Introduction

GUI component, layout and appearance, and textual bloopers are fairly easy to spot when I review software or conduct usability tests. I can usually find enough of them to make client managers feel satisfied that they got their money's worth.

However, it pays to dig a bit deeper because a more important set of bloopers usually lies just below the surface. These are bloopers that are not examples of misusing a specific GUI component, arranging components badly, or displaying incomprehensible labels and messages. Instead, they are violations of wellestablished general user interface design principles for interactive systems. They concern dynamic aspects of the software: how it works, not just how it appears.

I call these "interaction" bloopers. Although they are more abstract than the bloopers described in the previous sections, they nonetheless can make learning to use a product or service as well as accomplishing one's work once one has learned difficult, inefficient, and frustrating, thereby hampering productivity. Interaction bloopers are the focus of this chapter of the book.

User interface design principles for interactive systems have emerged from research on human perception, reading, information processing, problem solving, and motivation [Card et al., 1983; Norman and Draper, 1986; Rudisill et al., 1996], as well as from decades of experience with computers, online services, equipment control panels, and electronic appliances. Some important general design principles were presented in Chapter 1.

More comprehensive explanations of user interface design principles are available in any of several books on how to design effective interactive...