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Margaret R. Tarampi, Sarah H. Creem-Regehr, William B. Thompson; Evidence for intact spatial updating in observers with severely degraded vision. Journal of Vision 2009;9(8):1027. doi: 10.1167/9.8.1027.
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In low-vision navigation, an essential ability is the accurate judgment of object locations in the environment. We investigated distance perception in normal vision and simulated low-vision conditions to examine the perceptual capabilities of individuals with profound low-vision. In order to replicate our previously reported findings that distance judgments remained accurate even under simulated low-vision (VSS 2008) and to explore the effects of simulated low-vision on a more complex distance-dependent spatial updating task, we employed the triangulation task of eyes-closed indirect walking. This requires that the observer continually update the location of stimuli while walking, without any further visual feedback of their movement or the stimuli location. Participants were normally sighted and tested monocularly in two conditions. In the first condition, participants wore goggles with theatrical lighting gels, resulting in a tested acuity between 20/381 and 20/1261, and a tested contrast sensitivity between near 0 and 0.75. In the second condition, participants wore goggles with clear flat lenses. Participants remained naïve to the test room until after the low-acuity condition was performed. The test room had 7.7m × 10.5m of walkable space and was lit approximately evenly. Targets were two sizes of black matte boxes, located on the ground-plane at egocentric distances of 1.5, 3.1, and 6 meters. The observer viewed the target and the environment for 5 seconds. While blindfolded, they were instructed to either perform a direct or indirect walking task. They then walked without vision to the apparent target location directly or indirectly. For both walking tasks, walked distances did not differ between normal and degraded vision conditions. Walked distances in the normal vision condition showed somewhat less between-subject variability than for the degraded vision condition. Future work will examine if the order of the conditions, or if advance knowledge of the task affect performance.
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