A mother asked the teacher of Class II how it was possible for her child to…

Theories of child language acquisition explain how children come to produce language. Imitation and reinforcement (behaviourist) accounts hold that children learn language by directly copying and being rewarded for specific utterances modelled by others. Nativist theory, associated with Noam Chomsky, instead holds that children are born with an innate biological capacity for language that lets them internalise grammatical rules and generate sentences they have never directly heard, while constructivist theory (Piaget) frames language as one outcome of children actively building understanding through interaction with their environment.

In the stem, the child produces a sentence that no adult or sibling has ever said to her — nothing was modelled for her to copy or reinforce. A pure imitation or reinforcement account cannot explain an utterance that was never presented as an example. This points instead to an innate biological capacity that lets a child generate original combinations of words from the grammar she has internalised, without needing to have heard that exact sentence before.

• As per the constructivist approach, children can invent new languages — constructivism explains how children build understanding of an existing language through interaction with their world; it does not claim that children invent brand-new languages of their own, so it does not match a child producing an unmodelled sentence within the same language.

• Children learn language only by imitating adults — a pure-imitation view predicts a child can only reproduce sentences an adult or sibling has actually said, so it cannot account for a sentence nobody modelled for her.

• The human brain is innately wired to learn language — the nativist explanation: an inborn grammatical capacity lets children generate sentences beyond anything they were directly taught, which is exactly what the stem describes.

• A child learns language when we reinforce the development of the child’s language — a reinforcement account explains why a child might repeat and refine utterances that caregivers have rewarded, but it does not explain a wholly unmodelled sentence, since there was nothing to reinforce.

The apt answer is therefore that the human brain is innately wired to learn language — the nativist explanation for a child’s novel, unmodelled language use.