real world columns: off and on

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 allowing the user to keep the toast handle pressed 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. Understandably 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 gray 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 technician somewhere had obviously said, ‘Hey, if we put a line of LEDs in we could do this it would look really cool.’ Fortunately it was tucked away on the back of the unit. Unfortunately these units were often placed back-to-back in shared office spaces so that the user could see the LEDs on the back of the unit opposite, with the result that their gaze was being continually distracted by whizzing bright, red lights in their peripheral vision. Much later, a Silicon Graphics machine (was it the Indigo?) had a different approach; one LED that indicated the machine’s status by its color: red = power on, yellow = booting up, green = ready, black = ‘not-plugged-in-you-git’. In my next book (‘Design for New Media’ Addison-Wesley 2004, ISBN 0201-596091) I mention the standby-mode indication in the Apple G4s when they were first introduced. It was on / off with an edge; the light ‘pulsed’ on and off like something from a 50s sci-fi movie. The communication was both functional and emotional. Not just ‘I am on and in standby mode’ but ‘I am super powerful and am waiting like a crouching tiger for your next command.’

By far the most annoying ‘is it on?’ syndrome occurs when setting things up to switch on in the future, things like video recorders and alarm-clocks. Especially unfamiliar and cheap digital alarm-clocks in hotel rooms. Is it going to wake me up at 7:30 so I can finish my presentation slides or not? As well as problems with things being on or off in the future there are also usability problems with things having being on or off in the past. Heat falls into this category; the clothes-iron switched off and put in the cupboard, the electric ring on the cooker that was on a minute ago. The indicator light is off, but that is not the important fact as far as the user is concerned, the user should be told if it is hot or not and there is not a one-to-one relationship between being on and being hot. This problem is elegantly solved by the Braun hair-curler which has a nice heat-sensitive blob on the end that changes color according to whether it is hot or cold, irrespective of power being on or off. Now that really is a bit of interaction design guaranteed to make your hair curl!