I started my programming career writing COBOL programs for banks. One of my early tasks had me writing a program that would send a letter to all of our loan customers, informing them of a change in the payment notices. Included in that letter was to be a sample of the new payment coupon, which was to be clearly marked as a sample so that nobody would think it was bill and send a payment.
My design for the sample coupon included the words NOT AN INVOICE and NO PAYMENT REQUIRED and DO NOT PAY FROM THIS SAMPLE printed in several places. In addition, the account number printed on the coupon was something innocuous like “123-456-789”, and the customer’s name and address on all the coupons were the same:
123 Main St.
And the amount due was “$123.45”.
My boss had me take that to the branch manager for approval. The manager praised my good thinking for including the NOT AN INVOICE and other wording, and the obviously fake name and address. His comment: “I was worried that customers might complain about an extra payment notice, but what you have here is clearly a sample. Nobody will be confused by this.”
To my knowledge, nobody called to complain that they had already made their payment and that they didn’t appreciate this erroneous invoice. We did, however, receive several checks for $123.45, with the account number 123-456-789 written in the Memo field, nicely packaged up with the sample payment coupon. It’s fortunate that the checks had the senders’ addresses on them. Otherwise we would not have known who to contact.
The first lesson I learned from this experience is that some people see only what they expect to see ( “Oh, look, a loan payment notice from the bank. Guess I’ll pay it.”). Later (with a similar mailing some months later) I learned that if you want people to stop and think about what they’re looking at, make a glaring error. If I had made that amount $7,743,926.59, I suspect nobody would have sent a check. We might have had a few calls from irate customers saying that they couldn’t possibly owe seven million dollars on their $15,000 loan, but it’s likely that they’d examine the notice a little more carefully before picking up the phone.
If you want people to notice something in a document, make an error that’s impossible to miss. That’ll force them to look more carefully at the rest of the page.
Oddly enough, the converse of that is also true in some situations. When preparing for room inspections at military school, I’d purposely leave something out of order. I wouldn’t make it too obvious, but it’d be something that the upperclassmen always looked for, and that was commonly in error. I found that if I tried to make my room perfect, those guys would spend entirely too much time looking for something wrong. But if I made one or two easy-to-find errors, they’d find the discrepancy, mark it down, and then leave the room happy that they did their jobs.
I think the difference is expectation. When somebody sends you information that you assume to be correct (like a statement from your bank), a glaring error makes you examine the rest of the information more carefully. But an upperclassman who’s looking for an opportunity to gig a subordinate will stop as soon as he’s found an error or two. He has proven his superiority and he has other rooms to inspect.
I’ve heard that the tactic works for tax auditors, too: give him an obvious reason to make you pay a little extra tax, and he’ll give the rest of your records a cursory glance before declaring everything in order. He’s proven his worth, so he can pack up his calculator and head off to torture his next victim.