Central message

There are two broad categories of artifacts, surface and internal. Surface artifacts have only surface representations, that is, they contain only visible representations of symbols. Internal artifacts contain information that is not know by, or visible to, the user. In order for a user to make sense of an internal artifact there must be an interface, a surface representation, between the user and the internal representation of the internal artifact. Problems arise when the artifact's surface representation does not match the person's surface representation.

In order to minimize problems with technology and to make technology work for people artifacts must be designed with people in mind. Norman discusses ill-fitting interfaces from the proper use of graphs and charts to the design of voice messaging systems. To minimize problems with artifacts they should be designed on our terms. That is, the technology should be designed to meet the needs of the user. Users must not be required to change to meet the needs of the technology.

Application

Proper application of a technology's affordances (its possible functions) allows the designer to create an artifact that people can use in a manner that fits their needs. Voice messaging, as an example, utilizes only a narrow range of the telephone system's affordances. Users of voice messaging systems are often frustrated when they are unable to talk with a person until they have listened to countless messages and pressed quite a few buttons. Voice messaging systems are designed to meet the needs of the sponsor, e.g. corporation, not the user. Norman says this condition of mismatching needs results when the people benefiting from the technology (the sponsor) are not the same people forced to deal with the technology's deficits (the users).

Value

When artifacts are designed to meet the needs of the users and those artifacts take advantage of the affordances of the technology the person and the artifact become an effective system. The person and the artifact become smarter than the person or the artifact.