Virtual reality (VR) is typically defined in terms of technological hardware. This paper attempts to cast a new, variable-based definition of virtual reality that can be used to classify virtual reality in relation to other media. The defintion of virtual reality is based on concepts of "presence" and "telepresence," which refer to the sense of being in an environment, generated by natural or mediated means, respectively. Two technological dimensions that contribute to telepresence, vividness and interactivity, are discussed. A variety of media are classified according to these dimensions. Suggestions are made for the application of the new definition of virtual reality within the field of communication research.

Multimodal interactive systems support multiple interaction techniques such as the synergistic use of speech and direct manipulation. The flexibility they offer results in an increased complexity that current software tools do not address appropriately. One of the emerging technical problems in multimodal interaction is concerned with the fusion of information produced through distinct interaction techniques. In this article, we present a generic fusion engine that can be embedded in a multi-agent architecture modelling technique. We demonstrate the fruitful symbiosis of our fusion mechanism with PAC-Amodeus, our agentbased conceptual model, and illustrate the applicability of the approach with the implementation of an effective interactive system: MATIS, a Multimodal Airline Travel Information System. KEYWORDS: Multimodal interactive systems, software design, software architecture, I/O devices, interaction languages, data fusion. INTRODUCTION One new challenge for Human Computer In...

mproving the quality of hypermedia design and reducing its cost is an important challenge for the information industry. One way to tackle the problem is to provide hypertext designers with appropriate development environments. Hypertext engineering environments that provide sets of integrated tools boost designers ’ efficiency and effectiveness.

Peripheral information is information that is not central to a person's current task, but provides the person the opportunity to learn more, to do a better job, or to keep track of less important tasks. Though peripheral information displays are ubiquitous, they have been rarely studied. For computer users, a common peripheral display is a scrolling text display that provides announcements, sports scores, stock prices, or other news. In this paper, we investigate how to design peripheral displays so that they provide the most information while having the least impact on the user's performance on the main task. We report a series of experiments on scrolling displays aimed at examining tradeoffs between distraction of scrolling motion and memorability of information displayed. Overall, we found that continuously scrolling displays are more distracting than displays that start and stop, but information in both is remembered equally well. These results are summarized in a set of design recommendations.

Since the early 1960’s, researchers have built a number of programming languages and environments with the intention of making programming accessible to a larger number of people. This article presents a taxonomy of languages and environments designed to make programming more accessible to novice programmers of all ages. The systems are organized by their primary goal, either to teach programming or to use programming to empower their users, and then, by each system’s authors ’ approach, to making learning to program easier for novice programmers. The article explains all categories in the taxonomy, provides a brief description of the systems in each category, and suggests some avenues for future work in novice programming environments and languages.

At first glance it seems absurd that busy people doing important jobs should want their computers to interrupt them. Interruptions are disruptive and people need to concentrate to make good decisions. However, successful job performance also frequently depends on people's abilities to (a) constantly monitor their dynamically changing information environments, (b) collaborate and communicate with other people in the system, and (c) supervise background autonomous services. These critical abilities can require people to simultaneously query a large set of information sources, continuously monitor for important events, and respond to and communicate with other human operators. Automated monitoring

The purpose of this article is to review where we stand with regard to modeling the kind of cognition involved in human-computer interaction. Card, Moran, and Newell's pioneering work on cognitive engineering models and explicit analyses of the knowledge people need to perform a procedure was a significant advance from the kind of modeling cognitive psychology offered at the time. Since then, coordinated bodies of research have both confirmed the basic set of parameters and advanced the number of parameters that account for the time of certain component activities. Formal modeling in grammars and production systems has provided an account for error production in some cases, as well as a basis for calculating how long a system will take to learn and how much savings there is from previous learning. Recently, we were given a new tool for modeling nonsequential component processes, adapting the "critical path analysis " from engineering to the specification of interacting processes and their consequent durations.

The paper argues that new approaches for delivering HCI knowledge from theory to designers will be necessary in the new millennium. First the progress made developing cognitive theories of interaction and their impact on the design process is reviewed. Direct application of current cognitive theories to design has been limited by scalability problems. This has led to bridging models that attempt to deliver insights from theory to design models in a more tractable manner. However, these too have met with limited success. An alternative is to represent HCI knowledge as claims and adopt the task-artefact approach to design in which theories are embedded in well-designed artefacts and explained to designers as psychologically motivated design rationale. Claims are proposed as a possible bridging representation that may enable theories to frame appropriate recommendations for designers and, vice versa, enable designers to ask appropriate questions for theoretical research. However, claims provide design advice grounded in specific scenarios and examples, which 1 limits their generality. Hence claims are their associated artefacts needs to be generalised so

people. This calls for new models of the interaction between humans and robots, taking advantage of human social and communicative skills. Furthermore, human-robot relationships must be understood in the context of use of robots, and based on empirical studies of humans and robots in real settings. This paper discusses social aspects of interaction with a service robot, departing from our experiences of designing a fetch-and-carry robot for motionimpaired users in an office environment. We present the motivations behind the design of the Cero robot, especially its communication paradigm. Finally, we discuss experiences from a recent usage study, and research issues emerging from this work. A conclusion is that addressing only the primary user in service robotics is unsatisfactory, and that the focus should be on the setting, activities and social interactions of the group of people where the robot is to be used. Keywords: service robots, human-robot interaction, social robots, speech interfaces and collaborative aspects of interaction with a service robot 1.

The current variety of alternative approaches to usability evaluation methods (UEMs) designed to assess and improve usability in software systems is offset by a general lack of understanding of the capabilities and limitations of each. Practitioners need to know which methods are more effective and in what ways and for what purposes. However, UEMs cannot be evaluated and compared reliably because of the lack of standard criteria for comparison. In this article, we present a practical discussion of factors, comparison criteria, and UEM performance measures useful in studies comparing UEMs. In demonstrating the importance of developing appropriate UEM evaluation criteria, we offer operational definitions and possible measures of UEM performance. We highlight specific challenges that researchers and practitioners face in comparing UEMs and provide a point of departure for further discussion and refinement of the principles and techniques used to approach UEM evaluation and comparison. 1.