In one pair of light switches, the left switch controlled a lamp to the right, and the right switch controlled a lamp to the left. The previous resident’s solution to this poor mapping was to put a red dot on one of the switches, presumably as a reminder. I put up with that for about 3 days, and then it was time to fix the mapping.

Now, the left switch is for the lamp on the left, and the right switch is for the lamp on the right. That’s natural mapping.

If you want to read more about natural mapping, check out this blog about interaction design and usability. It presents a classic natural-mapping problem: on a kitchen stove, which dial controls which burner?

Meanwhile, at my home there are other problems with light switches, but they aren’t about mapping. In one case, the light switch is far from the door, so at night I must cross a dark room to reach the switch. In another case, the light over the stairs is controlled by two switches that are improperly wired, so both switches must be in the “on” position. If you guessed that one switch is upstairs and the other downstairs, you’re correct. To light the stairs, often I must run up or down the dark staircase to flip the switch.

All this is both amusing and irritating and, as I already said, a daily reminder that usability doesn’t just happen. To get it right, usability takes planning and attention during implementation.