科學美國人 20110417

"Uh we'll be um right back um after, um this message." Now does that sound like a pro speaker? It's better to remove ums and uhs right?—"We'll be right back after this message." Well not always, according to new research in the journal Developmental Science. When it comes to teaching our toddlers how to speak uhs and ums help the child to focus on words that follow. Researchers studied children between the ages of 18 and 30 months as they sat on their parents’ lap in front of a monitor. The screen displayed two images. One was familiar, such as a banana, and the other an abstract made-up object. A recorded voice said things like: I see a banana, or There is uh, um, uh a banana. When the voice stumbled, children who were more than 24 months tended to look at the made-up object more often than at the familiar object. Because children who’ve reached that age understand that uhs often precede unknowns. Not that, uh, you’d want to, uh, riddle your um sentence with, uh, uhs. But on your next trip to the museum with the little one, it’s ok if you point to a skeleton and say, "Oh, that’s an uh, uh um, a velociraptor! "