Research. At nine months, babies learn grammar from ‘the music of speech’

05.05.2023

Published in Science Advances, the joint study between research teams at the universities of Padua and Barcelona, reveals how children are able to learn the grammar of language much earlier than previously thought: they do so by the prosodic cues of the language, often referred to as ‘the music of speech.’

Until now, researchers thought that children were only able to learn the relationships between distant words in sentences after the first year of age, that is, after they started speaking. A recent study entitled Prosodic cues enhance infants' sensitivity to nonadjacent regularities shows that children are able to learn these relationships as early as nine months.

The research, conducted by Ruth de Diego Balaguer and Ferran Pons of the Neuroscience Institute of the University of Barcelona, in collaboration with Anna Martinez Alvarez and Judit Gervain, of the University of Padua and the CNRS in Paris, shows brain sensitivity to these regularities at the age of 9 months. The publication suggests that children are able to solve this task mainly by listening very carefully to the speech rhythm and pitch. By observing and monitoring behavior measures and neural responses, the researchers noticed that when pronouncing nonadjacent dependent words with a higher pitch or marked intonation the children better understood the dependencies between them. To measure the responses non-invasively, researchers used near-infrared spectroscopy (NIRS), which analyzes how infrared light reflects based on oxygen changes in the bloodstream and as a respond to different experimental conditions.

When presenting the children with monotone language or flat pitch, their brains demonstrated a reduced level of nonadjacent dependency learning. However, when the same sentence was spoken in a higher pitched tone that highlighted related A and B syllables, the neural responses indicated that the children were able to learn the relative dependencies of words.

This selectivity of transposition of dependencies, through prosodic cues, allows young children to learn the language efficiently even before their first birthday as they are already equipped with powerful learning mechanisms at such an early age.

This study indicates that while rudimentary sensitivity to non-adjacent regularities may be present as early as 9 months, robust and reliable learning is only achievable at this age when melodic information is present that helps infants' brains detect constituent words with a non-adjacent dependency.