title: Modeling peripheral visual acuity enables discovery of gaze strategies at multiple time scales during natural scene search.
abstract: Like humans, monkeys make saccades nearly three times a second. To understand the factors guiding this frequent decision, computational models of vision attempt to predict fixation locations using bottom-up visual features and top-down goals. How do the relative influences of these factors evolve over multiple time scales? Here we analyzed visual features at fixations using a retinal transform that provides realistic visual acuity by suitably degrading visual information in the periphery. In a task in which monkeys searched for a Gabor target in natural scenes, we characterized the relative importance of bottom-up and task-relevant influences by decoding fixated from nonfixated image patches based on visual features. At fast time scales, we found that search strategies can vary over the course of a single trial, with locations of higher saliency, target-similarity, edge–energy, and orientedness looked at later on in the trial. At slow time scales, we found that search strategies can be refined over several weeks of practice, and the influence of target orientation was significant only in the latter of two search tasks. Critically, these results were not observed without applying the retinal transform. Our results suggest that saccade-guidance strategies become apparent only when models take into account degraded visual representation in the periphery.
authors: Department of Physical Medicine and Rehabilitation, Northwestern University and Rehabilitation Institute of Chicago, Chicago, IL, USA Department of Neurobiology, Northwestern University, Evanston, IL, USA.
authors: Pavan
authors: P
authors: Ramkumar
authors: Department of Physical Medicine and Rehabilitation, Northwestern University and Rehabilitation Institute of Chicago, Chicago, IL, USA Instituto Gulbenkian de Ciência, Oeiras, Portugal.
authors: Hugo
authors: H
authors: Fernandes
authors: Department of Physical Medicine and Rehabilitation, Northwestern University and Rehabilitation Institute of Chicago, Chicago, IL, USA.
authors: Konrad
authors: K
authors: Kording
authors: Department of Neurobiology, Northwestern University, Evanston, IL, USA.
authors: Mark
authors: M
authors: Segraves
mesh_terms: D000818:Animals; D003198:Computer Simulation; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology*; D008253:Macaca mulatta; D010364:Pattern Recognition, Visual / Q000502:physiology*; D012438:Saccades / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology*
keywords: edge–energy; eye movements; natural scenes; nonhuman primates; orientation statistics; peripheral vision; priority map; relevance; saliency; visual search