6 Small to big, and big to small

It is easy to imagine language acquisition as if it were always a process that puts more basic building blocks together to form more complex units; from phoneme to syllable, from syllable to words, from words to sentences. It is important to understand that as well as this part-to-whole progression, there is also a whole-to-part process taking place simultaneously in development.

Exactly when children say their first words depends on what we mean by a word. This might seem pedantic but consider, for example, a child that only says ‘wantmilk’ in this way many times over and never says ‘want’ or ‘milk’ in any other linguistic contexts. From the adults’ perspective ‘wantmilk’ might be interpreted as two words but from the child’s perspective it is not so clear. They could just be using ‘wantmilk’ as ‘that chunk of sound that gets me milk’.

At a stage where most of children’s other productions consist of single words, children also produce utterances such as ‘Where’s it gone?’, ‘There it is’ and ‘Oh dear’, which contain words that have not previously occurred on their own in the child’s speech. Such frozen utterances can make up to 50 per cent of the first 400 multi-word utterances produced by 2 year olds (Lieven, Pine and Barnes, 1992).

The ability to use formulaic multi-word utterances is a hallmark of native fluency and an aspect that adult, second-language (L2) learners sometimes struggle with. There is evidence that adults are both less likely to extract multi-word utterances and less capable of benefiting from them than children (Arnon and Christiansen, 2017).

Because adults already know that words exist from their first language (L1), they are more likely to use word-based rather than prosodic cues to segment speech, leading them to overlook the kind of supra-word regularities children are adept at detecting. Their existing knowledge of how language works is, in this case, a hindrance to acquiring how another works. This is amplified by the fact that adult-to-adult input is much more likely to contain longer sentences and is less repetitive than CDS, and adults are more likely to be literate, making them more prone to a word-by-word processing strategies. These differences in the way children and adults chunk and segment speech are one reason children are better language learners than adults.