What to observe
Watch at the rotation on the right. The wheel defined by the dark-bright sectors is rotating clockwise and the spokes are rotating counter-clockwise?
Look again… The spokes stay put! Rather, each spoke makes a tiny shift in one direction and then slowly (subliminally) moves back.
What to do
Watch the rotation for a while, then stop it, and observe that the illusory motion has caused a motion aftereffect .
You can change the speed, and the gray-modulation depth of the sectors. The illusory motion is still evoked with very low contrast. |