Second-order motion conveys depth-order information.

Jay Hegdé, Thomas D. Albright, Gene R. Stoner

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


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 languageEnglish (US)
Article number1
Pages (from-to)838-842
Number of pages5
JournalJournal of Vision
Issue number10
StatePublished - Oct 13 2004


  • 3D surface and shape perception
  • Depth
  • Motion-2D

ASJC Scopus subject areas

  • Ophthalmology


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