A baby's babbling isn't just a random exercise in mouth control. It's a step that prepares the young for speech and language, researchers said Thursday.

Psychologists have discovered a strong link between babbling and the language processing centres in the brain. They found babies as young as five months engaged the left hemisphere of the brain, where language originates.

Cognitive neurologist Prof. Laura-Ann Petitto of Dartmouth College in New Hampshire and graduate student Siobhan Holowka at McGill University in Montreal studied babbling motions by 10 infants up to one year old.

Babies' brains are organized for language
Babies' brains are organized for language

The researchers watched videotapes of five babies learning English and five learning French. Two independent coders who weren't aware of the study's goals randomly focused on the babies' mouth movements.

In adults, the right side of the mouth opens a tad wider while talking. Our brains naturally correct for the disparity so it is virtually imperceptible. But by slowing down the video recordings, the researchers were able to look for the "right mouth asymmetry."

Researchers focused on three different kinds of mouth activity:

  • babbles – sounds with consonant-vowel repetition (da-da-da or ga-ga-ga)
  • non-babbles – vocalizations without constant-vowel repetition (ahhhhhh)
  • smiles – mouth movements showing enjoyment, often accompanied by contractions around the left eye

They found both English and French babies had right mouth asymmetry when babbling, equal mouth opening for non-babbling and left mouth asymmetry for smiles, Petitto said. Smiling is prompted by the right side of the brain, the emotional centre.

Petitto believes mouth motion is universal for babies learning all languages.

"We are currently exploring whether this baby-friendly research method could also be used as a diagnostic tool to determine if there are linguistic or developmental problems even before a baby can utter its first word," said Petitto in a release.

If parents and pediatricians recognize problems sooner then they may be able to start treatment earlier, she said.

The study appears in Friday's issue of the journal Science.