There are 12 black dots at the intersections in this image.
Your brain won’t let you see them all at once.
This occurs because the eye’s stimulated light receptors can sometimes influence the ones next to them, creating illusions.
The brain can see some black dots but guesses when it fills in the peripheral vision. Because mostly grey lines appear in the periphery, the black dots don’t appear.
12 Black Dots - How many dots can you see at once?