Toyota Corolla Usability Fail

I think you can imagine my surprise when, upon approaching my '02 Corolla the other day, I noticed that most of my left headlight assembly, including the turn signal, where totally smashed. After a bit of an investigation, including security at the firm I work at, it became apparent I wasn't going to find out who did it. While this sucks hard, it isn't the really interesting thing about this story.

As I got back into the (thankfully) still drivable car and headed home, I noticed that the left turn signal indicator was blinking a bit more rapidly than the right. I then realized that this had been happening for at least a week. Apparently, the slightly faster blink rate on the dashboard display indicates that the turn signal is out. At first glance, one might think, "How nice of Toyota to include a warning to tell me that my turn signal is broken!" If we think a bit more deeply though, it is quite apparent that the signal they chose will fail miserably in achieving its goal for many people.

Any well designed system must provide both feedback for user actions and visibility into the present state of the system. One way to accomplish this is to exploit natural mappings. For instance, the blinking turn signal on a car dashboard maps very well to the operation of the car's actual turn signal. When we see this, we can safely assume that the signal is operational. In my case, it was not at all apparent that a slightly more rapid blink mapped to the real signal being broken. If anything, I would simply assume that the real signal is blinking a bit faster.

What puzzles me about this situation is that Toyota made probably the worst design choice possible given the obvious intent. Imagine that instead of a slightly more rapid blink, they would have chosen not to have the dashboard blink at all when the light is out. This would lead a reasonable user to conclude that, since the blinking no longer occurs, either the dashboard or the signal itself is malfunctioning. Even a solid red light (as opposed to the blinking green) would probably do the trick. Either of these solutions would result in the user/driver taking a quick look at the actual turn signal.

In my case, I may have actually been able to figure out who/what trashed the front of my car.