Can you count the black dots
in the image below?
Or do the black dots move too fast?

There are no black dots.
They're an optical illusion.

Look at the image below.
Are the horizontal lines parallel
or do they slope?

Though they appear to slope,
they're each parallel.

How many legs does the elephant have?

Do you see a musician or a girl's face
in the image below?

If you look hard, you'll see both.

What do you see in the image below?