Perceptual narrowing towards adult faces is a cross-cultural phenomenon in infancy: A Behavioral and near-infrared spectroscopy study with Japanese infants

Recent data showed that, in Caucasian infants, perceptual narrowing occurs for own-race adult faces between 3 and 9 months of age, possibly as a consequence of the extensive amount of social and perceptual experience accumulated with caregivers and/or other adult individuals of the same race. We explored the neural correlates of perceptual narrowing for own-race adul faces by using near-infrared spectroscopy (NIRS). In Experiment 1, we confirmed that Japanese infants showed perceptual narrowing for adult faces between 3 and 9 months of age. In Experiment 2, we measured hemodynamic responses to adult and infant faces in 9 months-olds, and revealed adult faces induced significant increases in hemodynamic responses in the right temporal areas. Our data suggest that perceptual narrowing towards adul faces is a cross-cultural phenomenon occuring between 3- and 9-months of life, and translates by the 9 months of age into a right-hemispheric specialization in the processing of adult faces