Previous research has shown that children go through a stage in which
they know that the number words each refer to a distinct numerosity, y
et do not know WHICH numerosity each number word picks out (Wynn, 1992
). How do children attain this level of knowledge? We explore the poss
ibility that particular properties of how number words are used within
sentences inform children of the semantic class to which they belong.
An analysis of transcripts of the spontaneous speech of three one-and
two-year-old children and their parents (from the CHILDES database; M
acWhinney & Snow, 1990) suggests that the relevant cues are available
as input in parents' speech to children, and that children generally h
onour these properties of number words in their own speech. Implicatio
ns of this proposal for word learning more generally are discussed.