The newest illusion getting ready to break the internet isn’t a dress. It’s seemingly just a bundle of pastel colors.

But if you concentrate on the image for long enough, roughly 30 seconds, something astonishing will happen: The swirl of pastels will disappear entirely. Check it out for yourself:

This phenomenon is an example of Troxler’s fading, discovered by Swiss doctor Paul Troxler back in 1804. Troxler discovered that the brain stops paying attention to visual scenes that don’t change. This effect is similar to what happens when you put your socks on — at first, you’re completely aware of them, but as the day goes on you stop noticing them altogether.

Since the image is so blurry and rather indistinct, there is little for the eyes to focus on. If you combine that with an intense, concentrated stare, the colors fade from view completely.

Though you don’t realize it, your eyes are constantly in motion, making microscopic movements and adjustments throughout the day.