Chapter 21 - The Processing of Sign Language: Evidence from Aphasia

Abstract

This chapter provides an overview of the effects of left- and right-hemisphere damage in users of signed languages, and explores the theoretical implications of these findings. The aim of this chapter is to document the present status of the field and to foreshadow issues that are likely to be of interest in future studies. The studies to date provide ample evidence for left-hemisphere mediation of sign language in the deaf. Sign language disturbances following left-hemisphere damage show linguistically significant breakdown that is not attributable to more general problems in motor or symbolic processing. There is also growing evidence for the role of the right hemisphere in sign language processing, especially in the realm of comprehension. Whether these language deficits reflect general spatial-cognitive deficits or whether right-hemisphere neural systems function as part of a linguistic system in the deaf requires further investigation. Recent in vivo imaging of blood flow in normal congenitally deaf and hearing signers also points to an increased role of the right hemispheremnot entirely expected, given previous lesion studies.