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Shinsuke Shimojo, Daw-An J Wu, Kensuke Shimojo, Eiko Shimojo, Takashi Suegami, Mohammad Shehata, Noelle R Stiles, Christopher C Berger, Armand R Tanguay; Vision in the Extreme Periphery (1a):Auditory Modulation of Flicker Perception. Journal of Vision 2019;19(10):174a. doi: https://doi.org/10.1167/19.10.174a.
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© ARVO (1962-2015); The Authors (2016-present)
Background: Peripheral vision (20 to 40° eccentricity) has been extensively characterized, but there has been little study of the extreme periphery (40 to 95+°). Extreme peripheral vision is important for behavioral fitness, both in evolutionary history and in modern contexts such as driving and sports. The extreme periphery is also subject to the greatest signal ambiguities, and thus requires the most inferential processing to be effective. We are conducting a series of psychophysical studies to test a general “compensation hypothesis” whereby the ambiguity in the extreme periphery is compensated for by sources such as unambiguous signals from the fovea or another sensory modality. We investigated the perception of flicker rate in the fovea vs. in the extreme periphery, and report a new synchronized sound modulatory effect. Methods: Two targets flickering in synchrony (5 Hz) were presented, one at foveal fixation and the other at various eccentricities (15 to 55°). Observers (N = 7) reported whether the peripheral stimulus appeared to be faster, at the same frequency but out-of-phase, or in sync. Sounds synchronized with the flickering targets were added in one block. Results: (1) The peripheral flicker appears faster (and/or out-of-phase) compared to the fovea. The effect is stronger in the more extreme periphery. (2) The synchronized sounds suppressed the fast-flicker illusion, causing the two stimuli to be perceived in sync with the foveal flicker. Higher frequency sounds (8 to 10 Hz) retrieved the original effect (apparent faster peripheral flicker). These basic observations were confirmed at the VSS 2017 demo night (N > 150). Discussion: The findings suggest that basic visual properties (e.g., flicker) can be perceived quite differently in the extreme periphery even with stimuli that are well above threshold and well below flicker-fusion limits, indicating that competing integrational weights drive binding among foveal vision, peripheral vision, and auditory inputs.
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