Apparently, is because you use more of the right side of your brain.

From this source: http://www.news.com.au/heraldsun/sto...81-661,00.html

THE Right Brain vs Left Brain test ... do you see the dancer turning clockwise or anti-clockwise?

If clockwise, then you use more of the right side of the brain and vice versa.

Most of us would see the dancer turning anti-clockwise though you can try to focus and change the direction; see if you can do it.

LEFT BRAIN FUNCTIONS
uses logic
detail oriented
facts rule
words and language
present and past
math and science
can comprehend
knowing
acknowledges
order/pattern perception
knows object name
reality based
forms strategies
practical
safe

RIGHT BRAIN FUNCTIONS
uses feeling
"big picture" oriented
imagination rules
symbols and images
present and future
philosophy & religion
can "get it" (i.e. meaning)
believes
appreciates
spatial perception
knows object function
fantasy based
presents possibilities
impetuous
risk taking