What's special about horizontal disparity

Abstract

Horizontal disparity has been recognized as the primary signal driving stereoscopic depth since the invention of the stereoscope in the 1830s. It has a unique status in our understanding of binocular vision. The direction of offset of the eyes gives the disparities of corresponding image point locations across the two retinas a strong horizontal bias. Beyond the retina, other factors give shape to the effective disparity direction used by visual mechanisms. The influence of orientation is examined here. I argue that horizontal disparity is an inflection point along a continuum of effective directions, and its role in stereo vision can be reinterpreted. The pointwise geometric justification for its special status neglects the oriented structural elements of spatial vision, its physiological support is equivocal, and psychophysical support of its special status may partially reflect biased stimulus sampling. The literature shows that horizontal disparity plays no particular role in the processing of one-dimensional stimuli, a reflection of the stereo aperture problem. The resulting depth is non-veridical, even non-transitive. Although one-dimensional components contribute to the stereo depth of visual objects generally, two-dimensional stimuli appear not to inherit the aperture problem. However, a look at the two-dimensional stimuli that predominate in experimental studies shows regularities in orientation that give a new perspective on horizontal disparity.

Aging Delays Completion of Head Rotation Cycles in Continuous Gaze Stabilization Exercises despite Putative Healthy Vestibular Function

“…This transitional hemifield blockage would have caused perceptual deficits such as described in monocular observers to whom facial structures reduce gaze fixation affordance, especially when viewing time is limited [40]. This argument is further supported by evidence that horizontal disparity is the primary driver to effective position (depth) perception [41], while vertical disparity may favor direction perception [42] less relevant in the context of fixed targets as presented in our design. Another potential aspect influencing head cycle duration was cervical joint proprioception, as cervical joint position error tends to increase with aging [43].…”

Aging Delays Completion of Head Rotation Cycles in Continuous Gaze Stabilization Exercises despite Putative Healthy Vestibular Function

“…This transitional hemifield blockage would have caused perceptual deficits such as described in monocular observers to whom facial structures reduce gaze fixation affordance, especially when viewing time is limited [40]. This argument is further supported by evidence that horizontal disparity is the primary driver to effective position (depth) perception [41], while vertical disparity may favor direction perception [42] less relevant in the context of fixed targets as presented in our design. Another potential aspect influencing head cycle duration was cervical joint proprioception, as cervical joint position error tends to increase with aging [43].…”

Aging Delays Completion of Head Rotation Cycles in Continuous Gaze Stabilization Exercises despite Putative Healthy Vestibular Function

“…This transitional hemifield blockage would have caused perceptual deficits such as described in monocular observers to whom facial structures reduce gaze fixation affordance, especially when viewing time is limited [40]. This argument is further supported by evidence that horizontal disparity is the primary driver to effective position (depth) perception [41], while vertical disparity may favor direction perception [42] less relevant in the context of fixed targets as presented in our design. Another potential aspect influencing head cycle duration was cervical joint proprioception, as cervical joint position error tends to increase with aging [43].…”

Aging Delays Completion of Head Rotation Cycles in Continuous Gaze Stabilization Exercises despite Putative Healthy Vestibular Function

“…This transitional hemifield blockage would have caused perceptual deficits such as described in monocular observers to whom facial structures reduce gaze fixation affordance, especially when viewing time is limited [40]. This argument is further supported by evidence that horizontal disparity is the primary driver to effective position (depth) perception [41], while vertical disparity may favor direction perception [42] less relevant in the context of fixed targets as presented in our design. Another potential aspect influencing head cycle duration was cervical joint proprioception, as cervical joint position error tends to increase with aging [43].…”