Humans exhibit machine-like eye movements (consistent and repeatable) in space and time while performing demanding acuity tasks. To investigate these, we used an adaptive optics imaging and display system in 6 human subjects (4 females, 2 males) to present ultra-sharp Vernier acuity stimuli briefly every 2 s while simultaneously measuring eye movements, including precisely where on the retina each stimulus fell. We found that drifts and microsaccades combined to confine the landing location of the anticipated stimulus to a tiny retinal region centered on the preferred retinal locus (PRL). The variance of landing location was smallest at the time of stimulus presentation and a few hundred milliseconds after. We correlated where the stimulus fell in space and time with correct or incorrect responses. The PRL and a small area around it, including the anatomical fovea, conferred the best acuity. Acuity declined consistently in the rare events in which the stimulus fell more than 5 minarc from the PRL. We also found that acuity was best when the last microsaccade occurred sufficiently prior to stimulus presentation. Our findings reveal a highly evolved oculomotor system where gaze direction during fixation is rarely far enough from the PRL to compromise visual resolution when a person makes natural fixational eye movements.

Rigorously tracking eye and head behavior in space is key to building realistic models of the stimulus that reaches our retina. The motion structure of this stimulus or retinal flow - the substrate fo...

A VR street-crossing task revealed that increasing task-irrelevant scene variability simultaneously reduced crossing attempts and confidence in being able to cross successfully, and delayed crossing i...

Every movement unfolds with a simple question: Where is my body? The nervous system answers through proprioception - the sense of limb position (static position sense) and movement (dynamic propriocep...

With so little money to go round, the costs of competing for grants can exceed what the grants are worth. When that happens, nobody wins.

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Intercepting moving targets is a widespread challenge across many species. In humans, heuristics that use optic variables have excelled in guiding interception, relying on a closed-loop system to couple optic variables directly with direction of ...

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