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YINGZI XIONG, Diamond Brunt, Gordon E Legge; Estimates of Direction and Distance by People with Vision and Hearing Impairment. Invest. Ophthalmol. Vis. Sci. 2021;62(8):3572.
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© ARVO (1962-2015); The Authors (2016-present)
Accurate judgements of direction and distance are important for safe mobility. For people with vision or hearing impairment, it is important to optimally utilize their residual vision and hearing in such activities. Here we asked how people with various combinations of vision and hearing impairment integrate their residual vision and hearing in judging direction and distance.
There were three groups—vision impairment (VL, N = 9); dual sensory impairment with combined vision and hearing impairment (DSL, N = 6); and healthy controls (N = 6). Their mean acuities were 0.73, 0.42 and 0.0 logMAR; mean contrast sensitivities were 0.98, 1.35 and 2.0 logCS; and mean hearing thresholds were 9.1, 36.0 and 7.5 dB, respectively. Subjects were asked to walk to a briefly presented (5 s) target on the floor in a room under dark or normal lighting conditions. There were three types of targets—1) broadband auditory sound pulses, 2) visual LED flashes (8.4 cd/m2), and 3) both auditory pulses and visual flashes (audiovisual targets). In a direction trial, the target was presented from one of six directions on the horizontal plane (±6°, ±13° and ±20°). In a distance trial, the target was presented at one of six distances from straight ahead (0.9m to 5.4m). Precision was calculated as the standard deviation of 6 trials for each subject response for each target modality.
The lighting conditions did not significantly affect the subjects’ distance or direction precision. For both distance and direction estimation, the three groups had similar precision in the visual condition, but the DSL group showed significantly lower precision in the auditory condition than the other groups. Within each group, the auditory condition always showed lower precision than the visual and audiovisual conditions, regardless of the lighting conditions. The audiovisual condition always had similar precision to the visual condition in all three groups, possibly indicating that subjects primarily relied on their vision while the auditory signal provided little additional benefit.
Our preliminary results showed that visual localization remains intact with vision impairment, but sound localization is susceptible to hearing impairment. In both direction and distance judgments, when localizing multimodal targets subjects primarily rely on their vision regardless of their vision and hearing status.
This is a 2021 ARVO Annual Meeting abstract.
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