Project description
A closer look at goal-directed eye and hand movements
Humans continuously make saccadic eye movements to see their surroundings with the high precision of the fovea. Each saccade shifts the image on the retinas, such that the visual system needs to integrate blurry peripheral views of objects with their high-resolution equivalents once brought into the fovea. Understanding how this seamless integration is achieved is critical for theories of human perception. The EU-funded project PremotorPerception combines psychophysical protocols that enable a continuous assessment of visual sensitivity throughout the visual field with transcranial magnetic brain stimulation to investigate the role of specific brain areas underlying these modulations. We assess dynamic modulations of visual processing before saccades and goal-directed hand movements that enable continuous perception as the eyes move.
Objective
When inspecting a visual scene, we make a succession of saccadic eye movements to analyze objects of interest with the high precision of the fovea. Each saccade drastically shifts the image on the retina. As the acuity of the fovea markedly decreases with eccentricity, to maintain a stable percept, the visual system needs to seamlessly integrate blurry peripheral representations with their high-resolution equivalents once brought into the fovea by the saccade. We hypothesize that this integration is achieved by predictive and selective tuning of feature sensitivity shortly before the eye movement, to assimilate pre and postsaccadic percept. Combining a new psychophysical protocol that enables a continuous assessment of visual sensitivity throughout the view field with a powerful reverse correlation approach, we will conduct a systematic investigation of human presaccadic orientation and frequency modulations across space and time. We will establish whether local feature information is predictively modulated shortly before a saccade to enable a stable, continuous perception across the eye movement, and contrast the observed presaccadic modulations to the dynamics elicited by the preparation of goal-directed hand movements. Furthermore, using transcranial magnetic stimulation (TMS) we will selectively disrupt the functioning of early and higher visual areas to reveal their temporal interplay and characterize their respective contribution to both presaccadic attention and covert attentional orienting in the absence of eye movements. Understanding how the human visual system seamlessly integrates foveal and peripheral feature representations is not only critical to further our understanding of healthy and impaired human perception, but also forms the basis for artificial vision. Our findings will help constrain computational models of perception and attention and could improve the design of safer human-machine interfaces, e.g. for driving and air traffic control.
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Funding Scheme
MSCA-IF - Marie Skłodowska-Curie Individual Fellowships (IF)Coordinator
10117 Berlin
Germany