Why we nod off on Fridays

Notice anything odd about the jury verdict below?

"We, the Jury, find the Defendant Guilty of the offense of POSSESSION OF CRACK COCAINE.
"We, the jury, further find that the amount of crack cocaine WAS in the amount exceeding ten one hundred (100) grams as charged in the indictment."

Neither, apparently, did the jurors. But the defendant did. And if you read closely, you'll notice what he noticed: that the word "ten" in the second sentence is extraneous.

It may seem like a small error, but it was big enough that an Ohio appeals court ruled the defendant's prison sentence should be cut to just one year instead of 10.

The case nicely illustrates how easily we overlook things, relying instead on context to guide our understanding of what we read or see.

"Overlooking" mistakes are so common that researchers have given them their own designation: they are called “proofreader’s errors.” These humdrum errors reveal some interesting quirks about the way human perception works. One is that perception is economical; we notice some things and not others. And what we notice, to a degree, depends on who or what we are. If you're a dentist, you probably notice someone's teeth; if you're a manicurist, you notice hands.

In any event, our attention is not always equally distributed. When reading, for instance, we tend to pay a lot of attention to the beginnings words -- an area that we expect to be rich in cues about what may follow -- and less attention later on. Investors, interestingly, appear to do the same thing: they pay more attention to financial news released at the beginning of a week, but tend to nod off on Fridays.