User interface (UI) design rules and guidelines, developed by early HCI gurus and recognized throughout the field, were based on cognitive psychology (study of mental processes such as problem solving, memory, and language), and early practitioners were well informed of its tenants. But today, practitioners with backgrounds in cognitive psychology are a minority, as user interface designers and developers enter the field from a wide array of disciplines. HCI practitioners today have enough experience in UI design that they have been exposed to UI design rules, but it is essential that they understand the psychological basis behind the rules in order to effectively apply them. Jeff Johnson, the author of Morgan Kaufmann's successful GUI Bloopers presents the first practical guide to help designers and developers understand the psychology behind these tried and tested user interface design rules. Johnson applies his engaging, often humorous style--already well known to designers and developers--to describe, in practical terms, the psychological basis for each rule, the value of understanding the reasons for each rule, how they interact in actual systems, and the tradeoffs designers have to make when confronted with conflicting rules or with tight budgets and deadlines. Johnson is not attempting to redefine rules--he is simply taking the existing rules and presenting them in a practical way for current practitioners who either do not have a background in psychology or took the classes so long ago, the fundamentals have faded--tantamount to if you learn a language but don't practice it, the nuances fade. The book will explain what interactive system designers and usability testers need to know about human perception and cognition. It will give designers just enough of a background in psychology that user-interface design guidelines make intuitive sense rather than being just a list of rules to learn and follow. * The first practical, all-in-one source for practitioners on user interface design rules and why, when and how to apply them. * Provides just enough background into the reasoning behind interface design rules that practitioners can make informed decisions in every project. * Gives practitioners the insight they need to make educated design decisions when confronted with tradeoffs, including competing design rules, time constrictions, or limited resources.