This line of research examines how children develop natural-number concepts through the use of emergent language and innate representational resources. Specifically, how children come to understand that number words (1) refer to numerosity, as opposed to some other property of individuals or sets, and (2) quantify over discrete entities. Some researchers contend that children understand these semantic restrictions from very early on and that this knowledge, in fact, guides children's learning of the first few numberwords. Conversely, it has been argued that children extrapolate these restrictions from the first few number-word meanings. Results from the present studies support this latter view by providing evidence that number concepts are constructed over time, via a predictable developmental trajectory.

Study 1 demonstrates that only children who understand the cardinal principle of counting (those who are able to use counting to determine the number of items in a set) reliably extend number words to numerosity. Study 2 shows that children must learn the cardinal meanings of three or more number words in order to apply higher, unknown number words to discrete entities. Each of these two studies provides evidence that children do not connect number words to specific discrete quantities upon first encounter with the number-word list. Rather, they make the connection around the same time they figure out the cardinal principle. Study 3 addresses how children make this connection by exploring the proposal that children use the pairing of number words with count nouns as an indication that objects are preferred referents of number words. The results of this last study indicate that linguistic context facilitates learning the semantic functions of number words well before a child learns the specific meaning of each of these words. Additionally, this study provides supporting evidence for the claim that Mandarin noun classifiers provide information analogous to count mass distinctions in English. Implications for theories of number-concept construction will be discussed in relation to the findings of each of these studies.