The perceived visual direction of monocular objects in random-dot stereograms is influenced by perceived depth and allelotropia

Abstract

The proposed influence of objects that are visible to both eyes on the perceived direction of an object that is seen by only one eye is known as the "capture of binocular visual direction". The purpose of this study was to evaluate whether stereoscopic depth perception is necessary for the "capture of binocular visual direction" to occur. In one pair of experiments, perceived alignment between two nearby monocular lines changed systematically with the magnitude and direction of horizontal but not vertical disparity. In four of the five observers, the effect of horizontal disparity on perceived alignment depended on which eye viewed the monocular lines. In additional experiments, the perceived alignment between the monocular lines changed systematically with the magnitude and direction of both horizontal and vertical disparities when the monocular line separation was increased from 1.1 degrees to 3.3 degrees . These results indicate that binocular capture depends on the perceived depth that results from horizontal retinal image disparity as well as allelotropia, or the averaging of local-sign information. Our data suggest that, during averaging, different weights are afforded to the local-sign information in the two eyes, depending on whether the separation between binocularly viewed targets is horizontal or vertical.

Relative contributions of the two eyes to perceived egocentric visual direction in normal binocular vision

“…Hariharan-Vilipuru and Bedell (2009) suggested that horizontal and vertical disparities may exert different effects on the perceived direction of monocular line targets (reference and test targets) surrounded by binocular random dot stereograms for monocular target separation less than approximately 3 deg. To address this possibility for binocular targets, 10 subjects repeated experiment 2a using targets with vertical retinal image disparity.…”

Slant of a Surface Shifts Binocular Visual Direction

“…The role of a surface on visual direction has also been reported for a monocular stimulus. Recent studies have shown that when a monocular image is embedded in a binocular random-dots pattern, its visual direction is affected by the binocular visual direction of the pattern (e.g., [41,42,43,44,45,46,47,48,49,50]). Furthermore, Ono, Mapp, and Howard [51] argued that a background presented with a given monocular stimulus can affect the visual direction of the stimulus.…”

Topical Review: Methodological Variables in Clinical and Laboratory Measurements of Fixation Disparity

“…In one of these articles, Raghunandan et al 85 described those factors that promote binocular capture. Binocular capture is correlated with the proximity of the binocular and monocular targets, the density of the binocular targets surrounding the binocular target, the disparity of the fusional stimuli, and the separation of the monocular contours from one another 132 . These investigators also demonstrated that binocular capture is dependent on the spatial frequencies of the monocular contours 85 .…”

“…Binocular capture is correlated with the proximity of the binocular and monocular targets, the density of the binocular targets surrounding the binocular target, the disparity of the fusional stimuli, and the separation of the monocular contours from one another. 132 These investigators also demonstrated that binocular capture is dependent on the spatial frequencies of the monocular contours. 85 Specifically, the effects of binocular capture are very limited if the vertical separation of the monocular contours is less than a period width of the spatial frequency of these contours.…”