As part of a recent project, I’m compiling some general rules for interaction design. One of them is a feedback rule based on switches with polar states versus those with discrete states.
The theory behind this rule is that people need feedback from any device they use, especially if it is polar, meaning having two states. Even if the device the switch controls should in theory reveal that it’s on, it’s important to have an indicator.
The simplest example of this rule is a ceiling fan. When you turn it on at the wall, the switch points upward and so you are aware that the fan is on, so even if it is broken, you know there is power going to the device. The sanity ends there, however, because with most fans now there is no way to tell at what speed the fan is running except by looking at it, which requires you take ten or fifteen seconds to watch it spin up and equalize.
Fan speed is controlled by a discrete state switch that is entirely out of sight. There are two hanging linked pullcords on most fans, with the one on the left turning the fan light on/off and the one on the right changing speed between slow, medium, and fast. Neither of these pullcords give us state information; a fan with a dead light bulb will look the same as one that’s off. And as mentioned above there is no way to tell what speed setting the fan is using, so that if cat hair jams it and the fan grinds slowly while it thinks it’s going full tilt ahead, you can’t tell visually.
Whether in our bedrooms, or in our complex enterprise application interfaces, it is important to think for the user and give them as many helpful hints as possible, so they can continue moving forward through their day and thinking about whatever it was that they were doing. Technology should just work, because each time we have to stop and figure out the gadget, we lose concentration on our primary jobs.
Fans could have pullcords with markers on them to indicate state, and enterprise applications could always use two icons for any toggle, one of which indicates clearly the state of the button is on. People don’t yet see the wisdom of this, but as more time is lost in confusion, we’re seeing how important it is to make all of our application states, instructions, documentation and personal feelings abundantly clear.