More years ago than I would like to admit, I worked for a store in Sterling Virginia, in the outer DC suburbs. This store had twin metal-framed glass doors, one of which was always locked and bore the sign "Please Use Other Door." A significant percentage of customers would try to push the locked door open. We clerks found this very amusing.
One day while we were expressing our amusement, another customer came up and politely set us straight. He pointed out that there were over a dozen notices on the doors. As far as he was concerned, there was nothing special about the "Please Use Other Door" sign, it was just one of many pieces of visual clutter on the door. The mistake was ours in using the doors as a bulletin board; most people consider a door something to go through and not something to stop and read in detail.
This has stuck with me for over 30 years because you can draw so much from it. It was a good prelude to reading The Design of Everyday Things by Don Norman.
First, as the title of this post says, anything is obvious when you already know it. But it's not fair to expect people who don't already know it to consider it obvious. Think about this the next time you deal with a petty bureaucrat who expects you to be familiar with some arcane and arbitrary regulation.
Second, use something for its primary purpose. Using the door as a bulletin board made it less useful as a door.
Third, less is more. To make something obvious, take away other things. When we removed the clutter from the doors, people mostly quit using the wrong door.
Fourth, don't be a jerk. If someone ran into a door, it was an honest mistake caused by our violations of these rules. Laughing at them was not appropriate.
Fifth, when you see someone being a jerk, don't be one yourself. The non-confrontational way that the customer pointed out the error in our reasoning drove the lesson home.
