HANOVER, N.H. Baby babbling, universally uttered by healthy hearing babies when they are about seven months old, is thought to mark the developmental moment when a young child embarks on the road to spoken language. Now, new insight into why this behavior occurs can be found in the hands of hearing babies as they acquire a natural signed language.
According to a study published in the September 6, 2001, issue of Nature, lead author Laura Ann Petitto, a Professor in the Department of Education and in the Department of Psychological and Brain Sciences at Dartmouth College, suggests a fresh approach to how babies begin the remarkable process of acquiring language.
The results of the study, titled "Language Rhythms in Babies Hand Movements," support the idea that babies are born with sensitivity to highly specific rhythmic patterns naturally found in languages. It is so powerful that a baby can find and produce the rhythms of language even without vocal input from parents. The study further suggests the tantalizing idea that a baby's perception of the rhythmic pattern is a key mechanism that launches the process of human language acquisition.
Petitto conducted the study with students and colleagues at McGill University (Montreal, Canada): Siobhan Holowka, Lauren Sergio (now an assistant professor at York University) and Professor David Ostry (also with Haskins Laboratories in New Haven, Conn.). They examined the hand movements of hearing babies born to profoundly deaf parents and compared them to the hand movements of hearing babies with hearing parents.
"Hearing babies with signing deaf parents make a special kind of movement with their hands, with a specific rhythmic pattern, that is distinct from the other hand movements," said Petitto. "We figured out that this kind of rhythmic movement was linguistic. In fact, it was babbling, but with their hands."