Q. Quick! Count the number of times that the letter F appears in the following sentence:
"Finished files are the result of years of scientific study combined with the experience of years."
A. Did you count 3? The answer is actually 6, but most people will count 3. It turns out that the brain has a hard time correctly processing the word "of" because the "f" in "of" makes a "v" sound in our heads instead of an "f" sound.