This illusion has an interesting history. Many years back, I chanced upon a still picture which looked like a ball of 'fluff' (click it on the right to see full size), where the outer ridges faded away to white. The idea was to stare at the centre, and it would gradually disappear. It was an interesting effect at the time, and I made my own enhanced version much later with lots of little coloured blobs, and called it "Vanishing Fluff".
Years later, I found Michael Bach's excellent "Motion Induced Blindness" illusion. At the time I was intrigued that anything so bright as those small dots could disappear.
It then occurred to me; how about if we combine the two effects into one illusion? Can we get away with making massively large objects dissapear? Just possibly...
Press F11 to view full screen, and stare at the center of the animation, and keep staring until you see the red and yellow blobs dissappear!
If you can't make it work, try sitting closer to the screen. If you still have trouble, then try this easier version
The illusion is a perfect example of Troxler's fading
. When still, extended vision on an object in peripheral vision is maintained, then that object may somewhat fade, especially if it is blurred, faint, or if other movement is taking place to distract attention away from it.