2. Perception

Here is a little test.

There are two shapes below that need to be given a name. The two names are 'KIKI' and 'BOUBA'. Which one has the name KIKI?

This test was created way back in 1929 to show how people connect sounds to shapes. Most people choose the starry shape to have the name 'KIKI'. When asked, people say the sound KIKI is very sharp and so it belongs to a sharp object whilst the sound BOUBA is somehow a relaxing, smooth sound.

The point, is that people have an in-built perception of the world and it is best to design an interface that is harmonious with that perception, otherwise the interface feels 'wrong' and confusing.