Q.How is language acquired in human beings?

Language is acquired through a broadly predictable sequence of stages — crying, cooing, babbling, the one-word stage, and the two-word/telegraphic stage — and, most psychologists agree, through a combination of inherited readiness (nature) and learning through experience (nurture). …

Language development follows a broadly predictable sequence across children everywhere, even though individual children vary in rate. It begins with undifferentiated crying, which gradually differentiates by pitch and intensity, joined by cooing sounds. Around six months, babbling begins, elaborating by nine months into repeated sound strings (echolalia). Around the first birthday, most children enter the one-word stage, followed by holophrases, and by 18-20 months, the two-word stage, marked by telegraphic speech (mostly nouns and verbs). By close to the third birthday, focus shifts to mastering grammar.

On how this happens, the chapter presents two complementary accounts. B.F. Skinner explained language acquisition through general learning principles: association (linking a bottle with the word 'bottle'), imitation (picking up words heard from adults), and reinforcement (being rewarded with smiles or hugs for correct speech), with shaping gradually bringing a child's speech closer to adult accuracy. Noam Chomsky argued this cannot be the whole story, since children produce entirely new sentences they have never heard and could not simply be imitating; he proposed that children are born with an innate 'universal grammar' and go through a critical period fo …