Deaf Children Are Verb Attenders:
Early Sign Vocabulary Development
in Dutch Toddlers
As we say in Dutch, meten is weten ("measuring is knowing"). This is a twentieth-century claim that might well be true for physical objects and events but is certainly less sure for living systems such as languages and their users. In that respect, the MacArthur Communicative Development Inventory (MCDI) has proven itself to be a useful tool for assessing early vocabulary growth in many spoken languages (Fenson et al., 1993, 1994); however, it needs to be refined for use with children learning a sign language. In this chapter I explain how the MCDI has been adapted for use in Sign Language of the Netherlands (SLN), with applications to the diagnostic process as well as the selection and categorization of lexical items in research. In the process of applying this instrument of early language assessment, it became clear that important theoretical issues were involved. The age of detection of deafness, ranging from 6 to 30 months, indicates later onset of learning compared with samples of hearing children learning spoken languages. In addition, deaf babies with hearing parents seem to be exposed to "imperfect input" from parents who are themselves early second-language learners of SLN. This later onset of language learning is indeed revealed in vocabulary size and rate of growth—but not to the extent one would expect.
In interpreting the data, one is confronted with categories that divide nouns and verbs, but are these traditional linguistic categorizations for words of spoken languages comparable to lexical categories of