Counting Cubes Optical Illusion

How many cubes do you see in this optical illusion?

See Another Random Optical Illusion

Six or seven - it depends on how you look at this optical illusion. If you consider one cube to start alone at the top, then you will see 6 cubes.

If you count starting with two cubes in the top line, then you'll see 7 cubes.

Explanation

Since we live in a three dimensional world, our mind tries to convert the two dimensional optical illusion into 3D. There are clues in the picture as to what it should look like if it were 3D, however, the clues are not concrete and can be interpreted in two different ways.