— Babies learn to speak the same way that some birds learn how to sing.
Infants don't learn to speak just by imitating the sounds of older humans in their midst, according to new research. Mom's gentle touch, or her loving smile, helps the baby learn that some sounds are more pleasing than others, thus moving it along the avenue of language development.
"The parents responses serve as cues to the infant that that was a successful sound," says psychologist Michael Goldstein of Franklin and Marshall College in Lancaster, Pa. Goldstein began a research project while working on his doctorate at Indiana University that flies in the face of much conventional wisdom.
His findings, published in a recent issue of the Proceedings of the National Academy of Sciences, show that humans learn to speak through a variety of mechanisms, including both imitation and social interaction with others. Most experts have contended that we learn to talk purely by imitation, but Goldstein's work suggests it is far more complicated than that.
A Lesson From the Birds
So while he's barely out of graduate school, he's already on a course that establishes him as a high-profile target in the ongoing debates about the development of verbal skills. And he owes it all to cowbirds.
The brown-headed cowbird is one of the stranger critters in the avian world, in that the females lay their eggs in the nest of another species and let another bird hatch and nurture their young. Within about a month, the young cowbirds desert their foster home and join whatever flock of cowbirds they can find in the vicinity.
Goldstein began studying cowbirds because he was intrigued by one aspect of their maturing process. Only male cowbirds learn to sing. But they are taught to sing by females.
And here's the odd part.
"The females don't sing," says Meredith West, Goldstein's faculty adviser at Indiana University, a specialist in behavior development in animals and humans. "In fact, they can't sing."
The males in the flock don't teach them because, West says, "they hang off on their own. They don't interact with the younger males."
So the adult females are tasked with teaching the young males how to do something they can't do themselves. They do it by paying attention to the youngsters and letting them know when they are getting closer to the right song.
"If you and I were trying to talk, and I started looking away, and looking down, and not giving you any feedback or not paying any attention to what you were saying, you would change how you tried to talk," she says. "And that's just what happens with the birds."
Goldstein wanted to take that a step further and see if human infants follow a similar course. So he set up a terrific playroom at Indiana University and elicited the support of 30 moms with 8-month-old babies, about the age that infants begin pronouncing vowels and forming marginal syllables.
The moms were divided into two groups of 15, one to test the effect of social interaction, and the other to serve as a control group for the experiment. Each mom and her baby spent two half-hour sessions in the playroom. The first was just a getting acquainted session to allow the baby and the mom to be comfortable with the setting, Goldstein says.