While the child won’t be able to make the next-stage sound for several months, there’s still a very important interaction with parents going on. They basically take turns “talking,” as if having a mock conversation. The baby coos, and the daddy responds, “Is that so?” The baby babbles again, and the daddy in jest returns, “Well, we’ll have to ask Mom.”
While most parents seem to intuit their role in this turn-taking pattern spontaneously—without being told to do so by any handbook—they don’t all do so equally well. A remarkable study of vocal turn-taking found that when four-month-old infants and their parents exhibited better rhythmic coupling, those children would later have greater cognitive ability.
According to Goldstein, “Turn-taking is driving the vocal development—pushing the babies to make more sophisticated sounds.”
Parents find themselves talking to their baby in the singsongy cadence that’s termed “parentese,” without knowing why they’re strangely compelled to do so. They’re still using English, but the emotional affect is giddily upbeat and the vowels are stretched, with highly exaggerated pitch contours. It’s not cultural—it’s almost universal—and the phonetic qualities help children’s brains discern discrete sounds.
Around five months, a baby has gained enough control of the muscles in the vocal tract to open her throat and push breath through to occasionally produce “fully resonant” vowels. “To a mother of a five-month-old,” Goldstein said, “hearing a fully resonant sound from her baby is a big deal. It’s very exciting.” If her response is well-timed, the child’s brain notices the extra attention these new sounds win. At this point, parents start to phase out responding to all the old sounds, since they’ve heard them so often. That selective responsiveness in turn further pushes the child toward more fully-resonant sounds.
Soon the baby is adding “marginal syllables,” consonant-vowel transitions—rather than “goo” and “coo,” more like “ba” and “da,” using the articulators in the front of the mouth. However, the transition from the consonant to the vowel is drawn out, since the tongue and teeth and upper cleft can’t get out of the way fast enough, causing the vowel to sound distorted. (This is why so many of a baby’s first words start with B and D—those are the first proper consonants the muscles can make.)
As early as six months, but typically around nine months, infants start producing some “canonical syllables,” the basic components of adult speech. The consonant-vowel transition is fast, and the breath is quick. The child is almost ready to combine syllables into words. “We used nine-month-olds in our study because at that age, they are still commonly expressing all four types of babble,” Goldstein said. Quasi-resonant vowel babble might still be in the majority, and canonical syllables quite rare.
With this developmental scale in mind, it’s shocking to hear the difference in how the baby vocalizes over the course of Goldstein’s experiment. In the first ten minutes (that baseline natural period when the mom responded as she might at home), the average child vocalized 25 times. The rate leapt to 55 times in the middle ten minutes, when the mom was being coached to “go ahead” by Goldstein. The complexity and maturity of the babble also shot up dramatically; almost all vowels were now fully voiced, and the syllable formation improved. Canonical syllables, previously infrequent, now were made half the time, on average.
To my ear, it was stunning—the children literally sounded five months older, during the second ten-minute period, than they had in the first.
“What’s most important to note here is that the infant was not mimicking his parent’s sounds,” Goldstein noted.
During those middle ten minutes, the parent was only caressing the child, to reward the babble. The child wasn’t hearing much out of his mother’s mouth. But the touching, by itself, had a remarkable effect on the frequency and maturity of the babble.
Goldstein reproduced the experiment, asking parents to speak to their children as well as touch them. Specifically, he told half the parents what vowel sound to make, the other half he fed a consonant-vowel syllable that was wordlike, such as “dat.” Not surprisingly, the tots who heard vowels uttered more vowels, and those who heard syllables made more canonical syllables. Again though, the babies weren’t repeating the actual vowel or consonant-vowel. Instead, they adopted the phonological pattern. Parents who said “ahh” might hear an “ee” or an “oo” from their baby, and those who said “dat” might hear “bem.” At this tender age, infants aren’t yet attempting to parrot the actual sound a parent makes; they’re learning the consonant-vowel transitions, which they will soon generalize to all words.
To some degree, Goldstein’s research seems to have unlocked the secret to learning to talk—he’s just given eager parents a road map for how to fast-track their infants’ language development. But Goldstein is very careful to warn parents against overdoing it. “Children need breaks for their brain to consolidate what it’s learned,” he points out. “Sometimes children just need play time, alone, where they can babble to themselves.” He also cites a long trail of scholarship, back to B.F. Skinner, on how intermittent rewards are ultimately more powerful than constant rewards.
And lest any parent pull her infant out of day care in order to ensure he’s being responded to enough, Goldstein says, “The mix of responses a baby gets in a high-quality day care is probably ideal.”
Tamis-LeMonda also warns against overstimulation. Her moms weren’t responding at that high rate all day. “In my study, the mothers were told to sit down and play with their infant and these toys. But the same mom, when feeding the baby, might respond only thirty percent of the time. When the child is playing on the floor while the mom is cooking, it might be only ten percent. Reading books together, they’d have a very high response rate again.”
Goldstein has two other points of caution, for parents gung-ho on using his research to help their babies. His first concern is that a parent, keen to improve his response rate, might make the mistake of over-reinforcing less-resonant sounds when a baby is otherwise ready to progress, thereby slowing development. This would reward a baby for immature sounds, making it too easy for the baby to get attention. The extent to which parents, in a natural setting, should phase out responses to immature sounds, and become more selective in their response, is thus far unknown.
Goldstein’s second clarification comes from a study he co-authored with his partner at Cornell, Dr. Jennifer Schwade. As Goldstein’s expertise is a tot’s first year of life, Schwade’s expertise is the second year, when children learn their first 300 words. One of the ways parents help infants is by doing what’s called “object labeling”—telling them, “That’s your stroller,” “See the flower?,” and “Look at the moon.” Babies learn better from object-labeling when the parent waits for the baby’s eyes to naturally be gazing at the object. The technique is especially powerful when the infant both gazes and vocalizes, or gazes and points. Ideally, the parent isn’t intruding, or directing the child’s attention—instead he’s following the child’s lead. When the parent times the label correctly, the child’s brain associates the sound with the object.
Parents screw this up in two ways. First, they intrude rather than let the child show some curiosity and interest first. Second, they ignore what the child is looking at and instead take their cues from what they think the child was trying to say.
The baby, holding a spoon, might say “buh, buh,” and the zealous parent thinks, “He just said ‘bottle,’ he wants his bottle,” and echoes to the child, “Bottle? You want your bottle? I’ll get you your bottle.” Inadvertently, the parent just crisscrossed the baby, teaching him that a spoon is called “bottle.” Some parents, in Goldstein and Schwade’s research, make these mismatches of speech 30% of the time. “Beh” gets mistaken by parents as “bottle,” “blanket,” or “brother.” “Deh” is interpreted as “Daddy” or “dog,” “kih” as “kitty,” and “ebb” as “apple.” In fact, at nine months old, the baby may mean none of those—he’
s just making a canonical syllable.
Pretending the infant is saying words, when he can’t yet, can really cause problems.
Proper object-labeling, when the infants were nine months, had an extremely strong positive correlation (81%) with the child’s vocabulary six months later. Crisscrossed labeling—such as saying “bottle” when the baby was holding a spoon—had an extremely negative correlation with resulting vocabulary (–68%). In real life terms, what did this mean? The mother in Schwade’s study who was best at object labeling had a fifteen-month-old daughter who understood 246 words and produced 64 words. By contrast, the mother who crisscrossed her infant the most had a fifteen-month-old daughter who understood only 61 words and produced only 5.
According to Schwade’s research, object labeling is just one of any number of ways that adults scaffold language for toddlers. Again, these are things parents tend to do naturally, but not equally well. In this section, we’ll cover five of those techniques.
For instance, when adults talk to young children about small objects, they frequently twist the object, or shake it, or move it around—usually synchronizing the movements to the singsong of parentese. This is called “motionese,” and it’s very helpful in teaching the name of the object. Moving the object helps attract the infant’s attention, turning the moment into a multisensory experience. But the window to use motionese closes at fifteen months—by that age, children no longer need the extra motion, or benefit from it.
Just as multisensory inputs help, so does hearing language from multiple speakers.
University of Iowa researchers recently discovered that fourteen-month-old children failed to learn a novel word if they heard it spoken by a single person, even if the word was repeated many times. The fact that there was a word they were supposed to be learning just didn’t seem to register. Then, instead of having the children listen to the same person speaking many times, they had kids listen to the word spoken by a variety of different people. The kids immediately learned the word. Hearing multiple speakers gave the children the opportunity to take in how the phonics were the same, even if the voices varied in pitch and speed. By hearing what was different, they learned what was the same.
A typical two-year-old child hears roughly 7,000 utterances a day. But those aren’t 7,000 unique sayings, each one a challenge to decode. A lot of that language is already familiar to a child. In fact, 45% of utterances from mothers begin with one of these 17 words:
what, that, it, you, are/aren’t, I, do/don’t, is, a, would, can/can’t, where, there, who, come, look, and let’s.
With a list of 156 two-and three-word combinations, scholars can account for the beginnings of two-thirds of the sentences mothers say to their children.
These predictably repeating word combinations—known as “frames”—become the spoken equivalent of highlighting a text. A child already knows the cadence and phonemes for most of the sentence—only a small part of what’s said is entirely new.
So you might think kids need to acquire a certain number of words in their vocabulary before they learn any sort of grammar—but it’s the exact opposite. Grammar teaches vocabulary.
One example: for years, scholars believed that children learned nouns before they learned verbs; it was assumed children learn names for objects before they can comprehend descriptions of actions. Then scholars went to Korea. Unlike European languages, Korean sentences often end with a verb, not a noun. Twenty-month-olds there with a vocabulary of fewer than 50 words knew more verbs than nouns. The first words the kids learned were the last ones usually spoken—because they heard them more clearly.
Until children are eighteen months old, they can’t make out nouns located in the middle of a sentence. For instance, a toddler might know all of the words in the following sentence: “The princess put the toy under her chair.” However, hearing that sentence, a toddler still won’t be able to figure out what happened to the toy, because “toy” came mid-sentence.
The word frames become vital frames of reference. When a child hears, “Look at the ___,” he quickly learns that ___ is a new thing to see. Whatever comes after “Don’t” is something he should stop doing—even if he doesn’t yet know the words “touch” or “light socket.”
Without frames, a kid is just existing within a real-life version of Mad Libs—trying to plug the few words he recognizes into a context where they may or may not belong.
This key concept—using some repetition to highlight the variation—also applies to grammatical variation.
The cousin to frames are “variation sets.” In a variation set, the context and meaning of the sentence remain constant over the course of a series of sentences, but the vocabulary and grammatical structure change. For instance, a variation set would thus be: “Rachel, bring the book to Daddy. Bring him the book. Give it to Daddy. Thank you, Rachel—you gave Daddy the book.”
In this way, Rachel learns that a “book” is also an “it,” and that another word for “Daddy” is “him.” That “bring” and “give” both involve moving an object. Grammatically, she heard the past tense of “give,” that it’s possible for nouns to switch from being subjects to being direct objects (and vice versa), and that verbs can be used as an instruction to act (“Give it”) or a description of action taken (“You gave”).
Variation sets are the expertise of a colleague of Schwade’s at Cornell, Dr. Heidi Waterfall. Simply put, variation sets are really beneficial at teaching both syntax and words—and the greater the variations (in nouns, verbs, conjugation and placement) the better.
From motionese to variation sets—each element teaches a child what is signal and what is noise. But the benefits of knowing what to focus on and what to ignore can hardly be better illustrated than by the research on “shape bias.”
For many of the object nouns kids are trying to learn, the world offers really confusing examples. Common objects like trucks, dogs, telephones, and jackets come in every imaginable color and size and texture. As early as fifteen months old, kids learn to make sense of the world by keying off objects’ commonality of shape, avoiding the distraction of other details. But some kids remain puzzled over what to focus on, and their lack of “shape bias” holds back their language spurt.
However, shape bias is teachable. In one experiment, Drs. Linda Smith and Larissa Samuelson had seventeen-month-old children come into the lab for seven weeks of “shape training.” The sessions were incredibly minimal—each was just five minutes long and the kids learned to identify just four novel shapes (“This is a wug. Can you find the wug?”). That’s all it took, but the effect was amazing. The children’s vocabulary for object names skyrocketed 256%.
A nine-month-old child is typically-developing if he can speak even 1 word. With the benefit of proper scaffolding, he’ll know 50 to 100 words within just a few months. By two, he will speak around 320 words; a couple months later—over 570. Then the floodgates open. By three, he’ll likely be speaking in full sentences. By the time he’s off to kindergarten, he may easily have a vocabulary of over 10,000 words.
It was one thing to learn about these scaffolding techniques from Goldstein and Schwade—but it was another thing to actually see their power in action.
Ashley had that chance shortly after we returned from Cornell, when she met her best friends, Glenn and Bonnie Summer, and their twelve-month-old daughter Jenna, for a casual dinner in Westwood, a shopping area in West Los Angeles. Ashley thinks of Jenna as her niece, and she had brought a tiny, red Cornell sweatshirt for the baby. During dinner, Ashley also couldn’t help but try some of the scaffolding techniques on Jenna.
Every time Jenna looked at something, Ashley instantly labeled it for her. “Fan,” Ashley pronounced, when Jenna’s gaze landed on the ceiling fan that beat the air. “Phone,” she chimed, whenever Jenna’s ears led her eyes to the pizza joint’s wall-mounted telephone, ringing off the hook. Whenever Jenna babbled, Ashley immediately responded with a word or touch. Ashley clearly noticed the di
fferent babble stages in Jenna’s chatter.
Jenna turned to her mother and made the baby sign gesture “More,” tapping her fingertips together. She wanted another piece of the nectarine Bonnie had brought for her.
After giving the little girl the fruit, Bonnie complained: “It’s the one baby sign she knows—a friend of mine taught it to her—and now I can’t get Jenna to say ‘More.’ She used to try saying the word out loud, but now she only signs it. I hate it.”
Ashley felt a little guilty; she too was messing with Jenna’s language skills. But her guilt vanished when she realized that Jenna was babbling noticeably more than before. Jenna was looking straight at Ashley when she talked, using more consonant-vowel combinations, right on cue. Ash was ecstatic. There, in a Westwood dive, she and her niece had replicated Goldstein’s findings, even down to the same fifteen-minute time frame.
Emboldened, Ashley asked Jenna’s parents if she could try something. Jenna had about ten words in her spoken vocabulary—“milk,” “book,” “mama,” and “bye bye,” among others. But her parents had not yet been able to directly teach her a new word, on the spot. Since Goldstein’s experiment had worked so well, Ashley decided to try Schwade’s lesson on motionese. She took a small piece of the nectarine and danced it through the air, while saying, “Fr-uu-ii-t, Jen-na, fr-uu-ii-t.” Jenna looked wide-eyed.
“Now, you do it,” Ashley instructed Glenn and Bonnie.
“Froo-oooo-ooottt,” Glenn said, bobbing the next piece of nectarine up and down. His attempt sounded more like a Halloween ghost than parentese. Ashley coached him—a little more singsong, a little more rhythm in the hand movement. Glenn tried it a second time: “Fro-ooo-oo-ttt.” He set the nectarine chunk in front of Jenna.
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