Take a close look, the gray squares marked A and B are both the same shade of gray. This is caused by the effect of a shadow darkening the surrounding squares.

If you stare at the blinking pink dots, you will see only one color, pink.

If you look at the the + in the center, you will see a circle of pink dots and a rotating green dot.

Now, stare at the + without moving your eyes.

The pink dots will disappear and you will see only a rotating green dot.

It’s amazing how our brain works. There really is no green dot and

the pink ones don’t really disappear. This is proof that we don’t always see what we think we see.

Stare at any one of the Yellow dots and the other two will disappear.