Abstract
Psychophysical and neurophysiological studies have revealed that the visual system is sensitive to both "first-order" motion, in which moving features are defined by luminance cues, and "second-order" motion, in which motion is defined by nonluminance cues, such as contrast or flicker. Here we show psychophysically that common types of second-order stimuli provide potent cues to depth order. Although motion defined exclusively by nonluminance cues may be relatively rare in natural scenes, the depth-order cues offered by second-order stimuli arise ubiquitously as a result of occlusion of one moving object by another. Our results thus shed new light on the ecological importance of second-order motion. Furthermore, our results imply that visual cortical areas that have been shown to be responsive to second-order motion may be extracting information not just about object motion as has been assumed, but also about the relative depth of objects.
Original language | English (US) |
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Article number | 1 |
Pages (from-to) | 838-842 |
Number of pages | 5 |
Journal | Journal of Vision |
Volume | 4 |
Issue number | 10 |
DOIs | |
State | Published - Oct 13 2004 |
Keywords
- 3D surface and shape perception
- Depth
- Motion-2D
ASJC Scopus subject areas
- Ophthalmology