テーマ： 「Developmental study on face recognition」
要 旨： Much evidence suggests that face representation constantly adapts to reflect the individual’s current social and perceptual experience, giving rise to a number of face processing biases. Nevertheless, little is known about whether the plasticity of these biases varies across the lifespan. I will present evidence from a series of studies with infants and adults showing that face representation remains plastic into adulthood, but plasticity decreases with age.
Research with infants has shown that between 3 and 9 months face discrimination abilities narrow, resulting in perceptual tuning (i.e., perceptual narrowing) towards over-experienced face categories that are most frequent and relevant in the infant’s environment and decreased sensitivity to non-relevant face types.
Using behavioral (visual habituation), electrophysiological (EEG) and neuroimaging (fNIRS) paradigms we showed that during the same time-window infants' face processing abilities tune towards adult faces. However, natural experience acquired from birth with an older sibling's face prevents such tuning to occur, allowing 9-month-olds to maintain the ability to discriminate child faces.
Finally, in a series of studies conducted with adult women who, as first-time mothers, are exposed to the face of their child, we showed that the only condition in which later-acquired experience affects performance is when early exposure to a sibling’s face occurred in the participant's first 3 years of life. The reactivation effect engendered by later-acquired experience is already apparent after 4 months of exposure to the child's face, and that the effects of early-acquired experience are still visible after 12 months of exposure.
Overall, these findings show that visual experience acquired in the first 9 months of life has a critical role in the emergence of neurocognitive specialization for adult faces, and it has continuous effects into adulthood, as it preserves the system from the loss of plasticity that would otherwise take place.