I'm also not an expert, but I suspect a confounding problem is the fact that they eyes never stop moving, even when it feels to us like we're looking at a singl

I'm also not an expert, but I suspect a confounding problem is the fact that they eyes never stop moving, even when it feels to us like we're looking at a single point: https://en.wikipedia.org/wiki/Eye_movement#Saccades https://en.wikipedia.org/wiki/Eye_movement#Saccades