Six or Seven Cubes?

This optical illusion is very curious. Look at it and count the number of cubes you see.

Did you come up with six or seven cubes?

This optical illusion causes us to change our perception, as you look at this image the black tiles will change from being the top of six cubes to being the front of seven cubes.

Which count is easiest for you to see? Did you tally six or seven cubes initially?