Trends in Cognitive Sciences
ReviewDo deaf individuals see better?
Introduction
Compensatory plasticity holds that the lack of auditory stimulation experienced by deaf individuals is met by enhancements in visual cognition. However, reports in the educational and cochlear implant literature document deficient visual cognition in deaf individuals. This discrepancy is probably due to the complex etiology of deafness. When free from various confounding factors, deafness per se is seen to shift the spatial distribution of attention such that attention to the peripheral visual field, but not the central visual field, is heightened. Associated neural bases reveal a widespread reorganization from higher association cortices to early sensory cortices. A common feature found across reorganized areas is their fundamental multimodal organization, reinforcing recent views on the role of multimodal integration at all stages of cognitive processing [1].
Section snippets
The complex etiology of deafness
The bulk of the literature on deafness reports either no change in or worse performance by deaf individuals on a variety of tasks as compared to hearing 2, 3. Amid this large literature describing deficiencies in deaf individuals, some recent evidence documents enhancement of a few perceptual and cognitive skills following congenital deafness 4, 5. Discrepancies in the literature might be largely explained by the fact that most studies reporting deficient functions typically include deaf
Selective effects of deafness on visual cognition
Changes in visual cognition following congenital deafness are highly specific. Not all aspects of vision are modified. Visual sensory thresholds are comparable in Deaf and hearing individuals, be it for brightness discrimination, visual flicker, different aspects of contrast sensitivity, or direction and velocity of motion 8, 9, 10, 11. Enhanced performance has been reported in some areas, such as processing of the visual periphery or motion processing, but only under conditions of attention.
Deafness alters the spatial distribution of visual attention
Differences between Deaf and hearing individuals are noted mostly under conditions of attention, as when processing in the face of uncertainty and/or selecting a target from among distractors. Could Deaf/hearing differences be better characterized as a generalized attentional difference? This proposal needs qualification as few population differences have been documented on standard attentional paradigms. Studies of attentional orienting, using the Posner-cueing paradigm, report no robust
Neural correlates of cross-modal plasticity
The enhanced peripheral vision noted in Deaf individuals could be mediated by several distinct brain mechanisms. First, the sensory representation of the peripheral field in early visual cortex might be expanded in genetically deaf individuals. In hearing individuals, it is known that a larger part of the visual cortex is dedicated to processing central vision than peripheral vision. A greater amount of visual cortex might be dedicated to the processing of the visual periphery in Deaf
Summary
The study of plastic changes in Deaf individuals, born profoundly deaf within the Deaf community, highlights the impact of auditory deprivation on cognition without the confounds often associated with deafness. Auditory deprivation leads to enhanced peripheral visual attention, an enhancement particularly notable when contrasted with central attention. Such behavioral change could put deaf individuals at risk in academic or clinical settings that typically rely on the use of centrally presented
Acknowledgements
We thank Helen Neville, Elissa Newport and Courtney Stevens for their helpful feedback and stimulating discussions. D.B. acknowledges support from NIH-DC04418, the Charles A. Dana Foundation and the James S. McDonnell Foundation.
References (73)
- et al.
Is neocortex essentially multisensory?
Trends Cogn. Sci.
(2006) - et al.
Feeling vibrations: enhanced tactile sensitivity in congenitally deaf humans
Neurosci. Lett.
(2001) - et al.
Visual contrast sensitivity in deaf versus hearing populations: exploring the perceptual consequences of auditory deprivation and experience with a visual language
Brain Res. Cogn. Brain Res.
(2001) - et al.
Motion velocity thresholds in deaf signers: changes in lateralization but not in overall sensitivity
Brain Res. Cogn. Brain Res.
(2004) - et al.
Visual field asymmetries for motion processing in deaf and hearing signers
Brain Cogn.
(2002) - et al.
Attention to central and peripheral visual space in a movement detection task: an event related potential and behavioral study. II. Congenitally deaf adults
Brain Res.
(1987) Altered visual-evoked potentials in congenitally deaf adults
Brain Res.
(1983)- et al.
Parafoveal attention in congenitally deaf and hearing young adults
Brain Cogn.
(1985) Auditory deprivation affects processing of motion, but not color
Brain Res. Cogn. Brain Res.
(2002)- et al.
The effects of spatial attention on motion processing in deaf signers, hearing signers, and hearing nonsigners
Brain Cogn.
(2002)
Allocation of attention, reading skills, and deafness
Brain Lang.
Differences in visual search tasks between congenitally deaf and normally hearing adults
Brain Res. Cogn. Brain Res.
Distracted and confused? Selective attention under load
Trends Cogn. Sci.
Multisensory convergence in calcarine visual areas in macaque monkey
Int. J. Psychophysiol.
Vibration-induced auditory-cortex activation in a congenitally deaf adult
Curr. Biol.
Social perception from visual cues: role of the STS region
Trends Cogn. Sci.
Anatomical mechanisms and functional implications of multisensory convergence in early cortical processing
Int. J. Psychophysiol.
Cross-modal plasticity in deaf subjects dependent on the extent of hearing loss
Brain Res. Cogn. Brain Res.
Behavioral and neuroplastic changes in the blind: evidence for functionally relevant cross-modal interactions
J. Physiol. (Paris)
Cross-modal innervation of primary visual cortex by auditory fibers in congenitally anophthalmic mice
Neurosci. Lett.
The morphometry of auditory cortex in the congenitally deaf measured using MRI
Neuroimage
Attention to central and peripheral visual space in a movement decision task. III. Separate effects of auditory deprivation and acquisition of a visual language
Brain Res.
Visual imagery and visual–spatial language: enhanced imagery abilities in deaf and hearing ASL signers
Cognition
Mental rotation within linguistic and non-linguistic domains in users of American sign language
Cognition
Temporal processing in deaf signers
Brain and Language
The impact of cochlear implants on young deaf children: new methods to assess cognitive and behavioral development
Arch. Otolaryngol. Head Neck Surg.
Deaf adults without attention deficit hyperactivity disorder display reduced perceptual sensitivity and elevated impulsivity on the Test of Variables of Attention (T.O.V.A.)
J. Speech Lang. Hear. Res.
Intermodal competition and compensation in development
The acquisition of American Sign Language
Chasing the mythical ten percent: parental hearing status of deaf and hard of hearing students in the United States
Sign Language Stud.
Left hemisphere dominance for motion processing in deaf signers
Psychol. Sci.
Central and peripheral visual processing in hearing and nonhearing individuals
Bull. Psychon. Soc.
Changes in the spatial distribution of visual attention after early deafness
J. Cogn. Neurosci.
Visual attention to the periphery is enhanced in congenitally deaf individuals
J. Neurosci.
Segregation of form, color, movement, and depth: anatomy, physiology, and perception
Science
Cross-modal plasticity: where and how?
Nat. Rev. Neurosci.
Cited by (375)
Connectome alterations following perinatal deafness in the cat
2024, NeuroImageEffects of noise and noise reduction on audiovisual speech perception in cochlear implant users: An ERP study
2023, Clinical NeurophysiologyAudio- or visual disability and plasticity of the spared modality
2023, Bulletin de l'Academie Nationale de MedecineCrossmodal plasticity in hearing loss
2023, Trends in Neurosciences