While this is not a well studied phenomenon, as in to the extent of having well formed theory, we do know that eyes constantly perform micromovements. One of t

While this is not a well studied phenomenon, as in to the extent of having well formed theory, we do know that eyes constantly perform micromovements. One of the prevailing hypotheses states that due to low inherent resolution of the retina these micromovements are used to create sort of sub-pixel resolution. Hence, visual cortex inherently works in predictive/generative mode with constant feedback correction. This hypothesis is sometimes used to explain phenomena like pareidolia and might as well be used to explain perception of UFOs.