The young brain is adept at making fine distinctions, between language sounds for instance, that elude adults. With a little exposure to a foreign language, they can keep this ability longer. Now a study shows the same thing is true for recognizing faces.
Babies quickly advance from promiscuous babbling to articulate gabbing, but along the way they lose the ability to distinguish between some spoken sounds, like "r" and "l" in English, which trouble some speakers of East Asian languages. A little exposure to a nonnative language allows infants to retain their verbal flexibility longer, so a team led by infant researchers Olivier Pascalis of the University of Sheffield in the United Kingdom and Charles Nelson at the University of Minnesota in Minneapolis wondered if the same applied to face recognition.
The researchers had mothers show photos of Barbary macaque faces to their 6-month-olds for about 10 minutes per week over the course of 3 months. Before and after training, the team tested the babies using pairs of monkey mug shots, some they had seen before and some new. When the babies looked more at one photo, the researchers assumed it was of an individual unfamiliar to the infant, as infants are drawn to novelty.
Even with the sparse training, the infants retained their ability to distinguish between monkeys at 9 months, the team reports online this week in Proceedings of the National Academies of Sciences. (Babies not given the training lost the ability to distinguish monkey faces by 9 months of age.) Similar training didn't help adults, even primatologists, who Pascalis describes as "hopeless" at the task. "It looks like early on in life the whole brain is more plastic than we thought," he says.
It's a "carefully conducted" study, says psychologist Amy Needham of Duke University in Durham, North Carolina. Such findings prove experience plays an important role in shaping the early development of face processing, she says.