Abstract: - As humans investigate the visual environment, they make two to three fixations a second. At each fixation, each eye has to focus on the target to obtain sharp vision, the two eyes must be correctly aligned on the target, and the retinal images formed on the two retinas are to be fused into a single percept. These processes must be achieved rapidly and effectively, in order to form a robust and reliable perception before we move to the next fixation.
We know that the visual system exploits regularities of the natural environment to facilitate the perceptual task. The natural environment has specific regularities: it contains many opaque objects such that farther objects are often occluded by nearer ones. It is also structured by gravity, so many surfaces are earth-horizontal (e.g., grounds and floors) or earth-vertical (trees and walls). As a result, these regularities are constrained and dependent on position in the visual field.
We've shown how the visual system is finely adapted to these regularities to optimize binocular coordination and stereopsis but also the eye focus. This result provides an insight on the neural mechanisms of human vision, that can be exploited in different research and applicative fields from neuroscience and experimental psychology to virtual and augmented reality, but also computer and robot vision.