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| Volume 4, Number 6, Article 5, Pages 459-468 |
doi:10.1167/4.6.5 |
http://journalofvision.org/4/6/5/ |
ISSN 1534-7362 |
Induced contrast asynchronies
Arthur G. Shapiro |
Department of Psychology, Bucknell University, PA, USA |
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Anthony D. D’Antona |
Department of Psychology, Bucknell University, PA, USA |
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Justin P. Charles |
Department of Psychology, Bucknell University, PA, USA |
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Lindsay A. Belano |
Department of Psychology, Bucknell University, PA, USA |
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Jared B. Smith |
Department of Psychology, Bucknell University, PA, USA |
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Mallory Shear-Heyman |
Department of Psychology, Bucknell University, PA, USA |
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Abstract
We document a new type of perceptual effect in which asynchronous contrast signals are presented simultaneously with synchronous luminance signals. The template for the basic effect consists of two physically identical disks (.75-deg diameter, 40 cd/m2), one surrounded by a dark annulus (1.5 deg, 20 cd/m2) and the other by a light annulus (1.5 deg, 60 cd/m2). The center disks are modulated in time, with a maximum luminance of 55 cd/m2 and a minimum luminance of 25 cd/m2. With this stimulus configuration, the luminance signals of the disks modulate in phase with each other while the contrast signals relative to the surrounds modulate in anti-phase. Observers can track the contrast and luminance signals when the luminance is modulated at 1 Hz but perceive primarily the contrast signal at 2-6 Hz. We show that the asynchrony can be perceived with a thin annular surround, that the appearance of the asynchrony is dependent on the modulation amplitude, and that a decrease in the relative strength of the asynchrony at 1 Hz corresponds to the band-pass shape of the temporal contrast sensitivity function in the presence of light and dark edges. We also introduce variations of the induced contrast asynchrony principle in which a single modulated disk is surrounded by a half-light and half-dark split annulus; we refer to these configurations as the window-shade and rocking-disk illusions.
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