Why you should be talking to your infant: The science of baby talk, Part 1

The word infant comes from the Latin “īnfāntem” ‘unable to speak’.

A TikTok mom recently went viral because she asked:

Does anybody else not talk to their baby? My daughter is 11 months old, and she can’t talk so I don’t talk to her. Is that weird? Should I be just saying things so she can learn how to talk? I make noises, I do funny faces, I dance, but I don’t converse.

Unfortunately this mom was so thoroughly excoriated in the comments and in numerous response videos that she took the original video down.

But this isn’t a dumb question!

If you aren’t familiar with research on child language acquisition, it’s entirely reasonable to wonder whether baby talk is bad for your child, or whether it’s pointless to speak to children before they begin speaking themselves. The word infant itself even comes from the Latin īnfāntem ‘unable to speak’. In some cultures parents rarely talk to infants, and those children learn their native languages just fine. How important can talking to your newborn really be if not everybody does it?

Well, pretty important actually. Even those purportedly low-conversation parents in other cultures actually talk to their kids quite a bit, just in different ways and on different timetables. (We’ll learn more about that in Part 4 & Part 5 of this series.)

On the other end of the spectrum, many parents have been terrified into thinking that they’re not speaking to their children enough because of an infamous 1995 study showing that children from lower socioeconomic backgrounds hear up to 30 million fewer words by age 4 than their high-income peers, and that this gap correlates with reduced vocabulary development and educational outcomes (Hart & Risley 1995).

But as we’ll see in Part 6 of this series, the sheer amount of exposure kids have to language doesn’t actually make much difference for their language development. Those reported differences in vocabulary size are a) questionable, and b) have more to do with other socioeconomic factors than hitting a daily word count with your toddler.

So in this series, we’ll look at what the research has to say about speaking to your infant, answering the following questions along the way:

ℹ️ Articles in this Series

• Part 1: Why you should be talking to your infant (this issue)
• Part 2: What is baby talk?
• Part 3: Is baby talk good for your child? (forthcoming)
• Part 4: Do all cultures use baby talk?
• Part 5: Baby talk in the languages of the world
• Part 6: How much should you talk to your child?
• Part 7: What really matters when talking to your child

Should you talk to your newborn?

Simply plopping your child on the couch to watch some reality TV won’t teach them language.

Should you be talking to your newborn child? The short answer is decidedly yes. Infants need some type of linguistic input to be able to learn a language—it’s not as though they’re born with an innate knowledge of English or any other language. Instead, they’re born with an incredibly advanced cognitive toolkit that allows them to learn any language they’re exposed to within just a few years.

But that exposure is crucial. We know from cases of extreme childhood neglect that if children aren’t sufficiently exposed to language before puberty (a timeframe known as the critical period or sensitive period in linguistics and developmental psychology), language acquisition becomes significantly more difficult and ultimately less successful. The most infamous and heart-wrenching case is that of Genie, who was confined in a dark room with minimal contact from about 20 months of age until she was almost 14 years old.

When Genie was finally discovered she was extremely malnourished. Physically, she looked like a 6- or 7-year-old, weighed 59 pounds, had difficulty standing and walking, and couldn’t chew solid food. She never spoke, and seemed to only understand a few words at best. As she was treated and given a healthier cognitive and social environment, her rehabilitation quickly triggered the onset of puberty. Her cognitive development reached that of a 6- to 8-year-old by the following year. After 5 months she began to use single words, and her vocabulary grew quickly. She started to combine two, then three, then four words (1), and after two years she produced apparent cases of embedded clauses (2):

1. want milk
   Genie love Curtiss
   big elephant long trunk
2. ask [go shopping]
   tell [door lock]

However, Genie never mastered the complexities of English morphology and syntax. All grammatical words and morphology were missing.

Less lurid but still unfortunate cases have also been documented for profoundly deaf children who were not exposed to sign language in childhood. Because 90–95% of deaf children are born to hearing parents (Baker et al. 2016: 66), it occasionally happens that those parents fail to realize that their child is deaf, so the child doesn’t receive any useful linguistic input until much later—usually not until they start school. These children are called late learners. Many late learners will nonetheless spontaneously develop a manual communication system using a combination of gestures they observe in their surroundings and signs they invent. This creates an idiosyncratic form of communication called homesign (Baker et al. 2016: 53). Homesign is generally not a fully-developed language, but rather is more like a pidgin: an extremely limited lexicon with no grammatical constructions.

Unfortunately, late learners suffer lifelong consequences from their delayed acquisition. Deaf children who began learning a sign language at age 5 were significantly less fluent than native signers (who are exposed to sign language from birth) even after 30 years of daily use. While able to fully express themselves, their use of complex morphology and syntax is systematically different from that of deaf children who learned sign from birth (Sandler & Lillo-Martin 2017: 386). Deaf children who weren’t exposed to sign language until age 12 or later were profoundly hindered in their ability to learn sign (Newport 1990). In one case of three deaf children who were not exposed to language of any kind until they were about 14 years old, by two years later they were acquiring vocabulary on a timeline similar to typical toddlers, with many words for concrete objects and actions but few grammatical words like prepositions (Ramírez, Lieberman & Mayberry 2013). In another case, a deaf boy was raised in a rural area with little formal education before age 12, and no access to the deaf community. At age 15, he was fitted with hearing aids and began learning Spanish, but he struggled to learn grammatical constructions like pronouns and the singular-plural distinction (Saxton 2017: 80). A final case is Chelsea, a deaf woman who did not start learning language until her early thirties, who showed similar results to Genie (Curtiss 1988).

So we’ve established that children need linguistic input as early in childhood as possible in order to fully master language. But does any kind of input work? Could you simply plop your child on the couch to watch some reality TV? If only it were that easy! It’s well established that children cannot learn language from media alone. In fact, a 2024 study even found that the greater the total screen time of children aged 2;5 to 4;0 on weekends, the worse their vocabulary and grammar skills (Tulviste & Tulviste 2024). Children need social cues to help direct their attention and start associating social meaning with linguistic meaning. One salient illustration of this is the case of Jim, a hearing child born to deaf parents whose only exposure to English was via (a great deal of) television, and whose parents did not generally speak or sign to him (Sachs, Bard & Johnson 1981). By age 3;9, Jim’s language use was decidedly abnormal for children his age:

• This is how plane
• I want that make
• House chimney my house chimney

Jim could learn new vocabulary, but was limited in his ability to form grammatical sentences.

Other studies have shown that children can’t learn new words from television before the age of 2 (Snow et al. 1976; Kuhl, Tsao & Liu 2003; Mumme & Fernald 2003; Anderson & Pempek 2005; Krcmar, Grela & Lin 2007). After age 2, it’s possible for children to learn some vocabulary from television, but only from shows designed specifically for children, and only well-designed ones (Rice & Woodsmall 1988; Rice et al. 1990; Barr & Wyss 2008). (Children who watched Teletubbies did not show significant vocabulary development, while children who watched Dora the Explorer, Blue’s Clues, or Dragon’s Tales showed greater vocabulary gains [Linebarger & Walker 2005; Uchikoshi 2005].) One study showed that children only learned new vocabulary from video when an adult facilitated their learning with concomitant social interaction (O’Doherty et al. 2011), again showing the importance of socially-directed cues for child language learning (see also Anderson & Hanson 2017). By comparison, one study showed that children aged 21–27 months learned new vocabulary from a shared book reading activity, but none from TV viewing (Patterson 2002).

Linguist Noam Chomsky actually once claimed explicitly that “a child may pick up a large part of his vocabulary and ‘feel’ for sentence structure from television” (Chomsky 1959: 42). Chomsky believes that mere exposure is sufficient for language acquisition, because he thinks that some part of grammar is innate rather than learned, a position known as linguistic nativism. But as Saxton 2017: 131 trenchantly states, “Chomsky’s early assertions about language acquisition are the result of armchair speculation, not empirical enquiry.” In reality, the amount of speech that children overhear does not predict vocabulary size, whereas the amount of speech specifically targeted at them does (Shneidman et al. 2013). The body of first language acquisition research has shown that targeted social interaction is crucial for child language development.

So we’ve established that some type of interactive linguistic input is necessary for children to learn language. But what kind of language works best? Baby talk? Normal adult speech? We’ll look at this question in the next two issues of the Linguistic Discovery newsletter! If you haven’t already subscribed, be sure to do so to receive the other issues in this series.

ℹ️ Articles in this Series

• Part 1: Why you should be talking to your infant (this issue)
• Part 2: What is baby talk?
• Part 3: Is baby talk good for your child?
• Part 4: Do all cultures use baby talk?
• Part 5: Baby talk in the languages of the world
• Part 6: How much should you talk to your child?
• Part 7: What really matters when talking to your child

📚 Recommended Reading

“The birth of a word”

MIT researcher Deb Roy wanted to understand how his infant son learned language—so he wired up his house with video cameras to catch every moment (with exceptions) of his son's life, then parsed 90,000 hours of home video to watch gaaaa slowly turn into water. Astonishing, data-rich research with deep implications for how we learn.

HELLO Lab Presents

The Hearing Experience & Language Learning Outcomes (HELLO) Lab at the University of Connecticut has a great series of YouTube Videos about child language acquisition for parents.

• HELLO Lab on YouTube

How babies talk: The magic and mystery of language in the first three years of life

The infinite gift: How children learn and unlearn the languages of the world

📑 References

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• Barr, Rachel & Nancy Wyss. 2008. Reenactment of televised content by 2-year olds: Toddlers use language learned from television to solve a difficult imitation problem. Infant Behavior & Development 31(4). 696–703. https://doi.org/10.1016/j.infbeh.2008.04.006.
• Chomsky, Noam. 1959. Review of “Verbal behavior” by B.F. Skinner. Language 35(1). 26–58. https://doi.org/10.2307/411334.
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