you see the Phantom Spots?
You may see spots where the white lines intersect, but if
you try looking right at one, it will disappear. The spots,
of course, aren't really there. They're caused by the way
your eyes respond to light and dark areas. When an area is
surround by light, your eye compensates by "turning down"
the brightness a bit, making you see darkened blobs. In this
grid, the areas surrounded by the most white are at the intersections
of the white lines. Since this phenomenon works best in your
peripheral vision, the spots disappear when you look right