The visible ground surface as a reference frame for scaling binocular depth of a target in midair.

Abstract

The natural ground surface carries texture information that extends continuously from one’s feet to the horizon, providing a rich depth resource for accurately locating an object resting on it. Here, we showed that the ground surface’s role as a reference frame also aids in locating a target suspended in midair based on relative binocular disparity. Using real world setup in our experiments, we first found that a suspended target is more accurately localized when the ground surface is visible and the observer views the scene binocularly. In addition, the increased accuracy occurs only when the scene is viewed for 5 sec rather than 0.15 sec, suggesting that the binocular depth process takes time. Second, we found that manipulation of the configurations of the texture-gradient and/or linear-perspective cues on the visible ground surface affects the perceived distance of the suspended target in midair. Third, we found that a suspended target is more accurately localized against a ground texture surface than a ceiling texture surface. This suggests that our visual system usesthe ground surface as the preferred reference frame to scale the distance of a suspended target according to its relative binocular disparity.

Attention modulates perception of visual space

“…We also tested the complementary scenario, where the visible surface was the ceiling rather than the ground. However, we did not predict a strong effect of attention, owing to the lower field bias of attention 12 and/or insufficient visual representation of the ceiling surface in the upper field 13–15 .…”

“…Since ground representation is the reference frame for locating a target in mid-air 15,19–21 , attention should affect spatial perception above the ground surface, that is, the volume of perceptual space extending from the observer’s eyes to the ground surface representation. To investigate this, we modified the stimuli in Experiment 1 by placing the target at eye level instead of having it coplanar with the textured surface and by presenting both the ground-texture and ceiling-texture backgrounds simultaneously (Experiment 2, Fig.…”

Frontal extents in virtual environments are not immune to underperception

“…1, bottom) and linear perspective (lines formed by intersections between the walls and floor/ceiling planes), and either cue could have been responsible for the differences between VEs. Experimental manipulation of linear perspective cues affects perceived distance, perhaps by influencing perceived eye level (Wu, Zhou, Shi, He, & Ooi, 2015). It is therefore possible that the linear perspective cue was responsible for judgment differences across the two VEs.…”

Space Perception of Strabismic Observers in the Real World Environment

“…Yet, several studies have shown that relative binocular disparity information can affect relative depth judgment in the intermediate distance range. [20][21][22][23][24] This being the case, would it be possible that the visual system also uses the relative binocular depth information in the intermediate distance range to judge the absolute (egocentric) distance between the observer and target? A recent study of observers with normal binocular vision from our laboratory reveals that this is possible, at least in the reduced cue environment where the predominant visual depth cues were texture gradient and relative binocular disparity.…”

“…A recent study of observers with normal binocular vision from our laboratory reveals that this is possible, at least in the reduced cue environment where the predominant visual depth cues were texture gradient and relative binocular disparity. 24 We showed that the relative binocular disparity between a target suspended in midair and the ground surface was used to improve the accuracy of perceived absolute distance. If the visual system also capitalizes on the relative binocular disparity information of the suspended target and the ground surface in the full cue environment where there are ample other monocular cues, as used in the present study, we can hypothesize that strabismic observers with poor stereopsis will not be able to judge accurately the location of a suspended target in the intermediate distance range.…”