IIG

Learning to use a computer application sometimes requires considerable effort. Sonsequently, some potential users avoid difficult-to-learn applications. Other users do not learn all the relevant parts of the application, and can therefore not exploit if fully. The ease-of-learning of an application must therefore be considered in addition to its ease-of-use. Two different kinds of user interfaces (UI) are compared experimentally with regard to their ease-of-learning properties. The two different UIs employ two common design approaches. In the general-purpose (GP) approach the UI of different applications have similar structures, so that knowledge gained in one application is useful in other applications. An example of such reusable GP knowledge is, "The file and edit pull down menues are always found at the upper left corner of the application window". In the domain-oriented (DO) approach the UI is structured to represent the problem domain knowledge. A DO example is when pointing at an icom and pressing the right mouse button produces a menu of possible operations on the domain object represented by the icon. In the experiments, both a GP and a DO UI were employed with the same single 3D-shape design ("solid modeler") application. The participants were persons using computers 1-2 hours per week. They had to learn the system and perform three similar tasks with both UI's. The performance time with the DO UI was about 30% less than with the GP. The use of the DO UI also resulted in increased domain knowledge which was manifested in a better utilization of the system. Most users were also more comfortable with the DO UI. The results suggest that DO UI may generally be more suitable for casual users.