Young children become amazingly proficient communicators during the first three years of life. As the Birth to Three Matters framework points out, they use 'the hundred languages of children' - body language (including facial expressions and dance); sign language (their own and family inventions as well as an officially recognised sign language); painting, drawing and mark-making; and oral expression. They have been acutely active listeners since their days in the womb, where they learned to recognise the speech patterns, tunes and tones of the languages used in their home contexts.

Language theory research informs us that young children's language development is influenced by many factors, including having sensitive adults and older children around them who will listen and attend to their expressions and who will use and model appropriate language themselves. This has been called 'Motherese' by researchers led by Cathy Snow. Children's babbling during their first year includes the sounds of every world language and 'crib talk' demonstrates their intense interest in the sounds they hear around them.

Although children with a hearing loss will stop babbling, if they grow up in a home with parents who can sign, they will follow the same patterns of development using their first language - signing - and will sign their first word at around the same age that hearing children speak theirs.

Between two and three years of age most children will be able to use language to influence the people closest to them, indicating the links with brain development and their growing ability to 'mind read' (this means they are beginning to understand the minds of their parents, sisters and brothers and try to manipulate them through persuasion, mock tears, teasing and so on).

Research shows that, in general, boys acquire language more slowly than girls, which means the girls may stop learning through hands-on exploration. It also means that we need to consider very carefully how we involve boys in activities designed to promote early language and literacy.

What are the main theories that influence the way practitioners in early chilhood education and care settings think about language development?

Chomsky: Language Acquisition Device
Although other theories were proposed earlier, it may be best to begin with Chomsky's theory that humans are born with a special biological brain mechanism, called a Language Acquisition Device (LAD). This theory supposes that the ability to learn language is inborn, that nature is more important than nurture and that experience using language is only necessary in order to activate the LAD. Chomsky's background is in linguistics, and psycholinguists continue to contribute much to our understanding of languages and how children acquire them. His theory is described as Nativist. The main contribution of his work has been to show that children's language development is much more complex than the Behaviourists ('Show the way', Nursery World, 18 March 2004), who believed that children learn language merely by being rewarded for imitating.

One problem with Chomsky's theory is that it does not take enough account of the influence that thought (cognition) and language have on each other's development.

Piaget: cognitive constructivism
Piaget's central interest was children's cognitive development ('Building up', Nursery World, 20 May 2004). However, he theorised that language was simply one of children's ways of representing their familiar worlds, a reflection of thought, and that language did not contribute to the development of thinking. Cognitive development, he argued, preceded that of language.

Vygotsky: social constructivism and language
Unlike Chomsky and Piaget, Vygotsky's central concern was the relationship between the development of thought and that of language. He was interested in the ways in which different languages might impact on how a person thinks. He suggested that what Piaget saw as young children's egocentric speech was in fact private speech, the child's way of using words to think about something, a step on the road from social speech to thinking in words. So Vygotsky's theory views language first as social communication, gradually promoting both language itself and cognitiion. Theorists who also followed this tradition and whose ideas can contribute to our understanding include his contemporary Bakhtin, and Bruner.

Recent theorising: intentionality
Some critics of earlier theories suggest that children, their behaviours and their attempts to make sense are often lost when the causes of language development are thought to be 'outside' the child or else mechanistically 'in the child's brain.'

These contemporary researchers and theorists recognise that children have 'agency' - that they are active learners co-constructing their worlds. Their language development is part of their holistic development, emerging from cognitive , emotional and social interactions. The social and cultural environment, the people in it and their interactions, and how children come to represent all these in their minds, are absolutely fundamental to language development. It is a child's agenda, and the interactions generated by the child, that promote language learning.

However, this does not mean the adult's role, actions and speech are considered of less importance. But adults need to be able to 'mind read' and adjust their side of the co-construction to relate to an individual child's understanding and interpretation.

Intentionality theories have existed since Aristotle, and this model of language development draws on Piaget, acknowledging the importance of cognitive development. However, 'intentionality' emphasises holistic development, so including emotions and other aspects of growth and learning.

The intentionality model makes sense when we think about the way in which most children's language accelerates between 18 months and four years of age, when increases in cognitive capabilities give children a better understanding of both verbal and non-verbal categories. They will also use 'over-extended categories' less (such as babies and toddlers labelling all men 'daddy' or all animals 'dogs').

Messages for practice
Theories about language development help us see that enjoying 'proto-conversations' with babies (treating them as people who can understand, share and have intentions in sensitive inter-changes), and truly listening to young children, is the best way to promote their language development