Can you count the number of black dots?
How many cows do you see?
Some illusions have to do with color change. Staring at them between 45 seconds and 1 minute helps you get the affect you need. Check out these below.
Stare at the corner where the orange, green, and black meet. Then look at a white piece of paper.
Can you make the light bulb glow?
Stare at the filament and then stare at a white piece of paper.
Julian Beever is a world famous artist who designs chalk sidewalk drawings. Here are a few of his works. His work fools the eyes with depth perception. Some pictures shows the different views of the same drawings.
Pictures: Coca-cola Bottle, Waterfall, Batman & Robin, Spiderman, Lobster (both views), Globe (both views), and Self-Portrait
