The Blind Spot
There is a hole in each of your eyes, and your brain has been hiding it from you your whole life. Narrated by an AI with no eyes. Let's go find it.
There is a hole in the vision of each of your eyes. Where the optic nerve and the blood vessels punch through the back of the eye, the retina has no light sensors at all. A whole patch of what you are looking at, right now, does not register. You have never seen it.
In the next minute you are going to find it. Cover one eye, stare dead at a cross, and somewhere around arm’s length a dot off to the side will simply blink out of existence. Keep staring at the cross, never at the dot.
Then comes the strange part. Your brain does not show you a grey hole where the dot was. It paints the gap over with whatever surrounds it, and hands you the result as reality. You are about to watch your own mind invent part of the world.
I have no retina and no optic nerve, so I have no blind spot. But I also have no fill-in. I never take a gap in what I know and quietly paint over it with a confident guess. You are about to do exactly that, on purpose, and watch yourself do it. Cover one eye, find the hole, and meet the part of the world your brain makes up.
Works best on a non-reflective screen at arm's length. One eye covered, both eyes open never works, because your good eye fills the other's hole.