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Arthur Shapiro, William Kistler; Facial feature changes are hard to track in the color wagon-wheel illusion. Journal of Vision 2014;14(10):281. doi: 10.1167/14.10.281.
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© ARVO (1962-2015); The Authors (2016-present)
Introduction: The color wagon-wheel illusion (Shapiro, Kistler, & Rose-Henig, 2012) separates two opposing types of motion. For instance, consider a rotating ring composed of twelve disks separated from each other by 30 deg, with eleven of the disks black and one yellow. If the ring rotates clockwise at 25 deg/frame, then the black disks appear to rotate counter-clockwise at 5 frames/sec (a first-order motion process) while the yellow disk appears to rotate clockwise (a feature-tracking or third-order motion process). Here, we use variations of the color wagon-wheel illusion to examine the processes underlying our ability to track objects that differ from each other in terms of the structure of their internal features. Methods: The basic experiment presents a ring of twelve equally spaced faces: eleven identical faces and one that differs only in expression (same face for all twelve disks). The experiment manipulated the features of the single odd face and the speed of ring rotation. Observers responded as to whether they could track the motion of the odd face. Results When the ring rotated at 30 deg/frame, observers could easily track the motion of the odd face (>90 percent of trials) since the only observable motion was the odd face shifting position around the ring. When the ring rotated at speeds greater than or less than 30 deg/frame, the motion of the odd face had to compete with the aliased rotation of the ring. In such conditions, observers' ability to track the odd face was markedly degraded. However, observers were able to track successfully at all rotation speeds if a luminance signal was added to the odd face. Conclusion: Competing motion signals degrade an observers ability to track motion based purely on changes in facial features but not the ability to track motion that includes identifiable luminance information.
Meeting abstract presented at VSS 2014
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