This is quite amazing ...
If you see this lady turning clockwise you may be surprised to learn that she can be seen turning counterclockwise, as well. You might even see her switch direction, if you continue looking.
Some people see her rotation both ways, but most people see it only one way.
The illusion explained (according to Wikipedia).
See if you can make her go one way
and then the other.
BOTH DIRECTIONS CAN BE SEEN.