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Unequal retinal and extra-retinal motion signals produce different perceived slants of moving surfaces

Freeman, Tom C. A. ORCID: and Fowler, Tom A. 2000. Unequal retinal and extra-retinal motion signals produce different perceived slants of moving surfaces. Vision Research 40 (14) , pp. 1857-1868. 10.1016/S0042-6989(00)00045-6

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Eye movements introduce retinal motion to the image and so affect motion cues to depth. For instance, the slant of a plane moving at right-angles to the observer is specified by translation and a component of relative motion such as shear. To a close approximation, the translation disappears from the image when the eye tracks the surface accurately with a pursuit eye movement. However, both translation and relative-motion components are needed to estimate slant accurately and unambiguously. During pursuit, therefore, an extra-retinal estimate of translation must be used by the observer to estimate surface slant. Extra-retinal and retinal estimates of translation speed are known to differ: a classic Aubert–Fleischl phenomenon was found for our stimuli. The decrease in perceived speed during pursuit predicts a corresponding increase in perceived slant when the eye tracks the surface. This was confirmed by comparing perceived slant in pursuit and eye-stationary conditions using slant-matching and slant-estimation techniques. Moreover, the increase in perceived slant could be quantified solely on the basis of the perceived-speed data. We found no evidence that relative-motion estimates change between the two eye-movement conditions. A final experiment showed that perceived slant decreases when a fixed retinal shear is viewed with increasing pursuit speed, as predicted by the model. The implication of the results for recovering metric depth estimates from motion-based cues is discussed.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Psychology
Subjects: B Philosophy. Psychology. Religion > BF Psychology
R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
R Medicine > RE Ophthalmology
Uncontrolled Keywords: Depth perception; Eye movements; Motion; Extra-retinal signals
Publisher: Elsevier
ISSN: 0042-6989
Last Modified: 21 Oct 2022 08:59

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