Stare at the red dot for a minute or two:

TroxlerIllusionFrom the SEED article on it:

Stare at the red dot in the center of the figure for a minute or two. Before long, the green ring will disappear—it simply seems to fade into the white background. There are no tricks: This is a simple, static image file. The effect has been known for more than two centuries and is named for its discoverer, Ignaz Paul Vital Troxler (1780–1866), a Swiss physician and philosopher. “Troxler fading” is actually related to what you experience when you get “dizzy”: You become so habituated to a phenomenon (spinning in a circle or seeing a green ring in your peripheral vision) that you stop noticing it’s there. Or, rather, you don’t realize that your perceptual system has begun actively ignoring it.

I feel like my perceptual system might actively ignore other things, BUT HOW WOULD I KNOW?