(© 2005 Simone Gori & Kai Hamburger)
When one approaches the stimulus pattern, the radial lines appear to rotate in a counterclockwise direction, whereas when one recedes from it, they appear to rotate clockwise. In the complex version of the pattern, the illusory rotation is stronger and there may be some residual counter rotation in the surround.
Read more about the illusion and possible explanations
The Rotating-Tilted-Lines Illusion,
