The results of change blindness studies and other experiments strongly suggest that the visual system can focus on only one or very few objects at a time (maybe 30 or 40 objects per second), and that anything lying outside a given moment's cone of interest gets short shrift.

This is because the brain has evolved mechanisms for combating data overload, allowing large rivers of data to pass along optical and cortical corridors almost entirely unassimilated. It peels off selected data for a close, careful view, filling gaps and compiling a cohesive portrait of reality based on a flickering view.