In fact, a significant number of user requirements for people with disabilities apply to almost any user, given the right circumstance or task context . Whether a user's hand is broken, painful due to repetitive strain injury, or permanently paralyzed, there are similar needs. Whether someone is unable to look at a screen because he is driving, or cannot see a screen because he is blind, the user requirements have much in common. Whether a user does not hear because she is talking to somebody on the phone, paying attention to her task, working in a noisy environment, or happens to be deaf is less important than the fact that users in these contexts need alternate sources of information. Any cadet that was not in the average range for a given item was asked to leave the courtyard.
Universal designs target the broadest possible range of user capabilities.
Examples of products that embody this theme include automatic doors, remote control thermostats, and velcro. Proponents of universal design do not assume that all users will be able to use all designs, but instead argue that by redefining our definition of the user, a much wider range of users can be accommodated without significant extra effort. Watch out for that Ramp Universal Design is a worthy goal, but it is important to acknowledge that there are complex customization-related HCI issues that must be resolved before it can be achieved with computers. An example of this principle in action was illustrated to us by a colleague who caught her foot at the base of a wheelchair ramp and tripped. The resulting fall produced injuries that included a sprained wrist and numbness in one hand.