And, according to Scientific American, when I “errr” and “hmmm” too. Those weird verbal tics help children learn:
Such vocal hesitations, called disfluencies, tend to occur before we use a word that is infrequent or unfamiliar in our speech. They also precede words used for the first time in a conversation.
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New experiments at the University of Rochester suggest that around the age of two, children make an association between the disfluencies they hear and the likelihood that new words will follow them.
In the study, kids aged 16 to 32 months sat on their parent’s lap in front of a computer monitor that showed images of paired objects, one recognizable (such as a ball) and one imaginary but equally colorful.
The first time a pair appeared, a voice from the computer said, “I see the ball.” The second time it said, “Ooh, what a nice ball.” The third time it instructed the children to look at one of the objects in the pair, using a made-up word for the invented object such as “gorp.”
During this third step, sometimes the voice said simply, “Look! Look at the ball,” or “Look! Look at the gorp.” In other trials, the sentence included a disfluency: “Look! Look at the, uh, ball,” or “Look! Look at the, uh, gorp.”
When kids heard the disfluency, they paid significantly more attention to the unfamiliar object for the next two seconds—before the computer finished the sentence with either “ball” or “gorp.” During the “fluent” trials, when the computer did not say “the, uh,” the children were no more likely to fixate on one object over the other.