(Video) Mandarin Speaker: [Mandarin]PK: So what have we done to their little brains? (Laughter) We had to run a control group to make sure that just coming into the laboratory didn't improve your Mandarin skills. So a group of babies came in and listened to English. And we can see from the (8)______ that exposure to English didn't improve their Mandarin. But look at what happened to the babies exposed to Mandarin for 12 sessions. They were as good as the babies in Taiwan who'd been listening for 10-and-a-half months.