Face recognition across varying poses in 7-and 9-month-old infants: The role of facial expression

Three studies were conducted to determine whether 7- and 9-month-old infants generalize face identity to a novel pose of the same face when only internal face sections with and without an emotional expression were presented. In Study 1, 7- and 9-month-old infants were habituated to a full frontal or three-quarter pose of a face with neutral facial expression. In Study 2, 7-month-olds were habituated to a face with a positive or negative expression. In the novelty preference test, immediately following habituation, infants were shown a pair of faces: the habituation face in a novel pose and a novel face in the same pose. Generalization of facial identity was inferred from longer fixation time to the novel face. Whereas 7-month-old infants did not dishabituate to the novel face with neutral expression, 9-month-olds fixated longer on the novel face with neutral expression (Study 1). However, when faces displayed a positive or negative expression 7-month-olds also looked longer at the novel face, indicating generalization of the habituation face to a novel pose (Study 2). Study 3 showed that 7-montholds' generalization ability in Study 2 cannot be explained by an inability to discriminate between the two poses of the habituation face. Results showed 9- but not 7-month-olds recognized neutral looking faces in a novel pose, and 7-month-olds' face recognition ability was enhanced by emotional facial expression.