in which I talk about wands

Been on the road a lot the past few days, visiting Carnegie Mellon and the University of Michigan. Still don’t know how I will choose a grad school.

I did have a kind of interesting usability experience while driving my father’s Prius. In all the cars I can remember using the windshield wipers, in order to turn them on you either push upward on a little wand next to your steering wheel, or you rotate something upward. Further movement upward increases the speed. In the Prius, however, you move the wand downward to turn the wipers on. And for the intermittent setting, there is a little tube on the wand to rotate and adjust the speed. This is labeled with the word “interval,” and little vertical bar that is wide at the top and narrow at the bottom.

Now, when I first started using the wipers, I assumed that rotating the tube upwards would increase the speed of the wipers. Actually, the opposite is true. I realized that, aside from being used to “up = more,” I’d looked at the little bar and assumed the wider the bar, the higher the speed. But really what it meant was, the wider the bar the longer the interval.

This makes a certain amount of sense, and was easy to remember once I realized it, but I’m not sure it is the design decision I would make. I think that typically, such markers are used as indicators of intensity–higher volume, more brightness, more speed.

For example, I’ve been staying in cheap hotels, so I’ve been using those air conditioning units built into the wall with a thermostat and controls built in. Typically the thermostat is not very sophisticated, you turn it one way for warmer air and the other way for cooler air and you hope you get it somewhere comfortable. And the way they mark this is not by having one bar that widens the whole way, to indicate low temperature at one end and high temperature at the other, but to have one red bar the widens at the hot side, and one blue bar that widens at the cold side: indicating the relative intensity of heating or cooling, not the overall temperature of the room.

This is how you know you are destined for a career in usability: you read one little book by Donald Norman and the next thing you know, you try to turn on you windshield wipers and start musing about the meaning of the marking on the wiper control.

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