NurtureShock (28 page)

Wondering what parents’ prevailing assumptions about language acquisition were, we polled some parents, asking them why they
thought one kid picked up language far faster than another. Specifically, we were asking about two typically-developing kids,
without hearing or speech impairments.

Most parents admitted they didn’t know, but they had absorbed a little information here and there to inform their guesses.
One of these parents was Anne Frazier, mother to ten-month-old Jon and a litigator at a prestigious Chicago law firm; she
was working part-time until Jon turned one. Frazier had a Chinese client base and, before having Jon, occasionally traveled
to Asia. She’d wanted to learn Mandarin, but her efforts were mostly for naught. She had decided that she was too old—her
brain had lost the necessary plasticity—so she was determined to start her son young. When she was dressing or feeding her
baby, she had Chinese-language news broadcasts playing on the television in the background. They never sat down just to watch
television—she didn’t think that would be good for Jon—but Frazier did try to make sure her child heard twenty minutes of
Mandarin a day. She figured it couldn’t hurt.

Frazier also assumed that Jon would prove to have some level of innate verbal ability—but this would be affected by the sheer
amount of language Jon was exposed to. Having a general sense that she needed to constantly talk to her child, Frazier was
submitting her kid to a veritable barrage of words.

“Nonstop chatter throughout the day,” she affirmed. “As we run errands, or take a walk, I describe what’s on the street—colors,
everything I see. It’s very easy for a mother to lose her voice.”

She sounded exhausted describing it. “It’s hard to keep talking to myself all the time,” Frazier confessed. “Infants don’t
really contribute anything to the conversation.”

Frazier’s story was similar to many we heard. Parents were vague on the details, but word had gotten out that innate ability
wasn’t the only factor: children raised in a more robust, language-intensive home will hit developmental milestones quicker.
This is also the premise of popular advice books for parents of newborns, which usually devote a page to reminding parents
to talk a lot to their babies, and around their babies. A fast-selling new product being sold to parents is the $699 “verbal
pedometer,” a sophisticated gadget the size of a cell phone that can be slipped into the baby’s pocket or car seat. It counts
the number of words the baby hears during an hour or day.

The verbal pedometer is actually used by many researchers who study infants’ exposure to language. The inspiration behind
such a tool is a famous longitudinal study by Drs. Betty Hart and Todd Risley, from the University of Kansas, published in
1994.

Hart and Risley went into the homes of a variety of families with a seven- to nine-month-old infant. They videotaped an hour
of interactions while the parent was feeding the baby or doing chores with the baby nearby—and they repeated this once a month
until the children were three. Painstakingly breaking down those tapes into data, Hart and Risley found that infants in welfare
families heard about 600 words per hour. Meanwhile, the infants of working-class families heard 900 words per hour, and the
infants of professional-class families heard 1,500 words per hour. These gaps only increased when the babies turned into toddlers—not
because the parents spoke to their children more often, but because they communicated in more complex sentences, adding to
the word count.

This richness of language exposure had a very strong correlation to the children’s resulting vocabulary. By their third birthday,
children of professional parents had spoken vocabularies of 1,100 words, on average, while the children of welfare families
were less than half as articulate—speaking only 525 words, on average.

The complexity, variety, and sheer amount of language a child hears is certainly one driver of language acquisition. But it’s
not scientifically clear that merely hearing lots of language is the crucial, dominant factor. For their part, Hart and Risley
wrote pages listing many other variables at play,
all
of which had correlations with the resulting rate at which the children learned to speak.

In addition, the words in the English language that children hear most often are words like “was,” “of,” “that,” “in,” and
“some”—these are termed “closed class” words. Yet children learn these words the most slowly—usually not until after their
second birthday. By contrast, children learn nouns first, even though nouns are the least commonly-occurring words in parents’
natural speech to children.

The basic paradigm, that a child’s language output is a direct function of the enormity of input, also doesn’t explain why
two children, both of whom have similar home experiences (they might both have highly educated, articulate mothers, for instance)
can acquire language on vastly divergent timelines.

A decade ago, Hart and Risley’s work was the cutting edge of language research. It’s still one of the most quoted and cited
studies in all of social science. But in the last decade, other scholars have been flying under the radar, teasing out exactly
what’s happening in a child’s first two years that pulls her from babble to fluent speech.

If there’s one main lesson from this newest science, it’s this: the basic paradigm has been flipped. The information flow
that matters most is in the opposite direction we previously assumed. The central role of the parent is not to push massive
amounts of language
into
the baby’s ears; rather, the central role of the parent is to notice what’s coming
from
the baby, and respond accordingly—coming from his mouth, his eyes, and his fingers. If, like Anne Frazier, you think a baby
isn’t contributing to the conversation, you’ve missed something really important.

In fact, one of the mechanisms helping a baby to talk isn’t a parent’s speech at all—it’s not what a child
hears
from a parent, but what a parent accomplishes with a well-timed, loving caress.

Dr. Catherine Tamis-LeMonda, of New York University, has spent the last decade looking specifically at parent-responsiveness
to infants, and its impact on language development. Along with Dr. Marc Bornstein of the National Institutes of Health, she
sent teams of researchers into homes of families with nine-month-old babies. For the most part, these were affluent families
with extremely well-educated parents living in the New York City area. The researchers set some age-appropriate toys down
on the floor and asked the mother to play with her child for ten minutes.

These interactions were videotaped, and the ten-minute tapes were later broken down second by second. Every time the baby
looked to the mother, or babbled, or reached for a toy was noted. The children did this, on average, about 65 times in ten
minutes, but some kids were very quiet that day and others very active. Every time the mother responded, immediately, was
also noted. The moms might say, “Good job,” or “That’s a spoon,” or “Look here.” The moms responded about 60 percent of the
time. Responses that were late, or off-timed (outside a five-second window), were categorized separately.

The researchers then telephoned the mothers every week, for the next year, to track what new words the child was using that
week—guided by a checklist of the 680 words and phrases a toddler might know. This created a very accurate record of each
child’s progression. (They also repeated the in-home videotape session when the infant was thirteen months old, to get a second
scoring of maternal responsiveness.)

On average, the children in Tamis-LeMonda’s study said their first words just before they were thirteen months old. By eighteen
months, the average toddler had 50 words in her vocabulary, was combining words together, and was even using language to talk
about the recent past. But there was great variability within this sample, with some tots hitting those milestones far earlier,
others far later.

The variable that best explained these gaps was how often a mom rapidly responded to her child’s vocalizations and explorations.
The toddlers of high-responders were a whopping six months ahead of the toddlers of low-responders. They were saying their
first word at ten months, and reaching the other milestones by fourteen months.

Remember, the families in this sample were all well-off, so
all
the children were exposed to robust parent vocabularies. All the infants heard lots of language. How often a mother initiated
a conversation with her child was not predictive of the language outcomes—what mattered was, if the infant initiated, whether
the mom responded.

“I couldn’t believe there was that much of a shift in developmental timing,” Tamis-LeMonda recalled. “The shifts were hugely
dramatic.” She points to two probable mechanisms to explain it. First, through this call-and-response pattern, the baby’s
brain learns that the sounds coming out of his mouth affect his parents and get their attention—that voicing is important,
not meaningless. Second, a child needs to associate an object with a word, so the word has to be heard just as an infant is
looking at or grabbing it.

In one paper, Tamis-LeMonda compares two little girls in her study, Hannah and Alyssa. At nine months old, both girls could
understand about seven words, but weren’t saying any yet. Hannah was vocalizing and exploring only half as often as Alyssa—who
did so 100 times during the ten minutes recorded. But Hannah’s mom was significantly more responsive. She missed very few
opportunities to respond to Hannah, and described whatever Hannah was looking at twice as often as Alyssa’s mother did with
Alyssa. At thirteen months, this gap was confirmed: Hannah’s mom responded 85% of the time, while Alyssa’s mom did so about
55% of the time.

Meanwhile, Hannah was turning into a chatterbox. Alyssa progressed slowly. And the gap only increased month by month. During
their eighteenth month, Alyssa added 8 new words to her productive vocabulary, while in that same single-month period, Hannah
added a phenomenal 150 words, 50 of which were verbs and adjectives.

At twenty-one months, Alyssa’s most complicated usages were “I pee” and “Mama bye-bye,” while Hannah was using prepositions
and gerunds regularly, saying sentences like: “Yoni was eating an onion bagel.” By her second birthday, it was almost impossible
to keep track of Hannah’s language, since she could say just about anything.

This variable, how a parent responds to a child’s vocalizations—right in the moment—seems to be the most powerful mechanism
pulling a child from babble to fluent speech.

Now, if we take a second look at the famous Hart and Risley study, in light of Tamis-LeMonda’s findings, this same mechanism
is apparent. In Hart and Risley’s data, the poor parents initiated conversations just as often with their tots as affluent
parents (about once every two minutes). Those initiations were even slightly richer in language than those of the affluent
parents. But the real gap was in how parents
responded
to their children’s actions and speech.

The affluent parents responded to what their child babbled, said, or did over 200 times per hour—a vocal response or a touch
of the hand was enough to count. Each time the child spoke or did something, the parent quickly echoed back. The parents on
welfare responded to their children’s words and behavior less than half as often, occupied with the burden of chores and larger
families. (Subsequent analysis by Dr. Gary Evans showed that parent responsiveness was also dampened by living in crowded
homes; crowding leads people to psychologically withdraw, making them less responsive to one another.)

Tamis-LeMonda’s scholarship relies on correlations—on its own, it’s not actually proof that parent-responsiveness
causes
infants to speed up their language production. To really be convinced that one triggers the other, we’d need controlled experiments
where parents increase their response rate, and track if this leads to real-time boosts in infant vocalization.

Luckily, those experiments have been done—by Dr. Michael Goldstein at Cornell University. He gets infants to change how they
babble, in just ten minutes flat.