Introduction

This chapter reports on the findings of an experiment into the learning of British Sign Language (BSL) by Christopher, a linguistic savant, and a control group of talented second language learners. The results from tests of comprehension and production of morphology and syntax, together with observations of his conversational abilities and judgments of grammaticality, indicate that despite his dyspraxia and visuo-spatial impairments, Christopher approaches the task of learning BSL in a way largely comparable to that in which he has learned spoken languages. However, his learning of BSL is not uniformly successful. Although Christopher approaches BSL as linguistic input, rather than purely visuo-spatial information, he fails to learn completely those parts of BSL for which an intact nonlinguistic visuo-spatial domain is required (e.g. the BSL classifier system). The unevenness of his learning supports the view that only some parts of language are modality-free.

Accordingly, this case illuminates crossmodality issues, in particular, the relationship of sign language structures and visuo-spatial skills. By exploring features of Christopher's signing and comparing it to normal sign learners, new insights can be gained into linguistic structures on the one hand and the cognitive prerequisites for the processing of signed language on the other.

In earlier work (see Smith and Tsimpli 1995 and references therein; also Tsimpli and Smith 1995; 1998; Smith 1996; Smith and Tsimpli 1996; 1997; Morgan, Smith, Tsimpli, and Woll 2002), we have documented the unique language learning abilities of a polyglot savant, Christopher (date of birth: January, 6 1962).