Early light switches vs iPod/iTunes
The light switch was often the first button to really make an impact on the lives of many people. Around 1900, homes were first getting electricity in some parts of the world. Before, they had gas lamps or even candles. Now, they could just push a button to turn the light on. Modern!
A light switch must have an On and an Off. (Dimming came much later.) While most of our light switches now are simple rockers, the earliest light switches had two buttons, On and Off. But now that you have two buttons, how do you show which button is which? This is possibly the earliest instance of struggling to find the right icon for buttons. Let’s see some examples.
White and black. White means light, black means no light, or dark. A purely elegant solution. But notice this: what does In vs. Out mean? Does the white button Out mean that the light is On now (status) or that if you push it, you will make the light go On (action). Sound familiar? This is the exact same problem we have today with the Play/Pause button.
Look at iTunes. When no music is playing, the Play icon is shown, saying “this is what will happen when you push it.” (action) When you’re playing, it switches to Pause.
But now look at the iPod. It’s the exact opposite. When you are playing, the indicator says Play (status). When you are paused, the indicator says Pause. The difference here is that in iTunes, the button icon and the indicator are the same thing. In the iPod, they’re separate.
Luckily, in iTunes/iPod, you have the simple external feedback of sound playing to help inform you. And with the light switch, you simply have the light in the room for feedback.
Let’s look at two others. Here is the most common double button light switch.
A white dot (or pearl inlay) for On and pure black for Off. They’ve gotten clever here. The white and black Bakelite switches we saw above are separate parts, which is more expensive to produce. Here, they just make all black parts and put dots on half of them. Cheaper and communicates On/Off just as easily.
Okay, explain this one.
O and L. Um, okay. Got any great ideas? The best I can come up with is Off and Light, at least in English. But if you do that, and you install it to have the L oriented correctly, you put Off in the top position and On in the bottom. Notice the assumption I made above that On was always in the top position and Off in the bottom. This approach is still used today with rocker switches.
So it’s a simple light switch with two buttons, but there are three variables to communicate status and action. 1. Position (top or bottom), 2. Status (in or out), 3. Icon (color, presence/absence, letters).
This is a classic example of the challenges facing interaction designers and designers in other related fields (visual, web, industrial, etc.) A lot of elements must be considered and really thought through to make something that should be easy to use, actually and intuitively easy to use.
In this case, all these elements may be irrelevant. If you can see, you know the status of the light. It’s surrounding you. If you go to the switch, you probably just want to change the current status. So you hide the button (In) for the button that matches the current status, because pushing it is pointless. Then you project and provide the button (Out) the other option. Now, you don’t even have to look at the switch. To change the status, just push the only button you can feel. Done.