These moments of connection are sweet, emotional encounters, but researchers know they are much more. Research scientists at the University of Washington鈥檚 (I-LABS) recognize this 鈥渟ocial ensemble鈥� as the nascent that lay down the pathway to language 鈥� the gateway to connection, education and the world of ideas. Given that these distinctive interactions appear to be universal and uniquely human, I-LABS researchers wondered what their developmental purpose could be. What they found was not only that the babies鈥� brains 鈥渓it up鈥� during these interactions, but that the degree to which individual babies responded to social interactions predicted the child鈥檚 language growth beyond 2-陆 years of age.

鈥淲hat we were trying to see is whether that social ensemble 鈥� the parentese, the warm smiles, the touches, and the back and forth that says you’re paying attention 鈥� has a (developmental) goal in addition to the emotion that鈥檚 connecting these two people,鈥� says Dr. Patricia Kuhl, I-LABS鈥� co-director, and holder of the Bezos Family Foundation Endowed Chair in Early Childhood Learning, who led a groundbreaking longitudinal study linking infants鈥� individual brain responses to social interactions and their future language development.

Using a magnetoencephalography () brain-imaging device 鈥� a safe, silent, noninvasive technique I-LABS has tailored for studying infants 鈥� the researchers monitored the brains of a group of 5-month-old infants during social and nonsocial interactions with an adult. The researchers then followed up with the children at 18, 21, 24, 27 and 30 months. Their findings were published in the April issue of and represent the first such study to track the relationship between infants鈥� social responses and their language acquisition.

Arriving Ready for Language

Even before they produce their first words, infants are learning phonetic sound patterns. They come into the world able to pick out the human sounds that make up words in any language. Previous independent studies have shown that there is a 鈥渟ensitive period鈥� for phonetic learning between 6 months and one year when these initial universal phonetic capacities narrow down and become specific to their native languages.

鈥淭esting the babies at 5 months was important because we were trying to establish that this social connection that lights up the baby鈥檚 brain and gets them ready to learn comes first and sets them up for when this sensitive period begins,鈥� says Kuhl, the study鈥檚 lead author. 鈥淭he social interaction is of cognitive importance and gets the baby ready for what鈥檚 coming around six months. The exaggerated face and silly-sounding speech (the 鈥榚nsemble鈥�) come intuitively and are the original 鈥榟ook鈥� that pulls them and primes them for the learning to come.鈥�

For the study, Kuhl says, researchers set the infants up in the MEG device and an adult female researcher engaged with the baby, speaking in parentese and reacting warmly back and forth using the tried-and-true adult-baby call and response. For the experiment鈥檚 nonsocial control, the researcher would then turn and speak to another adult seated just out of the infant鈥檚 view. The intention was to capture typical social interactions that babies experience regularly in their home environments.

The researchers鈥� findings showed that at 5 months, face-to-face social verbal interaction between an infant and an adult who鈥檚 sensitive to the baby鈥檚 cues significantly increases the child鈥檚 brain activity in regions involved with attention, compared with a nonsocial control. Even more exciting to those interested in babies鈥� language learning, the scientists found that babies鈥� individual levels of brain activity during the social interactions showed a strong positive association with their subsequent language skills.

鈥淣ot all children鈥檚 brains lit up to the same degree to the social ensemble,鈥� Kuhl says. 鈥淭heir social attention is different. The ones with more social attention learned language faster.鈥�

The Joy of Face-to-Face

Kuhl says the researchers knew from previous studies that social interaction 鈥� rather than, say, watching a video or app 鈥� is essential for language learning. The current study shows that parents鈥� natural use of parentese, coupled with smiles, touch and their warm volley and return captures infants鈥� attention at an early age and makes them ready to latch onto language when that sensitive window opens around 6 months.

The researchers didn鈥檛 use the children鈥檚 parents in this study because they were concerned their history of interaction might color the babies鈥� responses, nor did they have the researcher turn from the baby to use a smartphone or device because they have seen in other research how upsetting that is to the babies. The researcher interacting with the babies had not met them before the experiment began but started the kind of natural interaction with them that might occur in the grocery store or when other adults drop over for a visit. She cooed back and forth with the baby, then, on cue, looked away to interact with another researcher 鈥渙ffstage鈥� for a moment. On another cue, she turned back to the baby and began the social interaction again.

The babies鈥� little brains loved all that attention and weren鈥檛 happy (as observed by MEG鈥檚 neural light show) when they were being ignored. Some babies鈥� brains really sparked at the social interaction and those were the babies who, by 2-陆 years, showed the greater vocabularies and more sophisticated use of language.

This doesn鈥檛 mean that babies have to be attended to at all times or they鈥檙e going to lose out on language skills, Kuhl is clear to state. No helicopter parenting here!

鈥淭hat would be the wrong message to take from this research,鈥� she says. 鈥淧art of these interactions鈥� special nature is that they only come occasionally. The interaction is there, then it goes away, and next time it comes, it鈥檚 like Christmas 鈥� something to be anticipated and excited about. So, parents shouldn鈥檛 stress and think, 鈥極h my gosh, here鈥檚 one more thing I have to think to do.鈥� Its magic is that it鈥檚 unexpected and babies are overjoyed by that.鈥�

More Questions, More Studies

As good studies do, this one has prompted almost as many questions as it鈥檚 answered. For one thing, researchers want to know about what鈥檚 happening with the brains of babies whose mothers are dealing with clinical depression.

鈥淚n mothers who have clinical depression, you don鈥檛 see the smiles, the parentese and the warm interactions,鈥� Kuhl says. 鈥淭here are all kinds of issues with these children, one of which is a depressed affect and a slow growth of language.鈥�

The current study also points to a greater understanding of autism and draws attention to other research, such as that of Dr. Karen Pierce of t he University of California San Diego, et al, showing that babies鈥� reduced attention to parentese can both contribute to downstream language and social challenges, and help diagnose toddlers with autism spectrum disorder.

鈥淲hen (Pierce) tests young children who are at risk for autism (because they have a sibling with autism) with a social versus nonsocial stimulus 鈥� such as people interacting versus cars or just sound 鈥� the children with autism tend not to like social, people-oriented stuff,鈥� Kuhl says. 鈥淎nd the more they tend not to, the more severe their clinical symptoms for autism are.鈥�

Another fascinating study in the I-LABS pipeline is the differences between mothers and fathers in their deployment of parentese. Preliminary research indicates that men are talking to their babies only 25 percent of the time, compared with mothers. They do use the social ensemble to interact with babies, but ongoing research is looking at whether fathers stop using parentese earlier in the child鈥檚 development, and if they do, why that may be the case.

奥丑补迟鈥檚 that about? We鈥檒l have to stay tuned.

Meanwhile, we can go ahead and indulge our impulse to engage in that silly social way with babies and know that we aren鈥檛 just forming emotional connections; we鈥檙e helping open their pathway to life with other humans.

鈥淚 suppose if you were on an island by yourself and had all the survival skills you needed to discover food, water and shelter, you might be able to survive as an isolate,鈥� Kuhl says. 鈥淏ut everything we know about human beings is that we inherently crave connection with each other. And language is the gateway to any communicative connection we have. It鈥檚 our social-emotional glue.鈥�

Both research teams used the nonprofit LENA鈥檚 to glean their findings. The wearable device delivers detailed information on what children hear throughout the day. It measures the number of words spoken near the child in addition to the child鈥檚 own language-related vocalizations.

It also counts child-adult interactions, called 鈥渃onversational turns,鈥� which both research groups say are critical to language acquisition.

鈥淚t is the conversational turns that drive brain development,鈥� said Brown鈥檚 Sean Deoni, adding he鈥檚 concerned for the long-term success of children born after the pandemic began. 

The joint finding is the latest of discovered when researchers compared babies born before and after COVID. 

Deoni is principal investigator at Brown鈥檚 Advanced Baby Imaging Lab. He and other staffers there first spotted the problem when they noticed that children who visited the lab after March 2020 took longer to complete cognitive tasks.

鈥淭hey were not as attentive, or at least not performing as well as we normally have seen,鈥� Deoni said. It was this change that prompted him to take a new look at various data points gathered from the nearly 800 children his facility has worked with in recent years. After examining their neuroimaging and neurocognitive results, he and his team found child motor and language scores decreased sharply in 2021 and 2022, prompting them to search for an explanation for the decline.

The inquiry led them to analyze information gathered from children ages 12 and 16 months who were born before 2019 鈥� well before the COVID outbreak 鈥� and after July 2020, months into its spread. The results showed a major drop in verbal functioning between the two groups. Those born after COVID demonstrated slower verbal growth over time.

Tests showed, too, these babies experienced a significantly slower rate of white matter聽development versus the children from studies done before the pandemic.

鈥淲hite matter is basically the wiring of the brain,鈥� Deoni said. 鈥淚t鈥檚 what carries information throughout the brain and to different cortical regions where it is processed. White matter damage, for example, is a hallmark of multiple sclerosis. Reduced white matter development is associated with reduced cognitive development.鈥�

Deoni and his team also found a significant drop in adult words per hour and conversational turns between the two groups of children. The deficit will have a significant impact on kids he said, citing his own group鈥檚 earlier research. 

Neither research team focused on the cause of the drop in caregiver interactions with babies, only the outcome, though Deoni cited the heightened stress, depression and burnout associated with the pandemic as possible explanations. 

Jill Gilkerson, a linguist specializing in early language acquisition and LENA鈥檚 chief research and evaluation officer, said the reasons might differ from one household to the next. 

鈥淚 don鈥檛 think we are going to be able to find a single cause to point to, and I鈥檓 not sure that we need to,鈥� she said. 鈥淲e hope this data validates concerns caregivers may be having, helps them know they are not alone in those feelings and furthers the conversation about the need to invest in support for families at every level.鈥�

LENA鈥檚 study showed child vocalizations dropped significantly across all groups of children, but particularly among those from the lowest socioeconomic level. The frequency of caregiver/child conversations also decreased dramatically, particularly among children from the poorest families, it found.

鈥淚t鈥檚 often the case that when these adverse events happen, it鈥檚 those who are already the most vulnerable that are hit the hardest鈥� and I think that we are seeing this here,鈥� Gilkerson said.

The connection between economic security and language acquisition was very much a pre-pandemic concern as well. A found that children growing up in low-income households hear 30 million fewer words than their peers from high-income backgrounds. A 2018 study raised questions about the extent of the gap, but the science is clear that children鈥檚 first three years are the most critical time for brain development.

LENA, based in Boulder, Colorado and founded in 2004, aims to improve children鈥檚 futures through early talk technology and data-driven programs. Its software measures a child鈥檚 language environment and provides feedback to parents and professionals vested in preparing them for school.

Its study of 136 COVID-era babies included only those who started gestating on or after the start of the pandemic in mid-March 2020: All were born after December 15 of that year. The findings from this group were compared to a pre-COVID pool, which captured recordings between 2017 and March 2020 and included 494 kids.

These language deficits, once shared with caregivers, are possible to correct. But, Gilkerson said, it鈥檚 important for groups like hers to suggest practical, easily applicable solutions.

鈥淲e need to 鈥� provide parents with strategies for integrating talk 鈥� interactive talk, quality talk 鈥� with their children during their regular routine,鈥� she said, rather than add a new task to their already stress-filled lives.

LENA鈥檚 latest research builds off earlier findings the group published in the journal in October 2018: That study showed early talk and interaction, particularly for children ages 18 to 24 months, can predict school-age language and cognitive outcomes. In that paper, LENA examined day-long audio recordings for 146 infants and toddlers completed monthly for six months.

LENA鈥檚 Language Environment Analysis software measured the total number of adult words and adult-child conversations. LENA conducted follow-up evaluations at 9 to 14 years of age. It concluded that adult-child conversations influence a child鈥檚 IQ, verbal comprehension and vocabulary scores 10 years later.

And while it鈥檚 true, both researchers acknowledged, that children are resilient, recent data does not yet reflect the bounceback from the pandemic.

鈥淲e are not seeing them hit a floor and all progressively get better,鈥� Deoni said. 鈥淲e are seeing them continue this downward trend.鈥�

And it鈥檚 not just a language acquisition problem. Reduced verbal development is being driven by poor motor development, Deoni said: This early foundational skill could have a lasting impact on children, one that can be hard to correct for as they age.

鈥淚鈥檓 worried about how we set things up going forward such that our early childhood teachers and early childhood interventionalists are prepared for what is potentially a set of children who maybe aren鈥檛 performing as we expect them to,鈥� he said.

To be clear, the baby talk we鈥檙e discussing is not of the goo-goo, gah-gah sort of speech. Infant-directed speech is the high-pitched, singsong, slowed-down way adults talk to babies that sets the stage for vocabulary-building conversational turns 鈥� Is that your hand? Look at that hand! And five little fingers! Most adults automatically fall into this exaggerated cadence and register of speech when they come face to face with a baby.

To discover their preference for infant-directed speech, a unique study of hundreds of babies involving 17 labs on four continents compared babies from bilingual backgrounds to babies from monolingual backgrounds, and exposed them to many different language combinations. According to primary investigator Dr. Krista Byers-Heinlein, associate professor of psychology at Montreal鈥檚 Concordia University, each baby was played short recordings of English-speaking mothers using both infant-directed and adult-directed speech. The global nature of the study ensured that many different language combinations were represented.

Regardless of their native language, the babies responded more to the recordings of infant-directed speech, or baby talk, than to the adult-directed speech. All the babies preferred the baby talk samples, which in this study were recorded in English, over adult-directed speech, but babies from homes in which English was spoken really liked it. In baby research, Byers-Heinlein says, looking indicates listening, and when the babies who came from homes in which English was spoken heard the recordings by English-speaking moms, they really perked up.

鈥淭he more familiar they were with the language, the better they liked that infant-directed speech,鈥� Byers-Heinlein says. 鈥淎 baby who was hearing English 75% of the time in their home would show a greater preference than a baby who was hearing English 25% of the time.鈥� The researchers were not testing the babies鈥� preference for English, but whether the infants were especially tuned in to infant-directed speech. The fact that the babies whose native language was English showed a marked preference for the English baby talk points to how exquisitely babies are listening and picking up on the languages they hear in their environment.

鈥淲e think that interest is the foundation of language acquisition,鈥� she says. 鈥淭hey hear it and think, 鈥極h, this is something for me. I should pay attention here.鈥� They鈥檙e paying attention to all the human speech they hear, but they really respond to the baby talk directed at them, and we think these adaptations help the learning process for them.鈥�

One of the hallmarks of infant-directed speech is that it is repetitive, she says. Look at the ball. Look at the ball. Do you see the ball? Babies are keenly attuned to repetition and the really close repetitions in infant-directed speech appear to help them start unlocking the sound, the words and the grammar they need to figure out language. Infants are more able to focus more efficiently and distinguish one word from another in the slowed-down cadences of infant-directed speech. Some studies have shown that babies learn words more effectively and demonstrate better long-term memory for words spoken in infant-directed speech.

Previous studies of the use of infant-directed speech have been primarily conducted in North America on monolingual babies. What distinguishes this research from other studies is the large-scale, multi-site study on bilingual infants. The project tested 333 bilingual babies and 384 monolingual infants in two age groups: 6 to 9 months and 12 to 15 months.

Knowing more about bilingual babies is essential, Byers-Heinlein says, because the number of bilingual families in both the U.S. and Canada continues to rise. According to the Annie E. Casey Foundation, nearly 14 million U.S. kids speak a language other than English at home. In California, 44% of children grow up in bilingual homes. The latest Canadian census has the number of bilingual residents at 18%, the highest on record.

The study arose as part of a remarkable research collaboration, , a project that brings researchers together to address challenging questions about the nature of early development and how it鈥檚 studied.

The ManyBabies project is conducted globally with Open Science at its core. The United Nations Educational, Scientific and Cultural Organization (UNESCO) describes Open Science as 鈥渁 methodology that allows scientific information, data and outputs to be more widely accessible and reliably harnessed with the active engagement of all the stakeholders.鈥� It encourages science to be more connected to societal needs and promotes equal opportunities for scientists, policymakers and citizens, making it a game-changer in bridging the science, technology and innovation gaps among and within countries.

According to UNESCO, the Open Science movement has spread rapidly across nations since its inception and its call for the 鈥渙pening of the gates of knowledge鈥� to accelerate the achievement of scientific solutions for global challenges.

According to Byers-Heinlein, 鈥淢anyBabies is the most exciting thing I鈥檝e been involved with in my career. I can鈥檛 believe this is a thing that is actually happening.

鈥淚nfant research has a number of problems,鈥� she says, 鈥渙ne of them being that our samples are so small. How many babies can I actually test in my lab? Just finding the babies, bringing them in, convincing the parents to take part in the study and then, half the babies don鈥檛 complete the study because they cry, or they get bored or they just don鈥檛 want to. I mean, they鈥檙e babies, right? They鈥檙e just hard to study 鈥� and especially if you consider how precise you need to be when you think of infants. A baby of 12 months is very different from an 18-month-old.

鈥淪o, imagine if you want to study adults, but you only want to recruit adults who are 52 years and one month old. That鈥檚 a little nuts. But with babies, that鈥檚 how precise you need to be.

鈥淎nd because of the way science works, the research has been very fragmented. I do things in my lab; you do things in your lab and maybe we publish something and talk about it at a conference. But how do we make real progress on these things and get the kind of samples we need?鈥�

The answer, through Open Science, is that the researchers put their heads together and start creating collaborative projects like ManyBabies. Byers-Heinlein compares it to the way scientists in other fields do their work; for example, particle physicists who don鈥檛 each have their own particle accelerator but plan the science together, collaborate and make progress in particle physics that none would have been able to accomplish on their own.

鈥淢anyBabies was born as a way for all these infant researchers to work together,鈥� she says. 鈥淔irst it was a few researchers talking to each other, then emails back and forth and people began to get really excited about the idea of planning a study together, then each tests the babies in our own labs. Our normal sample size might be 16 babies or maybe 32 babies. But now, we have studies involving hundreds of babies from around the world.鈥�

The study on bilingual babies is one of the first to come out of the ManyBabies project, and Byers-Heinlein says the collaboration is just getting started.

鈥淚t鈥檚 really unprecedented,鈥� she says. 鈥淭hink about coordinating across 69 labs and studying thousands of babies. It鈥檚 an incredible movement to work together and it鈥檚 opened up many more possibilities for further study. It鈥檚 a very rich data set. And the data is all completely public 鈥� anyone can take a look at all the data. It鈥檚 very unusual, because often scientists are hesitant to share their data with other researchers.鈥�

Here’s a look at some of the other fascinating 聽at ManyBabies. Meanwhile, be loud and proud when speaking to your infant in baby talk: It鈥檚 their love language, no matter what language you use.

For decades, a common belief has held that speaking more than one language in a child鈥檚 home confuses the child, makes it more difficult for them to learn English and might even hold them back in school and in life. The unfortunate consequence of this belief has been that some dual-language households have enforced an 鈥淓nglish-only鈥� rule around the children, leaving non-English speaking members of the family constrained and the child disconnected from some of the deepest and best of their heritage. Children may end up hearing less language overall if English is not a preferred language of adults in the household 鈥� at a time when their brains need language like their bodies need food.

In fact, the opposite is true. Researchers have found in numerous studies that bilingual babies learn English at the same rate as monolingual babies, with vocabularies that equal or exceed those of the English-only babies. Bilingual children have been found to have a more advanced ability to think about language and how it works, and there is some evidence that early exposure to a second language makes learning a third language easier.

Although the research is ongoing, multiple studies have found that juggling two languages from an early age actually enhances the mental skills and self-regulation referred to as 鈥渆xecutive function,鈥� which help people plan, solve problems and respond to the world around them in an orderly way. Some even indicate that being bilingual can offer protection decades later against age-related cognitive decline.

All over the world, as societies become more diverse and economies are globally connected, communities are working to create programs to introduce young children to learning a second language. Most are aimed at preschool children to kids in elementary school 鈥� a vast improvement on the traditional approach of starting young people on second languages in high school, but still a bit late.

According to Dr. Marley Jarvis, Outreach and Education Specialist at the University of Washington鈥檚 , researchers there have found it would make sense to start language learning much earlier: Babies鈥� brains are wired for language.

鈥淚 don鈥檛 want to say elementary school or later is too late for learning another language,鈥� Jarvis says. 鈥淥ne of the remarkable discoveries about our brains in the past couple of decades is their plasticity and their ability to change. Everything we do every day is changing our brains. But learning language later doesn鈥檛 happen in the same way it does with very young children, so we鈥檙e working against ourselves by waiting so long.

鈥淐hildren are already well-established in their first language before they even hit preschool.鈥�

In fact, Jarvis says, research shows that babies begin to learn language sounds while still in the womb. By the time they鈥檙e born they distinguish their mother鈥檚 voice from ambient sound and are even able to .

Babies come into this world equipped with one of the most powerful computers known to humankind 鈥� already on task analyzing massive amounts of data on arrival. About 800 sounds make up all the languages of the world; each human language only uses 40 or so of those sounds. As babies lie in their little bassinets, they are not only absorbing the sights, sounds and sensual cues from this bright new world, is sorting through those multiple data streams like greased lightning, cracking the code of human language, sorting out which of those human sounds are useful in their environment. By the time they鈥檙e 10 months old, babies have 鈥渃ommitted鈥� to their native language, specializing in the language they hear around them, and the sounds and syntax of other human languages fade into the background.

In the case of a child surrounded by speakers of two or more languages, that commitment extends to those languages as well. As I-LABS co-director Dr. Patricia Kuhl, an international authority on early learning and brain development, observes in the video 鈥淚gniting Bilingual Learning,鈥� babies鈥� language learning is time sensitive. The human brain will never be better at learning a second language than in the first three years of life.

Some parents fear that exposure to another language will limit the child鈥檚 English vocabulary, but researchers have also put that concern to rest with studies that show that bilingual children do not lag behind in the number of words they absorb. In fact, the vocabularies of bilingual children have been found to be than those of single-language children.

鈥淚n fact,鈥� Jarvis says, 鈥渨e have yet to see any evidence that a child is confused by more than two languages (though not all spoken at the same time). We haven鈥檛 seemed to find the limit. And they鈥檙e pretty good at knowing who is associated with which language. If you have a multilingual family, kids will naturally switch to the language appropriate to each person.鈥�

And, she says, the sorting and switching from one language to another 鈥� code-switching 鈥� actually helps the baby鈥檚 brain become more agile and resourceful. As they sort through their data streams to find which language is being spoken and then respond appropriately, they begin to develop the impulse control and strategic thinking so essential to executive function. Structural brain studies indicate that bilingual adults have greater brain tissue density in areas related to language, memory and attention, with the highest levels of tissue density among those who were exposed to two languages before the age of 5 years.

Research scientist Dr. Naja Ferjan Ram铆rez, director of the University of Washington鈥檚 Language Development and Processing Lab, is Slovenian, married to a native Spanish-speaker, and their 4-year-old son easily switches among English, Slovenian and Spanish. Though he sometimes uses Slovene endings on English and Spanish words, he modulates his language to match the situation he finds himself in. He may throw in a Spanish or Slovene word in his English dialog, but this is because he has a bigger library to choose from. This code-switching is not haphazard, she writes, but adheres to the linguistic logic of the languages he鈥檚 using.

Each time he does, like a bodybuilder reaching for a heavier weight, he鈥檚 building his brainpower.

For anyone wanting to teach their small children another language, it鈥檚 important to remember that the learning takes place in interaction, not in mere exposure to a recitation of words. It鈥檚 the social brain, Jarvis says, that鈥檚 important in any kind of learning, especially in these early years.

In one , a group of University of Washington students went through an online training program and learned to tutor small children through playful, interactive learning. The students then were sent to Spain to deliver group English sessions daily with Spanish-speaking children in the Community of Madrid鈥檚 public infant education centers. The key practices in their training were to address the children often in English and to speak to the children in 鈥減arentese鈥� (the higher-pitched, singsong language parents use to signal the child that this communication is for them). The learning context was highly social, with the tutors leading the children in games and activities that prompted face-to-face interaction. Tutors were trained to engage the children in frequent back-and-forth exchanges and to encourage the children to 鈥渢alk鈥� and interact with them. (I-LABS a series of research summaries with links to studies and practical family activities with tips for caregivers.)

Essentially, Jarvis says, the tutors played with the children in English in a highly social, engaging way for 45 minutes or so a day. The children in this study saw a nearly five-fold increase in their English speaking, compared with children in a control group in the school system鈥檚 English program. The children continued to develop in their native language, Spanish, at the same time. The big difference between the programs was the degree of social, back-and-forth, play-based interactions in the UW program.

If we want our children to meet the challenges of an increasingly diverse and global society, being fluent in more than one language will be an important element in that success. Parents who want their children to become the global citizens their brains are born to be can rest easy knowing that starting their children down that path as babies can only strengthen the child鈥檚 social and intellectual ability in the years to come.

鈥淐onversation is not necessarily about having a rich verbal language,鈥� says early learning scholar and author Dr. Kathy Hirsh-Pasek. 鈥淎t first, conversation can be coos and gestures and funny noises. A baby鈥檚 language learning is about the connection, the back and forth communication that happens way before words. It鈥檚 like a duet: babies learn language through interaction. It鈥檚 never too early to start because they are always listening 鈥� even in the womb.鈥�

A landmark study in 1995 reported on the 鈥�30-million-word gap鈥� that divides higher income children from those in lower income families. The gap refers to the number of words spoken to children鈥檚 ears by the adults in their lives. The size of the gap correlates with significant differences in vocabulary, language development and reading comprehension. Since that revelation, some educators and parents have pushed hard to have babies start learning words 鈥� lots of words 鈥� as early as possible.

This creates what both Hirsh-Pasek and her long-time collaborator Dr. Roberta Michnick Golinkoff describe as a 鈥渇lash-card鈥� approach to language, which emphasizes the words themselves rather than the interactions that are the true delivery mechanism of language. This way of presenting isolated words without context is like dumping words on the baby and hoping some stick. The process resembles how some of us studied for the SAT, but how many of those words do we remember now?

Before they can learn vocabulary, the scholars say, babies have to learn to isolate or segment words from the stream of sounds that surround them. They do this in a variety of brilliant ways, from sorting out statistical cues connected with how frequently they hear a word to the stress patterns in the words swirling around them. 鈥�Juice? You want some juice?鈥� By 6 months, babies recognize a novel word that follows their own name, but not a novel word after someone else鈥檚 name. Research shows that long before a child can produce words, they have stored the frequently heard word forms in their brilliant , ready for use when their vocal mechanism has developed enough to shape words.

At 24 months, the variability in babies鈥� vocabularies is breathtaking, ranging from 56 to 520 words, and these enormous differences, the scholars say, are rooted in both the verbal and nonverbal gestural interactions that take place between babies and their caregivers. The more of these back-and-forth interactions mothers and other caregivers have with their babies, the greater the child鈥檚 school-ready vocabulary by the time they鈥檙e off to kindergarten at 4陆 or 5.

鈥淭he beautiful thing about that is that it doesn鈥檛 take anything fancy,鈥� Hirsh-Pasek says. 鈥淚t鈥檚 free. You don鈥檛 have to buy anything to have these kinds of conversations with your child. Babies learn words like spiders spin webs 鈥� it happens entirely naturally.

鈥淏ut what you do need is be mindful of paying attention to your child. Because when you鈥檙e looking down at your cell phone and are locked into that, you ignore your child鈥檚 cues and questions and it breaks up the natural flow of conversation.鈥�

Scientists refer to those back and forth interactions that start even before the baby can say a single word as 鈥渃onversational turns鈥� and studies show that the more conversational turns children experience, the greater the activation of a major language-processing area of the brain (Broca鈥檚 area), regardless of the child鈥檚 economic status or even the number of adult words they hear.

鈥淲hat you鈥檙e going for isn鈥檛 just 鈥榲olley and return,鈥欌�� Hirsh-Pasek says. 鈥淚t鈥檚 more like volley and return and return and return 鈥� responding to the child then responding to their response. One of my colleagues says you should 鈥榮trive for five鈥� turns in the conversation.鈥�

One of the most effective ways to engage in this back and forth, the experts say, is through the challenging quality of 鈥�wh-questions.鈥� Like any good reporter, parents and caregivers need to master the fine art of 鈥淲ho, what, when, where, how and why.鈥�

Children respond more frequently and in more complex ways to wh-questions than to any other, Hirsh-Pasek says. 鈥淪tart by looking where the child is looking,鈥� she says. 鈥淭hen, ask them about that 鈥� not one of those 鈥榗lose-ended鈥� questions that can only be answered with yes or no. You want the questions that encourage and build conversations (鈥榃hat is that?鈥� 鈥業 wonder what the doggies are saying?鈥�), not the conversation crushers.鈥�

Children who hear a lot of these questions that challenge their thinking are generally better able to understand and produce them as well. While harried parents might not always think the incessant 鈥淲hy, why, why鈥� of a toddler is a great thing, in the long run, those questions and the interactions they elicit can lead to richer vocabularies and concepts about the world.

Research shows that middle-class parents pose more questions to their children, on average, than parents from less resourced environments. However, there are many differences within families in both groups.聽 Further, fathers on average pose more wh-questions than mothers do. Toddlers in under-resourced environments are exposed to less verbal input than their middle-income peers, but since fathers across socioeconomic groups ask more of these 鈥渃larification鈥� questions, researchers say they may play a unique role in supporting their children鈥檚 language and cognitive development. In one important study, African American fathers posed the most wh-questions of any of the groups regardless of income status.

The big bonus, scientists say, comes later in a child鈥檚 life when these challenging social interactions boost the complexity of their thinking and their verbal reasoning skills.

To develop a vocabulary, Golinkoff and Hirsh-Pasek say, children need to hear words embedded in sentences, and they need to hear different word types. They talk about this as the 鈥渁rchitecture of language,鈥� in which a child learns nouns as an entry point because they label concrete items, then moves on to verbs like 鈥渞un鈥� and 鈥渟patial-relational terms鈥� 鈥� e.g., 鈥渂ring the ball over here.鈥�

When parents and caregivers take cues from the child and play off what the child finds interesting, vocabulary comes alive. When a child says, 鈥湴鲁蟛钩兮�檚 that?鈥� they aren鈥檛 asking simply to be told, 鈥淭hat鈥檚 a toaster.鈥� They are asking for information on what the item is used for. Children need clear information about word meaning, Golinkoff says. To really know a word, the child has to have at least a minimal grasp of how that word might be used in different ways. They are hungry for context. 鈥淭hat鈥檚 a toaster. We use it to cook our bread sometimes, don鈥檛 we? It gets very hot. What else gets very hot?鈥�

Though stacks of research make it abundantly clear that such natural interaction and playful learning serve as the platform for vocabulary learning, Golinkoff and Hirsh-Pasek say that the educational system is increasingly moving in the opposite direction, more toward the flashcards paradigm than playful interaction. Children can eventually learn definitions, they say, but passive memorization will never yield the depth and retention needed for a child to actually master vocabulary and the logical thought processes that turn language into the keys to the kingdom. How a child learns is as important as what they learn and what ultimately will make vocabulary stick is the playful conversational concepts they learned, starting in the crib.

It all begins with a coo.