An overview of studies on sign language

In this article, psychological and psycholinguistic studies on sign language are reviewed. One of earlier studies is Wundt\u27s observation on natural signs of the deaf and some tribes like Indians. He reported that natural signs had motivational or imitative properties. From the observations on the developmental elaboration of sign use among American deaf children, the other researcher reported that those motivational or imitative signs would develop into arbitrary symbols, gradually acquiring linguistic rules, and losing their initial motivational or imitative properties. But if we regard a system of highly developped sign language as being composed of arbitrary signs only, we overlook an essential part of sign language. In sign discourse of the deaf, iconic, mimetric gestures are used as much as arbitrary signs. A question was raised about the iconicity of signs which might interfere with the information processing. A case that imagery plays an important role upon concept learning was illustrated, and it is suggested that there is little reason to consider that iconicity interferes in abstract thinking process. Inadequateness of research measures of earlier sign language studies derived from speech language studies, such as word order, syntax was discussed, and it is suggested that there exist many visuo-spatial rules specific to sign language