This is the one of the most astonishing things I have ever seen. Unbelievable. For the longest time I could not comprehend to the slightest of how any person could interpret that as going counter-clockwise. After staring at it for several minutes (well over 10 minutes), I looked away and looked back and seen counter-clockwise. Seriously amazing.
For anyone who doubts me, I guarantee that you are 100% incorrect to say it only moves in one direction as I now know it moves both clockwise and counter-clockwise, dependent on your perception at the specific period in time.
If I didn't know that this image does not digitally change to another one, while perceiving the image in either clockwise, or counter-clockwise, I would seriously bet everything I own on the direction that I am convinced of seeing at the time. (And I am referring to the girl herself and perhaps more specifically, which direction her outer leg is spinning. The shadow is not relevant.)
I can nearly change it at will now, although sometimes it seems more difficult than other times. However; I cannot actively change them in front of my own eyes, I have to look away first, they won't simply change direction.
I'll tell ya', when I started seeing her go counter clock wise, that was just amazing.
Thanks a lot for this.
INTP
EDIT: I am entirely blown away by this (Been looking at it now for over an hour, changing perception). How is it possible for it me to perceive it as both clock wise and counter clock wise? Each time I look at it, I regularly see it in clock wise motion. I then can look away and slowly use my peripheral vision to change the direction, then I can look at it directly and she is moving in counter clock wise motion. I suppose what is bothering me most about this is that while examining it in either direction.. I would truly bet my life that it is impossible to see it in another direction... Although now I know in my mind that it moves in both directions, clearly just knowing isn't enough. Someone is going to suggest that it's simply an optical illusion, but I need something more than that to satisfy my mind. It's truly like seeing the flip side of a coin.. if I could examine and extrapolate this to how I perceive a lot of aspects of life.. Well, let's just say it could be extremely useful.
EDIT 2: I've got it! I can get that chick spinning both ways on command. Damn that was hard.