Decipher

Try to decipher the following paragraph:Aoccdrnig to a rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoetnt tihng is taht the frist and lsat ltteer be at the rghit pclae. The rset can be a toatl mses and you can sitll raed it wouthit porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe.
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Try to count the number of alphabet "F" in the following paragraph
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FINISHED FILES ARE THE RE-SULT OF YEARS OF SCIENTIF-IC STUDY COMBINED WITH THEEXPERIENCE OF YEARS.
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Answer is "six"
Puzzled..

In fact , the brain can't treat "OF", incredible, not ? Whoever counts the six 'F' the first time is a genius, four is rather frequent, five is rather rare, three is normal. Less than three, you must change glasses ; -)

Explanation : During the quick reading, the eyes fix the "lexical" words, while jumping over the "grammatical" words (articles, conjunctions...). The 3 "OF" of the text are not directly fixed. 6 year old children are for the majority at the stage of deciphering and fix all the words. However, the concentration can explain easily why you succeeded, or why you were trapped.