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Christopher R. L. Cantor, Clifton M. Schor; Perception of Temporal Structure is Distorted Early in the Visual System. Journal of Vision 2009;9(8):1088. doi: https://doi.org/10.1167/9.8.1088.
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© ARVO (1962-2015); The Authors (2016-present)
Previously, we reported that human observers misperceive the temporal order of briefly presented adjacent visual stimuli that differ in duration. Our manipulation used ramped temporal envelopes (Gabor and Gaussian) to present the stimuli, and the induced temporal asynchrony (∼100 ms) was orders of magnitude larger than known thresholds for detecting temporal order with visual stimuli of equal duration (∼ 4 ms). We suggested that this sizable effect could be a direct result of early visual processing in the magnocellular visual pathway.
Here, we present new experiments investigating the perceived temporal structure of brief visual events. In support of our hypothesis, we present evidence that the magnitude of induced temporal asynchrony of ramped stimuli increases when energy is shifted to lower spatial frequencies. This finding is predicted by the temporal processing characteristics of early visual mechanisms that prefer different spatial frequencies. We also investigate perceived temporal order with stepped stimuli and a slightly different task, in which observers must judge the temporal order of a stimulus onset or offset relative to an ultra-brief flash. We find that step onset is delayed and step offset is advanced as compared to the flashed stimulus. These non-veridical temporal percepts are described in terms of a model of temporal processing in pre-cortical visual pathways.
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