Which dog is lighter in color?

This animation
was on my laptop for quite some time. I had it for almost a year. Today
anonymous user submitted me this
gif version, and when I opened it, only then I realized how great
this illusion actually is. If you look at the spinning
girl’s silhouette below, you will think it is spinning
clockwise, probably. When you check her
shadow below, momentarily the spinning
direction changes in your mind, and now the girl is spinning
counter-clockwise. It can be quite hard at the beginning to notice
switch of the spinning direction, but eventually you’ll manage. I posted
more
simple illusion of this kind while ago, and you can see
it here. Now, be honest – how long did it take you to see it spin
in both directions? Not as easy as the hidden tiger, ayeh? I lost
the link to the
original artist, but best I could come up with is the place I found it on.

Did you check the rotating girl? Keep staring at it for a bit then look at the shadow below then look back and it will seem to rotate in a different direction.

awsome gadget.