How do babies and toddlers learn language? (Spoiler alert: it’s incredible!)

Human communication is astounding. Nowhere is this more obvious than when looking at the communication skills of babies, toddlers and young preschoolers.

If you’ve ever spent time hanging out with a toddler or young preschooler, you’ll know that they are often very effective communicators – even if their speech, vocabulary, early word forms and sentence structures are limited, and still developing.

1. So how do they do it?

• Babies appear to be ‘conscious’ of the world around them from a very young age. Babies as young as five months old exhibit a pattern of brain activity associated with conscious experience in adults (Kouider et al., 2013).
• Even by 6-9 months of age, infants are developing language skills needed to understand others (e.g. Bergelson & Swingley, 2019), although it’s notoriously difficult to know exactly what’s going on within a young person’s mind.
• From 6-9 months of age, infants come to know that language is communicative in nature (Waxman & Gelman, 2009). 
• Infants seem to treat language used by others in their presence as intentional communication from an early age, even when they don’t understand the words (e.g., Vouloumanos et al., 2012).
• Astonishingly, babies younger than 12 months old seem to be able to discriminate between speech sounds in any language. As babies listen to their parents and others, they are (unconsciously) taking statistics on the speech sounds used in their home language(s). (For more on this amazing ability, see here). 
• At around 1 year of age, babies gradually lose their ability to discriminate between speech sounds in all languages, and zero in on the speech sounds used in their family’s heritage languages and other languages around them.
• Infants also track the statistical regularities with which words and objects co-occur to build direct associations between what they hear and see (e.g. Smith & Yu, 2008). 
• Typically (but not always) – and after a period of babbling – infants say their first words – usually around their first birthday.
• Shortly after 12 months of age, infants expect the same word to refer to different examples within a category.  For example, they will associate a horse with the word ‘horse’, even when the real brown horse in front of them is different from the grey toy horse they saw when originally learning the word (e.g. Book & Waxman, 2009). (It’s not rare for young children to overgeneralise here, e.g. going through a phase of calling every pet, mammal or even animal they see a ‘dog’.)  
• Many toddlers (and some infants as young as 12 months old) use and understand words that refer to absent objects (e.g. Ganea, 2005).
• 18-month-olds rapidly learn labels for new toys they are engaged with when the label is used by an adult who is also paying attention to the toy. When the label is said by an adult who is out of view, infants do not learn the label, even if they are paying attention to the object when it is labelled (Baldoin et al., 1996).
• Speech sounds, vocabulary, word combinations, and full sentences develop, with tremendous and dramatic growth in language content, forms, and uses over the next four or so years (Fenson et al., 1994).
• Within the same period, a wide variety of other abilities develop in parallel, including:
  • massive developmental changes in domain-general abilities – i.e. abilities not specific to language – working memory, executive functions, and general processing speed (e.g. Camos & Barrouillet 2019; Diamond 2013; Kail 1991);
  • motor skill development, including first steps, walking, and refined motor control for speech and gestures; and 
  • social cognition skills including action-prediction, gaze-following, processing directional actions as referential, the ability to compute others’ perspectives, and explicit reasoning about the relationships between beliefs, desires and actions, as well as others’ motives for action more broadly (including the development of theory of mind). 

2. Language learning and social thinking appear to develop together 

Language use is fundamentally social. Speech pathologists and other language professionals sometimes refer to the social use of language as “pragmatic language”, from the Greek noun “pragma”, meaning “act” or deed”. 

If you’d like more detail about pragmatic language development and young children, we’ve written:

• a short primer on what it means; and 
• an overview of some of the key pragmatic (social) milestones we expect to see with typically developing children from birth to 5 years of age.

Listeners of all ages use social reasoning to go beyond literal meanings of words to interpret them in context. If you know what someone is talking about, it’s easier to figure out what their words mean. If you know what words mean, it’s easier to figure out what someone is talking about (e.g. Frank, 2009; Bohn & Frank, 2019). 

For infants and young children, there is a strong correlation between social-communicative abilities and early language development. For example:

(a) Joint Attention and word learning

• Joint attention describes situations in which two individuals are knowingly attending to the same object at the same time (Tomasello, 1995). You can read more about it here.
• Often, jointly attending to something coincides with both individuals looking at an object, combined with occasional eye contact between them (Bohn & Frank, 2019).
• There is a very strong link between joint attention and word learning (e.g. Bottema-Beutel, 2016). 
• As infants get older, they improve their ability to coordinate attention with a partner (e.g. Mundy et al., 2017). 

(b) Non-verbal communication and language

There seem to be strong ties between early non-verbal communication skills and early language skills. For example, studies show: 

• Children who produce more points or comprehend pointing well have better developed language skills (e.g. Colonnesi et al., 2010; Luke et al., 2017; Frank, 2017). 
• Early use of gestures is strongly correlated with early vocabulary. Differences in gesture at 14 months of age is predictive of differences in language abilities at 4.5 years of age.
• Infants who show early sensitivity to social cues like gestures or gaze produce language referring to objects earlier (Carpenter et al., 1998).
• Following others’ gaze at 10 and 11 months predicts vocabulary growth in the second year of life.

For more information about the links between gestures and oral language, click here.

(c) Infant directed speech (also known as ‘parentese’)

Some adult behaviours, like infant directed speech, seem to lead infants and children to interpret actions as communicative. For example, 6-month olds are more likely to follow an adult’s gaze to an object when it is preceded by gaze or speech cues (Senju & Csibra, 2008).

For more about infant directed speech, and how to do it, check out this article.

(d) Mutual exclusivity of labels

• From around 17 months of age onward, and perhaps earlier, infants expect labels for objects to be mutually exclusive, and expect that new words refer to novel objects (e.g. Halberda 2003).  
• If you ask a 3-year-old to show you the “chromium one, not the green one”, she will choose the object with the unknown colour (Carey & Bartlett, 1978). 

(e) Knowledge of what a partner knows (and doesn’t know)

• By the age of 2 years, children adjust what they say to take account of their partner’s knowledge. For example, they name hidden objects and their location more often, and produce more gestures when their partner has not witnessed the hiding (O’Neill, 1996). 
• Slightly older children are more likely to use pronouns instead of nouns to refer to objects if the object has already been mentioned (Matthews et al., 2006).
• 3-4 year old children selectively mention facts when justifying a decision, depending on whether their partner knows the facts already (Koymen et al., 2016).
• 4-5 year old children fixate faster on an object when a familiar speaker uses an expression compared to when a new speaker uses the same expression (Graham et al., 2014).
• From around 5 years of age, children give general information about an object when the listener is unfamiliar with it, but more specific facts when they know that their partner already knows about it (e.g. Baer & Friedman, 2018).

(f) Overhearing and common ground

• Gaze and eye contact appear to be important for younger infants, but become less important after the age of 2 years. For example, older children learn new words:
  • from overhearing them (e.g. Gampe et al., 2012); and
  • via ‘common ground’ through direct social interactions with others. This includes:
    • information about absent objects (e.g. by pointing to the object’s previous location, where the child and parent had interacted with it); and 
    • other words and sentences spoken at around the same time, e.g. if an adult says they are hungry and then refers to a “dax”, even 2-year olds will tend to choose something edible as the “dax” (Sullivan & Barner, 2016).

(g) Partners’ communicative actions

• 3-5 year old children are good at learning from others’ communicative actions (e.g. Bonawitz et al., 2011), including language. When told by an adult that an object was a “small fep”, 3-5 year-old children chose a larger example of the object when asked to identify a “fep” (Horowitz & Frank 2016).
• From around 2.5 years, children start to use ‘politeness’ markers, such as “please” (e.g. Read & Cherry 1978). From the age of 3 years, children judged those who said “please” as more polite. From 4 years of age, children assume that a speaker using polite language is more likely to get what they want (Yoon & Frank, 2019). For more on politeness markers, including later developing indirect requests, see this article. 

3. Why do children learn language?

Big question! There are many theories, e.g.:

• humans have evolved an innate instinct for communication and language which means that babies’ brains are primed to process and use language (Ferry et al., 2010, see also Chomsky and Pinker’s work);
• people learn from one another via observation, imitation and modeling (e.g. Bandura, 1977);
• children come to the process of language acquisition, at around one year of age, equipped with two sets of cognitive skills, both evolved for other, more general functions: intention-reading, including joint attention; and pattern-finding (grammatical dimension, including categorisation, analogy and distributional analysis) (Tomasello, 2003); and
• language is meaningless without social interaction. Infants discover language is communicative – that they work out the broad function of language is to manipulate human behaviour – through their observation of the social world, including their interactions with parents and others (e.g. Bohannon & Bonwillian, 2009). 

Bohn & Frank have proposed a handy (although rather technical) framework to illustrate how they think communication is grounded in social thinking and interactions, and how people integrate different information sources – including language – to figure out what speakers are talking about: 

Source: Bohn & Frank, 2019

Putting aside the theories, there are clear evolutionary and functional advantages to language, both to humanity and for individuals. Early-developing communication skills advantage human babies with care and attention from adults. Later communication skills help children to succeed socially within groups of adults and peers. 

4. “My young child’s language might be delayed” – free information and resources

In general, the norms and milestones referred in this article are averages, for typically developing infants, toddlers and young children. Children develop at different rates in different areas. 

Our clinic, and most of this website, are dedicated to helping families of children with communication delays, differences, and disorders. If you are the parent of a late-talker, we want to help you to get up to speed so you can consider your options. Here are links to seven of our most popular articles, designed to help you to help your child, and to get the advice and help you need, when you need it:

• “My toddler doesn’t speak at all!” Don’t panic – get informed.
• I want to help my late talker to speak. What can I do?
• Late talkers: how I choose which words to work on first
• Parents of children aged 0-5 years: 10 practical ideas to increase your child’s participation and communication skills
• “Why should I let my late-talker play with other kids?” Because play promotes learning: here’s why and how
• “I’m concerned about my child’s language”: 6 1/2 questions speech pathologists should ask before assessing your child
• 6 principles we follow when assessing toddlers for language delays

As always, if you have any concerns about your child’s communication skills or development – or just want to chat  – please give your local speech pathologist a call.

Main source: Bohn, M. & Frank, M.C., (2019). The Pervasive Role of Pragmatics in Early Language. Annual Review of Developmental Psychology, 223-249.  

This article also appears in a recent issue of Banter Booster, our weekly round up of the best speech pathology ideas and practice tips for busy speech pathologists, providers, speech pathology students, teachers and other interested readers.

Sign up to receive Banter Booster in your inbox each week: