What to do – Follow the red dot with your gaze. Observe that some of the squares in the background seem to shift. The effect is fleeting for me – sometimes strong, sometimes missing. But all motion here –apart from the red dot– is illusory.
What else to do & observe – With the popup menu, select “lanes” rather than the circle. Many more settings wait for you to play with them (“Ranomize” is not useful yet).
Comment – This is a variant of the Pinna-Brelstaff illusion which already appeared in their 2000 paper. The same explanation applies.
Pinna B, Brelstaff GJ (2000) A new visual illusion of relative motion. Vision Res 40:2091–2096 [PubMed]
More sources on the other Pinna-Brelstaff page.