Norman, D. (1993). Chapter 4: Fitting the artifact to the person. Things that make us smart: Defending human attributes in the age of the machine (p. 77-113). Cambridge, MA: Perseus Books.
Artifacts help us keep track of the often meaningless, arbitrary tasks of daily life. Two viewpoints about artifacts exist. From a personal point of view, artifacts change our tasks rather than making us smarter or improving our memories. From a system point of view, a person and an artifact are more powerful together than either alone. The study of human capabilities and the study of artifacts are integral to one another. When designing artifacts, representations of how they work must be considered. Before advent of advanced electronic artifacts, the mechanisms of artifacts could be determined by observation and physical manipulation. These artifacts, whose properties and purposes are perceivable based on what can be observed, are categorized as surface artifacts. In recent time, artifacts have been developed using electronic technologies. By merely observing the artifact, it is difficult to ascertain how these devices work. These artifacts, which require an interface to transform information hidden within their internal representations into surface representations that can be used, are categorized as internal artifacts. Both surface and internal artifacts have advantages and disadvantages based on the appropriateness of their representations to the needs of a person. Artifacts, both physical and cognitive, must be designed so that they are easy to learn and use. As a part of the design process, both the task for which the artifact is being created and human nature must be considered. An artifact that is effectively designed will have perceived affordances that correspond with its defined purpose.
~ R. F.