How many disabled people are there in the world? That depends on your definition of disability of course, but try and define disability... Is it how badly a person fits into society, or is it how badly society adjusts to the physical capabilities of the person? The first definition leads to physical adaptation/augmentation of the person. The second definition leads towards adaptation of the built environment, and to adaptation of procedures and practices within society. This breadth of definition I call the "spectrum of adaptation". Medical electronics sits at one end, disability rights campaigning at the other. My own research sits somewhere in the middle, dealing with making devices such as mobile phones adapt better to user need.