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What we're going to be doing today is recording the electrical activity of her brain as she listens to words she understands and words she doesn't understand and to backward words. Different parts of the brain communicate with each other through these tiny electrical signals. And we can actually eavesdrop on activity and see what a brain is doing while she's listening to these different types of words.

Shoe. Book. Pint. Rate. Dog. Nose. Grand. Carbon. Milk. Verb.

Great job, Molly. You did so good. You are such a good listener.

One of the things that we found so far is that when children who are between 13 and 17 months of age are listening to words that they understand versus words that they don't understand. The words that they understand have more activity on both the left and the right side of the brain.

When children are about 20 months of age, or when they've undergone a big vocabulary spurt, they tend to be-- those differences are just in temporal parietal regions of the left hemisphere-- the language areas in adults. They're the only areas showing those differences. So there's a big change in the organization of the brain.

One of the things we're interested in is whether that's related to age and the maturation of the brain or whether it's related to experience with language. So we've studied children who are late talkers, who are older-- 20 months and 28 months-- and found that same shift from both sides to the left side, at a later point in development, which suggests that it's vocabulary science that's driving that.

We've also looked at children who are learning two languages at the same time and found different patterns of organization for the language that they have more words in than the words. So it can't really be brain maturation driving the changes, because it's the same child who has two languages. It's the same brain. Now we're studying children like Molly, who are younger, who have undergone this big vocabulary spurt at a younger age to look and see if we can find those changes earlier on in development.