Cognitive Processes

Perceptual and Cognitive Processes Impacted by Deafness

Recently researchers have found that deaf individuals are very good at detecting and reacting to visual information, compared with hearing people. For example, when asked to simply detect a visual flash (either centrally or in the periphery of vision), deaf individuals responded significantly faster than hearing individuals (both signers and nonsigners). In addition, deaf people are faster and more likely to reflexively move their eyes toward a visual target than hearing people. Such sensitivity to visual stimulation in the environment indicates that deaf people are more affected than hearing people by visual distractions. Thus, classroom designs, as well as web-based “virtual” environments, created for use by deaf people, need to limit or remove distracting visual events that can trigger rapid (and often involuntary) looks toward these stimuli, which can disrupt attention.

Many studies have now also shown that deaf people exhibit enhanced visuospatial abilities in the periphery of vision. Compared with hearing people (both signers and nonsigners), deaf individuals are better able to detect motion in the periphery of their visual field and to switch their attention toward the visual periphery. Thus, although processing sign language critically involves motion processing in the visual periphery, enhanced processing in this region appears to be linked to an absence of auditory input rather than to experience processing sign language. This behavioral enhancement is likely due to the fact that deaf individuals must rely more heavily on monitoring peripheral vision in order to detect new information entering their environment.

Deaf people also appear to have a superior ability to determine and remember the spatial orientation of objects by touch (haptic exploration while blindfolded). In one study, deaf signers, hearing [Page 134]signers, and hearing nonsigners were asked to determine the orientation of a bar (20 cm long and 1 cm in diameter) by feeling it with their right hands for 2 seconds while blindfolded. Participants were asked to remember the orientation of this “reference” bar, and after a delay, they used their left hands to orient a second “test” bar (located on the same table) such that the test bar would be parallel to the first bar. Deaf individuals outperformed both groups of hearing people on this task. One possible explanation for this finding is that deaf people rely more on visuospatial processing, and this leads to a better spatial understanding of objects in the environment. Deaf people do not simply have a superior sense of touch, because other studies have found no differences between hearing and deaf groups on tactile discrimination and detection tasks.

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