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PubMed · 16684555

Evidence for two interacting temporal channels in human visual processing.

John Cass·David Alais
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Abstract

Previous studies have generally estimated that two independent channels underlie human temporal vision: one broad and low-pass, the other high, and band-pass. We confirm this with iso-oriented targets and masks. With orthogonal masks, the same high-frequency channel emerges but no low-pass channel is observed, indicating the high-frequency channel is orientation invariant, and possibly pre-cortical in origin. In contrast, orientation dependence for low frequencies suggests a cortical origin. Subsequent masking experiments using unoriented spatiotemporal-filtered noise demonstrated that high-frequency masks (>8Hz) suppress low-frequency targets (1 and 4Hz), but low frequencies do not suppress high frequencies. This asymmetry challenges the traditional assumption of channel independence. To explain this, we propose a two-channel model in which a non-orientation-selective high-frequency channel suppresses an orientation-tuned low-frequency channel. This asymmetry may: (i) equalise the over-representation of low temporal-frequency energy in natural stimuli (1/f power spectrum); (ii) contribute to motion deblurring.

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Contrast SensitivityHumansOrientationPerceptual MaskingPhotic StimulationPsychophysicsSensory ThresholdsTime PerceptionVisual PathwaysJournal ArticleResearch Support, Non-U.S. Gov't

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John Cass, David Alais. 2006-05-08. Evidence for two interacting temporal channels in human visual processing.. https://doi.org/10.1016/j.visres.2006.02.015

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