that in 4-5 year-olds, as in adults, face aftereffects are stronger for adaptors far from the average (extreme distortions) than for adaptors closer to the average (mild distortions). This result provides the first compelling evidence that face-space coding is norm-based in children younger than 8 years of age, and rules out a qualitative shift from exemplar-based to norm-based coding as the source of developmental improvement in face identification performance beyond preschool age.