The central goal of this project is to understand how deaf individuals acquire reading skills. It is well known that the greater the residual hearing, the better the reading skills. This relationship explains, for the most part, the lower reading skills observed in the deaf community. However, above average reading skills have been noted in some profoundly deaf individuals, indicating that literacy can be achieved even in the absence of hearing. In this proposal, we focus on individuals who have had little-or-no access to the speech sounds of English through the auditory modality in order to determine those factors that facilitate reading above and beyond residual hearing. We propose to use the recruitment of standard left hemisphere language areas and their homologous areas on the right, as measured by fMRI, in conjunction with behavioral markers to characterize the reading strategies used by profoundly deaf readers.
Our first aim is to test the hypothesis that early acquisition of a sign language can promote reading by providing foundations necessary to develop literacy, such as a general understanding of the world and language use early on during development. We will test the hypothesis that sign language proficiency and working memory abilities are positively correlated with better reading skills. Using fMRI, we will ask whether this increase may rely on visual strategies usually not observed in hearing individuals.
Our second aim is to determine the impact of training in speech reception and production on reading by studying deaf readers who have had minimal access to signed communication, but have been orally trained. We will test the hypothesis that deaf individuals can develop a model of the sound structure of English, even in the absence of remaining hearing, and that this skill promotes the recruitment of the left hemisphere during reading. Finally, we will test the extent to which exposure to a natural language facilitates reading acquisition by comparing the two previous groups with deaf people who use a manual communication system (Signed English) that violates some of the regularities found in natural languages, such as English or American Sign Language.