Context, Cognition, and Deafness

7. Vocabulary Development of Deaf and Hard of Hearing Children

7 VOCABULARY DEVELOPMENT OF DEAF AND HARD OF HEARING CHILDREN Amy R. Lederberg and Patricia E. Spencer There has been an explosion of research on early vocabulary development of hearing children (e.g., Golinkoff and Hirsch-Pasek forthcoming; MacWhinney 1999). This exciting new research can be used to stimulate new insights into deaf and hard of hearing children's vocabulary development.1 Traditionally, the study of vocabulary was limited to descriptions of the content and size of children's lexicons. Recent research has shifted focus to the processes that underlie children 's word acquisition (Golinkoff and Hirsch-Pasek forthcoming; Lederberg, Prezbindowski, and Spencer 2001). Cognitive skills such as association, memory, categorization, and social cognition play an essential role in shaping children's vocabulary development. For typically developing hearing children, changes in cognitive skills seem to be, in part, causally connected to changes in the way in which they acquire words (Dromi 1999). Relations between cognition and vocabulary are very different for the vast majority of deaf and hard of hearing children who have hearing parents and thus limited access to linguistic input. For these children, cognitive development typically outpaces their linguistic development (Lederberg and Everhart 2000; Mayberry 1992). Therefore, the cognitive skills that limit and facilitate vocabulary development among hearing children are unlikely to affect language in the same way for deaf children. This opens the possibility that deaf children's vocabulary development may not only be delayed but different from that of hearing children. This chapter reviews and compares studies of vocabulary development of children who are deaf and hard of hearing with that of hearing children in order to discern these differences. 1. In this chapter, "deaf" refers to a severe to profound hearing loss while "hard of hearing" refers to a mild to moderate hearing loss. Our research has been supported 1Jy the March ofDimes Foundation and the Office ofSpecial Education . We would like to thank the school administrators, who havegiven us their support, and the teachers and parentsfor their participation in our study. With their dedication we are learning more about children's language development. We also want to thank the childrenfor participating and allowing us to learn from them. We are also grateful to Dr. Robert E. Johnson ofthe Gallaudet University Department ofASL, Linguistics, and Interpretation and Ms. Linda Stamper ofthe Gallaudet Research Institutefor their help in developing the nonce signs used in our research. Finally, we are most grateful to Amy Prezbindowskifor her continual support and significant contributions to our research. 88 VOCABULARY DEVELOPMENT OF DEAF AND HARD OF HEARING CHILDREN 89 Of course, we do not expect vocabulary to develop similarly among all children who are deaf or hard of hearing. A variety of factors are likely to affect acquisition of vocabulary, including type of linguistic environment and cognitive abilities . As we and others have discussed extensively elsewhere (e.g., Spencer and Lederberg 1997), a vast majority of deaf and hard of hearing children are relatively deprived of linguistic input and develop language in a less rich linguistic environment than hearing children or deaf children with deaf parents. We expect factors that affect the frequency, complexity, and diversity of linguistic input to influence vocabulary development. For children who are in a speech-only environment, degree of hearing loss and the type and age of amplification affect how much access the children have to linguistic input. For children acquiring sign, the skill and number of people who sign in the children's environment have a similar impact. Finally, children's cognitive abilities may influence their abilities to learn from their linguistic input and thus affect their pattern of vocabulary development. When data are available, the influence of these variables on deaf and hard of hearing children's vocabulary development are discussed. However, an extensive analysis of these variables is outside the scope of this chapter. Vocabulary development can be characterized along three dimensions: (1) the quantity and nature of words that a child knows; (2) the rate of vocabulary growth (i.e., the speed at which new words are learned and added to a child's vocabulary); and (3) word-learning processes or strategies that children use to facilitate and guide the learning of new words. These three dimensions are clearly interrelated and should be seen as different "windows" onto the changes to the way children learn new words as their skills develop. Past research on vocabulary development has primarily concentrated on ways to assess the extent of vocabulary knowledge (i.e., number of...