Induced contrast asynchronies

• Published in: Journal of vision (Charlottesville, Va.) Va.), 2004-05, Vol.4 (6), p.459-5
• Main Authors: Shapiro, Arthur G, D'Antona, Anthony D, Charles, Justin P, Belano, Lindsay A, Smith, Jared B, Shear-Heyman, Mallory
• Format: Article
• Language: English
• Subjects: Adult; Contrast Sensitivity - physiology; Female; Humans; Illusions - physiology; Light; Male; Pattern Recognition, Visual - physiology
• ISSN: 1534-7362; 1534-7362
• DOI: 10.1167/4.6.5

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.