Abstract
Children's face recognition ability does not reach adult levels until adolescence, consistent with neurological evidence that change in the selectivity of face-responsive brain regions continues into early adolescence. Yet it is not clear whether this developmental change is qualitative, with children using different kinds of coding mechanisms (e.g., configural or feature-based coding), or quantitative, involving refinement of the mechanisms used by adults. Accumulating evidence suggests that even young children use several qualitatively similar mechanisms to adults. However, little is known about the development of adaptive norm-based coding mechanisms which are central to adult face coding. The face identity aftereffect, in which adaptation to a particular identity enhances recognition of a computationally opposite identity, provides a clear demonstration of adaptive norm-based coding in adults. Eight year old children show adult-like face-identity aftereffects suggesting that the use adaptive norm-based face coding mechanisms is mature by this age. However, it is not known when such mechanisms emerge. We sought evidence for adaptive norm-based coding in young children (4–6 years) using the face identity aftereffect. In a simplified paradigm, children and adults learned to recognise two individual faces (e.g. Dan & Jim) and weaker versions of these faces (reduced identity-strength). Participants then played a game in which ‘robbers’ (the two adapting faces) were caught by members of one of two teams (the two learned identities and weaker versions) and participants identified the team that caught the robber. Both children and adults showed significant aftereffects but children's aftereffects were significantly larger than adults'. These data suggest that young children use adaptive norm-based coding but show greater plasticity in their norms. Hence, adaptive norm-based coding of faces may emerge early but mature relatively slowly, consistent with quantitative refinement of adult-like mechanisms.
This research was supported by an Australian Research Council Grant to L. Jeffery and G. Rhodes.