3.5: Language in Infants and Toddlers

Learning Objectives

By the end of this section, you will be able to:

• Describe the differences between language and communication
• Identify the features of language and language development
• Describe the milestones of language development in infancy and toddlerhood
• Compare the major theories of language development
• Identify factors that influence language development

Six-month-old Ibrahim has just woken from his nap, and his father Ahmed hears him babbling “da da da da” over the intercom. At first Ahmed is excited because it sounds like the baby is calling him. However, as he listens, he begins to wonder whether this is just another example of the babbling he first heard last week, when Ibrahim was saying “ba ba ba.” As he lifts his son out of his crib, Ahmed expresses his delight in seeing Ibrahim and begins to have a conversation with him in a higher-than-normal pitch. He narrates everything he is doing while changing his son’s diaper, and Ibrahim smiles as he talks and resumes babbling when he pauses. Father and son are both fully enjoying their conversation. Babbling and turn taking are just a couple of the important milestones in the development of language that Ibrahim will be achieving during his first two years of life.

Language development is a complex process influenced by both nature and nurture. As infants progress through their first year of life, they develop the components of language at a remarkable pace, laying the foundation for building more complex language abilities in the years to come.

Language and Communication

Although language and communication are part of our daily life, when asked, “What is language?” you might struggle to answer.

A communication system that uses words and rules to allow the transmission of information between individuals is language. Language can be spoken, written, or signed to communicate ideas to others, called productive language, or to comprehend ideas from others, called receptive language. We can also communicate without language, such as through gestures, facial expressions, body language, and sound. Language differs from these means, however, in having a set of systematic rules, such as grammar and spelling, and having infinite generativity, the capacity to create an unlimited number of meaningful messages. For example, if you were given the sentence, “Lifespan development is useful in your life,” you could convey that same message an infinite number of ways, such as by saying, “This class has so many life hacks!” or “Lifespan comes with a lot of useful tips!”

Features of Language

The main features of language include phonemes, morphemes, syntax, grammar, semantics, and pragmatics. Children (and all people) use all these features to communicate with others and learn language. You’ll learn about syntax, grammar, semantics, and pragmatics, which emerge in early childhood, in 5.4 Language in Early Childhood. For now, consider some of the smallest parts of language, phonemes and morphemes. A phoneme is the smallest unit of sound within a language. The sounds of the alphabet are phonemes, as are letter combinations that make a single sound like sh, er, and oo. For example, in the word “cats”, the phonemes are /c/ /a/ /t/ /s/. All languages have phonemes but in different numbers; English has about forty-four. Phonemes alone typically don’t convey any meaning, but once children learn phoneme sounds, they can combine them to create and comprehend meaning.

Another feature of language is a morpheme, the smallest meaningful units of language. Morphemes can be individual words, roots, prefixes, or suffixes. For example, mama, dogs, homework, and you are morphemes. Some words contain more than one morpheme. Dogs contains two: dog and s. Prefixes and suffixes like re- and -ed also serve as morphemes because they convey meaning. For example, the word redesigned consists of three morphemes: the root word design, the prefix re which means to do again, and the suffix ed meaning the action occurred in the past.

Contextual cues like tone of voice, body movements, and word emphasis also carry meaning and aid communication in all languages. For example, a toddler saying “dada” while crying as the father is leaving the room is expressing a different meaning than when saying “dada” and smiling when the father returns. We can also be more confident an infant understands phonemes when they look at “dada” and smile, as opposed to just making the sound dada by accident in a string of other sounds.

Link to Learning

In this video Patricia Kuhl shares findings about how babies learn one language over another.

Language and Communication Milestones

Infants and toddlers typically progress through several milestones in communication and language development, beginning with crying, cooing, babbling, and gestures before transitioning into using single words, two-word phrases, and finally full patterned speech.

Crying and Cooing

Newborns come equipped with their very first communication tool: crying. Crying allows infants to signal distress (Vermillet et al., 2022), and some research indicates their cries have different sounds and features that can help caregivers identify the type of distress and what the baby needs (Ji et al., 2021). For example, one cry might indicate the baby needs to burp to relieve pain, while another may indicate tiredness and a need for sleep.

During interactions and daily experiences, infants are also taking in sounds, rhythms, and language cues. By two months of age, they are making facial expressions and smiling during social exchanges, and they also start cooing, the deliberate generation of vowel sounds such as “oooo, aaaaa, uh” and gurgling sounds that serve as practice vocalization. An infant may coo to entertain themselves or to respond to others: The infant coos, the caregiver responds verbally, the infant coos in response. This interaction is an early lesson in the art of turn taking in conversation and most often occurs with a caregiver.

Babbling

Beginning around four to six months of age, with more experience and improving motor and brain development, infants begin to repeat consonant-vowel sounds like na and ba, called babbling. Typical consonant sounds in early babbling include /g/, /k/, /m/, /n/, /p/, /b/, and /d/. These are fairly universal no matter what language is spoken around the infant. However, infants quickly become more sensitive to what they are hearing and begin to use the phonemes in the language(s) to which they are regularly exposed (Plummer & Beckman, 2015). Some sounds they were making will disappear if they don’t hear them consistently.

Although caregivers often mistake early babbling for first words, ba-ba does not necessarily mean bottle at this stage. The infant has not yet tied their vocalizations to any meaning, and babbling can be just experimental sound making. Babbling can happen without sound too. Children who are deaf and those exposed to sign language may also babble by making hand movements to represent language (Laing & Bergelson, 2020; Lillo-Martin & Henner, 2021). Infants who babble more around six months also tend to have more productive language at twelve months (Werwach et al., 2021).

Gesturing

As early as seven months of age, infants may begin gesturing with hands and body to communicate, such as by shaking the head for “No” and waving the hands for “Goodbye” (Figure 3.20) (Crais et al., 2004). Because gesturing may be easier than saying words, caregivers can teach some simple gestures to enhance communication. Some even use this time as an opportunity to teach hearing children some sign language, such as the American Sign Language signs for “milk” or “food.”

Figure 3.20 The use of gestures, such as (a) pointing and (b) waving, is an aspect of communication that develops during the first year and aids in the development of language and parent-child interactions. (credit a: modification of work “Found a snail!” by Donnie Ray Jones/Flickr, CC BY 2.0; credit b: “Waving” by Kerry Ceszyk/Flickr, CC BY 4.0)

At around age nine months to a year, infants use their own gaze or a pointing gesture during interactions with adults to focus others on items around them (Baldwin, 2014). When adults respond by labeling or discussing the objects, receptive and productive language development are improved, and vocabulary development is enhanced. For example, an infant may point to a novel object and look at their caregiver quizzically. The caregiver’s response of naming the object, such as “That’s a flower,” can further support the infant’s growing language awareness and address their curiosity.

It Depends: Should Caregivers Use “Baby Signing” with Infants

A growing trend among caregivers is to use baby sign language to help infants communicate their needs before they can vocalize words. Baby sign language is a simplified form of American Sign Language with only a small subset of signs and no grammar rules. Babies start attending to signs as early as four months of age (Novack et al., 2022) and by six to eight months can learn to ask for basic needs such as milk or a diaper change.

The practice can be a fun way to engage with infants, who may be less fussy if they can communicate basic needs, but research does not indicate it will enhance language and cognitive development (Kirk et al., 2013). Some in the Deaf and hard-of-hearing community have also expressed concern about hearing individuals using and modifying language intended for their community. Baby signing is not language, because it is missing the syntax, morphology, and pragmatics that make American Sign Language a full language (De Meulder, 2019). With that understanding, however, teaching babies a few signs in the first year of life may improve their ability to communicate and help parents respond to their needs (Kirk et al., 2013).

First Words and Holophrases

Words are linguistic symbols that refer to an object, event, descriptor, or action, and learning what they mean is part of our language development. In terms of receptive language, infants can comprehend many more words than they can speak. They can recognize names of many common objects as early as six months (Bergelson & Swingley, 2012). One estimate is that children can produce thirty to ninety words around eighteen months of age but understand so many that it is difficult if not impossible to measure the number (Vehkavuori et al., 2021).

Some children say their first word as early as nine months of age, but around twelve months is typical. The first word of a child who speaks English is often a noun, like cup, ball, mama, dada, dog, cat, or the name of another person or object the child regularly interacts with (Clerkin & Smith, 2022; Nelson, 1974). In a verb-friendly language such as Chinese or Korean, children may learn more verbs and be taught to notice actions and relationships between objects (Yee, 2020).

When babies use one word to convey a complete thought, that word is called a holophrase. For example, “No” might really mean, “I don’t want that right now!” and “Ball” might mean, “Where is the ball?” or “Give me the ball.” The caregiver can rely on other communication cues to pick up the meaning of these holophrases.

Young children learning words make a common error called overextension, the use of a learned word to inappropriately name something else. This often happens when a child doesn’t have another word to use. For example, a child might call a tiger a kitty. Young children may also exhibit underextension, the inappropriate restriction of a word. For example, a child might call a pet cat “kitty” but not refer to any other cats as “kitty.”

Toddlers are still learning how to produce and coordinate the complex movements needed in speech, and the necessary muscles and nerves are still developing. In fact, many children don’t acquire all the English consonant sounds until five or six years of age (Crowe & McLeod, 2020). Thus, they also make pronunciation errors. For example, they may mistakenly interchange sounds like /b/ and /d/, or /c/ and /z/ (Shahid et al., 2021). They also tend to simplify words (Syafitri, 2021). For example, they may say “wabbit” instead of “rabbit” or “nana” instead of “banana,” opting for sounds that are easier for them to articulate. They may omit consonant sounds at the beginning or end of words or reverse sounds, such as by saying “pasghetti” for “spaghetti.” These errors are a normal part of the language development process, and most children outgrow them with practice. Severe or persistent errors may be a sign of a speech or language disorder, however, and should be evaluated by a speech-language pathologist (Preston et al., 2013).

Telegraphic Speech

By eighteen to twenty-four months of age, children are starting to combine words into short sentences. Shortened word utterances that convey meaning but do not rely on grammar rules are called telegraphic speech. For example, a child might say “More cookie” to indicate that they want more cookies or “Go papa house” to indicate they would like to go to grandpa’s house. Telegraphic speech doesn’t rely on grammar and often eliminates little words like “a” and “the.” The name was coined in the 1960s because this speech is similar to telegraph messages. Had it been identified today, it might be called text talk.

Vocabulary Expansion

Around sixteen to twenty-four months of age, children experience a vocabulary growth spurt and start learning new words at an accelerated rate. By about two years old, a toddler uses between fifty and 200 words; by three years old they have a vocabulary of up to 1,000 words and can speak in sentences.

Children go through what some call a “naming explosion” in which they learn several new words a week, showing impressive progress in receptive and productive language development. They learn new words by quickly connecting those they encounter and their meanings, a process often called fast mapping (Jackson et al., 2019; Landau et al., 1988; Markman & Wachtel, 1988). Table 3.10 summarizes the language milestones that occur over the first two years of life.

Table 3.10 Summary of Infant and Toddler Language Milestones

Age	Language and Communication Skills
Birth	Newborns cry to communicate distress.
2 months	Infants coo as they begin to practice vocalizations.
4–6 months	Infants begin babbling and include consonant sounds or hand signs. Infants pay attention to communication from others and may recognize their own name.
7–9 months	Infants begin gesturing and include the hands and body to communicate.
9–12 months	Infants first words and holophrases appear.
16–24 months	Toddler telegraphic speech and vocabulary expansion begin.

Major Theories of Language Development

How do very young children learn to communicate and use language? This section reviews some of the major theories of language acquisition: nativist, learning, and interactionist approaches.

The nativist approach takes a biological perspective, asserting that humans are born with the innate ability to learn language and that experience plays a very limited role. Noam Chomsky (1968) hypothesized a Language Acquisition Device (LAD) that is uniquely human and predisposes us to learn language. This view asserts that our brains allow us to analyze language to learn its rules quickly and efficiently.

Neurodevelopmental research has found that the brain is indeed wired for language at birth. In experiments that played different sounds to newborns, the left hemisphere of the brain was found to be more active in response to native language sounds, while the right responds more to non-native language sounds (Vannasing et al., 2016). What Chomsky called a LAD may actually be Broca’s and Wernicke’s areas in the brain’s left hemisphere. Broca’s area is specialized for language production and Wernicke’s area for language comprehension (Figure 3.21).

Figure 3.21 In the left hemisphere of the brain, Broca’s area is specialized for language production and Wernicke’s area for language comprehension. (CC BY 4.0; Rice University & OpenStax)

The brain clearly is critical for the development of language, but it does not tell the whole story. Other early language theories claimed learning and experience are critical, and that language is learned through social interactions. Thus, the learning approach to language development highlights the contribution of caregivers. One influential learning theorist, B.F. Skinner (1957), believed we learn language through operant conditioning. That is, as infants begin making random sounds, parents respond with interest, attention, and excitement that reinforce the infants’ vocalizations. For example, if a child says “mama,” a mother may smile and repeat the word back, encouraging the infant to repeat the sounds. Similarly, other learning theorists believed infants learn language by observing and imitating the language use of others (Bandura, 1989). Although evidence shows caregivers are indeed critical for language development, learning theories alone cannot explain language development.

According to the interactionist approach, language development occurs as the result of complex interactions between the biological readiness of children and the environment in which they are raised, and language exists primarily for the purpose of communication during social interactions. In newer approaches to language theory, researchers recognize that humans have biological resources that facilitate language learning, and that language is supported by environmental influences, including enriching social interactions (Brunner, 1983; Tomasello, 2003).

Support for the role of social interactions comes from research demonstrating that toddlers learn vocabulary better from face-to-face social interactions than from videos (Troseth et al., 2018). When language is presented on a screen, infants learn better in the presence of other infants (Lytle et al., 2018). It is more difficult for infants to fully experience the social cues needed to attract and keep their attention on a screen, and research has shown that screen time is associated with difficulties in learning social skills and reading emotions. We also know that when infants spend more time watching media, they spend less time talking and interacting with their caregivers, which can slow later vocabulary growth (Brushe et al., 2024; Kucker et al., 2024).

Influences on Language Development

Regardless of the theory of language development, a variety of biological and environmental factors influence language development. These include universal listening, caregiver influence, and different styles of toddler expressiveness.

Despite significant differences in parenting styles, living situations, and degrees of socialization, infants in different cultures achieve language development milestones at about the same ages, suggesting biological influences on language development. Research on language and sound perception found that infants may begin as universal listener, able to hear and distinguish the unique sounds within their native language as well as in non-native languages. However, by ten to twelve months of age, the ability to distinguish sounds outside their own language diminishes as their brains become specialized to respond to the sounds that are part of their native language (Ortiz-Mantilla et al., 2019; Werker & Tees, 1984). This loss of universal listening is also reflected in changes in their babbling patterns as they focus on producing sounds in the language(s) they are learning (Maneva & Genesee, 2002; Morgan & Wren, 2018).

Link to Learning

Before the age of one year, infants can discriminate between the sounds of their languages. As our brains develop and unused synapses are pruned, we lose this ability. Watch a young infant demonstrate their ability to discriminate between very similar sounds.

A strong link also exists between caregivers and language development. When many adults and even older children interact with infants and toddlers, their speech naturally changes in a way that attracts and keeps an infant’s attention. Such child-directed speech is distinguished by sing-song rhythm and higher pitch, more repetition, and the use of simple words (Farran et al., 2016). It also employs exaggerated vowel and consonant sounds and more facial expressions. Words are highly articulated and larger pauses are made between words so the child can hear the individual sounds. Infants attend to and listen longer to child-directed speech than to normal speech (Werker et al., 1994) and prefer it over adult-directed speech, even as newborns (Cooper et al., 1997; Many Babies Consortium, 2020). Children who hear child-directed speech learn words more rapidly than children who do not (Shi et al., 2022).

Children whose caregivers are more responsive to their vocalizations also tend to have larger vocabularies (Madigan et al., 2019; Vallotton et al., 2017). Parents can also help young children develop an understanding of grammar rules by modeling correct grammar in response to grammatical errors by the child. Two ways to do this are recasting and expansion (Cleave et al., 2015). For example, if a child says, “Her want toy,” the adult may recast the statement as a question with correct grammar: “Does she want your toy?” In expansion the adult keeps the basic structure of the child’s words and corrects semantic issues. The child might say, “Him is silly,” and the adult responds with, “He is silly.” This manner of modeling correct grammar for young children is associated with the development of better expressive language.

Life Hacks: Helping Infants Learn Language and Communicate

Caregivers play a critical role in language development for their infants. Here are some tips for maximizing the development of language:

• Take turns: When an infant coos at you, make the sound in return. Pause to allow them to respond.
• Make some noise: Interact with infants by talking about what you are doing, reading to them, or naming objects you are both looking at.
• Pay attention: If an infant or toddler points or gestures to something, teach them the word by saying or signing the name of the object.
• Exchange gestures: Encourage hellos and goodbyes, and give praise when toddler tries to speak with others.
• Consider using signs: If an infant wants to communicate their needs but cannot make the sounds of language, you can say a word and/or sign the word (such as “food” or “sleep”) to help them communicate what they feel (like hunger or fatigue).

Researchers have also identified two styles of toddler language. When using a referential style, toddlers more frequently talk about objects and things, while the expressive style, often used for social reasons, expresses feelings and needs. Children who use a referential style when talking like to have adults label objects in their environment or in books, whereas children who use an expressive style are interested in using language to communicate or just to be social. Some research has shown stronger patterns of referential speech among U.S. children whose mothers label objects when conversing with them, and more use of the expressive style for children with Korean mothers who emphasize actions and social routines when conversing with their child (Sung & Hsu, 2009). Expressive communication is useful in the context of social interactions, as when infants are encouraged to greet others by waving. This style of communication directs the child’s attention toward other individuals rather than toward things (Ashtari et al., 2020).

Variations in Language Development

Language development may sometimes follow a different pathway than described, due to developmental or environmental differences. These include the influence of impoverished environments, intervention and prevention with at-risk children, and bilingual and multilingual environments.

The quality of the environment influences language learning. For example, at the end of the twentieth century, many children in Romania were separated from their families and raised in impoverished orphanages where they experienced substantial neglect. These children showed significant language delays along with delays in cognition and motor development and deficits in socioemotional behaviors. Many could not produce intelligible words at 2.5 years old (Windsor et al., 2007). When Romanian dictator Nicolae Ceauşescu was overthrown and the plight of the children was discovered, many were moved into foster care as part of a large study on the impact of neglect on child development. Given careful and evidence-based intervention, they showed significant improvement in their language and other areas of development (Nelson et al., 2009). While stress and adversity are known to increase risks in child development, resilience can be promoted in language and overall development through early intervention and prevention, such as in individualized care and foster care (Humphreys et al., 2022).

Intervention and prevention strategies can also promote language development by improving parent-child reading strategies. For example, some research indicates that children from a low-SES background are exposed to less reading time and fewer interactive reading strategies (Barnes & Puccioni, 2017; Hoff, 2013). Parents can be taught the skills and knowledge needed to read effectively with their children, however, and increasing their motivation to do so improves their children’s later academic achievement in school (Peixoto et al., 2022). Effective interventions include such parent education and outreach by support agencies, as well as community-based programs like reading buddies, story hours at libraries, and access to books through organizations like Dolly Parton’s Imagination Library.

Link to Learning

Interventions that provide children with access to books early in life can improve literacy and academic outcomes. Dolly Parton’s Imagination Library gives books to millions of children from birth to age five years in five different countries.

Multilingualism is common in many parts of the world and is on the rise in the United States. Parents often have questions about the advantages or disadvantages of raising multilingual children. Over time, children learning more than one language from birth become proficient in each and achieve language milestones around the same time as young children learning only one language (Albareda-Castellot et al., 2011; Festman et al., 2017). When learning a second (or third) language after becoming fluent in the first, children often need more time to reach proficiency in the additional language(s) (Baker, 2011).

Children sometimes combine elements of different languages such as English and Spanish when communicating. Although it may seem they are confused, research shows that bilingual infants are able to discriminate between their two languages (Byers-Heinlein & Lew-Williams, 2013). Since children are born ready to learn languages, caregivers should feel comfortable exposing children to more than one language.

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