Evidence for "perceptual narrowing" in the ability to recognize faces, as also displayed when we lose abilities to differentiate between non-native sounds, such as those from foreign languages—and not because of memory deterioration—may represent a more general change in early neural network development than previously thought, suggest the researchers.

"It's one way of looking at the bigger question of how brains develop into the adult like form: When babies are born, do they already have this little face and language area, do they have areas dedicated to specific functions?" explains Michelle de Haan, a co-author of the Science study. It is possible that a combination of natural changes in the brain between six to nine months of age and visual cues from the environment hone recognition capabilities, she says.

Brain systems for processing visual cues and speech may develop with a similar timing and influence each other and provides ample areas for further studies, the researchers write. "Although it is difficult to compare directly the tuning of speech perception with the tuning of face perception, there may be overlap between these systems."