How does a babbling baby become a talking tyke? In June, researchers found part of the answer. Toward the end of the first year of life, they discovered, two brain areas begin coordinating to help babies figure out speech.
Until 6 or 7 months of age, babies can easily distinguish vowels and consonants from all languages. But by about 11 or 12 months, they’ve homed in on their native language — the one they’ve heard most — and started ignoring foreign sounds. Baby’s first word follows soon after.
To learn how this transition into speech occurs in the brain, the University of Washington’s Patricia Kuhl played babies in both age ranges separate recordings of their native tongue and a foreign one while measuring their brain activity.
When 7-month-olds heard either language, they showed similar activity levels in both the auditory system, which perceives sounds, and the motor system, which is involved in mimicking sounds. But 11- and 12-month-olds showed more activity in their auditory systems when they heard their native language. When they heard foreign words, on the other hand, it was their motor systems that lit up on the brain scan, indicating they had to work harder to imitate them.
According to Kuhl, these brain patterns show that once babies reach their first birthday, they not only pay closer attention to native words, they also prepare to start uttering them. At that age, the auditory system and motor system work together to set the stage for speech, Kuhl says.
Baby talk is an important part of that process, she adds. “The idea that a young child at 12 months can hear you say something and then know what to do to replicate that signal with their own mouths is remarkable,” Kuhl says.