Feedback is critical in any form of interaction. In a largely digital device such as a smartphone or laptop this is principally provided via visual feedback in the screen. Physical design can help by providing additional forms of feedback directly from the physical controls themselves.
The following diagram shows the different forms of common feedback.
- Loop (A) – This denotes direct feedback from the physical properties of the device itself. For example, if you twist a knob, you feel the knob move. This is the true device ‘unplugged’, the feedback you would experience if the controls were entirely disconnected from the underlying digital or electronic system.
- Loop (B) – This is where the logical system in some way mimics direct physical interaction. For example, the twist knob in BMW cars has tangible feedback that makes it appear to have a number of click stops, but this is provided using a motor. From the user point of view this may appear to be indistinguishable from loop (A), so it may be worth analysing this level of feedback as a form of semi-unplugged state. However, even very small delays with this kind of feedback make a substantial difference in the experience.
- Loop (C) – This is the normal digital feedback loop through screen, lights, sounds etc. If this is fast enough, and the connection clear, the user will begin to associate this with their physical actions in a direct way.
- Loop (D) – Some devices control some form of physical system: for example a kettle boils water, or the washing machine washed clothes. This may be evident, say from the sound of water boiling or seeing the foam moving through the glass front of the washing machine.