We're particularly attracted to movements outside the focus point, that's what makes it distracting. The retina cells (mainly rods) further away from the fovea are bad at distinguishing things, but excellent at detecting rapid movements.
It helps noticing prey when hunting or predators when being hunted. It does not help when trying to read some text.
It helps noticing prey when hunting or predators when being hunted. It does not help when trying to read some text.