An empirical explanation of aperture effects

Kyongje Sung, William T. Wojtach, Dale Purves

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


The perceived direction of a moving line changes, often markedly, when viewed through an aperture. Although several explanations of this remarkable effect have been proposed, these accounts typically focus on the percepts elicited by a particular type of aperture and offer no biological rationale. Here, we test the hypothesis that to contend with the inherently ambiguous nature of motion stimuli the perceived direction of objects moving behind apertures of different shapes is determined by a wholly empirical strategy of visual processing. An analysis of moving line stimuli generated by objects projected through apertures shows that the directions of motion subjects report in psychophysical testing is accounted for by the frequency of occurrence of the 2D directions of stimuli generated by simulated 3D sources. The completeness of these predictions supports the conclusion that the direction of perceived motion is fully determined by accumulated behavioral experience with sources whose physical motions cannot be conveyed by image sequences as such.

Original languageEnglish (US)
Pages (from-to)298-303
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number1
StatePublished - Jan 6 2009
Externally publishedYes


  • Inverse problem
  • Motion
  • Perception
  • Perspective transformation
  • Vision

ASJC Scopus subject areas

  • General


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