Atypical signed language development: a case study of challenges with visual-spatial processing.

In signed languages, the articulatory space in front of the signer is used grammatically, topographically, and to depict a real or imagined space around a signer and thus is an important consideration in signed language acquisition. It has been suggested that children who acquire signed languages rely on concomitant visual-spatial development to support their linguistic development. We consider the case of a native-signing deaf adolescent female with average intelligence who had been reported to struggle with spatial aspects of American Sign Language (ASL) as a child. Results of a battery of linguistic and nonlinguistic tests suggest that she has relatively good ASL skills with the exception of some specific difficulties on spatial tasks that require attention to ASL and nonlinguistic topographic space or changes in visual perspective (e.g., classifiers and referential shift). This child has some difficulties with visual-spatial abilities, and we suggest that this has affected her acquisition of those aspects of ASL that are heavily dependent on visual-spatial processing.