However, the basic application model that requires each document to belong to a specific application at any given time, still rules. The application model and a person's activities as the basic assumption for it, will eventually be left behind. The overall goal a person pursues will become the new starting point for building better suited, more usable computer systems. However, the user population is changing rapidly. That other areas for computing arise, besides offices and factories, is clear.
More computers find their way into the homes of families each year.
This requires, he states, some formal models of people and of interaction, models that need only be approximations, but that are precise enough to lead to design rules. Create a science of user-centered design. Take interface design seriously as an independent and important problem. Not many people are likely to be specialists regarding all this knowledge. Separate the design of the interface from the design of the system.