Skinner!

Language is a behaviour like anyother and is learnt through reinforcement and imitation- known as operant conditioning.

Support: Oxana, accents, Nelson's categories of words and regression.

Issues: Skinner never tested his theory on children- rats and pigeons instead. The Wug test. The Fis study. Poverty of Stimulus and virtuous errors. 

Cognitive Theory:

Piaget!

Children have to understand a concept to be able to use it in their language.

EG: object permanence and seriation.

Support: Berko and Brown's Fis study, Brown's order of grammatical inflections and Nelson's 50 words.

Issues: Children with impaired cognitive function still acquire language.

Noam Chomsky!

Language Acquisition Device- innate capacity to acquire language. Universal grammar.

Eric Lenneburg's critical period.

Support:Wug test, virtuous errors eg. overgeneralisation, Brown's meaning relations, same staged across the world.

Issues: did not experiment with children. Genie is a problematic case.

Social Interaction Theory:

Bruner!

Language Acquistion Support System.

Child Directed Speech. -interogatives, wider pitch, simple vocab, sing song intonation which engages and supports the child.

Support: Jim, Nelson's word categories and Bancroft 'Peek a Boo'

Issues: Cruttenden's football results and in some cultures like Papa New Guinea they don't use CDS.