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Flynn OJ, Shapiro AG. The Perpetual Diamond: Contrast Reversals Along Thin Edges Create the Appearance of Motion in Objects. Iperception 2018; 9:2041669518815708. [PMID: 35154630 PMCID: PMC8825246 DOI: 10.1177/2041669518815708] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 10/31/2018] [Indexed: 11/16/2022] Open
Abstract
The Perpetual Diamond produces motion continuously and unambiguously in one direction despite never physically changing location. The phenomenon consists of a steady, mid-luminance diamond bordered by four thin edge strips and a surrounding background field. The direction of motion is determined by the relative phases of the luminance modulation between the edge strips and the background. Because the motion is generated entirely by changing contrast signals between the edge strips and background, the stimulus is a valuable tool for tests of spatial contrast, temporal contrast, contrast gain, and color contrast. We demonstrate that observers see motion even when the edge strips subtend only seconds of arc on the retina (which is less than the frequently reported 10 minutes of arc) and that perceived motion is due entirely to changes in the difference in contrast phase modulation, independent from the luminance phase.
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Affiliation(s)
- Oliver J. Flynn
- Department of Psychology, American University, Washington, DC, USA; National Eye Institute, National Institutes of Health, Bethesda, MD, USA
| | - Arthur G. Shapiro
- Department of Psychology, American University, Washington, DC, USA; Department of Computer Science, American University, Washington, DC, USA
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