Language Development

The utterance of an infant’s first words might appear to signal the initiation of their language development journey. However, it’s important to recognize that the groundwork for language acquisition has been laid long before that initial word is spoken around the age of 12 months. Even from the earliest moments after birth, typically developing children are already in the process of acquiring the fundamental abilities required for both listening and speaking. Surprisingly, research has indicated that this trajectory of language development remains strikingly consistent, irrespective of the specific language or languages spoken within a child’s home environment.

Before Birth

During the final 12 weeks preceding birth, the developing fetus is exposed to external sounds from the surrounding environment within the womb. By the 24th week of pregnancy, the auditory system of the fetus has reached a level of maturity, allowing it to respond to various sounds. Mothers-to-be might notice fetal movement in reaction to loud noises, indicating a startle response that becomes consistent by the 28th week of pregnancy.

Intriguingly, these pre-birth experiences contribute to the early formation of speech sound memories in infants. Studies conducted with newborns have unveiled that certain sounds are treated as familiar by these newborns, while other sounds are regarded as unfamiliar. This differentiation in treatment implies that newborns had encountered and become accustomed to some sounds prior to their birth.

For instance, research from 1980 conducted by DeCasper and Fifer demonstrated that shortly after birth, newborns exhibit a preference for hearing their mother’s voice over the voice of a stranger. Similarly, a study by Jacques Mehler and colleagues in 1988 revealed that even newborns as young as 4 days old recognize sounds from their mother’s language as familiar, whereas they perceive sounds from another language not spoken at home as unfamiliar.

One particularly compelling study, conducted by DeCasper and Spence in 1986, involved instructing expectant mothers to read a specific Dr. Seuss book aloud during pregnancy. After birth, newborns displayed a preference for hearing the story that had been read during pregnancy, indicating that they recognized and were drawn to the familiar narrative. In contrast, newborns who had not been exposed to either story before birth did not exhibit a listening preference.


Upon birth, newborns exhibit a remarkable ability to distinguish speech sounds present in languages worldwide. This phenomenon is known as categorical perception and is not unique to humans; even chinchillas, a type of rodent, display similar perceptual abilities despite lacking the capacity to acquire human language.

An important distinction lies in the fact that the perceptual abilities of infants evolve during their first year of life due to their listening experiences. By the end of their first year, infants gradually lose the ability to distinguish speech sounds that are absent from the languages spoken in their environment.

Studies have demonstrated that infants’ recognition of syllables in speech is influenced by the frequency of exposure. Research by Peter Jusczyk and colleagues indicated that 9-month-old infants could differentiate frequently encountered single syllables from infrequently encountered ones. However, 6-month-old infants could not make this distinction. Similarly, research by Eleanor Saffran and colleagues revealed that 6-month-olds could recognize two-syllable sequences within continuous streams of syllables based on their frequency of occurrence.

Research by Roberta Golinkoff and Kathy Hirsch-Pasek, along with their colleagues, unveiled that children comprehend certain aspects of meaning in spoken sentences even before they produce their first words. In a study, young children with limited vocabularies were shown videos of Sesame Street characters engaged in actions. Spoken sentences describing the scenes were presented, and the children demonstrated a preference for videos that matched the sentence’s meaning. This indicated an early understanding that the subject of an action comes first in an English sentence, followed by the object affected by the action. This suggests that infants possess a rudimentary comprehension of sentence structure before they can construct full sentences themselves.


Following birth, infants’ initial form of communication is crying, which serves as a fundamental means of conveying needs and emotions. Within the first three months of life, babies develop distinct cries that signal hunger, discomfort, or frustration. By the third month, infants begin to laugh and coo. During the cooing phase, infants produce elongated vowel sounds like “oooh” and “aaaah.” As time progresses, their vocalizations become more intricate.

Around the sixth month, babies enter the babbling stage, during which they practice producing language sounds. Initially, canonical babbling occurs, involving the repetition of a single syllable, such as “babababa” or “dududu.” As they progress, their babbling becomes more varied, featuring sequences of different syllables, like “bagada” and “dabuga,” known as variegated babbling. Interestingly, 95% of children’s babbled productions consist of the 12 most common speech sounds found in languages worldwide.

Notably, infants babble sounds that might not be present in the languages spoken in their environment. However, as they approach their first birthday, infants produce fewer speech sounds not present in their linguistic environment. This trend reflects how infants’ loss of the ability to distinguish unfamiliar speech sounds during listening impacts their production of those sounds.

Language Development tab1Table  1    Language  Productions in the First Year

As children’s language development progresses, their first words often include familiar terms like “mama,” “dada,” or the names of beloved toys or pets. However, among these early words, children might also generate their own invented words, which are consistently used by the child to reference specific objects or actions. These invented words are known as idiomorphs. Although idiomorphs serve as functional communication tools for the child, they aren’t typically adopted by adults as part of the language.

For instance, a child might consistently use an invented word like “gump” to refer to a favorite food. Another example is provided by Kenji Hakuta in the book “Mirror of Language: The Debate on Bilingualism,” where he describes a child using the word “Whew!” as a greeting instead of the more common “hello.” This peculiar choice of greeting was influenced by the child’s mother habitually saying “Whew!” when entering the child’s room in the morning due to a noticeable odor, signaling the need for a diaper change.

Children’s use of idiomorphs is typically temporary, as they eventually replace these self-created words with words that align more closely with those preferred and used by adults in their environment.

Language Development tab2

Table  2    Children’s Phonological  Errors

Parents and caregivers often have an intuitive understanding of the intended meanings of children’s words, even if those words are not pronounced exactly as adults would prefer. Children’s pronunciations can differ from adult speech due to various phonological errors, which are common during early language development. Here are five common phonological errors children may make when producing words:

  1. Reductions: Children might omit sounds from the target word, leading to reductions in the pronunciation. Reduplication can also occur, where a syllable is repeated but with some sounds omitted.
  2. Substitutions: Children might replace one phoneme (speech sound) with another. For instance, they might substitute a sound they find easier to pronounce for a more difficult one.
  3. Assimilations: Children could change a speech sound within a word to make it more similar to a sound that appears later in the same word.
  4. Coalescence Errors: Coalescence errors involve shortening a word by omitting intermediate sounds.

As children’s speech develops, the quality of their pronunciations generally improves, but different speech sounds are mastered at different rates. For English-speaking children, achieving complete articulation of all speech sounds may take several years. Here’s an overview of when certain speech sounds are typically mastered by English-speaking children:

  • Initial consonants in words like “red” and “long”: Typically mastered by age 5.
  • Initial consonants in words like “church,” “shirt,” “zoo,” “joke,” “van,” and “thumb”: Typically mastered by age 6.
  • Initial consonant in the word “them”: Typically mastered by age 7.
  • Intermediate consonant in words like “treasure” and “measure”: Typically mastered by age 8.

Although most children eventually develop adult-like pronunciation naturally, some children may benefit from speech therapy. This therapy involves directed instruction and practice to help children improve specific speech sounds that they find challenging.

Building A Vocabulary

The process of building an extensive vocabulary is a remarkable feat for young children. By adulthood, a typical speaker of American English may know more than 40,000 words. Considering that children produce their first word around the end of their first year, this task is quite challenging. In order for children to achieve an adult-sized vocabulary by age 18, they would need to learn an average of at least six words per day. However, vocabulary acquisition is not linear and steady. Between 18 and 24 months, children’s vocabularies can rapidly expand, a phenomenon known as the “word spurt.” Researchers have proposed explanations for this phenomenon, such as children experiencing a “naming insight” where they realize that everything has a name, or internal cognitive changes that facilitate word learning, like understanding categorical groupings.

Early Word Learning Strategies

In their early stages of language development, children initially use referential learning. This involves learning words that refer to concrete aspects of their environment. During this period, children’s vocabularies are dominated by nouns, which are words that name objects. One effective strategy for vocabulary growth involves asking adults for help. When children point to an object and ask, “What’s that?” they engage in a type of word-learning interaction called the “original word game.” The adult provides the correct word, and the child may attempt to repeat it.

Word Learning Biases

Children also employ several biases when learning new words. These biases help shape their understanding of word meanings:

  1. Whole Object Bias: When encountering a new word, children often assume that the word refers to the entire object rather than just a part of it.
  2. Taxonomic Bias: Children tend to assume that a new word refers to a category of objects rather than a specific individual object. For example, “dog” refers to dogs in general, not just one particular dog.
  3. Mutual Exclusivity Assumption: Children assume that an object has only one label and that a new label cannot apply to an object that already has a label.

Word Usage Errors

Children’s early word usages may not always match adult conventions. They often make errors like overextensions and underextensions:

  • Overextensions: Children might use a word to refer to a broader category than intended. For instance, using “cow” to refer to all four-legged animals.
  • Underextensions: Children might use a word to refer to a narrower category than intended. For example, using “shoes” to refer only to a specific pair of shoes, not all shoes.

These learning strategies, biases, and patterns of word usage play a crucial role in how children build their vocabulary and understanding of language.

Constructing Sentences

In the journey of language development, children’s single-word utterances go beyond mere words, demonstrating sentence-level intent. This phenomenon is encapsulated by the term “holophrase,” which describes children’s single-word utterances that convey meanings more complex than individual words. For instance, the word “Daddy” can carry various meanings depending on the context. It could signify the presence of the person referred to as “Daddy,” request an action from them, point to a location where an object associated with “Daddy” is located, or even express a desire comparable to an adult’s sentence, such as “I want Daddy to come here.”

Around the age of 24 months, children transition to producing two-word utterances, which can be seen as miniature sentences. Roger Brown’s research identified 11 types of semantic relations commonly found in children’s two-word utterances, capturing about 75% of English-speaking children’s expressions. This discovery holds true across languages, as demonstrated by Dan Slobin’s research encompassing languages like Samoan, Finnish, and Russian.

As children progress between 24 and 36 months, their utterances increasingly resemble adult sentences. They begin producing longer utterances, often containing a subject, verb, and object. Additionally, children start using words with grammatical word endings or morphemes, like the -ed suffix for past tense verbs (e.g., walked, talked) and the -s suffix for plural nouns (e.g., cups, dolls). Jean Berko-Gleason’s seminal work exemplifies how children learn language rules through inventive experiments.

Berko-Gleason’s Wug test exemplifies children’s grasp of word formation rules. By presenting children with an unfamiliar bird-like creature named “wug” and then showing two of them, children as young as 3 effortlessly form the plural form, even though “wug” was a fabricated word. Similarly, testing the past tense rule, children correctly inflected verbs (e.g., “ricking” to “ricked”) after being shown a picture depicting an unconventional action. These findings underscore the incredible capacity of young children to internalize and apply grammatical rules even when encountering novel linguistic structures.

In the fascinating trajectory of language development, from holophrases to more complex sentences, children showcase their innate ability to grasp the intricacies of language, revealing a cognitive flexibility that shapes their linguistic journey.

 Language Development tab3Table  3    Semantic Relations of Two-Word  Utterances

In the fascinating journey of language development, children’s acquisition of word formation rules can lead to a phase of intriguing errors that shed light on their cognitive growth. In English, there are exceptions to the standard plural noun and past tense verb suffixes (-s and -ed). For instance, the plural of “foot” is “feet,” not “foots,” and the past tense of “eat” is “ate,” not “eated.” As children grasp these rules, they may occasionally overapply them, leading to errors like “foots” or “eated.” These errors are known as over-regularization errors, often arising after children have initially mastered the correct forms. For instance, children might correctly produce “go,” “went,” and “gone” within their first 24 months, only to later make mistakes like “goed” or “wented” once they internalize the past tense rule. Over time, as they refine their understanding of which words are regular and which are irregular, these errors decrease in frequency.

Children’s progression in mastering complex sentence structures suggests that sentence production unfolds through distinct stages. Initially, children understand the meanings of specific words but must then learn how to appropriately incorporate them into complete sentences. Edward Klima and Ursula Bellugi’s research highlights the gradual mastery of wh-questions, such as “What did you eat?” These questions are navigated in several stages. In the first, which emerges in the first half of the third year, children place the wh-word at the beginning of the question but maintain the subject-verb order of an affirmative sentence, as in “Where I should put it?” In the second stage, children correctly order the subject and verb in affirmative questions, as in “Where should I put it?” However, they still struggle with the appropriate order for negative questions, as seen in “Why you can’t sit down?” The final stage sees children proficiently constructing both negative and affirmative wh-questions, showcasing their enhanced grasp of sentence structures. Children typically reach this stage between 48 and 54 months, demonstrating their evolving mastery of complex question forms.

Edward Klima and Ursula Bellugi’s research also illuminates the developmental stages in children’s production of negative sentences. This progression begins with an early understanding of the meaning of negative words like “no,” evolving into the ability to correctly position negative words or morphemes within sentences. Initial negative sentences, such as “No eat cookie,” place the negative word at the sentence’s start. In the next stage, the negative word is positioned before the verb within the sentence, exemplified by “Doggie no bite.” In the final stage, children employ the contracted negative form along with the verb, paralleling adult usage, as seen in “Doggie doesn’t bite.”

From over-regularization errors to the meticulous mastery of complex sentence structures, children’s language development encapsulates the fascinating evolution of their cognitive and linguistic abilities.

Hearing-Impaired Children

Each year witnesses the birth of numerous children facing varying degrees of hearing impairment, with about 1 in 1,000 children being born with severe hearing loss. During the initial months of life, the vocalizations of deaf infants may bear a striking resemblance to those of their hearing counterparts. Deaf infants engage in the familiar acts of crying, cooing, and even beginning to babble. However, a nuanced examination reveals distinctions in their babbling patterns compared to those of hearing infants. The quantity and quality of babbling by deaf infants might differ, with a reduced presence of the consonant-vowel syllables characteristic of canonical babbling stages.

Deaf infants, when exposed to sign language from birth, embark on a journey of acquiring sign language skills akin to the developmental stages seen in hearing infants acquiring spoken language. American Sign Language (ASL), British Sign Language (BSL), and Chinese Sign Language (CSL), among others, are unique languages, each with its own set of grammatical rules. Just as hearing infants naturally progress through stages of language acquisition, deaf infants exposed to a signed language display manual babbling, initially producing gestures. These gestures then evolve into single-sign utterances and later into more intricate multi-sign combinations. With maturity, the complexity of their multi-sign combinations grows, mirroring the grammatical intricacies of sign sequences. Remarkably, signing children’s errors parallel those made by their spoken language counterparts, encompassing idiomorph signs, sign overextensions, sign underextensions, and sign over-regularizations. The sophistication of signed sentences exhibited by children similarly advances over time.

In essence, whether spoken or signed, the developmental trajectory of language among children demonstrates striking similarities, transcending the mode of communication.

Nature Versus Nurture

A perennial inquiry in the realm of human behavior is encapsulated in the timeless nature versus nurture discourse. The question at hand: to what extent does the capacity of children to acquire language stem from innate characteristics (nature) versus environmental influences and learning experiences (nurture)? Esteemed language researchers have fervently delved into this debate, seeking to delineate the contributions of nature and nurture in the astonishingly swift and facile language acquisition seen in typically developing children. Within this discourse, the name Noam Chomsky shines prominently, as he contended that children are endowed with an intrinsic “language acquisition device” (LAD), a mental structure containing fundamental linguistic principles common to all human languages. On the opposing front, critics argue that language acquisition can be parsed through the same lens as other forms of learning, attributed to children’s exposure to linguistic interactions and the linguistic milieu surrounding them.

Though the nature versus nurture puzzle in language development remains a puzzle yet to be definitively solved, mounting evidence suggests the substantial role of biology. This proposition gained traction since the publication of Eric Lenneberg’s seminal work “Biological Foundations of Language” in 1967, positing the existence of a “critical period” for language acquisition—an optimal developmental phase ranging from birth to puberty. While some, like Steven Pinker, contend that this window narrows down to birth to the age of 5, the consensus remains that post this period, acquiring language becomes an arduous endeavor with diminished success. Those who fail to encounter sufficient exposure to spoken or signed languages during this critical phase might struggle to attain native-level proficiency.

The most compelling substantiation for the biological underpinnings in language development arises from investigations into heritable language disorders. The term “specific language impairment” (SLI) designates scenarios where children exhibit linguistic processing challenges but perform unimpaired on general cognitive assessments. Prevalent in approximately 3% of the population, SLI has garnered significant attention. Notably, studies indicate that SLI is notably more frequent within families of individuals grappling with this disorder, eclipsing the general population incidence. The study by Myrna Gopnik and Martha Crago in 1991, focusing on a 30-member extended family, unveiled that 53% of the members were identified as having SLI. Intriguingly, this familial inheritance pattern hinted at a potential role for a single dominant gene in the manifestation of this disorder.

While the resolution of the nature versus nurture quandary in language development continues to elude us, the intricate interplay between inherent biological mechanisms and environmental influences remains a compelling frontier in the study of human linguistic capacity.


In the fascinating journey of language development, all typically developing children who are sufficiently immersed in a linguistic environment manage to unlock the intricate code of language within the initial years of life. This remarkable process is characterized by a cascade of milestones that paint a vivid portrait of the burgeoning linguistic abilities of young minds.

As the first year unfurls, the linguistic landscape transforms as infants venture beyond their cries into the realm of expressive language. By the culmination of this inaugural year, children are producing their inaugural words, while concurrently cultivating an intuitive grasp of the language enveloping them. This mastery of language comprehension becomes increasingly evident as children recognize and decipher a substantial portion of the spoken discourse that engulfs their world.

The ascent continues into the second year, where the lexicon of young learners burgeons exponentially. Within this period, children manage to stockpile a treasury of several hundred words, each becoming a vessel for expressing their burgeoning thoughts and feelings. This proliferation of vocabulary is nothing short of a linguistic feat, transforming children into adept communicators with a burgeoning repertoire of linguistic tools at their disposal.

The third year witnesses the gradual transformation of children’s linguistic productions, as their utterances metamorphose into forms bearing resemblance to the complex sentences woven by adults. It is during this stage that children’s linguistic creativity truly blossoms, and they start to experiment with the syntactic intricacies that enable them to convey nuanced meanings. This period of linguistic expansion not only highlights their ability to internalize grammatical structures but also underscores the multifaceted nature of their cognitive development.

In summary, the trajectory of language acquisition is a remarkable voyage, encompassing the progression from the enigmatic utterances of infancy to the eloquent expressions of childhood. This developmental odyssey serves as a testament to the human brain’s innate capacity to decipher and wield language, a remarkable journey fueled by the interplay of cognition, interaction, and the relentless pursuit of understanding the world through the power of words.


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