optical illusions

Check out them traveling feet on your right: one may think they tend to step out of phase every now and then when the radial grid becomes visible, yet in reality their movement is always constant and parallel. This becomes obvious whenever the grid disappears.

(Yes they are.)

Focus on the flashy green spot at the center. Note that the yellow dots have disappeared after a while – either one by one, or in pairs simultaneously. At one point they even start reappearing randomly!

The “disappearance” is merely an optical illusion, as all three yellow dots are actually continuously present on the screen!