Abstract

Researchers show that Japanese infants process faces from the most frequently encountered age and ethnic group predominantly in the right hemisphere of the brain by 9 months of age

 Okazaki, Japan – Newborn infants prefer to look at faces rather than other visual stimuli, and can distinguish between faces by their first birthday. Research has shown that between 6 and 9 months of age, babies’ brains become less sensitive to infrequent stimuli and instead tune in to those that are more frequent. This explains why 9-month-old Caucasian babies are better able to distinguish between adult faces than infant faces; because they are exposed more often to the faces of their caregivers. This phenomenon is called perceptual narrowing.
In a new study, a joint group of researchers from Japan’s National Institute for Physiological Sciences, Chuo University, Japan Women’s University and University of Milano-Bicocca have shown that perceptual narrowing toward adult faces is cross cultural. They explored 3- and 9-month-old Japanese babies’ recognition of Japanese adult or infant faces. The researchers recorded the length of time the babies looked at the faces.
 The study found 3-month-old babies recognize both adult and infant faces, but 9-month-olds recognize significantly only adult faces. This shows that perceptual narrowing towards adult faces occurs between 3 and 9 months of age in Japanese infants, similar to what has already been shown in Caucasian infants.
The neural processes underlying this developmental phenomenon are largely unknown, so the authors measured brain activity in 9-month-old participants during facial perception. “We measured the concentration of oxygenated hemoglobin, deoxygenated hemoglobin, and total hemoglobin in the right and left temporal areas of the brain,” study last author Ryusuke Kakigi says “We observed significant increases in hemodynamic responses in the temporal areas of the brain only when the participants were looking at adult faces.”
Interestingly, this enhanced hemodynamic response to adult faces was localized in the right temporal area. These results indicated that by 9 months of age, faces from an individual’s most frequently encountered ethnic and age group are processed predominantly in the right hemisphere. It will be interesting to see whether this neural specialization occurs before the perceptual specialization, as shown by the infant’s looking behavior. This can be investigated by applying similar neuroimaging techniques in 3-month-old infants.
 The article, “Perceptual narrowing towards adult faces is a cross-cultural phenomenon in infancy: a behavioral and near-infrared spectroscopy study with Japanese infants,” was published in Developmental Science at DOI: 10.1111/desc.12498

Summary Text: Results from a study out of research group of Japan’s National Institute for Physiological Sciences demonstrated that perceptual narrowing toward adult faces is a cross-cultural phenomenon occurring between 3 and 9 months of age and that becomes specialized to the right hemisphere by 9 months of age.
Primary Keywords: Biology; Social/behavioral science
Additional Keywords: Physiology; Neurobiology; Behavior
Twitter Comment: Facial processing is cross cultural and occurs in the right hemisphere
 

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