At seven months, babies ‘rehearse’ to start speaking

Even when they are only 7 months old, babies are mentally working out the mechanics of how to form words with their mouths - well before they’re able to utter their first recognizable syllable.

The latest discovery from the University of Washington’s Institute for Learning & Brain Sciences (I-LABS), in Seattle, underscores the importance of speaking to babies from the moment they are born, even though, in those early months, it may not look like it’s having much effect, said Patricia Kuhl, co-director of I-LABS.

Kuhl has spent her career deciphering language development in babies, but the latest discovery was a surprise even to her. Her findings were published recently in the Proceedings of the National Academy of Sciences.

Kuhl and her research team were able to plot the mental rehearsing that goes on in babies’ brains at 7 months using a noninvasive brain scanning technique called magnetoencephalography, or MEG. The UW I-LABS Brain Imaging Center is the first in the world to focus on children, and the MEG machine, sized for infants, is the technology behind the labs’ many discoveries.

As expected, when 7-month-old babies were listening to speech, the researchers saw brain activity light up in an auditory-processing area called the superior temporal gyrus. But researchers also saw activity in two other parts of the brain – Broca’s area and the cerebellum – which are responsible for planning the motor movements required for producing speech.

In effect, babies are rehearsing how to speak, even if they aren’t yet producing words. “This machinery (in the brain) is hooked up really early, amazingly early,” Kuhl said.

And that should underscore anew the importance of speaking to babies. “It shows what babies are missing when you don’t talk to them,” she said. “They’re responding in even bigger and better ways than we thought.”

The research also reinforces a longstanding observation of scientists working at I-LABS: that babies get the most out of one-on-one human interactions – simple speech or games with their caregivers – which can’t be replaced by high-tech toys or gizmos that promise to give babies a learning boost.

Kuhl described the findings as “a new way of looking at a variety of things we know about babies: They love listening to us talk, they love listening to exaggerated talk and they love social games.”

Some of Kuhl’s earlier research revealed that babies are born with the ability to distinguish between the phonetic sounds of all languages, but by eight months, their brains start to focus only on the sounds of the language being spoken at home.

The I-LABS researchers have also found that babies whose parents talked to them using “parentese,” the singsong, exaggerated way of speaking to a young child, knew more than double the number of words by their second birthdays than babies whose parents did not use parentese as often.

Kuhl’s next project: to look at what happens in the brain even earlier than seven months. She’s especially interested in brain activity in 3-month-old babies, because at that age, babies begin to produce their first vowel-like sound - the cooing noise that precedes babbling.

She’s also planning to examine how a baby’s brain reacts to music. And she wants to investigate whether these recent discoveries may offer insights into how autism develops, and how to better work with infants on the autism spectrum.