Volume 1, Number 2, Article 1, Pages 55-79 doi:10.1167/1.2.1 http://journalofvision.org/1/2/1/ ISSN 1534-7362
Perceiving slant about a horizontal axis from stereopsis
Martin S. Banks
Vision Science Program and Department of Psychology, University of California, Berkeley, CA, USA
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Ignace T. C. Hooge
Faculteit Sociale Wetenschappen, Universiteit Utrecht, Utrecht, The Netherlands
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Benjamin T. Backus
Department of Psychology, University of Pennsylvania, Philadelphia, PA, USA
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Abstract

Rotating a surface about a horizontal axis alters the retinal horizontal-shear disparities. Opposed torsional eye movements (cyclovergence) also change horizontal shear. If there were no compensation for the horizontal disparities created by cyclovergence, slant estimates would be erroneous. We asked whether compensation for cyclovergence occurs, and, if it does, whether it occurs by use of an extraretinal cyclovergence signal, by use of vertical-shear disparities, or by use of both signals. In four experiments, we found that compensation is nearly veridical when vertical-shear disparities are available and easily measured. When they are not available or easily measured, no compensation occurs. Thus, the visual system does not seem to use an extraretinal cyclovergence signal in stereoscopic slant estimation. We also looked for evidence of an extraretinal cyclovergence signal in a visual direction task and found none. We calculated the statistical reliabilities of slant-from-disparity and slant-from-texture estimates and found that the more reliable of the two means of estimation varies significantly with distance and slant. Finally, we examined how slant about a horizontal axis might be estimated when the eyes look eccentrically.

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History
Received March 23, 2001; published August 31, 2001
Citation
Banks, M. S., Hooge, I. T., & Backus, B. T. (2001). Perceiving slant about a horizontal axis from stereopsis. Journal of Vision, 1(2):1, 55-79, http://journalofvision.org/1/2/1/, doi:10.1167/1.2.1.
Keywords
stereopsis, binocular vision, cyclovergence, surface perception, depth perception
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