This photo shows a boiler which is used to warm up water for washing up dishes in the appartment where I used to live while in Germany. [It seemed to be fairly common for older houses to lack hot water pipes and use various electrical heating devices instead.] If washing up isn’t enough of a burden already, this device makes the process even more tedious and also does a great job of violating each and every principle that Norman has tried to teach us – namely those of affordances, visibility and feedback.
While modern water cookers manage with only one switch to turn the device on and off, this piece of machinery utilizes a weird combo-controller consisting of a turnable knob and a button. To switch the device on, one is first supposed to turn the knob approximately half a circle [although it could be turned more]. There there’s a faint red circle-symbol, one could assume, to indicate hot.
This is where the fun begins. At this stage users start wondering whether the device is on or whether there’s still something to be done. The boiler, of course, gives no feedback of its current state. The users usually try pressing the red square on the left hand’s side but though it looks like a button [and a power indicator], it’s actually just a piece of plastic.
The secret is that the center of the knob actually works as a button. Pressing it gives one of the worst tactile feedbacks one has likely ever experienced and there is no way of knowing if the button was pressed deep enough. Once the device is succesfully turned on, there is still no feedback until after a couple of minutes when the water starts to babble.
Further problems include that it can be hard to see if there is water in the tank and because the lack of indicators it’s rather easy to burn one’s fingers as well.
The simple solution of fixing the interface would include introducing a modelss switch with an automatic powercut feature, doubling as a state controller and possibly a method of turning the tank reddish when it contains hot water, akin to some modern stoves.