Easy Listening
Students should be jealous. Not only do babies get to doze their days away, but they’ve also mastered the fine art of learning in their sleep.
By the time babies are one year old, they can recognize a lot of sounds and even simple words. Marie Cheour at the University of Turku in Finland suspected that they might progress this fast because they learn language while they sleep as well as when they are awake.
To test the theory, Cheour and their colleagues studied 45 newborn babies in the first days of their lives. They exposed all the infants to an hour of Finnish vowel sounds one that sounds like "oo"; another like "ee" and the third boundary vowel peculiar to Finnish and similar languages that sounds like something in between. EEG (脑电图) recording of the infants brains before and after the session showed that the newborns could not distinguish the sounds.
Fifteen of the babies then went back with their mothers, where the rest were split into two sleep-study groups. One group was exposed throughout their night-time sleeping hours to the same three vowels, while the others listened to the other, easier-to-distinguish vowel sounds.
When tested in the morning, and again in the evening, the babies who’d heard the tricky boundary vowels all night showed brainwave activity indicating that they could now recognize this sound. They could identify the sound even when its pitch was changed, while none of the other babies could pick up the boundary vowel at all.
Cheour doesn’t know how babies accomplish this nighttime learning, but she suspects that the special ability might indicate that unlike adults, babies don’t "turn oft" their cerebral cortex (大脑皮层) while they sleep: The skill probably fades in the course of the first years of life, she adds so forget the idea that you can pick up the tricky French vowels as an adult just by slipping a language tape under your pillow. But while it may not help grown-ups, Cheour is hoping to use the sleeping hours to give remedial help to babies who are genetically at risk of language disorders.