An input device model of interactive systems design

This dissertation describes a model of input devices, a model for designing the human input interface to an interactive application, and a development environment incorporating both. Until recently research in user interface design has focused on constructing the graphic output component of the interface. Previous efforts to formalize design of the input component have met with limited success because the models lacked human factors criteria. This dissertation describes a model of input devices that builds on prior models by including human factors attributes. The model describes a wide variety of input devices including input hardware, virtual devices on input hardware, and graphical devices. Input devices are described using four basic components: a physical package, actions, input domain, and output domain. Complex devices are described as composites of other devices. The design process is one of selecting actions on devices to represent a sequence of conceptual task operations. A task description is used as a natural physical analog for the interface design. Selection begins with the most direct representation possible, adding representations and relaxing constraints when necessary. The process has two phases: a matching phase and a sequencing phase. The matching phase finds all actions on devices that match each task operation's functional and human factors requirements. The sequencing phase constructs sequences of actions to represent the entire task. The selection process considers general design constraints, such as device availability. Human factors criteria, such as compatibility between task, action, and feedback, also influence the process. Both the model of input devices and the design process are implemented in an interactive environment. The environment includes a set of knowledge-based tools that allow a designer to interactively describe a task, specify design constraints, and automatically apply the design process. The environment demonstrates the power of the model of input devices to support the design of effective use interfaces. It is an extensible environment for exploring both the model and the design process.