My poor eyeballs! I was staring at the swirl for about a minute and a half waiting to catch the movement in the picture below. It wasn't until I gave up and looked at the picture below that it actually started to move! Ha ha!
Principle Of Design: Emphasis Clearly in this drawing the artist wants you to focus on the two people in the middle. She did that by leaving space using different colours and contrast around them to draw you in.