6 Don Norman: Design Principles

Key Design Principles

Don Norman’s background is in industrial design, however his design principles are hugely important for any UX designer: Affordances, conceptual model, signifiers, mappings, discoverability and feedback. Before any product is launched, it seems to be useful to go through the list and consider the prototype in the light of these principles. I did rapid sketches to illustrate them, here they are:

Affordance is all the possibilities of the product, what it can actually do (not necessarily what it was designed to do), so for example, I can use a hammer for flattening the meat when making schnitzel, it was not designed to do it but it can, trust me, I tried!

Conceptual model is how we imagine the product works as a system, Don Norman uses the example of a cooling mechanism for a fridge and freezer, if the designer labels them as two separate circuits, the users will think they can regulate the temperature of the fridge separately from the temperature of the freezer, however, in Don Norman’s case the label was wrong and the circuit was just one, therefore it was impossible to regulate the temperature for only the freezer for example.

Signifiers are any ‘signals’ (sound, movement or visual signs) that indicate what affordances product has, what it can do/does. For example a blue colour and ‘C’ or ‘cold’ sign on a water tap signalizes that the tap should not run hot water.

Mapping is a relationship between the control and action of the product. For example, when I press a turn on button on remote control, the TV turns on. When I press a light switch, the light goes on. When I was younger my dad installed two new light switches in the corridor of our apartment, the upper one was for the kitchen and the lower one for the corridor, after a decade, we still occasionally confuse which one is which despite we coloured one. Only recently I realized that the problem we encountered was a problem of mapping.

Constraints are an important part of a design of a product which prevent you from doing the action that you are not supposed to do. For example, a washing machine has a lock that is uses during the washing cycle, you cannot open it during the cycle, for obvious safety reasons, and it only unlocks after the cycle is finished.

Discoverability is how easy you can discover about the functions and use of a product in its current state. If you have a remote control with too many buttons/functions, it will be really hard and time consuming job to navigate what are they for or how to do one selected task, most probably, you will give up and just use few basic ones.

Feedback is a reaction of a product after our action. If we put the oven on, it starts to heat up. If we turn on the TV, we can see the picture and and hear the sound of a program on TV. If we set an alarm on our phone, we can see a little clock which indicates that an alarm is set, etc.

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