Quick Eye Test

Count the number of F's in the following text:

FINISHED FILES ARE THE
RESULT OF YEARS OF SCIENTIFIC
STUDY COMBINED WITH THE
EXPERIENCE OF YEARS

Managed it ?
Scroll down only after you have counted them !

How many ?
Three ?
Wrong, there are six - no joke !
Read again !

FINISHED FILES ARE THE
RESULT OF YEARS OF SCIENTIFIC
STUDY COMBINED WITH THE
EXPERIENCE OF YEARS

The reasoning is further down . . .
The brain cannot process the word "OF".
Incredible or what ?
Anyone who counts all six F's on the first go is a genius, three is normal.