If you're more susceptible to interruption, you do more out of the box thinking.

The designer shouldn't think of a simple dichotomy between errors and correct behavior; rather, the entire interaction should be treated as a cooperative endeavor between person and machine, one in which misconceptions can arise on either side.

It was always amusing to be inside Apple and read what journalists said we were doing

Knowing how people will use something is essential

User-centered design means working with your users all throughout the project.

A challenge to the designers of the world: Make signs unnecessary.

The world is complex, and so too must be the activities that we perform. But that doesn't mean that we must live in continual frustration. No. The whole point of human-centered design is to tame complexity, to turn what would appear to be a complicated tool into one that fits the task, that is understandable, usable, enjoyable.