Looking for Details: Fine-Grained Visual Search at the Foveal Scale

Abstract

Visual search has traditionally been conceptualized as the process by which the visual system identifies relevant objects in the extrafoveal field for subsequent foveation. Standard models implicitly assume there is no need for a finer-level search within the 1-degree foveola, as stimuli falling in this region are already viewed at high resolution. Using state-of-the-art high-precision eye tracking with arcminute level accuracy to localize the line of sight, we show that the visuomotor system is capable of implementing effective visual search strategies with striking precision within the foveated region. This active behavior, mediated by microsaccades, tiny saccades just a few arcminutes in size, allows for an efficient examination of the details falling in the central fovea. Our findings challenge the traditional visual search view and reveal that at each fixation a finer priority map of the foveal input is established, underscoring the dynamic nature of these representations.