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Yoram Bonneh, Yael Adini, Dov Sagi, Misha Tsodyks, Moshe Fried, Amos Arieli; An oculomotor trace of implicit perceptual predictions. Journal of Vision 2012;12(9):1114. doi: 10.1167/12.9.1114.
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© ARVO (1962-2015); The Authors (2016-present)
Background: Making predictions and monitoring their accuracy is considered a fundamental aspect of the brain, implicated in motor control, perception and cognition. Evidence for predictive processing in perception includes among others the dependency of response times on prior events. Here we report a surprising reflection of implicit perceptual predictions in the pattern of oculomotor response to a sequence of events. Method: During fixation observers viewed and silently counted sequences of 100 randomly ordered small visual patterns of two types, flashed at 1 Hz repetition rate. The visual pattern pairs consisted of high and low contrast Gabor patches (contrast condition), red and blue circles and triangles (color and shape conditions) and rectangles above or below fixation (position condition). Eye-tracking at high-speed was applied and the average latency of the first microsaccade in a time window following stimulus onset was computed. Results: In all conditions, microsaccade inhibition typically lasted for 300-500 ms after stimulus onset as previously reported, but depended on the former 4-5 stimuli. Repetition (e.g. red after a sequence of reds) shortened the inhibition (speedup), while a change (e.g. blue after a sequence of reds) increased the inhibition (slowdown). The magnitude of the effect was 5-10 ms per item, 50-100 ms overall. Preliminary results indicate a diminished effect when stimuli were presented in a regular (repetitive) order, suggesting a high-level predictive process. Conclusion: Microsaccades are inhibited for a duration that depends on the history of preceding perceptual events. We describe this dependency in terms of a simple model that computes the likelihood of future events based on the recent past, assuming longer microsaccade latency for surprise. The current oculomotor measure of implicit perceptual predictions could be applied to non-communicating individuals.
Meeting abstract presented at VSS 2012
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