Design doesn't have to complicated, which is why this guide to human-centered design shows that usability is just as important as aesthetics. Even the smartest among us can feel inept as we fail to figure out which light switch or oven burner to turn on, or whether to push, pull, or slide a door. The fault, argues this ingenious -- even liberating -- book, lies not in ourselves, but in product design that ignores the needs of users and the principles of cognitive psychology.