The impact of deafness on cognition and visual language processing: Challenges from a neuroscience point of view.
Jerker Rönnberg, Birgitta Söderfeldt, Jarl Risberg.

The paper reviews lesion and imaging data, which have a bearing on cognitive and visual language processing notions. Lesion data are very consistent in showing that the same left-hemisphere anatomical structures are recruited for signed and spoken languages. Imaging data replicate this state of affairs but the role of the right hemisphere is also implicated. At present several hypotheses exit as regards to the role of the right hemisphere in sign language processing. The left-hemisphere involvement is also compatible with other independent data from deaf patients showing that visuospatial and motor nonlinguistic functions can be dissociated from visuospatial and motor linguistic functions. Furthermore, early use of sign language has recently been demonstrated to contribute to improved peripheral attention, enhanced spatial cognition, better memory for faces, and potentially also better perspective-taking abilities in the child (i.e., theories of mind). Early tactilely mediated visual speechreading, early reliance on visual speech and early exposure to cued speech also seem to promote better visual communicative skills. Some of the communalities between visual speech and sign have just recently begun to be explored within the working memory paradigm. It will be proposed that the cognitive neuroscience of the components of working memory is an important area, which can contribute much to the further understanding of cortical and cognitive processing of visual language.