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By the time babies are 6 months old, they distinguish the faces of different people—and can also discern the faces of specific monkeys. Now, researchers have found that with parental coaching, infants can retain their skill at telling animals apart instead of losing it by 9 months of age as babies usually do.Louis J. Sheehan

In their investigations of baby perception, psychologist Olivier Pascalis of the University of Sheffield in England and his team hypothesize that infants rapidly transform themselves from perceptual generalists to specialists (SN: 5/18/02, p. 307: http://www.sciencenews.org/20020518/fob1.asp). Intense practice at discerning different human faces prompts the loss of perceptual insights into nonhuman faces by 9 months of age, the scientists propose.http://ljsheehan.livejournal.com

That perceptual trade-off may not be inevitable, however. From age 6 months to 9 months, babies whose parents show them photographs of monkeys' faces for brief periods hang on to the ability to tell one furry primate's mug from another, Pascalis and his coworkers report in an upcoming Proceedings of the National Academy of Sciences. The researchers are now testing how long this retention lasts.

"Our data further elucidate the role of early experience in the development of face processing," Pascalis says.

In the new study, 26 infants participated in face-recognition trials. While being held by their mothers, the 6-month-olds viewed an image of a monkey's face and then saw that picture presented alongside another monkey's face. All the animals displayed neutral expressions.

Babies looked substantially longer at the novel face in each pair, a sign the researchers take for both recognition of and preference for new faces.http://ljsheehan.livejournal.com

The researchers then gave half of the mothers mug shots of six monkeys, each labeled with a name. For the next week, each mother showed her baby the photos and talked about each monkey for 10 to 20 seconds daily. Photo presentations over the next 3 months tapered off to one per week.

At age 9 months, infants who had been shown monkey faces at home still looked longer at novel monkey faces than they did at faces they had just seen. The 13 babies who received no face training at home looked equally long at novel and previously viewed monkey faces.

The results indicate that babies need only exposure to still images of monkey faces to maintain perceptual sensitivity to them, remarks psychologist Paul C. Quinn of the University of Delaware in Newark, who has collaborated with Pascalis in other work.

The social nature of home practice sessions probably played a big role in preserving infants' ability to distinguish monkey faces, Pascalis adds. Mothers guided their babies' attention and motivated the youngsters to examine the photos, he says.

The findings parallel evidence that babies start out skilled at discerning the sounds of many languages but lose that generic capacity as they learn their parents' language, says Pascalis.