I treat three related subjects: virtual-worlds research -- the construction of real-time 3-D illusions by computer graphics; some observations about interfaces to virtual worlds; and the coming application of virtual-worlds techniques to the enhancement of scientific computing. We need to design generalized interfaces for visualizing, exploring, and steering scientific computations. Our interfaces must be direct-manipulation, not command-string; interactive, not batch; 3-D not 2-D; multisensory, not just visual. We need generalized research results for 3-D interactive interfaces. More is known than gets reported, because of a reluctance to share "unproven" results. I propose a shells-of-certainty model for such knowledge.
Categorical menu layouts are currently designed according to conventions and opinions, rather than by employing format techniques. In this paper we describe a formal methodology for categorically organizing menus. We go on to show how color-coding can be applied to these layouts either to emphasize organization or to provide additional information. The results of a controlled study comparing layouts based on frequency of co-occurrence and similarity show that the formal menu-layout methodology is effective. However, the use of color-coding to identify categories is not supported. Potential reasons for this failure are discussed.
This paper investigates whether changes in the user/computer dialogue structure will affect the performance of users who are familiar with an earlier version of the product. Quantitative predictions using the Kieras and Polson (1985) production system model were derived to test whether changing the lexical attributes and structure of a popular menu-driven word-processor would permit transfer of existing knowledge of the word-processor to a new version. The results show that changes to the dialogue structure of the menu-system are not detrimental, while changes to the lexical attributes of the menus will hinder user performance.
For the past six years, we have been developing a commercial hypermedia system (KMS) based on our previous research with the ZOG system at Carnegie Mellon University. Our experience with ZOG and KMS has convinced us that the data model underlying an interactive system is more important than the user interface in shaping the overall system. In the paper, we show how the KMS data model has influenced important aspects of the user interface. In particular, we show how the properties of KMS frames -- their spatial nature, breadth-first view, homogeneity, small size, etc. -- affect the nature of the KMS user interface.
Human performance data are reported for two dialogue conventions involving menu interactions with integrated facilities. Users prepared material for overhead foils in a six session experiment. An initiation style of dialogue in a flexible menu hierarchy was compared with a strict hierarchy involving explicit termination of dialogue sequences. Although tasks could be performed in the same number of steps with either interface, initiation had greater time and transaction costs than termination. The results are discussed in relation to the trade-offs that need to be considered in designing for navigational flexibility and to requirements for modeling user behavior.
We describe two experiments that compare the relative utility of pictures, labels, and the combination of both as navigational aids for computerized catalog browsing. The results point to the usefulness of example pictures as search aids in the context of menu traversal through hierarchically structured pictorial databases. We take this outcome to be a reflection of the disambiguating role that pictures can play for verbal category labels.
The use of feet instead of hands to perform workstation cursor-positioning and related functions has been the subject of an on-going investigation. In the exploratory study reported here, a particular foot-operated device, the planar slide mole, was assessed against a mouse in a target-selection task. The study showed that novices can learn to select fairly small targets using a mole; for a target size of 1/8" square, the response time equaled that of the mouse when keyboard homing time was taken into account.
We offer an account of how users choose between alternative methods which take different times to accomplish the same task. Users offered a choice between two methods do not necessarily pick the faster. We argue that users reduce the complexity of the decision space by applying a 'simple compensation schema' acquired from everyday experience. Linear models of performance time enable us to predict how users will view the situation in terms of this schema, and how accurate assessment of the optimal choices within the schema-based assimilations can result in an apparent bias in favour of one method.
An important component of adaptable interactive systems is the ability to model the system's users. Previous systems have relied on user models tailored to the particular needs of that system alone. This paper presents the notion of a general user model, and describes some of our research on building a general user modelling facility that could be used by a variety of applications. This work focuses on the representation, maintenance, and acquisition issues of modelling long-term beliefs of the user, and describes a general facility for accomplishing these tasks.
Detailed user activity scripts from two previous studies of novice users working at a command language or a direct representation interface were submitted to independent expert judges for the justified ascription of misconceptions. Our initial hypothesis was that behavioral evidence for such misconceptions comes about as a result of well-articulated hypothetical reasoning. Although the evidence we obtained supports this view, it also suggests that for the direct representation case some activity normally attributed to misconceptions is non-reasoned in nature and governed by inherent powers of the representation.
Approaches to integrating human factors or user interface knowledge and expertise with software development are still exploratory and evolving. The human-computer interface provides a broader range of user interface challenges than earlier technology, but human factors is only now starting to be widely recognized as a distinct discipline requiring integration with system development. Devoting human and computer resources to user interface enhancement has been considered a luxury, and in many places still is, but the falling cost of computational power and the growing user resistance to poor interfaces, as well as a rising need for product differentiation in the marketplace, insure that human factors will become a necessity where it has not already. The need to develop organizational approaches to support the integration of human factors or user interface expertise with product development is thus a relatively new concern. The integration problems that have been identified include some that are shared with more established support activities such as technical writing, and others that are particular to human factors or result from the relative unfamiliarity of the discipline.
This paper generalises approaches to modelling an undo facility for interactive systems into a comprehensive user recovery and command reuse facility. It separates different undoing actions into distinct undoing functions and incorporates redoing capability in a more general command reuse capacity. Four adequacy criteria for such a facility are proposed and a general model is developed to meet these requirements. Partial, patterned and repetitive undoing and redoing actions are allowed on simple, complex and meta commands. The model subsumes the functionality of prior models.
Several striking characteristics of how often people repeat their actions on interactive systems are abstracted from usage data gleaned from many users of different classes over a period of months. Reformulated as empirically-based general principles, these provide design guidelines for history mechanisms specifically and modern user interfaces generally. Particular attention is paid to the repetition of command lines, and to the probability distribution of the next line given a sequential "history list" of previous ones. Several ways are examined of conditioning this distribution to enhance predictive power. A brief case study of actual use of a widely-used history system is also included.
Effective advice depends on knowledge of the plans and goals of the person requiring help. Planning advice must be at a cognitively appropriate level for the user. HICCUPS, a dynamic planning system for a direct manipulation statistics program, is based on an ideal user model. Plans are generated from goals inferred from explicit goal statements from the user, knowledge about the statistics program, and the recent interactions with the interface. This exploitation of environmental information and inherent domain structure to restrict the amount of search and inferencing is a vital part of intelligent reasoning which is both fast and effective.
"Wizard of Oz" techniques were used to observe the interaction between users of a statistical package and a human playing the role of an simulated intelligent advisory system. The results emphasized the complexities of the advisory process. More than half of the clients' requests sought help on planning actions toward achieving task goals. Further, protocols collected from the advisor while advice was given revealed the importance of constructing models of the user's current and past interaction with the application, and of addressing the high-level goals that underlie clients' explicit questions. The relevance of these findings to the development of intelligent advisory systems is discussed.
Current acoustic speech recognition technology performs well with very small vocabularies in noise or with large vocabularies in very low noise. Accurate acoustic speech recognition in noise with vocabularies over 100 words has yet to be achieved. Humans frequently lipread the visible facial speech articulations to enhance speech recognition, especially when the acoustic signal is degraded by noise or hearing impairment. Automatic lipreading has been found to improve significantly acoustic speech recognition and could be advantageous in noisy environments such as offices, aircraft and factories. An improved version of a previously described automatic lipreading system has been developed which uses vector quantization, dynamic time warping, and a new heuristic distance measure. This paper presents visual speech recognition results from multiple speakers under optimal conditions. Results from combined acoustic and visual speech recognition are also presented which show significantly improved performance compared to the acoustic recognition system alone.
Advisory system can be very powerful general tools for users. Formal query languages, menus, and direct manipulation interfaces might not suffice to access advisory systems' full functionality. The capabilities of natural language interfaces could be required. Unfortunately, natural language interfaces are not meeting the needs yet. Wide syntactic coverage is often traded off against handling ungrammatical sentences. However, this study shows that users request help with a very simple and restricted English, characteristic of unplanned or of child language. Moreover, users' utterances are frequently ungrammatical. It is argued that the simple syntax and the ungrammaticalities are determined by features intrinsic to advisory systems: users request help by typing to perform another primary task under real-time production constraints. Because of intrinsic performance constraints, users naturally resort to earlier and simpler forms of syntax. Natural language interfaces to advisory systems need not cover a wide variety of syntactic constructions but they must emphasize robust parsing.
We formulated a set of rules for producing key-commands that are alternatives for activating commands with a mouse from a menu. Because software is getting increasingly complex, it was important that the rules cover a wide variety of commands. The rules combined verb-modifier-object order and mnemonic abbreviations for the words in each slot. Our keybindings were shown not only to cover a wide set, but to be far easier to learn than EMACS (a common keybinding set) and a more robust form with respect to negative interference from prior and post-learning of another set.
Eight subjects experienced in the use of both 7000 and 11000 series oscilloscopes performed four typical tasks with each scope. The 7000 interface is a dedicated physical control system, while the 11000 system employs icons, pop-up menus, assignable controls, and a touch panel. On each trial the task time and measurement accuracy were recorded. Each experimental session was video recorded and verbal protocols were collected. These allowed decomposition of the subjects' behaviors into categories that would account for performance differences between the two scopes. A 77% performance difference is explained in terms of the cognitive factors of strategy selections and recall of operational details.
This study is a part of a research effort to develop the Questionnaire for User Interface Satisfaction (QUIS). Participants, 150 PC user group members, rated familiar software products. Two pairs of software categories were compared: 1) software that was liked and disliked, and 2) a standard command line system (CLS) and a menu driven application (MDA). The reliability of the questionnaire was high, Cronbach's alpha=.94 The overall reaction ratings yielded significantly higher ratings for liked software and MDA over disliked software and a CLS, respectively. Frequent and sophisticated PC users rated MDA more satisfying, powerful and flexible than CLS. Future applications of the QUIS on computers are discussed.
This paper describes the architecture and prototype of a system which dynamically determines how to present information to a user. The system utilizes a rule based approach to select one or more modalities for presenting information. Next the system determines one or more techniques to present the information within each of the previously selected modalities. This system also adapts to individual users providing flexibility not found in traditional presentation systems. Finally, models are used for storing knowledge about the user resulting in a system which can be easily enhanced as new data is obtained and can adapt to the needs of its users.
Most current approaches to the design of the human-computer interface result in systems that are difficult for users to master. This can be attributed to the absence of several key features, including: interface modularity; adaptability to the individual user; direct support of user intentions; and an intelligent advising capability. An architecture for the interface which facilitates the attainment of these four criteria is proposed. The architecture relies upon production system rules and various kinds of knowledge bases to tailor the user-computer dialogue to the ongoing context of the interaction. A prototype of this architecture has been implemented in LOOPS for interfacing to the UNIX system, and has been shown to enhance substantially the performance of novice users of the system.
In order to be able to show context-dependent responses to the user's actual needs, adaptive systems have to be provided with models of possible task contexts. Existing methods for the representation of tasks in HCI are insufficient for this purpose as they do not support task-oriented parsing (i.e. analysing the input stream in terms of higher level task units). This paper presents a Prolog implementation of a task-oriented parser (+ generator) based on a grammar notation called LEXITAS. As an application, an online coach for a UNIX-like file management system is described. Further applications, such as automated macro detection from given interaction protocols, are discussed.
The participants have all created systems designed to make it easier to build interactive graphics applications such as animated physics demonstrations: Borning, ThingLab; DiSessa, BOXER; Lewis, NoPumpG; Sherwood, CMU Tutor; Smith, Alternate Reality Kit. These systems represent a wide variety of technical approaches, including spreadsheet extensions, object-oriented programming, constraint management, and procedural languages. In preparation for the panel, the panelists have exchanged problems selected to demonstrate the strengths and weaknesses of their systems, and each has undertaken to solve all of the problems. Based on this experience the panelists will discuss general issues raised by the problems, the advantages and limitations of their systems, and what suggestions can be made about the value of particular approaches to making interactive graphics accessible to a wide audience.
The first step in program modification is comprehension. Several researchers argue that programmers utilize plan-based representations when composing or comprehending code. In this study we tested the psychological validity of this proposal and examined the nature of plan-based program representations. Experienced programmers were asked to segment code and sort programs. The segmenting data showed that programmers agree on the major components of a program and that these components are defined by goals in a plan representation. Pascal and FORTRAN programs that employ the same plan structure were segmented into similar components. Program sorting data also showed clustering into plan groups. However task related dimensions are also important parts of program representations.
Software documentation should be useful to the programmer trying to understand a program. The key in that sentence was the word should: by and large documentation has a very bad reputation. We have been working on trying to improve documentation, in order that it may realize its potential. In this case study, we examine a programmer's use of documentation constructed along some specific guidelines. These guidelines, developed from our previous studies of documentation, are intended to help programmers draw causal connections between non-contiguous portions of programming plans in the program. This documentation appears to be helpful to a particular class of programmers, i.e., those who come to a program without the requisite background knowledge.
A verbal protocol study of professional software designers has revealed three design process control strategies. At least one of them, the generation of opportunistic solutions at different levels of detail accompanied by problem domain modeling, had not been observed in previous empirical studies nor had been acknowledged in the software engineering practices. Specific breakdowns (difficulties) were associated with the different design process control strategies. Software tools should be provided to designers to alleviate these breakdowns. Parts of a cognitive model of software design, based on distributed control from specialists such as design schemas, design heuristics, and design methods, are presented to account for the observed control strategies.
The traditionally separate application areas supported by database systems and instructional systems are merging in the area of learning support environments (LSEs). We discuss the provision of tools in LSEs for navigating around large knowledge bases. The optimal form of navigation will depend on the nature of the user and of the learning requirements, and thus a variety of tools must be provided. We propose the use of a travel holiday metaphor as a means for structuring a set of navigation tools and illustrate its use in a system for teaching non-formal fields of knowledge.
A study comparing the speed, accuracy, and user satisfaction of three different touch screen strategies was performed. The purpose of the experiment was to evaluate the merits of the more intricate touch strategies that are possible on touch screens that return a continuous stream of touch data. The results showed that a touch strategy providing continuous feedback until a selection was confirmed had fewer errors than other touch strategies. The implications of the results for touch screens containing small, densely-packed targets were discussed.
The Palenque interactive multimedia digital video interactive prototype is based on themes, locations, and characters from "The Second Voyage of the Mimi" television show, which is being produced at Bank Street College. In the TV show, a cast of scientists and children explore the Yucatan's ancient Maya ruins and are introduced to the science of archeology. The Palenque prototype incorporates this theme to the extent that the user's experience is based on a virtual travel exploration of an ancient Maya site, Palenque, and on the perusal of a multimedia Palenque Museum database. One of our goals was to create a visually interesting database environment in which information in many formats could be browsed through spatially and thematically by children. In addition, we experimented with icon and window-based interface conventions that would make navigation around the video environment motivating and comprehensible for young users.
This paper describes a new approach for dealing with the vocabulary problem in human-computer interaction. Most approaches to retrieving textual materials depend on a lexical match between words in users' requests and those in or assigned to database objects. Because of the tremendous diversity in the words people use to describe the same object, lexical matching methods are necessarily incomplete and imprecise. The latent semantic indexing approach tries to overcome these problems by automatically organizing text objects into a semantic structure more appropriate for matching user requests. This is done by taking advantage of implicit higher-order structure in the association of terms with text objects. The particular technique used in singular-value decomposition, in which a large term by text-object matrix is decomposed into a set of about 50 to 150 orthogonal factors from which the original matrix can be approximated by linear combination. Terms and objects are represented by 50 to 150 dimensional vectors and matched against user queries in this "semantic" space. Initial tests find this completely automatic method widely applicable and a promising way to improve users' access to many kinds of textual materials, or to objects and services for which textual descriptions are available.
Fifteen Ph.D. students who are doing their dissertation research in topics in Human-Computer Interaction were selected from a pool of 42 applicants to spend a day and a half prior to the beginning of CHI'88 to discuss their research in a Doctoral Consortium. The consortium provides the opportunity for students * to discuss their research at a time when wide feedback can be most beneficial, * to learn of the breadth that contemporary research in Human Computer Interaction takes, * to acquire new methods for investigating aspects of their research questions and those related to them, * to get both research and professional advice from seasoned researchers in the field from both academic and industrial bases, both in the US and abroad, * and to develop a cohort group of colleagues.
Systems for animating algorithms have received considerable interest of late as effective means for understanding computer programs. Thus far, nothing has been reported in the literature concerning nature of the displays nor to what extent displays can be created automatically. This paper addresses these two issues. The first part presents a taxonomy of displays prevalent in algorithm animation systems; the second part uses the taxonomy to analyze those types of displays that can and cannot be created automatically from unmodified source code.
We describe an intelligent tutor for programming embedded in a graphical programming language. The tutor monitors students' problem solving and provides feedback and guidance. Explanations are generated from the content of the ideal model's problem solving rules. The graphical interface is designed to facilitate the acquisition of causal models of programming. Students work in a medium that corresponds to their planning operations. The interface enables forward and backward chaining, thus conveying the structure of the planning more effectively than a text-based interface. The interface also provides a graphical record of the solution history and current goals.
Two experiments investigated various techniques for displaying the evaluation of LISP functions in an interactive debugger. The studies examined three techniques of highlighting the flow of evaluation in a LISP function and two display formats for displaying LISP function information. The subjects in both experiments included highly experienced LISP programmers and occasional LISP users with moderate to little LISP experience. The dependent measure was the subjects' preference rating for each display technique. The results showed that occasional LISP users preferred range highlighting, an interlaced display of evaluation results, and a simultaneous display of called functions. However, expert LISP programmers had no differential preferences for highlighting techniques.
The introduction of automated information retrieval (IR) systems was met with great enthusiasm and predictions that manual literature searching soon would be replaced. Three decades later, IR systems have not progressed to the stage where any but the dedicated few can operate them without a highly skilled human intermediary acting as interface between user and system. In the interim, we have learned that the retrieval process is extremely complex both in terms of understanding people and their communication and in terms of understanding scientific information and technical vocabulary. Experiments with new techniques suggest to many the possibility of eliminating the human intermediary, either in large part or altogether; others would argue that the retrieval problems are too complex to be resolved for more than highly restricted domains. The possibility of eliminating the human intermediary is of current research interest to the several disciplines that are represented on this panel.
In a field study (29 engineers), the transfer from expertise acquired in training to software use at work was shown to be mediated by task application knowledge (i.e. knowledge used to connect skills learned in training with tasks at work). Moreover, person variables like setting long range goals and developing detailed plans and an organizational variable like job decision latitude (i.e. how much freedom do workers have to do their work) influenced the transfer process. People with high goal orientation and planfulness and with high job decision latitude showed a higher transfer.
Pacific Bell conducted a trial of The Coordinator, a tool for computer-supported cooperative work. The trial group had diverse job functions and was dispersed across a variety of geographical locations and computing environments. The trial attempted to both measure the effectiveness of The Coordinator as a communications tool and to evaluate the speech act communications paradigm on which it is based. Only the first of these two goals was realized. Changes in subjects' cognition were assessed using a series of semantic differential scales. One negative cognitive shift was supported by the data. However, the anecdotal evidence was far more negative, suggesting that the experimental methodology be enhanced to include measurement of affective dimensions of group dynamics. Implementation and support for cooperative work systems were found to be more difficult than anticipated. The test group was not convinced that The Coordinator offered functionality that was worth the effort involved in learning to use the product. An improved interface, more flexible terminology, and better implementation support is needed for successful installation of The Coordinator, or similar products.
A knowledge base which defines a user-computer interface is described. The knowledge base serves as input to a user interface management system, which implements the user interface. However, the knowledge base represents user interface design knowledge at a level of abstraction higher than is typical of user interface management systems. In particular, it represents objects, actions, attributes of objects, an object class hierarchy, and pre-and post-conditions on the actions. The knowledge base can be algorithmically transformed into a number of functionally equivalent interfaces, each of which is slightly different from the original interface. The transformed interface definition can be input to the UIMS, providing a way to quickly experiment with a family of related interfaces.
An effective user interface requires a dialogue layer that can handle multiple threads of interaction simultaneously. We propose a notation for specifying dialogues based on context-free attributed grammars with two extensions: fork operators for specifying sub-dialogues and context attributes for dispatching tokens. The notation is useful both as a means of communicating the behavior of the dialogue layer to designers and as input to a dialogue compiler that generates program code. In this paper we explain the motivation for our work and provide practical examples of the use of fork and context. In addition, we outline algorithms for parsing and for generating parser tables
Developers and behavioral scientists concerned with human-computer interaction need to learn more about problems caused by user differences, and prospects for dealing with diverse user populations. This panel is intended to heighten the awareness of CHI'88 conferees to recent research documenting user differences, experimental approaches to user-sensitive interface design, and the implications of user differences for system developers.
Recent developments in the design of human-machine interfaces have resulted in interfaces which make access to computer-based equipment more difficult for visually disabled people. The aim of this project was to explore whether it is possible to adapt such interfaces so as to make them usable by people who cannot see a screen. The approach adopted was based upon two principles: the replacement of visual interface entities by auditory analogues and appropriately constraining the resultant interface. Two forms of sound were used to embody the auditory interface: musical tones and synthetic speech. In order to test the principles a word processing program was implemented which demonstrated that a visual program might be adapted to be accessed through such an interface.
The multifunctional cursor (MC) is a technique for representing multiple operations in direct manipulation user interfaces. Icons for each of several simultaneously-available operations are overlaid into the cursor image. The MC improves user interface practice by removing syntactic inconsistencies, by reducing cognitive load, and by providing support for repeated operations.
Menus are largely formatted in a linear fashion listing items from the top to bottom of the screen or window. Pull down menus are a common example of this format. Bitmapped computer displays, however, allow greater freedom in the placement, font, and general presentation of menus. A pie menu is a format where the items are placed along the circumference of a circle at equal radial distances from the center. Pie menus gain over traditional linear menus by reducing target seek time, lowering error rates by fixing the distance factor and increasing the target size in Fitts' Law, minimizing the drift distance after target selection, and are, in general, subjectively equivalent to the linear style.
Software design is the act of determining the user's experience with a piece of software. It has nothing to do with how the code works inside, or how big or small the code is. The designer's task is to specify completely and unambiguously the user's whole experience.
-- David Liddle, From Bringing Design to Software, edited by Terry Winograd, 1996
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