When a device as simple as a door has to come with an instruction manual—even a one-word manual—then it is a failure, poorly designed. - Donald Norman

Serious accidents are frequently blamed on "human error." Yet careful analysis of such situations shows that the design or installation of the equipment has contributed significantly to the problems. The design team or installers did not pay sufficient attention to the needs of those who would be using the equipment, so confusion or error was almost unavoidable.

The major problems facing the development of products that are safer, less prone to error, and easier to use and understand are not technological: they are social and organizational.

In their work, designers often become expert with the device they are designing. Users are often expert at the task they are trying to perform with the device. [...] Professional designers are usually aware of the pitfalls. But most design is not done by professional designers, it is done by engineers, programmers, and managers.