Surface Separation Decreases Stereoscopic Slant but a Monocular Aperture Increases it

When an isolated surface is stereoscopically slanted around its vertical axis, perceived slant is attenuated relative to prediction, whereas when a frontal-plane surface is placed above or below the slanted surface, slant is close to the predicted magnitude. Gillam et al (1988 Journal of Experimental Psychology: Human Perception and Performance 14 163 – 175) have argued that this slant enhancement is due to the introduction of a gradient of relative disparities across the abutment of the two surfaces which is a more effective stimulus for slant than is the gradient of absolute disparities present when the slanted surface is presented alone. To test this claim we varied the separation between the two surfaces, along either the vertical or depth axis. Since these manipulations have been reported to reduce the depth response to individual relative disparities, they should similarly affect any slant response based on a gradient of relative disparities. As predicted, increasing the separation, vertically or in depth, systematically reduced both the perceived slant of the stereoscopically slanted surface and also the stereo contrast slant induced in the frontal-plane surface. These results are not predicted by alternative accounts of slant enhancement (disparity-gradient contrast, normalisation, frame of reference). We also demonstrated that sidebands of monocular texture, when added to equate the half-image widths of the slanted surface, increased the perceived slant of this surface (particularly when presented alone) and reduced the contrast slant. Monocular texture, by signalling occlusion, appeared to provide absolute slant information which determined how the total relative slant perceived between the surfaces was allocated to each.

[1]  I. Howard,et al.  Relative shear disparities and the perception of surface inclination , 1994, Vision Research.

[2]  C. Wheatstone.  XVIII. Contributions to the physiology of vision. —Part the first. On some remarkable, and hitherto unobserved, phenomena of binocular vision , 1962, Philosophical Transactions of the Royal Society of London.

[3]  B Gillam,et al.  Postfusional latency in stereoscopic slant perception and the primitives of stereopsis. , 1988, Journal of experimental psychology. Human perception and performance.

[4]  C. Blakemore,et al.  The neural mechanism of binocular depth discrimination , 1967, The Journal of physiology.

[5]  Charles Wheatstone.  On some remarkable and hitherto unobserved phenomena of binocular vision. , 1962 .

[6]  C. Erkelens,et al.  Binocular Perception of Slant about Oblique Axes Relative to a Visual Frame of Reference , 1995, Perception.

[7]  B Gillam,et al.  Evidence for disparity change as the primary stimulus for stereoscopic processing , 1984, Perception & psychophysics.

[8]  Casper J. Erkelens,et al.  Temporal aspects of binocular slant perception , 1996, Vision Research.

[9]  F. A. Miles.  Binocular Vision and Stereopsis by Ian P. Howard and Brian J. Rogers, Oxford University Press, 1995. £90.00 (736 pages) ISBN 0 19 508476 4. , 1996, Trends in Neurosciences.

[10]  K. A. Stevens,et al.  The Analogy between Stereo Depth and Brightness , 1989, Perception.

[11]  G. Westheimer,et al.  Depth attraction and repulsion of disparate foveal stimuli , 1987, Vision Research.

[12]  G. J. Mitchison,et al.  Vision: Viewing geometry and gradients of horizontal disparity , 1991 .

[13]  T Shipley,et al.  Stereoscopic acuity and horizontal angular distance from fixation. , 1969, Journal of the Optical Society of America.

[14]  Barton L. Anderson,et al.  The role of partial occlusion in stereopsis , 1994, Nature.

[15]  M. Fahle,et al.  Perceived Depth Scales with Disparity Gradient , 1991, Perception.

[16]  B. Julesz,et al.  Modifications of the Classical Notion of Panum's Fusional Area , 1980, Perception.

[17]  B. Rogers,et al.  Simultaneous and Successive Contrast Effects in the Perception of Depth from Motion-Parallax and Stereoscopic Information , 1982, Perception.

[18]  Casper J Erkelens,et al.  Anisotropy in Werner's Binocular Depth-contrast Effect , 1996, Vision Research.

[19]  Ian P. Howard,et al.  A Craik-O'Brien-Cornsweet illusion for visual depth , 1978, Vision Research.

[20]  S. McKee,et al.  The imprecision of stereopsis , 1990, Vision Research.

[21]  I. Howard,et al.  Relative Size Disparities and the Perception of Surface Slant , 1996, Vision Research.

[22]  B. Rogers,et al.  Anisotropies in the perception of three-dimensional surfaces. , 1983, Science.

[23]  B. Gillam,et al.  Perception of slant when perspective and stereopsis conflict: experiments with aniseikonic lenses. , 1968, Journal of experimental psychology.

[24]  Shinsuke Shimojo,et al.  Da vinci stereopsis: Depth and subjective occluding contours from unpaired image points , 1990, Vision Research.

[25]  B Gillam,et al.  The Role of Monocular Regions in Stereoscopic Displays , 1988, Perception.

[26]  I. Howard,et al.  Types of Size Disparity and the Perception of Surface Slant , 1997, Perception.

[27]  I P Howard,et al.  Depth Interactions between Inclined and Slanted Surfaces in Vertical and Horizontal Orientations , 1998, Perception.

[28]  Tribhawan Kumar,et al.  Influence of remote objects on local depth perception , 1991, Vision Research.

[29]  Martin Kaye,et al.  Stereopsis without binocular correlation , 1978, Vision Research.

[30]  D. Badcock,et al.  Depth-increment detection function for individual spatial channels. , 1985, Journal of the Optical Society of America. A, Optics and image science.

[31]  Brian J. Rogers,et al.  The Perception and Representation of Depth and Slant in Stereoscopic Surfaces , 1992 .

[32]  G. Westheimer.  Spatial interaction in the domain of disparity signals in human stereoscopic vision. , 1986, The Journal of physiology.

[33]  Walter C. Gogel,et al.  Relative visual direction as a factor in relative distance perceptions. , 1956 .

[34]  B Gillam,et al.  A Proximity-Contingent Stereoscopic Depth Aftereffect: Evidence for Adaptation to Disparity Gradients , 1993, Perception.

[35]  G. Westheimer,et al.  The perception of depth in simple figures , 1984, Vision Research.

[36]  Barbara Gillam,et al.  Perspective, Orientation Disparity, and Anisotropy in Stereoscopic Slant Perception , 1992, Perception.

[37]  H. Collewijn,et al.  Motion perception during dichoptic viewing of moving random-dot stereograms , 1985, Vision Research.

[38]  C Blakemore,et al.  On the existence of neurones in the human visual system selectively sensitive to the orientation and size of retinal images , 1969, The Journal of physiology.

[39]  A. Ames.  Binocular vision as affected by relations between uniocular stimulus-patterns in commonplace environments. , 1946 .

[40]  B Gillam,et al.  Orientation Disparity, Deformation, and Stereoscopic Slant Perception , 1991, Perception.