Language Plays Key Role in Infant Learning
"Infants probably are, to some extent, capable of language; we just have to think about what we mean by infant language," said Marie Balaban, an assistant professor of psychology at The Johns Hopkins University.
The infants were shown either toy cats, horses, bears or whales. If their category happened to be cats, a scientist would say: "See the feline? Do you like the feline?" The researcher talked in the slow, exaggerated enunciation that adults use when addressing babies.
But at other times, instead of saying, "See the feline?" the experimenter would say: "See what I have? ... Do you like that?" She would omit any reference to the category of animal.
The research clearly showed that hearing the word feline helped the babies learn that the toys belonged to the same category of animal. The infants did not as easily learn that the toys were alike when they were accompanied only by the question, "See what I have?"
Balaban and Waxman will present their findings at 8:30 a.m. on Saturday, April 20, during the International Conference on Infant Studies, in Providence, R.I.
They tested 44 babies, showing each of the 9-month-olds five toys from a specific category of animal. Half of the babies were told the name of the animal, and the other half were simply asked, "See what I have?" They were allowed to look at and play with each toy for 15 seconds.
After the fifth toy, the experimenter simultaneously brought out two more toys. One was a new animal in the same category the baby had just been shown, and the other toy was an animal from a completely different category. If the babies spent more time looking at the toy from the new category, that showed they had learned that the other toy was a member of a familiar category, so they naturally were more interested in the new category.
The difference between the two groups of infants was significant: the infants who were earlier told the name of the familiar category preferred the new category 62 percent of the time, but the babies who were not told the animal names showed no significant preference for the novel category.
Previous research on how, and when, the brain begins connecting objects and words has focused on toddlers and preschool children.
"I think our findings depart from convention in the sense that we are suggesting that words facilitate infants' object categorization at an age that is earlier than would have been expected," Balaban said. "We are suggesting that language has an influence on thinking, even at this young age."
In related research, Waxman and Balaban arrived at similar results, but using different methods. Those results will be detailed in a paper to be published later this year in the Journal of Experimental Child Psychology.
In that research, infants were shown pictures of different types of birds, pigs, dinosaurs and rabbits. The slides were sometimes accompanied by a woman's tape-recorded voice saying the name of the animal, again, in the slow and exaggerated enunciation adults use when speaking to babies. At other times, the slides were accompanied only by flat electronic tones. Still another study matched the images with a sound resembling a word, with the same slow enunciation, but with the sharp edges of speech filtered out so that what remained was a vague word-like sound that would make little sense to an adult.
The researchers discovered that the babies needed the animal names to learn that they were all members of the same category. When the slides were accompanied only by a tone, the babies did not as easily learn that the images were related.
Further supporting that hypothesis, the nonsensical, but word-like sounds had an effect similar to that of the real words; they enhanced the infants' ability to learn that the animal pictures represented a category.
"The critical thing is that they are hearing this word with different pictures, and somehow it's helping them form a category," Balaban said.
In the research, 84 babies were tested in three separate studies, one each to analyze how words, tones or nonsense words influenced the way that infants processed the images.
In each of the three studies, the 9-month-old babies were shown nine slides of images of animals in a specific category.
Then, after viewing the ninth slide, the babies were shown two pictures at once: one of the pictures was another animal belonging to the same category they had already seen, such as birds; the second picture was an animal from a completely different category, such as a dinosaur.
The infants' interest could be gauged by carefully observing how much time they spent looking at either animal.
Infants who heard words accompanied by slides spent 56 percent of the time looking at the slide from the new category. But infants who heard tones spent only 45 percent of the time looking at the picture from the new category; they spent more time still looking at the slide from the old category.
Babies who heard the word-like, nonsensical sounds when they looked at slides reacted as though they had heard real words; they spent 55 percent of the time looking at the picture from the new category.
While the findings indicate that words help the brain learn the nature of objects, it isn't clear why it groups objects into categories.
"I think that's an interesting question: what does it mean to have a category in your mental structure?" Balaban noted.
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