I Can Hear You Whisper (5 page)

Clearly, experience matters. Even today, psychologists and linguists continue to recalibrate their assessment of the balance of power between what is innate in language and what is learned. There is
a lively, ongoing debate, for instance, on whether it's the ability to use language specifically that's innate—i.e., is language a unique skill that is separate from everything else we do; is it “special”?—or is it that pattern-learning abilities are innate and we apply them to language as we do to other skills? Either way, most argue that the old debate about the relative importance of nature (what is neurologically determined) and nurture (what is culturally determined) is not just moot but even “misguided.” In
The Scientist in the Crib
, Alison Gopnik, Patricia Kuhl, and Andrew Meltzoff, who are researchers at the forefront of thinking about what babies can do and why, have this to say: “For human beings,
nurture
is
our nature [emphasis original]. The capacity for culture is part of our biology, and the drive to learn is our most important and central instinct. The new developmental research suggests that our unique evolutionary trick, our central adaptation, our greatest weapon in the struggle for survival, is precisely our dazzling ability to learn when we are babies and to teach when we are grown-ups.”

Neuroscientists like Elissa Newport focus on the neurobiology of language learning and separate out discrete units for study. A developmental psychologist like Athena Vouloumanos, whose laboratory I visited at New York University, takes a different approach as part of what she calls the “interactivist” school of thought. “Now the shift is looking at language as a human, cooperative, social activity,” she told me. “What's the relationship between language competence and abilities and the rest of human social life?”

Evolutionarily speaking, language is the most sophisticated tool that humans have mastered. It can be glorious and evocative or dirty and demeaning and is often described as our crowning achievement as a species. It allows us to tell stories, to instruct and inform, to write novels and reference books, to recount our history. To be shut out of language, as the deaf were before the development of sign language, is to be shut out of culture and society. “Something special is going on with people,” says Vouloumanos. “Some part of our evolutionary history has given some genetic underpinning to our language ability. That's an obvious sign that some part of that ability is innate.”

Although birds and chimpanzees have been taught to do amazing things, not one animal has yet been able to generate original language. Children do this every day when they produce sentences that they did not hear an adult speak, such as “The sun is sweating you,” to take an example from the son of linguist Charles Yang.
“Children,” points out Yang, “are innovators, not just imitators.”

Songbirds interest linguists a lot, however. Though they may never learn to talk, they do learn to sing in much the same way babies learn to speak. Like humans, songbirds are born with an innate ability to generate their songs, but they don't begin singing at birth. First, they listen to their fathers (and in a very few species their mothers) and memorize the songs. At first, their own attempts at sound are really “unstructured chirps,” much like a human baby's babbling. With practice, they begin to sound more and more like their parents. Scientists have experimented with songbirds in various ways. Chicks hatched in a laboratory were later exposed to the songs of a variety of species, including their own. They showed a clear preference for their native song. But in other experiments, baby birds that never heard their native songs never learned to sing at all. Furthermore, any exposure to their own songs had to come within a sensitive period when they were still able to learn to produce them. Alex, I would learn, was under a similar deadline.

Babies, unlike birds, cannot be raised in a laboratory. If they are hearing, they are enveloped in sound from birth. One of the first challenges a baby faces is pulling apart the stream of sound that surrounds her every day. I imagine a baby literally carried along in a basket on wave after wave of sound: music playing on a radio, her parents talking, a big brother pretending to be an ambulance, water running, a dog barking, birds singing in the tree outside. Adults effortlessly sort through these competing noises, attending to speech as the most critical element. Before they can do the same, babies have to understand that they should.

In her Infant Cognition and Communication Laboratory at NYU, this is exactly the question Vouloumanos is asking: Is there something special about speech for babies from the start? She works with babies every week, trying to piece together the process of speech perception. “We [humans] understand before we can do,” says Vouloumanos. “How do we come to that understanding?” On the day I visited, twelve-month-old Elijah was back for the second time. He had first come to the lab at six months and proved himself a natural. Outgoing and cheerful, he cruised along the bright red couch in the newly renovated reception area to make his way to the basket of toys he spotted as soon as he entered the room. It wasn't hard for the adults in the room to deduce that Elijah wanted to get to the blocks; his eyes were glued to the prize. But how could we tell what he, in turn, knew about us and our intentions? At what level did Elijah, who couldn't yet say more than a few words, understand the words he heard?

To study babies, researchers have developed habituation studies. They present an infant with a series of the same sound or image until he or she becomes bored. Then they change the sound or image and the baby will indicate that he or she recognized the change. In newborns and very young infants, they do that by sucking faster on a pacifier. Put sensors on the pacifier and you can measure the rate of sucking. In older babies who can focus their attention visually, researchers measure “looking time.” A baby will look longer at something interesting or surprising than at the same old, same old.

Elijah was part of a study that day in which Vouloumanos was asking whether children his age understand that language is communicative. That is, whether they expect that a word spoken by one person can affect the actions of another. Elijah sat in a room on the lap of his mother, Jody, and was presented with a little play.

A purple triptych screen like a Punch and Judy puppet show was arranged in front of him, with a window onto a small stage in the middle panel. Graduate students and interns played different roles. In the first scenes, one “actor” tried to put a cube in a box but couldn't reach. Three times, in three different “scenes,” the actor tried to reach the box, in order to familiarize Elijah with what was going to happen. This was the habituation phase. Then a second “actor” appeared, one who
could
reach the box. Now the first actor could try to get the second actor to help. In some scenes, that first actor turned toward the second and said a nonsense word—“koba”—followed by the second actor successfully putting the cube in the box. That result makes sense if you expect the spoken word to communicate the first actor's intention. In other scenes, instead of turning and speaking, the first actor cleared her throat. Throat clearing should not communicate anything to actor two except that perhaps actor one is getting over a cold. So if, after the throat clearing, actor two
does
do what actor one wanted, that should be surprising. Elijah should look longer because it should not be the ending he expected.

Alas, on this particular day, even a cooperative baby like Elijah is unable to complete the trial. He gets caught up in trying to make his mother look at the play performed in front of them, and keeps turning his head away from the stage. He doesn't pay enough attention to the action itself. So it goes when you're working with babies.

Over the past ten years, however, Vouloumanos and her colleagues, particularly Janet Werker, her advisor when she was at the University of British Columbia, have pulled enough information out of babies to give us a good idea of
the somewhat methodical way babies focus on and master different aspects of sound. Before three months of age, for instance, babies show a preference for speech over other sounds, even if the other sounds are acoustically similar to speech. By six months, a baby knows the difference between speech produced by humans and sounds produced by animals. Vouloumanos tested this by showing babies images of human faces, ducks, and rhesus monkeys while playing human speech, ducks quacking, and monkeys grunting. Babies looked longer at human faces when they were listening to human speech. An interesting additional result: If the humans were not speaking but laughing or making other non-speech sounds, the babies didn't show any preference for the human faces, which suggests that speech is indeed special and distinct from the other noises that come out of human mouths.

By nine months, a baby can tell if the sound sequence he's hearing is part of his native language or not. We know this because there are certain sounds, known as phonemes in linguistics, that appear in one language but not another. At birth, early language expert Patricia Kuhl has shown, babies are multilingual. They arrive in the world able to hear and distinguish the various phonemes of all the world's languages. That's logical, since a baby doesn't know until he is born what his native tongue will be. Over the course of the first year of life, babies hear more and more of the language they will grow up speaking, so those phonemes become familiar. Gradually, as Charles Yang puts it, they “unlearn” the other languages. This explains why a Japanese baby can distinguish between an English “r” and “l,” but a Japanese adult cannot without extensive practice.

It also explains why, when researchers played tapes of a person speaking in French to French babies, the babies didn't really care much, so to speak, but when they played someone talking in Russian, the babies took note of the difference. For an English-speaking child, says Vouloumanos, this is like recognizing that “splot” could be an English word, but that “vzglad,” which means “looking” or “glaring” in Russian, could not.

At twelve months of age, a baby has progressed to working on meaning. When she hears her mother talk, she looks around to try to see what Mom might be talking about. She is trying to find a “referent” for the words her mother used.

The cues babies use to do all of this fall into three categories: linguistic, acoustic, and perceptual. Linguistic cues depend on having some kind of sense of language sounds—for example, understanding that there is a relationship between “is” and “-ing” in English. If you hear one, you often hear the other. Acoustic cues not surprisingly include what a child hears. An example is the fact that pauses in sentences mark boundaries, not necessarily between words but between phrases. “If a kid is trying to figure out how language works,” says Vouloumanos, “chunking out units by phrases lets you analyze them separately.”

Perceptual cues generally involve higher-order thinking and include a range of factors from the meanings of words to visual hints. I wondered about visual perceptual cues, since they must have been important to Alex. On the wall of my office, there's a photograph of Alex and me taken the summer he was one, right around the time of his first evaluation. I'm carrying him on my chest in a sling as we walk at the beach. I'm gazing into his face and laughing. He is smiling up at me under his sun hat. It looks as if we'd just shared a lovely joke. I'm sure I said something silly, just as I'm sure he didn't hear me. Despite that, the picture is evidence of communication. From my facial expression and perhaps my gestures, to which he must have been keenly attuned, he knew to start giggling.

Deaf babies learning sign language, Vouloumanos told me, use a fuller range of visual cues that echo the acoustic cues hearing babies hear, such as watching for pauses between phrases. They babble with their hands and when they do vocalize the sounds of English, they use far more sounds that they can see (such as “ba”) on the lips of the talker. Blind babies, by comparison, babble differently. They use more sounds that do not rely on visible articulations, such as “ga.”

Vouloumanos is in the midst of studying gesture by asking if babies understand from the beginning that pointing is communicative. Her hunch is that they do, that babies understand that someone who is pointing is trying to direct their attention. There is disagreement about how old an infant is before she understands that by pointing at an object or person, I want to tell her something about that object or person. If a baby points at a toy, is he underlining his own interest in that toy? Or is he trying to get his mother to share his interest? When his mother points at a different toy, she's creating a line of sight and movement with something interesting at the end of that line. The studies thus far have shown that by fourteen months of age, babies do understand what they can accomplish by pointing. When we met, Vouloumanos was bringing eleven-month-olds into the lab to see what they knew. What I knew was that during the year he was one, Alex had an entire vocabulary in his forefinger. Point to Mom, point to the swing, point to himself. Mom gets the message that he wants to be pushed. The length and strength of the pointing indicated the intensity of his feelings.

Social cues are particularly intriguing to researchers these days. If, as Vouloumanos suggested, language is a cooperative, social activity, it's important to understand what aspects of it derive from social interaction. The latest research attempts to tease out the relationship between language and social skills. In general, babies with better social skills also develop better language skills. Returning to songbirds for a moment, neuroscientists have found that the neurological period in which young birds are able to learn can be extended by social interaction. For humans, the question is, “Which comes first?” says Vouloumanos. Or to put it in academic terms, which is the “motor of development”?