Two experiments examined the role of visual horizon information on absolute egocentric distance judgments to on-ground targets. suggested that the visual system may utilize the angle of declination from a horizontal line of sight to the target location (horizon-distance relation) to determine absolute distances on infinite ground surfaces. While studies have supported this hypothesis, less is known about the specific cues (vestibular, visual) used to determine horizontal line of sight. The current study investigated this question by requiring observers to judge distances under degraded vision given an unaltered or raised visual horizon. The results suggest that visible horizon information does influence perception of absolute distances as evident through two different action-based measures, walking or throwing without vision to previously viewed targets. Distances were judged as shorter in the presence of a raised visual horizon compared to the unaltered horizon. The results are discussed with respect to how the visual system accurately determines absolute distance to objects on a finite ground plane and for their implications for understanding space perception in low-vision individuals.
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