Within this field there are, I believe, three crucial, but difficult, inter-linked questions.
First: how do children learn to talk? It’s obvious that somehow most children do this in about ten years without any special guidance, training or instruction. But how? The more we know about this the better we can help those children for whom learning to talk is not so easy.
Second: Why should it be that different sorts of speech and language problem commonly go together – by what are known as ‘co-morbidities’.
Third, why is it that children’s speech errors pattern in the way they clearly do? Order in disorder is a strange anomaly. There shouldn’t be any sort of pattern at all.
These three questions are linked together. But there is a paradox.
On the one hand, it is obvious that no two children are the same, not even supposedly identical twins. On the other, there has to be a commonality in the learning of speech and language. Despite the huge range of childhood experiences, people brought up in a given language community have a common understanding of the community language. Without this common understanding, there would be a monstrous unfairness in the idea of law. Business contracts would be meaningless. And there would be no wit or plays on words or verbal comedy. But this common understanding would be impossible without a commonality in the learning process
This common understanding is reached without children ever being given what is known as ‘privileged information’ about how things work in their target language. Of course, children wouldn’t understand if anyone ever tried to explain any of the critical points. But no two children hear the same things. In the case of any given language, what children happen to hear said, and what they are taught (if they are taught at all) vary widely and randomly. Children make all sorts of mistakes in learning to talk. But not quite all sorts.
Across different languages, there are variations in the use of tone or pitch. In English tone is used for emphasis and to mark questions. But in about half the world’s languages, tone is also used to make words different from one another. Most children start working out how tone is used in their target language by around two and a quarter. It is not obvious how they do this. But at least where the target language is English some children have problems here.
The working of tone is just one of the things which can’t be learnt just by listening and copying.
Children seem to know what to do with words like who, what, when, where and why without being told or taught. The questions “Who do you want to play with?” and “Who do you want to play with you?’ differ only in the last word – about who is to do the playing. But in both cases, who is understood in a position to the right of the position in which it is pronounced. Children understand the difference without having this explained.
Or take questions like “Who ate what?” or “What did who say when?” Such questions are very rare in everyday conversation. But only one of the question words is said at the beginning of the sentence. When children do ask such questions (even though they only do so very seldom), they never make mistakes like ‘Who what ate?” or “What who ate?” with the question words together before any other words. Why don’t children ever make this sort of mistake?
Something quite contradictory happens in expressions of surprise, as in “He said what?” or “She went where?” which are not really questions, where a question word like what or where is used in the position where it is understood. But children don’t seem to confuse these expressions of surprise with proper questions where the question word is pronounced at at the beginning.
It is still not understood how speech and language acquisition works. But I believe that progress is being made towards finding out. My job is to use the science which goes into trying to find an answer to help your child.