The culprit? Working too late/long, too many distractions? Maybe, but the suspect at the top of the list is your own brain. Your brain has a natural tendancy to fill in the blanks when you're reading. If a word is missing such as "the," "of," or "and," you will read it as if it's there. As for misspellings, especially of simple words, as long as the 1st and last letters of the intended word are spelled correctly, then you will see/read the word as if it were correct. Don't believe me? Here's an example paragraph that demonstrates this annoying phenomenon:
"I cdnuolt blveiee taht I cluod aulaclty uesdnatnrd waht I was rdanieg. The phaonmneal pweor of the hmuan mnid. Aoccdrnig to rscheearch at Cmabrigde Uinervtisy, it deosn't mttaer in waht oredr the ltteers in a wrod are, the olny iprmoatnt tihng is taht the frist and lsat ltteer be in the rghit pclae. The rset can be a taotl mses and you can sitll raed it wouthit a porbelm. Tihs is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the wrod as a wlohe. Amzanig huh? Yaeh and I awlyas thought slpeling was ipmorantt!" - anonymous
It's the same reason why you can read a word that has been split for formatting purposes at the end of a sentence without slowing you down in the least. So don't despair! Just remember - your brain was just made to work that way, and if you publish with a POD distributor, Kindle, Apple, or Smashwords, you can always submit a corrected file...
Until next week!