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Updated: May 13, 2026

Eye Movements in Visual Duration Perception: Disentangling Stimulus from Time in Predecisional Processes
Published on: January 19, 2024
Cortical response tracking the conscious experience of threshold duration visual stimuli indicates visual perception
Krithiga Sekar1, William M Findley, David Poeppel
1Department of Physiology and Neuroscience, New York University School of Medicine, New York, NY 10016, USA.
Abstract:
At perceptual threshold, some stimuli are available for conscious access whereas others are not. Such threshold inputs are useful tools for investigating the events that separate conscious awareness from unconscious stimulus processing. Here, viewing unmasked, threshold-duration images was combined with recording magnetoencephalography to quantify differences among perceptual states, ranging from no awareness to ambiguity to robust perception. A four-choice scale was used to assess awareness: "didn't see" (no awareness), "couldn't identify" (awareness without identification), "unsure" (awareness with low certainty identification), and "sure" (awareness with high certainty identification). Stimulus-evoked neuromagnetic signals were grouped according to behavioral response choices. Three main cortical responses were elicited. The earliest response, peaking at ∼100 ms after stimulus presentation, showed no significant correlation with stimulus perception. A late response (∼290 ms) showed moderate correlation with stimulus awareness but could not adequately differentiate conscious access from its absence. By contrast, an intermediate response peaking at ∼240 ms was observed only for trials in which stimuli were consciously detected. That this signal was similar for all conditions in which awareness was reported is consistent with the hypothesis that conscious visual access is relatively sharply demarcated.
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