How Active is Visual Perception?
Our eyes are never at rest. Rapid gaze shifts (saccades) occur 2-3 times per second, and we are normally not aware that eye movements continually occur even during the inter-saccadic periods of "fixation", the very periods in which visual information is acquired and processed. In this talk, Rucci will argue that the incessant motion of the eye is a critical information processing stage: a computational element of an active sensorimotor strategy by which the visual system processes spatial information in the temporal domain. Rucci will review recent experimental and theoretical findings to address three main questions: (1) How is spatial information encoded in the modulations of luminance resulting from eye movements? (2) How is this information extracted and interpreted? (3) Can this stage of processing be tuned to the task by controlling fixational eye movements? The proposal that the visual system actively represents space through time replaces the traditional notion of the early visual system as a passive encoding stage that optimizes overall information transmission with that of an active, tunable system for feature extraction, whose function can be fully understood only in conjunction with eye movements. It implies that eye movements are in part responsible for fundamental properties of spatial vision that are, at present, solely attributed to neural mechanisms.
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