Dartmouth College, USA, UC San Diego, USA, Université Paris Descartes, France
(© 2011 Peter Tse, Patrick Cavanagh, David Whitney & Stuart Anstis)
Fixate the blue dot.
When you attend to the whole white layer”s motion, the red dots appear to be slanted to the right.
When you attend to the whole black layer”s motion, the red dots appear to be slanted to the left.
When you don”t attend to either layer, the dots are aligned vertically, which they in fact are in every case.
