Optical illusions do weird things to our senses, like making us see or hear things that aren’t really there. This illusion recently shared by Reddit user NightBreeze13 does something unique: Stare at it long enough and the image seems to disappear completely.
This is called Troxler fading or the Troxler effect, a phenomenon first identified by Ignaz Paul Vital Troxler in 1804. According to The Verge, it’s what happens when we fix our eyes on an unchanging scene for a long-enough period of time. When sensory information is new our brain places a lot of importance on it. But if certain stimuli have been consistently hitting our senses for a while, like a dull toothache or the hum of a refrigerator, our brains have a way of tuning them out.
— Core77 (@core77) April 11, 2018
This is the case with the picture above. Choose a fixed spot in the image to stare at and allow at least a minute or so to pass. The colors should gradually fade from your vision, leaving a white square in its place.
So why does the effect work here, and not when you’re staring out a window or at a painting? The blurriness helps: The smallest movements, whether they’re from your eyes or the object of your gaze, feed you new sensory information, thus resetting the process. If your eyeballs wiggle slightly while staring at this image, your brain will have a harder time noticing it because it’s already so blurry.
But having a steady gaze is still important. If you don’t see anything happening after looking at the illusion for a minute, trying moving your cursor over the image and staring at that. Closing one eye can also help you keep the other eye as still as possible.
[h/t The Verge]