Research has shown parallels in the development of linguistic aspects found in sign languages and spoken languages when acquired as a first language (Newport & Meier, 1985). Deaf children of deaf parents (DCDP) are exposed to sign language early and are able to acquire it effortlessly. However, only about 10% of deaf children have deaf parents. More commonly the deaf child is born into a hearing family. These hearing parents usually use a communication system in which spoken words are supported simultaneously with signs. Such a sign system differs considerably from a sign language as it is not a natural language. Deaf children of hearing parents (DCHP) come into contact with sign language when they go to a school for the deaf. Research indicates that DCHP do acquire sign language structures, but this acquisition is delayed (Knoors, 1992). In this study a description of the development of morpho-syntactic and lexical aspects of the Sign Language of the Netherlands is given. The sign language production of three DCDP is analysed every six months from 1;0 to 3;6. Furthermore, the sign language production of three DCHP at the age of 3;6 is compared with that of the DCDP at the same age. The study includes both general measures such as Mean Length of Utterance and Type/Token Ratio and aspects specific to sign languages such as the use of POINTS in two sign combinations. Recommendations will be made with respect to the improvement of observational research on language acquision of DCDP and DCHP.
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