Language on the brain
Scientists are particularly interested in the brains of people who speak more than one language fluently because that skill is hard to acquire after about age 7.
In one of Kuhl's studies, for example, native Mandarin Chinese speakers spoke Chinese to 9-month-old American babies for 12 sessions over 4 weeks. Each session lasted about 25 minutes. At the end of the study, the American babies responded to Mandarin sounds just as well as did Chinese babies who had been hearing the language their entire lives. (English-speaking teenagers and adults would not perform nearly as well).