We study adults who have had different sensory and/or language experience in order to assess the degree to which biological biases in cerebral development depend upon and can be modified by input from the environment.
Studies of visual processing in congenitally deaf individuals suggest that certain aspects of visual development are enhanced after auditory deprivation. These include the perception of and attention to peripheral visual space and to motion. These results imply that some neural systems are more modifiable by (and dependent upon) early sensory experience than are others. Using several different experimental approaches we ascertain the mechanisms whereby the altered processing and altered neural substrates arise in development. In past studies of blind individuals we compared the nature and extent of neuroplasticity after auditory and visual deprivation.
Current research is examining selective attention and language processing in deaf adults and is funded by NIH/NIDCD (2007-2012).
Studies comparing language processing in English and American Sign Language (ASL) suggest there are strong biases that render areas within the left hemisphere a suitable substrate for language processing regardless of the structure or modality of the language. In addition, these studies show that when a language depends upon the perception of spatial location and motion (as is the case for ASL) areas within the right hemisphere are also part of the language systems of the brain. These studies suggest that early language experience plays a central role in determining cerebral organization. Studies of bilingual persons who acquired languages at different ages suggest that early exposure to language is a good predictor of language skills and of cerebral organization for language. Acquisition of the phonology and grammar of language may be more dependent upon and vulnerable to language experience than is acquisition of a lexicon.
Current research is examining the effects of delays in sign language exposure on brain organization for language and the neural systems mediating signed and spoken language and is funded by NIH/NIDCD (2007-2012).