@conradhackett Hahahaha! I love it. These illusions each have different "techniques" for "solving" them. (look at the whole image, look closely at one part of the image, stare at the spot with the least detail and wait, blur your vision, etc.) What takes time is finding which technique to apply.
Once I hit on the right one, the image quivered a bit and pop, there were 16 circles and the rectangular figures disappeared.
So yeah, they're in there.