Is it on?

Abstract

I have an electric water-kettle with a little red light on it. The interaction design is enough to make your hair curl; the light goes on when the kettle is plugged in and it goes off when you press the switch to boil the water. Straight away there are problems because the kettle is using one light for three states; off, on and not-plugged-in-you-git. Furthermore, the two states that are furthest apart in terms of what the user wants are the two states that are represented with the light off. Namely the state of; 'kettle is on, heating up and everything is just fine, you will be drinking hot coffee in just a few minutes', and the state of; 'kettle doesn't even have any power you idiot, it will be ages before it starts boiling because that will never happen. In about ten minutes you will wonder why you are not drinking a cup of hot coffee and then you'll figure it out'. I also used to have a toaster that solved the 'not-plugged-in-you-git' problem by not keeping the toast-in handle down when there was no power. You put a slice of bread in, pressed the handle down, the toast holder slides down into the machine, you let go and instead of staying in there the bread just popped up straight away. There can be problems with misinterpretation of this, I have watched visitors to the house repeatedly banging away at the handle to press the bread down thinking that the toaster was a bit old and didn't stay down properly. Understandable they didn't immediately think to check the power supply. Computers too have on/off indicators. Sometimes they are a simple red LED, but sometimes they are more involved. There are good designs and bad designs. Early Sun computers, (and I mean early here; pre-IBM PC, when Perq was just a gleam in Sun's eye) had an awful design. A Sun workstation in that time was an industrial-strength collection of grey units connected by thick, coiled cables. The on/ off indicator was a row of red LEDs next to the power socket on the back of the system box. To show that the computer had power these LEDs would be flashed in sequence from left to right and then again from right to left, the effect was of a little bright red dot zipping from side to side continually. Some …