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Martina Poletti; Attention and eye movements at the foveal scale. Journal of Vision 2018;18(10):894. doi: https://doi.org/10.1167/18.10.894.
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© ARVO (1962-2015); The Authors (2016-present)
In humans, high visual acuity is restricted to a small (~1o) region of the retina: the foveola. Even if the foveola covers less than 1% of the visual field, the stimulus within this region can be complex, particularly when examining natural scenes. What are the roles of attention and eye movements in foveal vision? Studying attention at this scale is challenging because small eye movements continuously shift the image on the retina, covering an area as large as the foveola itself. Furthermore, localizing the line of sight within a 1 degree region is challenging and beyond the capabilities of most eye-trackers. Thanks to a combination of techniques allowing for high-resolution recordings of eye position, retinal stabilization, and accurate gaze localization, we circumvented these challenges and examined how attention and visual exploration are controlled at the scale of the foveola. Here we show that fine spatial vision in the foveola is enhanced by means of three different mechanisms: (a) Visual exploration. The precise repositioning of the preferred retinal locus by means of microsaccades enables visual exploration of foveal stimuli. Visual exploration at the foveal scale is driven by both bottom-up and top-down factors and it follows scanning strategies similar to those implemented by saccades at larger scales. (b) Covert shifts of attention. High-resolution attentional reallocations independent of eye movements improve vision at selected foveal locations. (c) Microsaccade preparation. Planning of microsaccades enhances fine spatial vision at the microsaccade future landing position at the expenses of other nearby locations within the foveola. Our findings indicate that the coupling between visual functions, oculomotor activity and attention play a crucial role in foveal vision, enabling processing of fine spatial detail during fixation.
Meeting abstract presented at VSS 2018
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