Abstract: A multiple view system uses two or more distinct views to support the investigation of a single conceptual entity. Many such systems exist, ranging from computer-aided design (CAD) systems for chip design that display both the logical structure and the actual geometry of the integrated circuit to overview-plus-detail systems that show both an overview for context and a zoomed-in-view for detail. Designers of these systems must make a variety of design decisions, ranging from determining layout to constructing sophisticated coordination mechanisms. Surprisingly, little work has been done to characterize these systems or to express guidelines for their design. Based on a workshop discussion of multiple views, and based on our own design and implementation experience with these systems, we present eight guidelines for the design of multiple view systems.

Abstract: A user interface software tool helps developers design and implement the user interface. Research on past tools has had enormous impact on today's developers—virtually all applications today are built using some form of user interface tool. In this article, we consider cases of both success and failure in past user interface tools. From these cases we extract a set of themes which can serve as lessons for future work. Using these themes, past tools can be characterized by what aspects of the user interface they addressed, their threshold and ceiling, what path of least resistance they offer, how predictable they are to use, and whether they addressed a target that became irrelevant. We believe the lessons of these past themes are particularly important now, because increasingly rapid technological changes are likely to significantly change user interfaces. We are at the dawn of an era where user interfaces are about to break out of the “desktop” box where they have been stuck for the past 15 years. The next millenium will open with an increasing diversity of user interface on an increasing diversity of computerized devices. These devices include hand-held personal digital assistants (PDAs), cell phones, pages, computerized pens, computerized notepads, and various kinds of desk and wall size-computers, as well as devices in everyday objects (such as mounted on refridgerators, or even embedded in truck tires). The increased connectivity of computers, initially evidenced by the World Wide Web, but spreading also with technologies such as personal-area networks, will also have a profound effect on the user interface to computers. Another important force will be recognition-based user interfaces, especially speech, and camera-based vision systems. Other changes we see are an increasing need for 3D and end-user customization, programming, and scripting. All of these changes will require significant support from the underlying user interface sofware tools.

Abstract: Design activity has recently attempted to embrace designing the user experience. Designers need to demystify how we design for user experience and how the products we design achieve specific user experience goals. This paper proposes an initial framework for understanding experience as it relates to user-product interactions. We propose a system for talking about experience, and look at what influences experience and qualities of experience. The framework is presented as a tool to understand what kinds of experiences products evoke.

Abstract: A challenge for human-computer interaction researchers and user interf ace designers is to construct information technologies that support creativity. This ambitious goal can be attained by building on an adequate understanding of creative processes. This article offers a four-phase framework for creativity that might assist designers in providing effective tools for users: (1)Collect: learn from provious works stored in libraries, the Web, etc.; (2) Relate: consult with peers and mentors at early, middle, and late stages, (3)Create: explore, compose, evaluate possible solutions; and (4) Donate: disseminate the results and contribute to the libraries. Within this integrated framework, this article proposes eight activities that require human-computer interaction research and advanced user interface design. A scenario about an architect illustrates the process of creative work within such an environment.

Abstract: The level of end-user satisfaction with information technology (IT) has widely been accepted as an indicator of IT success. The present research synthesizes and validates the construct of IT end-user satisfaction using a meta-analysis. It accomplishes this by analysing the empirical results of 45 end-user satisfaction studies published between 1986 and 1998 and by focusing on relationships between end-user satisfaction and nine variables: perceived usefulness, ease of use, user expectations, user experience, user skills, user involvement in system development, organizational support, perceived attitude of top management toward the project and user attitude toward information systems (IS) in widely divergent settings. The present analysis found positive support for the influence of all nine variables on end-user IT satisfaction but to varying degrees. The most significant relationships were found to be user involvement in systems development, perceived usefulness, user experience, organizational support and user attitude toward the IS. This has implications for IS analysis and design as well as user training and the development of training support packages.

Abstract: This paper considers appropriate research methodologies for the development of Universal Usability. It is written from the viewpoint of research which has the long term objective of developing technological systems for everyone, including people with disabilities. It considers whether new research paradigms are appropriate and how they are different from those used within traditional technological research. It suggests the development of a new paradigm of “User Sensitive Inclusive Design” which includes people with disabilities within a User Centred Design methodology, and recommends a collaborative approach to the development of such a methodology.

Abstract: ti m e Conception Completion Functional Specifications Content Requirements Interaction Design Information Architecture Visual Design Information Design Interface Design Navigation Design Site Objectives User Needs User Needs: externally derived goals for the site; identified through user research, ethno/techno/psychographics, etc. Site Objectives: business, creative, or other internally derived goals for the site This picture is incomplete: The model outlined here does not account for secondary considerations (such as those arising during technical or content development) that may influence decisions during user experience development. Also, this model does not describe a development process, nor does it define roles within a user experience development team. Rather, it seeks to define the key considerations that go into the development of user experience on the Web today. task-oriented information-oriented 30 March 2000 © 2000 Jesse James Garrett http://www.jjg.net/ia/

Abstract: Speech-based user interfaces are growing in popularity. Unfortunately, the technology expertise required to build speech UIs precludes many individuals from participating in the speech interface design process. Furthermore, the time and knowledge costs of building even simple speech systems make it difficult for designers to iteratively design speech UIs. SUEDE, the speech interface prototyping tool we describe in this paper, allows designers to rapidly create prompt/response speech interfaces. It offers an electronically supported Wizard of Oz (WOz) technique that captures test data, allowing designers to analyze the interface after testing. This informal tool enables speech user interface designers, even non-experts, to quickly create, test, and analyze speech user interface prototypes.

Abstract: The purpose of this paper is to describe theory and research from several disciplines, not generally understood by web developers, which the author believes are applicable to creating engaging and immersive ecommerce environments. These disciplines include aesthetic experience (AE), Flow, landscape assessment, and a proposed aesthetic framework. The link between these different areas is aesthetics, specifically aesthetic experience. Developing ecommerce sites based on models related to aesthetics can provide an organized means of designing engaging and immersive sites which are more likely to lead to positive user experience. IT personnel commonly understand the psychological aspects of human-computer interaction (HCI). Similarly, the toolbox of every web designer and Internet system architect should include knowledge of the concepts related to engaging and immersive environments.

Abstract: A method for creating personalized user profiles using a client computer. A client computer executes a method which monitors user activities and collects content and context information based on the monitored user activities. The client computer processes the content and context information to determine concepts of interest to the user and the user's level of interest in the concepts. Information related to the concepts and the user's interest level associated with the concepts is used to create a personalized profile for the user on the client computer.

Abstract: Introduction Eric Bergman, Sun Microsystems A high level overview of the burgeoning field of information appliance and consumer product interaction design. Provides a brief commentary on the various chapters in the book, and the themes that bind them together. A Conversation with Don Norman Eric Bergman, Sun Microsystems & Don Norman, Nielsen Norman Group Don Norman discusses his notion of the "Invisible Computer" and why he believes that information appliances are the best alternative to the complexity of current interactive devices. Design Considerations for Information Appliances Mike Mohageg & Annette Wagner, Sun Microsystems Two senior members of the Sun Microsystems Consumer User Experience Group describe the high level issues that the team considers when designing products for consumer users. The chapter has a special focus on set top box and internet phone appliances. Designing Information Appliances at Netpliance Scott Isensee, Ken Kalinoski, Karl Vochatzer Explains the "Netpliance" philosophy, and the design challenges and processes involved in creating the total user experience - hardware software and services - for a line of information appliances. This chapter has a particular focus on scaling content and UI to support devices of varying capabilities. Designing the Palm Pilot: A Conversation with Robert Haitani Eric Bergman, Sun Microsystems & Robert Haitani, Handspring Robert Haitani, design lead for the original Palm Pilot project, talks about the evolution of the product from a simple block of wood to perhaps the first and arguably most commercially successful information appliance. Interaction Design and Usability of Microsoft Windows CE Sarah Zuberec, Microsoft Corporation Focuses on how Windows CE was designed and tested, and the challenges Microsoft faced in retaining a Windows identity while evolving to fit in a consumer device environment. The EPOC User Interface in the Psion Series 5 Nick Healey, Slash Design Ltd. The author provides guidance about design considerations and processes as applied to personal digital assistants with issues and examples from the Psion line of personal digital assistants. Designing Mobile Phones and Communicators at Nokia Kaisa Vaananen-Vainio-Mattila and Satu Ruuska, Nokia Research A view into the challenges of designing for users who don't have time, attention, or a display that users of many other small devices might expect. The authors provide case studies that illustrate Nokia's design and evaluation methodologies, as well as the design and usability issues raised in their target environment. Designing the User Interface for a Vehicle Navigation System: A Case Study Aaron Marcus, Aaron Marcus & Associates A case study of a vehicle navigation system designed for Motorola. Provides interesting insight into the challenges of designing for users on the move. Interactive plush characters as social interfaces Erik Strommen, Microsoft Corporation An overview of the theory and design behind the development of Microsoft's interactive plush toys, with case studies of different toys developed for different ages, including how user testing with children influenced the product's design. Design Lessons from Interactive Games Chuck Clanton, Aratar An analysis of games that explores how good design creates a seductive experience with an inviting challenge ramp and compelling game play. The author discusses the implications for consumer oriented user interfaces in non-game environments. Interactive Persuasion with Netsmart Devices B.J. Fogg, Persuasive Technology Lab, Stanford University Discusses how netsmart devices-- specialized, embedded, and networked computer technologies --might be integrated into people's daily routines to motivate and persuade.

Abstract: Numerous techniques exist for ensuring the usability of information and communication technology for use at work, but will these techniques be applicable in the very different context of home use? This paper reviews the techniques that are now routinely used in the design of technology for the office to identify a new research agenda to facilitate good design of information and communication technology in the home.

Abstract: This paper describes a method for an information filtering agent to learn user's preferences. The proposed method observes user's reactions to the filtered documents and learns from them the profiles for the individual users. Reinforcement learning is used to adapt the most significant terms that best represent user's interests. In contrast to conventional relevance feedback methods which require explicit user feedbacks, our approach learns user preferences implicitly from direct observations of browsing behaviors during interaction. Field tests have been made which involved 10 users reading a total of 18,750 HTML documents during 45 days. The proposed method showed superior performance in personalized information filtering compared to the existing relevance feedback methods.

Abstract: A method for assisting a user in learning is provided. The method may comprise receiving performance information of a user after the user uses an interactive learning appliance (21). The user performance information is generated by the user's use of the interactive learning appliance (21) which is adapted to educate the user about one or more predetermined subjects. The performance information, which may be in the form of a user log file, may be received at a server computer (17) from a site (16) where the user is present.

Abstract: People use tools to achieve desired results. Goal-directed behavior is a human characteristic. While in rare instances someone might speak of being "guided" by tools, we do not generally think of tools as having goals. We would like our tools to be able to suggest what they are for (in the words of Norman [3], to offer affordances), but we do not expect them to control what we do. We hope to provide craftsmen with tools that enable them to engage in conversations with their materials. In an ideal world, the mantra for our tools would be "My purpose is to serve you." Every tool should feel like it was custom designed for you, the user in your context.

Abstract: Software architectures, platforms, and data constructs are disclosed which provide a system for enabling a non-technical or lay user to perform discrete technical tasks necessary to build a complete network-based, multiuser application. The system also allows the user to have a uniform user experience throughout development of the application. For example, the platform can be used to construct and maintain an Internet or online Web site capable of handling e-commerce transactions or can be used to develop a customer relationship management system. A software architecture is described that enables many users to perform a variety of tasks via a wide-area network, such as an enterprise network or the Internet. The architecture has several services, systems, and an extensible database for storing data objects. The database has an underlying structure referred to as a schema that can be extended with previously undefined attributes without having to alter the basic format of the schema. The architecture also includes an integrated platform that enables each of the users to perform the tasks by controlling interaction or communication between the services and systems, and the extensible database.

Abstract: Preface. Part I. Participatory Design. 1. Accelerated Business Concept Modeling: Combining User Interface Design with Object Modeling Simon McGinnes and Johnny Amos. Introduction. Mental Models, Business Concepts, and Object Models. Barriers and Enablers. Framework. Dynamic System Development Method (DSDM). Facilitated Workshops. Accelerated Business Concept Modeling. Philosophy. Integrating User Interface Design and Modeling. Reducing Design Choice. Experience in Commercial Organizations. Introduction. Experiment. Qualitative Results. Quantitative Results. Combining the Results. Possible Further Research. Conclusion. References. Part II. Scenario- and Task-Based Design. 2. Scenarios, Objects, and Points of View in User Interface Design Mary Beth Rosson and John M. Carroll. Introduction. Designing with Objects. Responsibility-Driven Design. Task-Object Interactions in Scenario-Based Design. An Example: The Virtual Science Fair. Developing Basic User Interaction Scenarios for the Virtual Science Fair. Elaborating Virtual Science Fair Scenarios with an Object Perspective. Trade-offs Suggested by Objects and Their POVs. User Interactions in the Virtual Science Fair Scenarios. Trade-offs in Object-Oriented User Interaction. Discussion. Model-First Design. Refining the Object Metaphor. Tools for Scenario-Based Design. Conclusion. References. 3. Designing with Idiom Mark van Harmelen. Introduction. Idiom. Designing and Specifying User Interfaces with Idiom. Early Work with Users and the Domain. Scenario Generation. Coarse-Grained Task Modeling. Interaction Exploration Using Sequence Diagrams. Describing Tasks and Identifying Referents. The Domain Model. Visualization Using Sketches. Formulating Abstract Descriptions of the Interactive System. The Core Model. Finer-Grained Task Models. The View Model. Concrete User Interface Design. Interaction Sequences. Prototypes. Generation of Use Cases. Conclusions. How Does Idiom Perform?. Idiom as an Accommodating Framework. Acknowledgments. References. 4. Entity, Task, and Presenter Classification in User Interface Architecture: An Approach to Organizing HCI Practice John M. Artim. Introduction. CHI97 Workshop Framework. Organizing Descriptions. Architecture. System Architecture. User Interface Architecture. An ETP-Based User Interface Architecture. Key Processes in Practice. User Task Modeling: Requirements. Extracting a Domain Concept Description: Analysis. User Interface Design. Implications for Usability Testing. System Design and Implementation. ETP Summary. ETP and Ontological Drift. Conclusion. Acknowledgments. References. Part III. Use Case Based Design. 5. User Interface Design in the Rational Unified Process Philippe Kruchten, Stefan Ahlqvist, and Stefan Bylund. The Rational Unified Process. The Structure of the Rational Unified Process. Workers. Activity. Steps. Artifacts. Workflow. Additional Process Elements. Guidelines. User Interface Design in the Rational Unified Process. Use Cases. Analysis Model and Boundary Classes. Workflow. Worker: The User Interface Designer. Artifact: The Use Case Storyboard. Properties. Timing. Responsibility. Activity: User Interface Modeling. Artifact: The User Interface Prototype. Purpose. Timing. Responsibility. Activity: User Interface Prototyping. Guidelines: Use Case Storyboard. Describing the Flow of Events-Storyboard. Desired Guidance. Average Attribute Values and Volumes of Objects. Average Action Usage. Summary of the Flow of Events-Storyboard. Creating Boundary Class Diagrams. Creating Boundary Object Interaction Diagrams. Complementing the Diagrams of a Use Case Storyboard. Capturing Usability Requirements on the Use Case Storyboard. Referring to the User Interface Prototype the Use Case Storyboard. Conclusion. References. 6. Wisdom--Whitewater Interactive System Development with Object Models Nuno Jardim Nunes and Joao Falcao e Cunha. Introduction. The Working Context: SSDs and Lightweight Techniques. Chapter Structure. Wisdom: Process, Architecture, and Notation. The Wisdom Process. The Wisdom Architecture. The Wisdom Notation. The Wisdom Method. Requirements Workflow. 2 Analysis Workflow. Design Workflow. Wisdom and the CHI97 Metamodel. Conclusion. Acknowledgments. References. 7. Structure and Style in Use Cases for User Interface Design Larry L. Constantine and Lucy A. D. Lockwood. Introduction. Use Cases Undefined. Concrete and Essential Use Cases. Notation. Usage-Centered Design. A Usage-Centered Process. Task Modeling, Scenarios, and Use Cases. Use Case Decomposition. Use Case Narrative Style and User Interface Design. Language and Structure in Models. Common Narrative Styles. Task Goals and User Intentions. Structured Essential Use Cases. Identity and Purpose. Relationships. Process. Elements of Style in Structured Essential Narratives. Objects. Included Use Cases. Conditional Interaction. Partial Ordering. Extensions. Use Case Maps. Representing Use Cases. Representing Relationships. Business Rules. Recommendations. References. Part IV User-Centered Design. 8. A User-Centered Approach to Object-Oriented User Interface Design Jan Gulliksen, Bengtransson, and Magnus Lif. Introduction. Usability and User-Centered Design. Design Methods and Tools. Learning Object-Oriented Design. Prototyping and Iterative Design. System Development Processes. ISO 13407: Human-Centered Design Processes for Interactive Systems. The Rational Unified Process. The Dynamic Systems Development Method. Design in Context. The Usability Designer. User Interface Modeling. Experiences in Promoting User-Centered Design at the Swedish National Tax Board. Methods of Enhancing the User Interface Design Process. Introducing User-Centered Design. Obstacles to the Development Work. Discussion. References. 9. Toward Unified Models in User-Centered and Object-Oriented Design William Hudson. Introduction. Why Bring User-Centered Design to UML? Why Not Another New Method? How Can UML Be Made User-Centered? Survey of User-Centered Techniques and Methods. Description of the Survey. The User-Centered Top Ten. User-Centered Techniques. User-Centered Methods. The Informal UML Method. Perspectives. Confusion over Use Cases. No Separation of User and Domain Models. No Deliberate User Interface Design. Lack of Contextual Information. No Usability Evaluation. A Unified Approach to Use Cases and Scenarios. Goal-Based Use Cases. Scenarios versus Use Cases. Context of Use. Essential Use Cases. Use Cases as Requirements. A User-Centered UML Method. Incorporating the User-Centered Top Ten. Modifying UML for User-Centered Design. Applying UML Notation to User-Centered Design. Comparisons with Other Use Case-Driven Methods. Rational Unified Process. Usage-Centered Design. Conclusions. The Benefits. The Challenges. The Future. References. Part V. Summary. 10. Interactive System Design Using Oo&hci Methods Mark van Harmelen Introduction. Problems in Object-Oriented Practice. Oo&hci Methods. An HCI View of the Design of Interactive Systems. Cognitive Engineering. User-Centered Design and Human-Centered Design. Model-Based User Interface Design. System Visualization and Design Using Scenarios. Describing Concrete User Interface Designs. The Process of Interactive System Design. Ensuring Design Quality. HCI Summary. Creating an Integrated Oo&hci Approach. The Foundations of an Integrated Approach. Characteristics of an Oo&hci Approach. Activities in the Oo&hci Process. Activities and Examples. An Oo&hci Domain Model. Adopting an Oo&hci Approach. Conclusion. Acknowledgments. References. About the Authors. Index.

Abstract: The original vision of ubiquitous computing [14] is about enabling people to more easily accomplish tasks through the seamless interworking of the physical environment and a computing infrastructure. A major challenge to the practical realization of this vision involves the integration of commercial-off-the-shelf (COTS) hardware and software components: consider the awkwardness of such a mundane task as exporting a textual memo written on a Palm Pilot to a Microsoft Word document.It is not enough to overcome the protocol and data format mismatches that currently impede the interoperation of these entities: for the user experience to be truly seamless, we must provide a framework for the dynamic connection of such endpoints on demand, to support the ad-hoc interactions that are an integral part of ubiquitous computing. To this end, we offer a dynamic mediation framework called Paths. A Path consists of dynamically instantiated, automatically composable operators that bridge datatype and protocol mismatches between components wishing to communicate.Because operator composability is inferred from the type system, adding support for a new type of endpoint requires only incremental work; because the control and data flow for Paths are largely decoupled from the communicating endpoints, it is easy to connect COTS or legacy components. We describe the Paths architecture, our prototype implementation, and our experience and lessons based on several production applications built with the framework, and outline some continuing work on Paths in the context of the Stanford Interactive Workspaces project.

Abstract: The present invention provides a method and system for providing information and/or an interface in a computer system. The method includes determining that a user is accessing the system; analyzing the user's role in the system without a need for the user to provide a description of the user; returning an estimate of the user's role based upon the analyzing step; and displaying or modifying the information and/or the interface based upon the returned estimate. The method and system in accordance with the present invention dynamically determines the appropriate information and/or interface for presentation to differing users. The present invention provides the means for information and graphical user interface (GUI) creators to present different information or GUIs to different user types, such as administrators and end users, and to different user experience levels, such as expert and novice, without requiring users to describe themselves. The present invention accomplishes this by performing a programmatic analysis of a user's rights within a system to derive type and experience level information using information already available according to the standards used by the system.

Abstract: According to conceptual changes on design methodology, this paper presents some research results on a new generation of CAD systems. This new software has not been used to achieve automatic design tasks. On the contrary, it has to make part of an inte grated design environment.A cooperative design modeler is then presented as a support for cooperative and integrated design methodology in this design envi ronment. It mainly allows every design actor to share a unique database owing to a formal exchange network. The modeler provides a graphic interface to add, edit, or modify data. Moreover, the modeler manages the shared database in order to realize heavy design tasks as data propagation or data coherence management.The presented modeler takes place in the global design environment connected to specific applications based on specific design tasks (process planning, structure analysis). An informal communication network worthwhile in any design group including human actors also assists the cooperative desig...

Abstract: A system for providing personalized program guide data and targeted advertising to an Internet user, a user of user television equipment, or a magazine subscriber is provided. The system provides a first communications system for accepting user preferences data relating to e.g. the user's favorite Television programs, channels, actors, categories of programs, etc. The system stores user preference data from multiple users in a user preference database. The system compares the user preference data with program guide data (e.g. program listings, articles, advertisements, reviews, etc.) to develop personalized user program guide data and advertisements which are transmitted back to the user through a second communications system different from the first communications system.

Abstract: Digital television user interfaces are composed of text, graphics and video. Usability issues that arise include information visualization, searching and navigation. This paper introduces two user interface prototypes for digital television. Both prototypes were tested with real users and the test results are discussed.

Abstract: This book is about a particular solution to the problem of how to design usable computer systems. Apart from this chapter, it may be read as a short history of the research efforts with respect to ETAG, which is the main subject of the book as well as the tool that is proposed to help create usable computer systems. Since answers are meaningless without the questions they address, this chapter discusses the questions underlying this research and, perhaps even more important, the reasons for asking these particular questions: the theoretical context which gave rise to them. This is especially important since a generally accepted approach to study and design in Human-Computer Interaction (HCI) is lacking. Moreover, the field might rather be characterised as a loosely organised collection of competing and often incompatible approaches. First, the chapter provides a general account of the subject matter of cognitive ergonomics, stressing the 'cognitive' part of it, and distinguishing it from related fields of research. Thereafter, the chapter focuses on creating usable computer systems as the primary aim of cognitive ergonomics, and it explains why this is not an easy task. Finally, the chapter defines cognitive ergonomics more precisely, as a science and engineer ing trade, that is concerned with user inter faces, and more specifically, their design. Guided by these three main characteristics of cognitive ergonomics, the major questions put forward in this thesis are derived and their background is discussed. 1.1 Cognitive Ergonomics Cognitive ergonomics is the study of human behaviour that is mediated by cognitive tools and devices. Cognitive tools are natural or artificial tools which require and determine the human ability to process information. The purpose of cognitive ergonomics is to adapt such cognitive tools and their usage so as to improve human information processing in terms of improved efficiency, fewer errors and accidents, and increased well-being. To this end it is necessary that cognitive ergonomics is able to analyse how such tools are used, to synthesise recommendations for design, and to evaluate uses and recommendations. An important area in cognitive ergonomics is the study of Human-Computer Interaction. Cognitive ergonomics is based on the premise that human interaction with computer devices is essentially a matter of knowledge representation and information processing, or: cognitive behaviour. Interacting with a computer system takes place by means of physical interaction: pressing buttons on a keyboard changes the physical state of the computer system which is fed back to 2 Chapter 1: Cognitive Ergonomics and UI Design the user by means of intensity changes of the light on the display unit. This description may be accurate, but it is as irrelevant as describing driving a car in terms of opening valves and pulling cables. It would rather be more sensible to describe interacting with a computer system in terms of writing a book with a word processor or calculating turnovers using a spreadsheet. To acquire 'common' human goals like writing a thesis or calculating the day's turnovers by means of a computer (or, for that matter any other tool, like a typewriter, pencil and paper, etc.), it is necessary to recursively subdivide and translate goals into commands for the word processor or spreadsheet. Since computer systems are not too sophisticated with respect to supporting human goals, the reformulation and translation processes of human goals and the interpretation of results of command invocations are necessarily human cognitive tasks. In cognitive ergonomics, interacting with a computer is assumed to involve different stages of human behaviour, such as formulating an intention and executing an action, and different levels of activity, such as the intention to improve a text and the intention behind physically executing a particular command (Norman, 1984). In cognitive ergonomic terms, users have to apply their knowledge about the computer system, in the form of a mental representation, to find the difference between a current state of affairs and a goal state within the user's task domain. Once established, the user has to devise a plan to diminish the difference, and reformulate the plan into the commands and command arguments of the computer system used. After issuing the commands, again, the user has to apply the knowledge about the system to transform feedback data from the computer into meaningful information about the success or failure of reaching the goal state within the task domain. As an example, consider making a paper copy of a report. In a paper office, one would acquire the report from its file, bring it to the copy machine to make a copy, and try not to forget to store the archive copy back in its place. In a 'paperless' office, it is necessary to know that reports are stored as computer files and that, in order to make a paper copy of a file, it has to be sent or copied to a printer device. The instruction how to copy a file varies between computer systems: dragging an icon representation of the report to a printer icon, typing in the name of the print command and the filename, etc. When the printer is not within visual or auditory reach, additional command specifications may be necessary to acquire information about the progress of the print command. Since computer usage primarily involves acquiring, transforming and applying (human) knowledge it may be clear that the basic thesis or central premise of cognitive ergonomics states that investigations should focus on cognitive factors in order to improve HumanComputer Interaction. The focus on cognitive factors distinguishes cognitive ergonomics from traditional or 'classical' ergonomics. As the name suggests, cognitive ergonomics may be seen as a mere branch of ergonomics, with which it shares the goal of facilitating human performance through adaptation of the tools to human characteristics and preferences. On the other hand, cognitive ergonomics differs from 'classical' ergonomics in that the focus is not so much on externally measurable quantities, such as movements, forces and body measures, but on A Formal Model for User Interface Design 3 psychological phenomena, such as knowledge, perception, and planning; phenomena that, generally, allow for indirect measurement only. Cognitive ergonomics is also closely related to cognitive psychology, in that both investigate a mental phenomena. Whereas cognitive psychology often uses computers to study human mental phenomena for the sake of acquiring general theories about mental behaviour, cognitive ergonomics studies mental phenomena and applies theoretical knowledge in order to solve the practical problems related to using computers. The abstract nature of cognitive psychological knowledge generally precludes applying it to practical problems without first making additional assumptions that may undermine the validity of solutions. Cognitive ergonomic theories are more directly connected to the domain of application. Finally, cognitive ergonomics is related to computer science in that both study the use of computer systems, but, whereas computer science investigates the technical requirements for using computers, cognitive ergonomics studies the human and cognitive requirements for doing so. Whereas cognitive ergonomics is related to general ergonomics and cognitive psychology via the subject matter of the investigations, computer science and cognitive ergonomics may be seen as mutual clients, where cognitive ergonomics is responsible for the design of the user interface (the user machine) that sets cognitive constraints, and computer science is responsible for the design and creation of the software (the soft machine) which sets and implements technical constraints for the overall design of computer systems. The fact that computer science and cognitive ergonomics are clients of each other does not express anything about their relative importance. Although there is a growing awareness that computer system design should include usability aspects, at present, especially in software engineering practice, the technical constraints are still predominant. Cognitive ergonomics and ergonomics in general are still regarded as additional to technical programming skills, rather than the opposite. Later on, it will be argued that, from a human task performance point of view, a far more important, and perhaps a leading role, should be assigned to cognitive ergonomics. At the start of this section, cognitive ergonomics was defined as the study to improve the use of cognitive tools in terms of efficiency, errors and accidents, and well-being. It may be possible to be more precise about the field and purpose of cognitive ergonomics. For example, humanitarians might insist that well-being refers to all human beings involved and exclude weapons, technocrats might want to focus on work systems and exclude enabling tools, and rationalists might want to restrict attention to purposive tools and exclude toys and pleasure. These statements may be caricatures but they do exemplify the risk of losing generality by playing the language game to strictly. Despite that cognitive ergonomics is not served by a priori excluding application areas and a more precise definition will not be provided, the work that is discussed in this thesis is restricted to the purposive usage of tools by means of discrete task performance. Computer systems are most commonly used to support work systems which makes it an obvious choice in HCI to focus on users who perform tasks for the purpose of acquiring specific goals and, because of the way to issue commands to computer systems, to focus on performing discrete tasks. 4 Chapter 1: Cognitive Ergonomics and UI Design Discrete tasks put specific requirements on cognitive processes such as perception, memory and attention which may differ considerably from the requirements of th

Abstract: Developing software components with user interfaces that can be adapted to diverse reuse situations is challenging. Examples of such adaptations include extending, composing and reconfiguring multiple-component user interfaces, and adapting component user interfaces to particular user preferences, roles and subtasks. We describe our recent work in facilitating such adaptation via the concept of "user interface aspects", which facilitate effective component user interface design and realisation using an extended component-based software architecture.