Spinning Silhouette illusion

{Source}

At first glance, the silhouette is spinning clockwise. but according to the source website, and the small sample test group I showed it to; you can reverse the spinning.

Here are some hints from the test group.

• You have to look down at the shadow, keep your eyes there for some seconds and then slowly move your eyes upward.
  Sometimes my brain even changes the direction when I look at different parts of the figure. Dont stare at her, keep your eyes moving up and down.
• when she turns clockwise she has the right foot up.. when counter-clockwise its the left foot.. just tell yourself which foot is up and she will turn in that direction…

 

{Original Source}