Biological Psychology and Neuropsychology

Deaf bilinguals for whom American Sign Language (ASL) is the first language and English is the second language judged the semantic relatedness of word pairs in English. Critically, a subset of both the semantically related and unrelated word pairs were selected such that the translations of the two English words also had related forms in ASL. Word pairs that were semantically related were judged more quickly when the form of the ASL translation was also similar whereas word pairs that were semantically unrelated were judged more slowly when the form of the ASL translation was similar. A control group of hearing bilinguals without any knowledge of ASL produced an entirely different pattern of results. Taken together, these results constitute the first demonstration that deaf readers activate the ASL translations of written words under conditions in which the translation is neither present perceptually nor required to perform the task.

This study addressed visual word recognition in deaf bilinguals who are proficient in German Sign Language (DGS) and German. The study specifically investigated whether DGS signs are activated during a monolingual German word recognition task despite the lack of similarity in German orthographic representations and DGS phonological representations. Deaf DGS-German bilinguals saw pairs of German words and decided whether the words were semantically related. Half of the experimental items had phonologically related translation equivalents in DGS. Participants were slower to reject semantically unrelated word pairs when the translation equivalents were phonologically related in DGS than when the DGS translations were phonologically unrelated. However, this was not the case in Turkish-German hearing bilinguals who do not have sign language knowledge. The results indicate that lexical representations are associated cross-linguistically in the bilingual lexicon irrespective of their orthographic or phonological form. Implications of these results for reading development in deaf German bilinguals are discussed.

How do deaf and deafblind individuals process touch? This question offers a unique model to understand the prospects and constraints of neural plasticity. Our brain constantly receives and processes signals from the environment and combines them into the most reliable information content. The nervous system adapts its functional and structural organization according to the input, and perceptual processing develops as a function of individual experience. However, there are still many unresolved questions regarding the deciding factors for these changes in deaf and deafblind individuals, and so far, findings are not consistent. To date, most studies have not taken the sensory and linguistic experiences of the included participants into account. As a result, the impact of sensory deprivation vs. language experience on somatosensory processing remains inconclusive. Even less is known about the impact of deafblindness on brain development. The resulting neural adaptations could be even more substantial, but no clear patterns have yet been identified. How do deafblind individuals process sensory input? Studies on deafblindness have mostly focused on single cases or groups of late-blind individuals. Importantly, the language backgrounds of deafblind communities are highly variable and include the usage of tactile languages. So far, this kind of linguistic experience and its consequences have not been considered in studies on basic perceptual functions. Here, we will provide a critical review of the literature, aiming at identifying determinants for neuroplasticity and gaps in our current knowledge of somatosensory processing in deaf and deafblind individuals.