A mother notices that her child sometimes says things that she has never heard…

Core idea:Psychologists offer competing accounts of how a child acquires her first language. Behaviourism (B. F. Skinner) holds that speech is learned the way any other behaviour is learned — through imitation of the people around a child and reinforcement whenever the imitated speech matches adult usage. Nativism (Noam Chomsky) instead holds that humans are born with an innate language faculty (the Language Acquisition Device) that lets them generate sentences they have never actually heard. Constructivism (Piaget) treats language as one output of a childs broader active construction of knowledge through interaction with the world, not as copied speech.

Applying it here:The mother explicitly states her belief as the child learning language by imitating people in her family and immediate surroundings — she is describing learning through imitation and exposure to those around her, which is exactly the behaviourist mechanism, not an innate faculty or an internally constructed system.

• Multilingualism — describes knowing or using more than one language; it is not a theory of how any single language is learned, so it cannot match a belief about a learning mechanism.

• Nativism — attributes language to an inborn faculty present from birth, largely independent of how much a child copies those around her — the reverse of an imitation-based belief.

• Constructivism — treats the child as an active builder of language rules through her own cognitive engagement with experience, not as a copier of others utterances.

Result:The imitation-based belief the mother holds is the Behaviourist account of language acquisition. The novel sentences she notices are what puzzle her — that observation is the classic evidence used to argue against a purely imitation-based account and for an innate faculty — but the question asks what her stated belief matches, not what best explains the novel utterances, and her belief is squarely behaviourist.