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Differences in perceived shape from shading correlate with activity in early visual areas
The perception of shape from shading depends on the orientation of the shading gradient [1–4]. Displays composed of elements with vertically oriented shading gradients of opposite polarity produce a strong and stable percept of ‘concave’ and ‘convex’ elements. If the shading gradients are rotated 90...
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Published in: | Current biology 1997-02, Vol.7 (2), p.144-147 |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | The perception of shape from shading depends on the orientation of the shading gradient [1–4]. Displays composed of elements with vertically oriented shading gradients of opposite polarity produce a strong and stable percept of ‘concave’ and ‘convex’ elements. If the shading gradients are rotated 90°, the depth percept is reduced and appears much more ambiguous. Results from psychophysical [1–6], neuropsychological [7] and computational studies [8,9] suggest that the perception of shape from shading engages specific mechanisms in early cortical visual areas. In a three-dimensional functional magnetic resonance imaging (fMRI) study at 1.5 Tesla using a three-dimensional, interleaved-echoplanar imaging technique and a surface radio frequency (RF) coil placed under the visual cortex, we investigated the activity in these early visual areas associated with viewing shape from shading displays at two different orientations. We found significantly greater activation in area V1 and neighbouring low-level visual areas of cortex when subjects viewed displays that led to weak and unstable depth percepts than when they viewed displays that led to strong and stable depth percepts. |
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ISSN: | 0960-9822 1879-0445 |
DOI: | 10.1016/S0960-9822(06)00058-3 |