The ontogeny of face identity; I. Eight- to 21-week-old infants use internal and external face features in identity.

A paradigm was designed to study how infants identify live faces. Eight- to 21-week-old infants were seated comfortably and were presented an adult female, dressed in a white laboratory coat and a white turtle neck sweater, until habituation ensued. The adult then left the room. One minute later either she or an identically garbed confederate returned. Looking time did not increase above habituation levels when the original experimenter returned, but increased substantially when the confederate entered the room. Furthermore, internal features alone could serve as the basis of face identity. Looking times of infants who had habituated to experimenters with masked outer features of hair, ears and neck also markedly increased when a second identically dressed experimenter returned. Identity in this instance could only be based on internal facial characteristics. A second study assessed the contributions of internal and external facial features to identity. Infants were habituated to an experimenter in a short wig. One minute later they saw her again, either in the same short wig or in a long one. Alternatively, they saw a second experimenter wearing either the short wig or the long one. Infants looked longer only to the stranger wearing the long wig. Very brief looking times occurred to the familiar adult, regardless of wig, and to the stranger wearing the familiar wig. This paradigm provides an approach to discover rules used by infants of different ages to process and identify adult faces and to establish the bases of face preference.