This is a test I received through email.
Count the number of "F" that you see in the text below
Are you ready....
> > >FINISHED FILES ARE THE RE-
> > >SULT OF YEARS OF SCIENTIF-
> > >IC STUDY COMBINED WITH THE
> > >EXPERIENCE OF YEARS
so, how many did you count.
You saw 3 of them, right?
NO, there are 6 F's up there.
Explanation is that the brain cannot see the F in OF
I counted only 3 F's and done the test twice.