Motivated by Chomsky's reasoning about the poverty of the linguistic input, a number of researchers have investigated the characteristics of child-directed speech (CDS) and their impact on children's language acquisition. In this article, we review studies that investigated the relationship between CDS and children's initial vocabulary acquisition. Results suggest that CDS's style, mean length utterance, frequency and variety of words have an impact on early vocabulary acquisition. These results have however to be interpreted with caution. In general, only correlational studies have investigated the contribution of CDS to early vocabulary development. In addition, most of them were conducted with English-speaking children. Experimental studies as well as studies including children speaking other languages are clearly necessary to further investigate this issue.
Language acquisition; Child-directed speech; Vocabulary