One avenue of research that has evolved from my dissertation is examining whether vision and attention are “enhanced” or altered in deaf people. Here, I asked How does life-long Deafness alter visual perception? Deaf people differ from hearing people in two ways that provide a unique means by which to study the effects of atypical sensory experiences during development. First, the lack of auditory input compels deaf people to rely more on their intact senses, especially vision, which may alter certain visual functions that are important for gaining information about the environment. Second, many deaf people use a visual-manual language (American Sign Language, ASL), which may alter certain aspects of visual processing that convey critical linguistic information, such as handshapes. To tease apart which aspects of altered visual processing are due to deafness versus ASL language experience, we compare visual sensitivity in Deaf Signers, Hearing Signers (who sign because they have deaf parents), and Hearing Nonsigners. Results from our studies show that some aspects of visual processing, such as peripheral attention, are altered by deafness while other aspects, such as form sensitivity and the hemispheric laterality of motion processing, are altered by experience with sign language.
What is particularly exciting now is extending this work to deaf infants and children and to higher-level visual processing. Many aspects of higher-level visual processing, such as perception of faces, and cognition have never been tested in the deaf population, let alone deaf infants and children. We are currently two years into our grant and have administered a battery of many perceptual and cognitive tests (that our lab has developed) to a total of 120 subjects, studying visuocognitive processing, language proficiency, and visual sensitivity to a wide range of visual stimuli, including faces, motion, contrast, shapes, orientation of elements, and temporal order. I presented some of these results in Sweden last year, and we are presenting results at the SRCD conference this April with my postdoctoral fellow Sarah Tyler. By the end of this year, we plan to have submitted two manuscripts on this work.
Relevant Publications:
Bosworth, RG & Dobkins, KR (1999). Left hemisphere dominance for motion processing in deaf signers. Psychological Science, 10(3). 256-262.
Dobkins, KR & Bosworth, RG (2001). Effects of set-size and spatial selective attention on motion processing. Vision Research, 41(12). 1501-1517.
Bosworth, RG & Dobkins, KR (2002a). Visual field asymmetries for motion processing in deaf and hearing signers. Brain & Cognition, 49(1). 152-169.
Bosworth, RG & Dobkins, KR (2002b). The effects of spatial selective attention on motion processing in deaf and hearing subjects. Brain & Cognition, 49(1). 170-181.
Bosworth, R. G., Petrich, JAF, & Dobkins, K. R. (2013). Effects of attention and laterality on motion and orientation discrimination in deaf signers. Brain & Cognition, 82(1), 117-126.