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Lomber Stephen, Kral Andrej; Superior visual detection capabilities in congenitally deaf Cats. Journal of Vision 2007;7(9):308. doi: https://doi.org/10.1167/7.9.308.
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© ARVO (1962-2015); The Authors (2016-present)
Deaf individuals may compensate for the absence of hearing by superior performance in other modalities. We examined visual capabilities of adult congenitally deaf cats on a wide range of visual tasks in order to define which visual abilities are involved in cross-modal compensation. Congenital deafness in three adult deaf animals was demonstrated by a lack of acoustically-evoked brainstem responses. Performance on a battery of seven visual tasks was examined and compared to three adult hearing cats. All six animals were tested on visual acuity, contrast sensitivity, discrimination of direction of motion, velocity and orientation, and detection of movement and detection of a flashed visual stimulus. Overall, for none of the visual capabilities examined was performance of the deaf cats inferior to that of the hearing cats. For the tests of visual acuity, contrast sensitivity, direction of motion discrimination, velocity discrimination, and orientation discrimination performance in the deaf cats was not different from that of the hearing cats. However, for the two tests of visual detection (movement detection and detection of a flashed stimulus) the deaf cats demonstrated superior performance to that of the hearing cats. For the deaf cats, movement detection thresholds were [[lt]]0.5deg/sec, while for the hearing cats thresholds were above [[gt]]0.5deg/sec. Detection of a 100 msec flashed red LED stimulus was significantly better for the deaf cats than for the hearing cats. Both superior rates of detection and faster reaction times were identified in the deaf cats. This superior performance was only identified at the most peripherally tested positions, at eccentricities of 75 and 90 degs. Therefore, while the visual abilities of congenitally-deaf cats are similar to hearing cats on most psychophysical tests, the performance of deaf cats on visual detection tasks is superior.
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