Child directed speech and language
It is often noted, originally by Catherine Snow (1972) and Elizabeth Bates (1976) and many others since, including Cat Bohannon (2023) that there is a characteristic way of talking to small children, used particularly by mothers, with short, simple words and sentences, some words modified to resemble children’s speech, as few embedded clauses as possible, slightly exaggerated intonation.
Originally this was characterised as ‘motherese’. Later, reflecting the view that this was demeaning to women, the term was replaced by ‘Child directed speech and language’, CDSL, or some variant. Snow and Bates proposed that the simplified forms of CDSL would constitute templates around which the vastly more complex structures of fully-developed language could be built one by one in a natural way.
It is obvious that the rate of CDSL use varies across families and individuals. It was thought that this ‘CDSL hypothesis’ could be tested by taking a sample of families, measuring the CDSL and the rate of language development, and that the hypothesis would be confirmed by a positive corelation. There does indeed seem to be a positive co-relation between these things. But it may not confirm the hypothesis. It is possible that CDSL is not so much a language acquisition device but more an expression of bonding with babies and small children. Such an idea is strengthened to the extent that something like CDSL seems to be sometimes used with small pets – who are surely not expected to learn to talk. It would be quite unsurprising if speech and language development was facilitated by good, strong bonding between parents and children. But that would have nothing to say about the hypothesis.
There is a further problem in the CDSL variation: What if it varies to zero? What if some children never experience any from either of their parents? In a survey of CDSL by Clare Galloway and Brian Richards (1994) it is revealed that although CDSL is common across cultures, it is not universal. Yet language still develops in cultures where CDSL is not used.
There is a much bigger problem. If CDSL was taken to the limit, children would have no experience of any complexity. And it is hard to see how normal acquisition could proceed. But CDSL is not commonly taken to the limit. “Darling, do you want your milky?” or “Do you want your milky, darling?” are not commonly thought to be complex or offences against a strict CDSL protocol. There is a possible simplification as “Want your milky?” with or without the darling. But the form with do you want is also possible. With or without the common contraction of do you to a single syllable, the syntax here is not simple at all. But significantly, the fact that darling, either precedes or follows the rest of the sentence marks it out as some special sort of entity, in this case, as a form particular to discourse.
Or consider “Do you want the jam you had yesterday?” It is not easy to see how this could be simplified without losing the sense. To ask the question, the relative clause in you had yesterday has to be included in the structure in this position.
On such reason, most scholars of syntax conclude that the CDSL hypothesis is mistaken. But every expression of bonding is obviously invaluable in ways going far beyond language development.