Language Acquisition

The LAD is Chomsky's hypothesised innate, domain-specific cognitive mechanism that enables children to acquire language. It is not a physical structure but a theoretical construct: the claim that humans are born with knowledge of the abstract principles (Universal Grammar) that constrain all possible human languages. When exposed to their specific language, children use UG to constrain the hypotheses they can form about grammar, enabling rapid acquisition despite the impoverished and noisy input they receive (the poverty of the stimulus argument). Evidence: children across all cultures acquire language in the same developmental sequence; they make systematic errors that reflect UG principles (e.g., overregularisation: "goed," "mouses"); children acquire structures they have never been explicitly taught and spontaneously reject ungrammatical sentences without correction.

Lenneberg (1967) proposed that a critical period for language acquisition closes around puberty, driven by cerebral maturation and reduced neural plasticity. Evidence: (1) Genie, a girl isolated until age 13 with no language exposure, never achieved full grammatical competence despite intensive instruction. (2) Deaf individuals who learn sign language after the critical period show permanent syntactic deficits compared to those who learn early. (3) Second language acquisition research consistently shows that age of acquisition is the strongest predictor of ultimate attainment in morphosyntax and phonology — even immigrants who move before puberty and achieve apparent fluency show subtle deficits relative to native speakers. Newport (1990) proposed the "less is more" hypothesis: children's limited processing capacity may actually facilitate language acquisition by forcing incremental learning.

Pre-linguistic stage (0–12 months): cooing (2–3 months), canonical babbling (6–8 months, CV syllables: "bababa"), then variegated babbling (varied syllable sequences). First words (10–13 months): holophrases — single words carrying full sentence meaning. Vocabulary spurt (~18 months): rapid word learning, partly driven by fast mapping. Two-word stage (~18–24 months): telegraphic speech retaining content words without grammatical morphemes ("mummy gone," "more milk"). Multi-word / telegraphic speech (24–30 months): mean length of utterance increases; grammatical morphemes begin appearing in a relatively fixed order (Roger Brown's stages). By age 5, most children have mastered the basic grammar of their language, with later development of complex structures (relative clauses, passives, discourse skills) continuing through middle childhood.

Nativism (Chomsky) emphasises innate biological endowment — Universal Grammar pre-specifies the structure of possible grammars, and the child's task is to set parameters from input. The social-interactionist view (Bruner, Tomasello, Vygotsky) emphasises that language is acquired through social interaction and the support of caregivers. Bruner's LASS provides scaffolded routines (e.g., peek-a-boo, book-reading) that highlight language-in-context; child-directed speech simplifies the input; joint attention enables word-world mapping. Tomasello's perspective adds that children are uniquely gifted intention-readers — they acquire language not by learning word-object associations but by inferring communicative intention. These accounts are not mutually exclusive: most contemporary researchers accept that some innate language-readiness is necessary, while social interaction and input quality powerfully shape developmental timing and ultimate attainment.