One began to sympathize with the dog whose muzzle is removed at the end of a prolonged Muzzling Order, and who does not quite know what to do with himself. ?span>C. G. Grey (in Jane's All the World's Aircraft 1919) If you start with the goal of making interfaces as simple as you can, taking account of our limitations and exploiting our abilities, there are two things you have to do. One is to understand what we can and cannot do, to study the maps of human thought presented by the science of cognitive psychology and see where they lead to the engineering discipline of cognetics. This book has followed one major highway from the map, one that leads from research into the division of abilities between our cognitive conscious and our cognitive unconscious, to an understanding that we have but one locus of attention and a recognition of the central nature of habit formation in how we react to various interface methodologies. We also learn that individual differences are small when dealing with habituation, in contrast to the large differences between individuals in other regards. From the science, we learn that modes, long recognized as undesirable, are at the heart of some of the most vexing irritants in current computer interface paradigms. Any complete cure requires that an interface be modeless and is enhanced by as much monotony as we can design in. The uniformity among individuals is exploited. Productivity is improved by our being able to spend less time doing a task, and this observation leads to the interface version of the classical time-and-motion study, the quantitative GOMS analysis. GOMS leads to a feel for what details make interfaces slow and fast to use and leads to the question of how fast and efficient an interface can be and to the need for quantitative measures of efficiency. Having gone down the road of understanding human capabilities, we then look at our present computer equipment and how we use it, finding a small set of elementary actions and methods that apply to a broad and varied landscape of applications. This uniformity can also be exploited. We are led by our studies in an unfamiliar direction that turns out to be a shorter path to usability than the standard methods provide. Fast search methods combine with the elimination of unnecessary mechanisms, such as file names and URLs, hierarchical file structures, and applications, to allow us to take speedy shortcuts. The ZIP allows us to fly over the terrain, to see more, and to get there more quickly. We have also taken a few side paths, for example, to see how cables can be made easier to use. This book has many lacunae; for example, I am sure I have missed prior work that I should have known about, and I may have failed to correctly attribute to their originators ideas that were not my own. Parts of this book lay out areas where, had I the resources, I would have performed experiments to test my conclusions and guesses. Please consider these areas as invitations for research. Thank you for having read this book and for joining me on a quest for more humane interfaces. Where our journey has crossed untrodden ground, I may have taken a wrong turn here and there. Nonetheless, I am convinced that my compass is a good one and that my overall direction is correct. Starting from what we know of human cognition, we have been led to fundamental changes in the design of human-machine interfaces. Nothing less will do. | 
