Saccade Amplitude Statistics are Explained by Cortical Magnification

How natural and artificial vision systems learn and develop depends on how they sample information from their environment. Humans actively do so through saccadic eye movements. The statistics of saccade amplitudes have been well-characterized in tightly controlled contexts such as viewing images on a computer screen. However, the degree to which such findings generalize to real-world contexts involving moving agents and objects is currently unknown. Here, we first analyze saccade amplitude statistics of both infants and adults during naturalistic free play. We find that these differ significantly from those previously reported for head-fixed picture viewing, with a relatively smaller/greater abundance of medium/large saccades. Next, we present a computational model that explains saccade amplitude statistics based on the foveated nature of vision and the associated space-variant magnification of different portions of the visual field in primary visual cortex. Finally, we demonstrate computationally efficient approximations to this space-variant sampling using a small number of discrete resolution levels.