Taking the form of physical books, virtual 3D books can be used as basic components of e-book systems, information workspaces, and digital libraries. This paper describes the page turning design of 3Book, a 3D book system that we recently developed. Our design aims to find a sensible balance among important factors such as visual realism, readability, interactivity, and scalability. To convey the impression of reading or viewing an actual physical book, we model all the faces of the book and synchronize the movements of various portions of the book during page turning. Our design delivers a seamless transition between two states of the book (i.e., when it is lying still and when it is turning pages). In addition, we deform the turning pages around an imaginary cone of changing sizes to produce realistically-looking curved pages.

Literature review and research roadmap for Department of Homeland Security National Visual Analytics program.

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Looking back on the tenth anniversary of the first Symposium on Information Visualization, much has been accomplished. The computer’s power has been exploited to give quick visual form to abstract data, to interact, and to warp detail to follow the user’s changing interest. Moreover, the design space of visualizations has been systematized with reference models, taxonomies, and monographs relating visualization to perceptual and graphical constraints. Looking ahead, however, I will argue that the era of pure information visualization is over. The path ahead depends on giving much more attention to the purposes of visualization and its use. Leaving aside communication, the purpose of information visualization is insight, or more particularly, a larger process that might be called sensemaking. I will sketch out the nature of sensemaking, exemplify it empirically in a practical, urgent setting, and suggest how theories of sensemaking could be developed. I will then describe systems that subsume information visualization as part of an emerging class of sensemaking systems combining visualization (the mind’s eye) with semantic content analysis and sensemaking operations (the mind’s muscle). Not surprisingly, a focus on sensemaking is a good generator of new visualizations. But these developments also suggest that it may be time for the information visualization field to alter its boundaries to go beyond the merely visual.

This paper extends previous work on focus+context visualizations of tree-structured data, introducing an efficient, space-constrained, multi-focal tree layout algorithm (“TreeBlock”) and techniques at both the system and interactive levels for dealing with scale. These contributions are realized in a new version of the Degree-Of-Interest Tree browser, supporting real-time interactive visualization and exploration of data sets containing on the order of a million nodes

Taking the form of physical books, virtual 3D books can be used as basic components of e-book systems, information workspaces, and digital libraries. This paper describes the page turning design of 3Book, a 3D book that we recently developed based on our previous experiences with WebBook. Our design achieves interactive page turning by employing page textures of multiple resolutions at different stages of page turning, solving the scalability problem. By modeling all the faces of the book and synchronizing the movements of various portions of the book during page turning, our design helps to convey the impression of reading or viewing an actual physical book.

We describe a novel technique for deforming the pages of virtual 3D books to produce a realistic page turning effect.

This paper describes the 3Book, a 3D interactive visualization of a codex book as a component for various digital library and sensemaking systems. The book is designed to hold large books and to support sensemaking operations by readers. The book includes methods in which the automatic semantic analysis of the book’s content is used to dynamically tailor access.

This paper describes the 3Book, a 3D interactive visualization of a codex book as a component for digital library and information-intensive applications. The 3Book is able to represent books of almost unlimited length, allows users to read large format books, and has features to enhance reading and sensemaking.

Subject indexes were an important step forward for books because they enabled the comparison and correlations of information without extensive reading, re-reading and memorization. In this short paper, we focus on the user interaction and usage scenario of a new system called ScentIndex that enhances the subject index of an eBook by conceptually reorganizing it to suit particular information needs. Users first enter information needs via keywords describing the concepts they are trying to retrieve and comprehend. ScentIndex then computes what index entries are conceptually related, and reorganizes and displays these index entries on a single page.

Intelligence analysts (IAs) engage in information seeking, evaluation, prediction, and reporting behavior in an information-intensive work environment. A Cognitive Task Analysis (CTA) was conducted to capture data that will provide input to support development of a model of the analyst's processes, biases, and analytic strategies. A hybrid method was used to conduct the CTA, including a modified version of the critical decision method - the critical analysis method. The essential distinction was that participants were asked to describe an example of a strategic analysis problem. Procedures used to conduct the critical analysis method are described in this paper. Several factors contribute to making the IA's task challenging: (i) time pressure to produce reports in a shorter timeframe, (ii) a high cognitive workload, and (iii) difficult human judgments that are required regarding uncertain validity and reliability of the data. Human judgments are involved in considering the plausibility of information, deciding what information to trust, and determining how much weight to place on specific pieces of data. Intelligence analysis involves a complex process of assessing the reliability of information from a wide variety of sources and combining seemingly unrelated events. This problem is challenging because it involves aspects of data mining, data correlation and human judgment.

We present a new technique for efficiently computing Degree-of-Interest distributions to inform the visualization of graph-structured data. The technique is independent of the interest distribution used, and enables fluid interaction with very large data sets (over 100,000 nodes).

In this paper we describe a visualization architecture (AVID) that employs a dynamic model of user interest to support the design and creation of highly responsive, scalable visualizations of hierarchical data. We present evidence of the architecture's efficacy, showcasing dynamic visualizations with near-immediate (<100ms) update times, even on structures of over 100,000 nodes. We discuss how the key concepts used generalize to arbitrary graph structures. Additionally, we present the results of a user study comparing a prototypical visualization built using AVID to a more traditional file-browser interface, showcasing up to 20% improvement in information access times.

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This paper proposes Degree-of-Interest trees. These trees use degree-of-interest calculations and focus+context visualization methods, together with bounding constraints, to fit within pre-established bounds. The method is an instance of an emerging "attention-reactive" user interface whose components are designed to snap together in bounded spaces.

This demonstration shows a method and implementation to interactively display large hierarchies (up to 10,000 nodes) within a web browser. This software computes a degree of interest (DOI) for each node in the hierarchy and displays an overview of the complete hierarchy while showing more detail for nodes with a higher DOI value.

This paper proposes Degree-of-Interest trees. These trees use degree-of-interest calculations and focus+context visualization methods, together with bounding constraints, to fit within pre-established bounds. The method is an instance of an emerging “attention-reactive” user interface whose components are de-signed to snap together in bounded spaces.

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The Special Interest Group on Computer Human Interaction (SIGCHI) has had a successful history of 20 years of growth in its numbers and influence. To help guide the continued evolution of the academic discipline and professional community, we invite several senior members to offer their visions for what the field of CHI actually accomplished over the past several decades, and what do we still need to accomplish? What do we need to do differently/better/smarter? What haven't we tried because the technology, the money or the will wasn't there in the past, but perhaps is now? The CHI field is more than just technology. We understand that our work can have a profound effect on individuals, families, neighborhoods, corporations, and countries. We know that we can influence education, commerce, healthcare, and government. How can we contribute to bridging the digital divides in developed and developing countries? What agendas can we offer for the academic, research, industrial, and civic spheres for the next 20 years? How can we be more ambitious? How can we truly serve human needs?

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Eye trackers output a stream of points at which the eye was looking. To give these points meaning, researchers analyzing eye tracking data need to map the points onto the meaningful objects at which the eye was looking. Performing this mapping has proven to be a tedious, time-consuming task. We present a software system that automates this task for Web usability studies that incorporate eye tracking.

In this paper, we present three taxonomic classification schemes based on Web users' responses to what Web activities significantly impacted their decisions and actions. The taxonomic classifications focus on three variables: the Purpose of people's search on the Web, the Method people use to find information, and the Content of the information for which they are searching. These taxonomies are useful for understanding people's activity on the Web and for developing ecologically-valid tasks to be used when studying web behavior.

Eye tracking studies of the Hyperbolic Tree browser suggest that visual search in focus+context displays is highly affected by information scent (i.e., local cues, such as text summaries, used to assess and navigate towards distal information sources). When users detected a strong information scent, they were able to reach their goal faster with the Hyperbolic Tree browser than with a conventional browser. When users detected a weak scent or no scent, users exhibited less efficient search of areas with a high density of visual items. In order to interpret these results we present an integration of the CODE Theory of Visual Attention (CTVA) with information foraging theory. Development of the CTVA-foraging theory could lead to deeper analysis of interaction with visual displays of content, such as the World Wide Web or information visualizations.

The purpose of this paper is to introduce a replicable WWW protocol analysis methodology illustrated by application to data collected in the laboratory. The methodology uses instrumentation to obtain detailed recordings of user actions with a browser, caches Web pages encountered, and videotapes talk-aloud protocols. We apply the current form of the method to the analysis of eight Web protocols, visualizing the structure of the interaction and showing the strong effect of information scent in determining the path followed.

Considering the amount of interest in studying Web-browsing behavior, there is a relative lack of tools for data collection in this area. Those tools that do exist have significant limitations on the data they are able to collect or on their suitability for efficient analysis. We present WebLogger, a tool which instruments Microsoft's Internet Explorer Web browser. We have found that WebLogger alleviates some of the problems associated with other approaches to browser-based data collection methods.

Focus + context information visualizations have sought to amplify human cognition by increasing the amount of information immediately available to the user. We study how the focus + context distortion of the Hyperbolic Tree browser affects information foraging behavior in a task similar to the CHI '97 Browse Off. In comparison to a more conventional browser, Hyperbolic users searched more nodes, searched at a faster rate, and showed more learning. However, the performance of the Hyperbolic was found to be highly affected by "information scent", proximal cues to the value of distal information. Strong information scent made hyperbolic search faster than with a conventional browser. Conversely, weak scent put the hyperbolic tree at a disadvantage. There appears to be two countervailing processes affecting visual attention in these displays: strong information scent expands the spotlight of attention whereas crowding of targets in the compressed region of the Hyperbolic narrows it. The results suggest design improvements.

Digital books can significantly enhance the reading experience, providing many functions not available in printed books. In this paper we study a particular augmentation of digital books that provides readers with customized recommendations. We systematically explore the application of spreading activation over text and citation data to generate useful recommendations. Our findings reveal that for the tasks performed in our corpus, spreading activation over text is more useful than citation data. Further, fusing text and citation data via spreading activation results in the most useful recommendations. The fused spreading activation techniques outperform traditional text-based retrieval methods. Finally, we introduce a preliminary user interface for the display of recommendations from these algorithms.

In the process of knowledge discovery, workers examine available information in order to make sense of it. By sensemaking, we mean interacting with and operating on the information with a variety of information processing mechanisms [3, 18]. Previously, we introduced a concept that uses the spreadsheet metaphor with cells containing visualizations of complex data. In this paper, we extend and apply a cognitive model called "visual sensemaking" to the Visualization Spreadsheet. We use the task of making sense of a large Web site as a concrete example throughout the paper for demonstration. Using a variety of visualization techniques, such as the Disk Tree and Cone Tree, we show that the interactions of the Visualization Spreadsheet help users draw conclusions from the overall relationships of the entire information set.

Information Foraging Theory is an approach to understanding how strategies and technologies for information seeking, gathering and consumption are adapted to the flux of information in the environment. The theory assumes that people, when possible, will modify their strategies or the structure of the environment to maximize their rate of gaining valuable information. Field studies inform the theory by illustrating that people do freely structure their environments and their strategies to yield high gains in information foraging. The theory is developed by (a) adaptation (rational) analysis of information foraging problems and (b) a detailed process model (ACT-IF). The adaptation analysis develops (a) information patch models, which deal with time allocation and information filtering and enrichment activities in environments in which information is encountered in clusters (e.g. bibliographic collections), (b) information scent models which address the identification of information value from proximal cues, and (c) information diet models which address decisions about the selection and pursuit of information items. ACT-IF is developed to instantiate these rational models and to fit the moment-by-moment behavior of people interacting with complex information technology. ACT-IF is a production system in which the information scent of bibliographic stimuli is calculated by spreading activation mechanisms. Time allocation and item selection heuristics make use of information sent to select production rules in ways that maximize information foraging activities.

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Information Foraging (IF) Theory addresses user strategies and technology for seeking, gathering, and using on-line information. We present IF-based models and evaluations of two interfaces: the Scatter/Gather browser for large document collections, and the Butterfly interface for surfing the citation link structure of scientific literatures. A computational cognitive model, ACT-IF, models observed users by assuming that they have heuristics that optimize their information foraging behavior in accordance with IF theory.

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Several visualizations have emerged which attempt to visualize all or part of the World Wide Web. Those visualizations, however, fail to present the dynamically changing ecology of users and documents on the Web. We present new techniques for Web Ecology and Evolution Visualization (WEEV). Disk Trees represent a discrete time slice of the Web ecology. A collection of Disk Tress forms a Time Tube, representing the evolution of the Web over longer periods of time. These visualizations are intended to aid authors and webmasters with the production and organization of content, assist Web surfers making sense of information, and help researchers understand the Web.

We present Information Foraging Theory as an approach to understanding how strategies and technologies for information seeking, gathering, and consumption are adapted to the flux of information in the cultural environment. The theory is developed within an evolutionary-ecological framework that includes analysis of adaptation, knowledge, and cognition. The theory is applied to field studies, controlled experiments, and technology design. We present the Information Diet Model and Information Patch Residence Time Model as optimization models of information foraging under some strong constraints. These are used to develop a specific production system model called ACT-IF that predicts the fine-grained information seeking and gathering behavior of participants using a sophisticated document browsing system. We also present the Overlapped Patch Foraging with Queueing Model to address situations in which information search and information handling may occur in parallel, the Extreme Variance Rule which deals with information foraging under deadlines and uncertainty, a general class of Dynamic Information Foraging Models, and the Hogg-Huberman Model of the phase space of cost functions for heuristic information search.

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The World-Wide Web has achieved global connectivity stimulating the transition of computers from knowledge processors to knowledge sources. But the Web and its client software are seriously deficient for supporting users' interactive use of this information. This paper presents two related designs with which to evolve the Web and its clients. The first is the WebBook, a 3D interactive book of HTML pages. The WebBook allows rapid interaction with objects at a higher level of aggregation than pages. The second is the Web Forager, an application that embeds the WebBook and other objects in a hierarchical 3D workspace. Both designs are intended as exercises to play off against analytical studies of information workspaces.

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Research on information visualization has reached the place where a number of successful point designs have been proposed and a number of techniques have been discovered. It is now appropriate to begin to describe and analyze portions of the design space so as to understand the differences among designs and to suggest new possibilities. This paper proposes an organization of the information visualization literature and illustrates it with a series of examples. The result is a framework for designing new visualizations and augmenting existing designs.

Clearly, the presentation method for information retrieved from the global information infrastructure (GII) makes a big difference to users. The NCSA Mosaic interface, for example, with its point-and-click multimedia page presentation, swelled popular interest in the World Wide Web. This experience suggests the possibility of increased usefulness if we apply visualization techniques to information retrieved from the GII. Note that, although the term "information visualization" is coming into use, the goal is really "information perceptualization." The latter implies a richer use of many senses, including sound and touch, to increase the rate at which people can assimilate and understand information. In discussing the visualization of retrieved information, it helps to consider four functional levels: (1) the infosphere, (2) the workspace, (3) sensemaking tools, and (4) the document. This simple classification lets us separate the functions served by the visualization from the techniques themselves, which can be applied across functional levels.

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(First paragraph): User interfaces, it has been said (Card, this volume), are an ineluctable part of interactive software systems. They are typically more than half the code, often far more. They typically cause more than half the problems, too - often far more. In short, they represent the sort of troublesome engineering problem that organizations would like to do something about.

Effective information access involves rich interactions between users and information residing in diverse locations. Users seek and retrieve information from the sources-for example, file servers, databases, and digital libraries and use various tools to browse manipulate, reuse, and generally process the information. We have developed a number of techniques that support various aspects of the process of user/information interaction. These techniques can be considered attempts to increase the bandwidth and quality of the interactions between users and information in an information workspace - an environment designed to support information work (see Figure 1).

Information foraging theory is an approach to the analysis of human activities involving information access technologies. The theory derives from optimal foraging theory in biology and anthropology, which analyzes the adaptive value of food-foraging strategies. Information foraging theory analyzes trade-offs in the value of information gained against the costs of performing activity in human-computer interaction tasks. The theory is illustrated by application to information-seeking tasks involving a Scatter/Gather interface, which present users with a navigable, automatically computer overview of the contents of a document collection arranged as a cluster hierarchy.

This paper describes Butterfly, an Information Visualizer application for accessing DIALOG's Science Citation databases across the Internet. Network information often involves slow access that conflicts with the use of highly-interactive information visualization. Butterfly addresses this problem, integrating search, browsing, and access management via four techniques: 1) visualization supports the assimilation of retrieved information and integrates search and browsing activity, 2) automatically-created "link-generating" queries assemble bibliographic records that contain reference information into citation graphs, 3) asynchronous query processes explore the resulting graphs for the user, and 4) process controllers allow the user to manage these processes. We use our positive experience with the Butterfly implementation to propose a general information access approach, called Organic User Interfaces For Information Access, in which a virtual landscape grows under user control as information is accessed automatically.

Although the document imaging industry has taken off in the last few years, document image filing for the individual information worker is still not widespread or effective. In this paper, we focus on building an electronic filing system for paper documents that supports the ad hoc, multifarious work of information workers. Motivated by interviews with researchers and a survey of descriptive studies of paper document filing, we have focussed on minimizing or delaying costs of document filing and supporting a rich variety of methods for accessing and using stored documents. We have implemented a prototype system called Protofoil for storing, retrieving, and manipulating paper documents as electronic images that integrates many user interface - paper and workstation - and information retrieval technologies. Protfoil has been tested through use in our laboratory, and has been deployed in a field study at a lawyer's office.

We present a new visualization, called the Table Lens, for visualizing and making sense of large tables. The visualization uses a focus+context (fisheye) technique that works effectively on tabular information because it allows display of crucial label information and multiple distal focal areas. In addition, a graphical mapping scheme for depicting table contents has been developed for the most widespread kind of tables, the cases-by -variables table. The Table Lens fuses symbolic and graphical representation into a single coherent view that can be fluidly adjusted by the user. This fusion and interactivity enables an extremely rich and natural style of direct manipulation exploratory data analysis.

In this paper we present a method, the Cost-of-Knowledge Characteristic Function, for characterizing information access from dynamic displays. The paper works out this method for a simple, but important, class of dynamic displays called direct-walk interactive information visualizations, in which information is accessed through a sequence of mouse selections and key selections. The method is used to characterize a simple calendar task for an application of the Information Visualizer, to compute the changes in characterization as the result of possible program variants, and to conduct empirical comparison between different systems with the same function.

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Making sense of a body of data is a common activity in any kind of analysis. Sensemaking is the process of searching for a representation and encoding data in that representation to answer task-specific questions. Different operations during sensemaking require different cognitive and external resources. Representation are chosen and changed to reduce the cost of operations in an information processing task. The power of theses representational shifts is generally under-appreciated as is the relation between sensemaking and information retrieval. We analyze sensemaking tasks and develop a model of the cost structure of sensemaking. We discuss implications for the integrated design of user interfaces, representational tools, and information retrieval systems.

The goal of virtual reality systems is to place the user in a three-dimensional environment that can be directly manipulated. Ideally, users cease to think of themselves as interacting with a computer and interact instead with the 2D environment. The usual definition of VR involves full immersion. That is, users wear head-mounted stereo displays to provide full visual immersion and special gloves that allow six-degree-of-freedom input for directly manipulating the environment. An alternative form of VR is being explored in a number of research labs. Nonimmersive VR also places the user in a 3D environment that can be directly manipulated, but it does so with a conventional graphics workstation using a monitor, a keyboard, and a mouse. The scene is displayed with the same 3D depth cues used in immersive VR: perspective view, hidden-surface elimination, color texture, lighting, shading, and shadows. As in immersive VR, animation and simulation are interactively controlled in response to the user's direct manipulation. Much of the technology used to support immersive and nonimmersive VR is the same. They use the same 3D modeling and rendering and many of the same interaction techniques.

UI Innovations are often driven by a combination of technology advances and application demands. On the technology side, advances in interactive computer graphics hardware, coupled with low-cost mass storage, have created new possibilities for information retrieval systems in which UIs could play a more central role. On the application side, increasing masses of information confronting a business or an individual have created a demand for information management applications. In the 1980s, text-editing forced the shaping of the desktop metaphor and the now standard GUI paradigm. In the 1990s, it is likely that information access will be a primary force in shaping the successor to the desktop metaphor. This article presents an experimental system, the Information Visualizer (See Figure 1), which explores a UI paradigm that goes beyond the desktop metaphor to exploit the emerging generation of graphical personal computers and to support the emerging application demand to retrieve, store, manipulate, and understand large amounts of information. The basic problem is how to utilize advancing graphics technology to lower the cost of finding information and accessing it once found (the information's "cost structure").

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Since its invention millennia ago, paper has served as one of our primary communications media. Its inherent physical properties make it easy to use, transport, and store, and cheap to manufacture. Despite these advantages, paper remains a second class citizen in the electronic world. In this paper, we present a new technology for bridging the paper and electronic worlds. In the new technology, the user interface moves beyond the workstation and onto paper itself. We describe paper user interface technology and its implementation in a particular system called XAX.

Advances in computer technology have created new possibilities for information retrieval systems in which user interfaces could play a more central role. Our analysis of the problem suggests that what is needed from the user's point of view is not so much information retrieval itself, but rather, the amplification of information-based work processes. User interfaces enabled by this technology may be able to amplify work by modifying the cost structure of information used in work. As a consequence, we have attempted to go beyond the usual notion of an information retrieval systems to develop an "Information Workspace" that encompasses the cost structure of information from secondary storage to immediate use. As an implementation of the concept, we describe an experimental system, called the Information Visualizer, and its rationale. The system is based on the use of (1) 3D/Rooms for increasing the capacity of immediate storage available to the user, (2) an animated scheduler-based user interface interaction architecture, called the Cognitive Coprocessor, for coupling the user to information agents, and (3) information visualization for interacting with the information structure. The system and its rationale are described.

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The Information Grid (InfoGrid) is a framework for building information access applications that provides a user interface design and an interaction model. It focuses on retrieval of application objects as its top level mechanism for accessing user information, document, or services. We have embodied the InfoGrid design in an object-oriented application framework that supports rapid construction applications. This application framework has been used to build a number of applications, some that are classically characterized as information retrieval applications, others that are more typically viewed as personal work tools.

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The task of managing and accessing large information spaces is a problem in large scale cognition. Emerging technologies for 3D visualization and interactive animation offer potential solutions to this problem, especially when the structure of the information can be visualized. We describe one of these Information Visualization techniques, called the Cone Tree, which is used for visualizing hierarchical information structures. The hierarchy is presented in 3D to maximize effective use of available screen space and enable visualization of the whole structure. Interactive animation is used to shift some of the user's cognitive load to the human perceptual system.

Tasks that involve large information spaces overwhelm workspaces that do not support efficient use of space and time. For example, case studies indicate that information often contains linear components, which can result in 2D layouts with wide, inefficient aspect rations. This paper describes a technique called Perspective Wall for visualizing linear information by smoothly integrating detailed and contextual views. It uses hardware support for 3D interactive animation to fold wide 2D layouts into intuitive 3D visualizations that have a center panel for detail and two perspective panels for context. The resulting visualization supports efficient use of space and time.

The market now contains a bewildering variety of input devices for communication from humans to computers. This paper discusses a means to systematize these devices through morphological design space analysis, in which different input device designs are taken as points in a parametrically described design space. The design space is characterized by finding methods to generate and test design points. In a previous paper, we discussed a method for generating the space of input device designs using primitive and compositional movement operators. This allowed us to propose a taxonomy of input devices. In this paper, we summarize the generation method and explore the use of device footprint and Fitts's law as a test. We then use calculations to reason about the design space. Calculations are used to show why the mouse is a more effective device than the headmouse and where in the design space there is likely to be a more effective device than the mouse.

This paper proposes a concept for the user interface of information retrieval system called an information workspace. The concept goes beyond the usual notion of an information retrieval system to encompass the cost structure of information from secondary storage to immediate use. As an implementation of the concept, the paper describes an experimental system, called the Information Visualizer, and its rationale. The system is based on (1) the use of 3D/Rooms for increasing the capacity of immediate storage available to the user, (2) the Cognitive Co-Processor scheduler-based user interface interaction architecture for coupling the user to information agent, and (3) the use of information visualization for interacting with information structure.

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A bewildering variety of devices for communication from humans to computers now exists on the market. In this article, we propose a descriptive framework for analyzing the design space of these input devices. We begin with Buxton's (1983) idea that input devices are transducers of physical properties in one, two, or three dimensions. Following Mackinlay's semantic analysis of the design space for graphical presentations, we extend this idea to more comprehensive descriptions of physical properties, space, and transducer mappings. In our reformulation, input devices are transducers of any combination of linear and rotary, absolute and relative, position and force, in any of the six spatial degrees of freedom. Simple input devices are described in terms of semantic mappings from the transducers of physical properties into the parameters of the applications. One of these mappings, the resolution function, allows us to describe the range of possibilities from continuous devices to discrete devices, including possibilities in between. Complex input controls are described in terms of hierarchical families of generic devices and in terms of composition operators on simpler devices. The description that emerges is used to produce a new taxonomy of input devices. The taxonomy is compared with previous taxonomies of Foley, Wallace, and Chan (1984) and of Buxton (1983) by reclassifying the devices previously analyzed by these authors. The descriptive techniques are further applied to the design of complex mouse-based virtual input controls for simulated three-dimensional (3D) egocentric motion. One result is the design of a new virtual egocentric motion control.

Computer graphics hardware supporting real-time interactive 3D animation has the potential to support effective user interfaces by enabling virtual 3D workspaces. However, this potential requires development of viewpoint movement techniques that support rapid and controlled movement through workspaces. Rapid movement through large distances avoids wasted work time; controlled movement near target objects allows the user to examine and interact with objects in the workspace. Current techniques for viewpoint movement typically use high velocities to cover distances rapidly, but high velocities are hard to control near objects. This paper describes a new technique for targeted viewpoint movement that solves this problem. The key idea is to have the user indicate a point of interest (target) on a 3D object and use the distance to this target to move the viewpoint logarithmically, by moving the same relative percentage of distance to the target on every animation cycle. The result is rapid motion over distances that slows as the viewpoint approaches the target object. The technique can be used with 2D and multidimensional input devices. We also extend the technologies to move objects in the workspace.

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A bewildering variety of devices for communication from humans to computers now exists on the market. In order to make sense of this variety, and to aid in the design of new input devices, we propose a framework for describing and analyzing input devices. Following Mackinlay's semantic analysis of the design space for graphical presentations, our goal is to provide tools for the generation and test of input device designs. The descriptive tools we have created allow us to describe the semantics of a device and measure its expressiveness. Using these tools, we have built a taxonomy of input devices that goes beyond earlier taxonomies of Buxton & Baecker and Foley, Wallace, & Chan. In this paper, we build on these descriptive tools, and proceed to the use of human performance theories and data for evaluation of the effectiveness of points in this design space. We focus on two figures of merit, footprint and bandwidth, to illustrate this evaluation. The result is the systematic integration of methods for both generating and testing the design space of input devices.

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An Interface is presented that is designed to help users switch among tasks on which they are concurrently working. Nine desirable properties for such an interface are derived. It is argued that a key constraint to building interfaces that support task switching is that low user-overhead switching among tasks required a large amount of display space, whereas actual display space is limited. A virtual workspace design is presented that greatly speeds the inevitable task-switching induced window faulting. The resulting interface is presented as a study in theory-based human-interface design. It is shown how in this case theory is important in inspiring a design, but design entailments outside the theory raise new issues that must be faced to make the design viable. These design experiences, in turn, help inspire new theory.

This paper presents the mail-order catalogue as a metaphor for the delivery of application software in an integrated work environment. It also describes, Catalogue, an adjunct to the Rooms multiple virtual workspace environment, which employs this metaphor. This mechanism can be used (1) to give users "instant starts" by letting the user's select a standard setup, (2) to allow users to assemble their own environment from standard components, (3) to parameterize a standard component, and (4) to load applications ready to run.

It can be argued that one of the chief impediments to progress in human engineering is the lack of a model of the human information-processor posed in such a way as to enable approximate engineering calculations to be made of human performance. The Model Human Processor is an attempt at such a model. The use of the model is illustrated through sample computations.

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A key constraint on the effectiveness of window-based human-computer interfaces is that the display screen is too small for many applications. This results in "window thrashing," in which the user must expend considerable effort to keep desired windows visible. Rooms is a window manager that overcomes small screen size by exploiting the statistics of window access, dividing the user's workspace into a suite of virtual workspaces with transitions among them. Mechanisms are described for solving the problems of navigation and simultaneous access to separated information that arise from multiple workspaces.

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Two experiments explored how users perform visual search to locate a target in a computer command menu. In Experiment 1, users searched for menu items while their eye movements were monitored. Visual search was well characterized by an unsystematic search model in which the user may search the same place more than once. This model predicted the distribution of search times, the lack of an item position effect, and the frequency of saccade directions. In Experiment 2, the unsystematic search model was used to describe the effects on search time of three menu-item arrangements and of practice. Initially, the arrangement of the menu, whether alphabetic, random, or categorical, influenced the time required by the search. But with practice, the user eventually learned the location of each item in the menu, rendering the arrangement of the menu unimportant.

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The use of text editors for writing original text has been little studied despite the importance of the task. A study conducted by Gould found that the composition rate of writers using a text editor was more than 50% slower than the same writers writing by hand. We show that the source of the slownenss is the design of the text editor and that using a display-oriented editor writers can write as fast and good typists faster than by hand. Like Gould, there was no quality difference based on the source of the letters and users of the text editor made many more modifications. Fewer than half of the modifications users made actually improved the text.

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