A few weeks ago I finished reading Designing with the Mind in Mind by Jeff Johnson, which was a great book that I'd highly recommend to anyone interested in the psychology of design. One of my favorite sections was in Chapter 8, "Limits on Attention, Shape, Thought and Action", was about primary goals and cleanup steps.
In short, once we finish the main goal of a given task, we tend to shift our (limited) attention other tasks entirely, forgetting all about the loose ends we left behind. Some examples Johnson used:
Leaving turn signals on after making a turn.
Forgetting to take original documents out of a scanner or fax.
Neglecting to close parentheses or quotations when typing. (Forgetting to close a block of code sounds pretty familiar...)
He goes on with more good examples and what can or has been done to avoid these "end-of-task short-term memory lapses", but my mind immediate went to an example of my own.
Cashiers: Guides to the Debit Card Machine
It's insane that no matter how many times I've used them, I almost always forget a step somewhere when using my debit card to checkout from a store. It normally goes like this:
I put my items up on the counter
Get greeted/ignored by the cashier
Swipe my debit card and enter my PIN
From here I typically get distracted by any number of things; chatting with my wife, monitoring prices as they scan, that annoying kid on register 7 -- whatever. Meanwhile a monochromatic, passive-matrix screen is prompting me for more information:
Do you want to make a donation?
Do you want this entire purchase on one card?
Do you approve X amount?
Do you want cash back?
No matter what the tiny green screen says, I'm not going to see it unless I'm looking directly at it, and that's frustrating for everyone involved. The person behind the counter has wait for me to notice the lull in activity or politely point out that I'm not paying attention, and I have to feel like a moron for forgetting to babysit a machine. What's more, you can recognize the especially frustrated employees because they don't even wait for you to mess up, they'll prompt you through the entire process in a droning "I've-said-this-1000-times-today" voice before you even open your wallet -- "It's going to ask you for X, you need to Y before you Z".
I can't really blame them -- if I turn my head away from the machine, I'm likely to forget all about it and it'll be up to the cashier to bring me back to task. Once I got a little huffy and said to the cashier, "The stupid thing should beep at me, or have a blinking red light or something. Doesn't it drive you crazy?"
She just smiled at me politely, because it DOES drive her crazy but there's nothing she can do about it.