"The discussion around invisible design often talks about using sensors and tangible interfaces instead of visual interfaces," says Timo Arnall on his blog. "But these systems are not inherently simpler or more familiar. They have their own material qualities with edges and ‘grain’ that need to be understood and learnt. Their invisibility can cause confusion, even fear, and they often increase unpredictability and failure... So it’s not useful to say that UI is ‘disappearing’ into sensing, algorithms and tangible interfaces, when we don’t fully understand them as UI yet."