This paper describes the Liveboard, a large interactive display system. With nearly one million pixels and an accurate, multi-state, cordless pen, the Liveboard provides a basis for research on user interfaces for group meetings, presentations and remote collaboration. We describe the underlying hardware and software of the Liveboard, along with several software applications that have been developed. In describing the system, we point out the design rationale that was used to make various choices. We present the results of an informal survey of Liveboard users, and describe some of the improvements that have been made in response to user feedback. We conclude with several general observations about the use of large public interactive displays.

NoteCards is an extensible environment designed to help people formulate, structure, compare, and manage ideas. NoteCards provides the user with a “semantic network” of electronic notecards interconnected by typed links. The system provides tools to organize, manage, and display the structure of the network, as well as a set of methods and protocols for creating programs to manipulate the information in the network. NoteCards is currently being used by more than 50 people engaged in idea processing tasks ranging from writing research papers through designing parts for photocopiers.

This paper describes a project underway to investigate computer support for collaboration. In particular, we focus on experience with and extensions to NoteCards, a hypertext-based idea structuring system. The forms of collaboration discussed include draft-passing, simultaneous sharing and online presentations. The requirement that mutual intelligibility be maintained between collaborators leads to the need for support of annotative and procedural as well as substantive activities.

It has often been suggested that users understand and reason about complex systems on the basis of a mental model of the system's internal mechanics. This paper describes an empirical study of how mental model knowledge is used in operating a stack calculator. One group of naive users were taught step-by-step procedures for solving typical problems on the calculator. A second group of naive users were taught the same procedures in conjunction with an explicit model of the calculator's stack mechanism. The users then solved problems on the calculator while thinking aloud. Analysis of the performance of these two groups indicates that the model had little effect in routine problem solving situations, but significantly improved performance for novel problems. Analyses of the think-aloud protocols indicate that the users employed five distinct modes of problem solving: skilled methods, problem reduction strategies, a conversion algorithm, model-based problem space search, and methods-based problem space search. Skilled methods, problem reduction strategies and the conversion algorithm were used for solving more routine problems and did not necessarily depend on mental model knowledge. Problem space search was used in the novel problems. For the model users, the states and operations of the stack mechanism served as the problem space to be searched for a problem solution. In contrast, the no-model users employed a less effective search strategy based on the recombination of pieces of known procedures. These results indicate that explicitly teaching naive users an appropriate mental model of a system can provide a psychologically effective and robust basis for operating the machine.

The computer is like a typewriter. The computer is like a filing cabinet. The computer is a personal servant ready to obey your every command.