Yeah well, it supposes you already know the words you're reading... or you won't have a clue on what the real spelling is.
In the same kind of ideas, here's a little something you may be aware already:
Quote:
Count the number of times the letter F appears in the following paragraph. If you haven't seen this before you will probably get it wrong at least once. So you don't think it's a trick, count it more than once.
FINISHED FILES ARE THE RE
SULT OF YEARS OF SCIENTI
FIC STUDY COMBINED WITH
THE EXPERIENCE OF YEARS...
There's six F's, but the human brain sees F's as V's in the word "of". That explains why we pronounce "ov", instead of "of" (as in off) when saying the word "of". Some say the word "of" is simply so common, the brain overlooks it thus misses the F's in it.