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IJHCS Tables of Contents: 404142434445464748495051525354555657

International Journal of Human-Computer Studies 47

Editors:B. R. Gaines
Dates:1997
Volume:47
Publisher:Academic Press
Standard No:ISSN 0020-7373; TA 167 A1 I5
Papers:33
Links:Table of Contents
  1. IJHCS 1997 Volume 47 Issue 1
  2. IJHCS 1997 Volume 47 Issue 2
  3. IJHCS 1997 Volume 47 Issue 3
  4. IJHCS 1997 Volume 47 Issue 4
  5. IJHCS 1997 Volume 47 Issue 5
  6. IJHCS 1997 Volume 47 Issue 6

IJHCS 1997 Volume 47 Issue 1

World Wide Web Usability: Introduction to This Special Issue BIBAHome Page for the Special IssueHTMLPDF 1-4
  Simon Buckingham Shum; Cliff McKnight
This special issue arises out of a symposium entitled "The Missing Link: Hypermedia Usability Research & The Web", held at The Open University's Knowledge Media Institute in May 1996 (Buckingham Shum, 1996). As the title suggests, we felt there was something missing between the vast amount of hypermedia and related human-computer interaction (HCI) research that has been conducted, and the most popular hypermedia system in existence -- the World Wide Web. Certainly, the web community, by and large, seemed to be ignoring the hypermedia research literature and, as Santayana (1905) notes, "Those who cannot remember the past are condemned to repeat it". However, it was possible that our view was inaccurate or even that the web was sufficiently different to its predecessors to make earlier findings irrelevant. The symposium set out to explore such issues.
   The idea for the symposium was obviously timely, following closely after two similar but independently organized events in the US. A workshop (Instone, 1996b) held during the Hypertext 96 conference was structured around the questions: What hypermedia research has influenced the web? What hypermedia research needs to be implemented in the web? What issues has the web raised which should be researched further? Similarly, the CHI 96 conference included a workshop on "HCI and the web" (Instone & Pemberton, 1996), subsequently reported by Instone (1996a).
Designing Information-Abundant Web Sites: Issues and Recommendations BIBAHTMLPDF 5-29
  Ben Shneiderman
"Gradually I began to feel that we were growing something almost organic in a new kind of reality, in cyberspace, growing it out of information...a pulsing tree of data that I loved to climb around in, scanning for new growth."
   (Mickey Hart, Drumming at the Edge of Magic: A Journey into the Spirit of Percussion, 1990)
   "Look at every path closely and deliberately.
   Try it as many times as you think necessary.
   Then ask yourself, and yourself alone, one question...
   Does this path have a heart?
   If it does, the path is good; if it doesn't it is of no use."
   (Carlos Castaneda The Teachings of Don Juan)
   The abundance of information on the World Wide Web has thrilled some, but frightened others. Improved web site design may increase users' successful experiences and positive attitudes. This review of design issues identifies genres of web sites, goals of designers, communities of users and a spectrum of tasks. Then an Objects/Actions Interface Model is offered as a way to think about designing and evaluating web sites. Finally, search and navigation improvements are described to bring consistency, comprehensibility and user control.
Fourth Generation Hypermedia: Some Missing Links for the World Wide Web BIBAHTMLPDF 31-65
  Michael Bieber; Fabio Vitali; Helen Ashman; V. Balasubramanian; Harri Oinas-Kukkonen
World Wide Web authors must cope in a hypermedia environment analogous to second-generation computing languages, building and managing most hypermedia links using simple anchors and single-step navigation. Following this analogy, sophisticated application environments on the World Wide Web will require third- and fourth-generation hypermedia features. Implementing third- and fourth-generation hypermedia involves designing both high-level hypermedia features and the high-level authoring environments system developers build for authors to specify them. We present a set of high-level hypermedia features including typed nodes and links, link attributes, structure-based query, transclusions, warm and hot links, private and public links, hypermedia access permissions, computed personalized links, external link databases, link update mechanisms, overviews, trails, guided tours, backtracking and history-based navigation. We ground our discussion in the hypermedia research literature, and illustrate each feature both from existing implementations and a running scenario. We also give some direction for implementing these on the World Wide Web and in other information systems.
Virtual Hierarchies and Virtual Networks: Some Lessons from Hypermedia Usability Research Applied to the World Wide Web BIBAHTMLPDF 67-95
  P. A. Smith; I. A. Newman; L. M. Parks
The paper considers the usability of the World Wide Web in the light of a decade of research into the usability of hypertext and hypermedia systems. The concepts of virtual hierarchies and virtual networks are introduced as a mechanism for alleviating some of the shortcomings inherent in the current implementations of the web, without violating its basic philosophy. It is suggested that virtual hierarchies and virtual networks will assist users to find task-relevant information more easily and quickly and also help web authors to ensure that their pages are targeted at the users who wish to see them.
   The paper first analyses the published work on hypermedia usability, identifying the assumptions that underlie this research and relating them to the assumptions underlying the web. Some general conclusions are presented about both hypermedia usability principles and their applicability to the web. These results are coupled with problems identified from other sources to produce a requirements list for improving web usability. A possible solution is then presented which utilizes the capabilities of existing distributed information management software to permit web users to create virtual hierarchies and virtual networks. Some ways in which these virtual structures assist searchers to find useful information, and thus help authors to publicize their information more effectively, are described. The explanation is illustrated by examples taken from the GENIE Service, an implementation of some of the ideas. This uses the World Wide Web as a means of allowing global environmental change researchers throughout the world to find data that may be relevant to their research.
How People Revisit Web Pages: Empirical Findings and Implications for the Design of History Systems BIBAHTMLPDF 97-137
  Linda Tauscher; Saul Greenberg
We report on users' revisitation patterns to World Wide Web (web) pages, and use the results to lay an empirical foundation for the design of history mechanisms in web browsers. Through history, a user can return quickly to a previously visited page, possibly reducing the cognitive and physical overhead required to navigate to it from scratch. We analysed 6 weeks of detailed usage data collected from 23 users of a well-known web browser. We found that 58% of an individual's pages are revisits, and that users continually add new web pages into their repertoire of visited pages. People tend to revisit pages just visited, access only a few pages frequently, browse in very small clusters of related pages and generate only short sequences of repeated URL paths. We compared different history mechanisms, and found that the stack-based prediction method prevalent in commercial browsers is inferior to the simpler approach of showing the last few recently visited URLs with duplicates removed. Other predictive approaches fare even better. Based on empirical evidence, eight design guidelines for web browser history mechanisms were then formulated. When used to evaluate the existing hypertext-based history mechanisms, they explain why some aspects of today's browsers seem to work well, and other's poorly. The guidelines also indicate how history mechanisms in the web can be made even more effective.
Gentler: A Tool for Systematic Web Authoring BIBAHTMLPDF 139-168
  Harold Thimbleby
We argue, with theoretical justification, that authoring hypertext and World Wide Web documents requires tool support if it is to be done well. Tools are essential for good design; without them iterative design and user testing are impractical to follow through because of the prohibitive costs of making even small changes reliably.
   Gentler is one such authoring tool. It uses a database of pages and a page layout language, providing reliable design features including hypertext linkage and navigation. With Gentler as a concrete example, we introduce an important principle for design: dual requirements. Features that hypertext document readers find beneficial are beneficial for document authors, and vice versa.
Dialogical Techniques for the Design of Web Sites BIBAHTMLPDF 169-195
  Lewis E. Erskine; David R. N. Carter-Tod; John K. Burton
In this paper, we present an empirical study of our use of scenario-based design in the evaluation and redesign of a web site. We practice a revised method of scenario-based design inferred from a theoretical perspective which treats design as inquiry, inquiry as dialogue and dialogue as the source of all tools, including mental constructs. The result is a set of techniques for using structured dialogue between users and designers to increase designers' understanding of specific domains of users' work. To the extent that the design of an artifact is grounded in the specific context of a work domain, systematic, efficient access to workplace expertise is a requirement of the design process. Because it is primarily "content-driven", the design of World Wide Web sites is particularly suited to the development of design rationale via structured dialogue which represents the ways of thinking and conversing characteristic of a work domain.
Experience with Developing Multimedia Courseware for the World Wide Web: The Need for Better Tools and Clear Pedagogy BIBAHTMLPDF 197-218
  David Benyon; Debbie Stone; Mark Woodroffe
The phenomenal growth of the Internet over the last few years, coupled with the development of various multimedia applications which exploit the Internet presents exciting opportunities for educators. In the context of distance education, the World Wide Web provides a unique challenge as a new delivery mechanism for course material allowing students to take a course (potentially) from anywhere in the world. In this paper, we describe our approach to the development of an Internet-based course designed for distance education. Using this experience, we provide general observations on the opportunities and constraints which the web provides and on the pedagogic issues which arise when using this delivery mechanism.
   We have found that the process of developing web-based courses is one area which requires careful consideration as technologies and tools for both the authoring and the delivery of courses are evolving so rapidly. We have also found that current tools are severely lacking in a number of important respects -- particularly with respect to the design of pedagogically sound courseware.
Bulletin BIB 219-222
 

IJHCS 1997 Volume 47 Issue 2

Task-Related Information Analysis BIBA 223-257
  Alistair Sutcliffe
Task analysis methods have paid little attention to specification of information displays. A method is described for analysing task-related information needs linked to design of information displays. The method starts by defining users' requirements with information types. These are added to the task model to specify what type of information is required during the task. The next step selects appropriate means of information delivery according to the users' needs. Different information access and display paradigms, e.g. hypertext, data retrieval and display media are considered. The method is illustrated with a case study of a shipboard information system.
Structure-Preserving Knowledge-Based System Development through Reusable Libraries: A Case Study in Diagnosis BIBA 259-288
  V. Richard Benjamins; Manfred Aben
Structure-preserving design has emerged as an important principle in Knowledge Engineering for developing knowledge-based systems. The principle prescribes the construction of increasingly more detailed models of the functionality of the knowledge-based system, while the information content and structure of the initial model are maintained throughout the process. It is, however, not trivial to come up with such models: their construction is still more an art than a science. Libraries with reusable components provide generic structures ready for selection and adaptation to the specific requirements at hand. We show the construction of a conceptual and formal model of a diagnostic reasoner through the use of two respective libraries, following the structure-preserving design principle. We include a proof that the high-level conceptual specification of the reasoner is ensured by the formal model presented.
Comparison of Contrasting Prolog Trace Output Formats BIBA 289-322
  Mukesh J. Patel; Benedict Du Boulay; Chris Taylor
This paper reports on a comparative study of three Prolog trace packages. Forty-three students of an introductory Prolog course solved five different Prolog programming problems in each of three different conditions (using isomorphic problem variants to disguise recurring tasks). Each of the three conditions provided subjects with static screen-snapshot-mockups derived from one of three different trace packages ("conventional" Spy; "graphical AND/OR tree-based" TPM*; "informative textual" EPTB). When traces explicitly displayed the information asked for in the problem, subjects solved the problems more quickly. Conversely, when trace output obscured the required information (or necessitated difficult detective work to uncover the information), solution times were longer and answers less accurate. Deciding on a "good" format for display is thus a task-dependent decision, and impacts directly on the user's cognitive ability to solve a problem.
Problems Integrating User Participation into Software Development BIBA 323-345
  C. M. Axtell; P. E. Waterson; C. W. Clegg
This paper is concerned with various problems that can impede the implementation and practice of user participation in the software development process. We describe a case study of a user centred design method in an in-house project. Taking a work organization perspective, we highlight several problem areas, relating to human and organizational issues. These arise from the internal processes of the method, the method's relationship with other procedures and the organizational context. We discuss the impacts of these problems and the interconnections between them. The key underlying issues identified are a lack of integrated effort and the failure to include the full range of necessary knowledge. Theoretical implications for knowledge work and the concept of user participation are discussed and practical recommendations given.
Bulletin BIB 347-353
 

IJHCS 1997 Volume 47 Issue 3

Preface: Group Support Systems BIB 355-356
  Ajay S. Vinze
Future Research in Group Support Systems: Needs, Some Questions and Possible Directions BIBA 357-385
  Jay F., Jr. Nunamaker
Group support systems (GSS) represent one of the real success stories of research by the MIS academic community. There is no doubt that GSS academic research has had an impact on practice in the MIS field. This paper discusses the future of GSS research in terms of what is needed, some important research questions, and offers some possible directions. Section 1 describes what a GSS is and explains the underlying fundamental background. Section 2 explains why GSS research is needed. Section 3 describes the multimethodological approach that is needed for well-grounded GSS research programs. Section 4 discusses some of the major issues in applying GSS in organizational settings. Section 5 explores the scope of GSS research and the questions that need to be answered. Section 6 provides keys to successful distributed collaboration from our experience. Section 7 starts to answer the difficult question "what is needed for a distributed workspace?" Section 8 begins to clarify just what virtual reality can offer for distributed collaboration. Section 9 explains the justification for a virtual reality representation of the distributed office. Section 10 explores what we need to get real work done in a virtual workspace including: support for sense making during the process, automating bottlenecks in the process, modeling through simulation and animation, multiple languages, education, crisis response and software inspection. Research in GSS is just beginning and thousands of questions must be answered before we can have an understanding of the field.
Using Group Support Systems to Discover Hidden Profiles: An Examination of the Influence of Group Size and Meeting Structures on Information Sharing and Decision Quality BIBA 387-405
  Brian E. Mennecke
This paper reports on an experimental study of information sharing for groups using a group support system (GSS). A group member's success or failure in sharing unique information can have important impacts on meeting outcomes. This research builds on previous work which has examined various factors that impact information-sharing performance. To examine these issues, groups processed a hidden profile task, i.e. a task with an asymmetrical distribution of information. In addition, group size (groups of four and seven) and the level of structure (structured or unstructured agenda) were manipulated. Results show that group size had no effect on information sharing. However, groups using the structured agenda shared more initially-shared information and initially-unshared information. Although no relationship was found between information-sharing performance and decision quality, a curvilinear (U-shaped) relationship between information sharing and satisfaction was observed. These results show that, for hidden-profile tasks, a critical performance level must be reached before performance is positively related to satisfaction. The paper concludes with a discussion of the findings and the implications for future research and use.
Satisfying User Preferences while Negotiating Meetings BIBA 407-427
  Sandip Sen; Thomas Haynes; Neeraj Arora
Our research agenda focuses on building software agents that can facilitate and streamline group problem solving in organizations. We are particularly interested in developing intelligent agents that can partially automate routine information processing tasks by representing and reasoning with the preferences and biases of associated users. The distributed meeting scheduler is a collection of agents, responsible for scheduling meetings for their respective users. Users have preferences on when they like to meet, e.g. time of day, day of week, status of other invitees, topic of the meeting, etc. The agent must balance such concerns, proposing and accepting meeting times that satisfy as many of these criteria as possible. For example, a user might prefer not to meet at lunchtime unless the president of the company is hosting the meeting. We apply techniques from voting theory to arrive at consensus choices for meeting times while balancing different preferences.
Attribution Accuracy When using Anonymity in Group Support Systems BIBA 429-452
  Stephen C. Hayne; Ronald E. Rice
This study explores the taken-for-granted assumption that "anonymous" comments posted on a group support system (GSS) are socially as well as technically anonymous. It analyses the accuracy of, and influences on, attributions of authors' identities in seven field groups with considerable work history after they used the system to enter technically anonymous comments about salient topics during a brainstorming session. GSS participants made attributions about authors' identities, but overall these attributions were about 12% accurate (ranging from 1 to 29%). The expected predictors of accuracy (an individual's total communication with the group, network centrality, and length of membership in the group) were inconsistent influences across the seven groups.
The Debiasing Role of Group Support Systems: An Experimental Investigation of the Representativeness Bias BIBA 453-471
  Lai-Huat Lim; Izak Benbasat
Past research has demonstrated that individual and group judgments are subject to systematic biases. Although much effort has been devoted to the debiasing of individual judgments, no corresponding work has been found on the debiasing of group judgments. This study examines the usefulness of a group support system (GSS) in addressing an important judgment bias, namely, the representativeness bias, which refers to the bias incurred in posterior-probability estimations by not properly utilizing all information sources, such as the base rates.
   The formation of a judgment is seen from the perspective of an information integration process. Two orthogonal dimensions of information integration -- interpersonal and intrapersonal -- are involved in group judgments. Interpersonal information integration concerns the aspect of information sharing among group members, and can be supported with the computer-mediated communication channel of GSS. Intrapersonal information integration deals with the information processing capacities and capabilities of individuals, and can be supported using a problem representation tool, as part of GSS.
   A laboratory experiment with a 2x2 factorial design was conducted. One hundred and twenty subjects, randomly allocated to 40 three-member groups, took part in the experiment. Data pertaining to both processes and outcomes were collected and analysed. Representativeness bias was reduced by the use of the problem representation tool. Increased use of the tool led to greater awareness about the base rate and, consequently, to better judgments in this problem context. On the other hand, computer-mediated communication did not reduce the representativeness bias. Although computer-mediated communication is capable of improving the interpersonal aspect of information integration, the representativeness bias is primarily a result of cognitive limitations, and benefits little from improved communication among group members. It is also possible that benefits of computer-mediated communication can be more readily derived by larger groups than by smaller groups of size three used in this study.
Technology, Culture and Persuasiveness: A Study of Choice-Shifts in Group Settings BIBA 473-496
  Maha El-Shinnawy; Ajay S. Vinze
In this paper we examine the impact of technology and culture and their interaction on the process and outcomes of group decision making. The conceptual foundation for this research draws on three domains: GSS, cross-cultural and group polarization. This paper uses the theory of persuasive arguments for studying group behavior in a computer-mediated, cross-cultural setting. Our findings illustrate that group decisions are a function of the medium of communication and the cultural setting in which the decision is attempted. In addition, the protocol analysis conducted demonstrates that the process of decision making in groups varies in terms of persuasive arguments exchanged as a function of the interaction between the medium of communication and the cultural setting observed. These results have both theoretical and practical implications for GSS research.
Groups Over Time: What Are We Really Studying? BIBA 497-511
  Joey F. George; Leonard M. Jessup
Researchers in the area of group support systems have recently begun to conduct studies of groups using technology working over time on common tasks. Few of these studies take place with real groups in organizations, where groups work on a single task over time, and where tasks have consequences. Few of these studies investigate models of group development and process other than Tuckman's unitary sequence model from 1965. The authors summarize what work has been done in the area of group support system groups over time, what has not been done and why and where we should go from here.

IJHCS 1997 Volume 47 Issue 4

Neural Network-Based Decision Class Analysis for Building Topological-Level Influence Diagram BIBA 513-530
  Jae Kyeong Kim; Kyung Sam Park
In order to reduce the burden of modeling decision problems, the concept of decision class analysis (DCA) was proposed. DCA treats a set of decision problems having some degree of similarity as a single unit. This paper presents a scheme within which a neural network is used to implement DCA. An influence diagram model is employed to represent the decision problem, since the diagram is a good tool for knowledge representation of complex decision problems under uncertainty. DCA under consideration is viewed as a classification problem where a set of input-output data pairs is given. We thus utilize a feed-forward neural network with a supervised learning procedure so as to develop DCA and then to generate an influence diagram in the topological level. This paper also presents the results of the neural net simulation with an example of a class of decision problems.
Attribute Grammars as a Robust Technical Basis for a Human-Computer Interaction General Purpose Architecture BIBA 531-563
  Giovanni Adorni; Agostino Poggi; Giacomo Ferrari
In this paper, we present a Natural Language Interface (NLI) that combines some of the advantages of using general purpose grammars with some of the features found in semantic grammars. This is achieved by an Attribute Grammar so as to create an intermediate representation which is interpreted in terms of domain-specific routines. NLI has been used as a component of a Human-Computer Interaction (HCI) system, working on different domains. After a discussion of the theory underlying the system, two examples of the use of NLI on practical domains are described: the first is in the field of three-dimensional scene generation, the second in the field of road map car planning. Some evaluation issues are also included in this paper.
Effects of Screen Presentation on Text Reading and Revising BIBA 565-589
  Annie Piolat; Jean-Yves Roussey; Olivier Thunin
Two studies using the methods of experimental psychology assessed the effects of two types of text presentation (page-by-page vs. scrolling) on participants' performance while reading and revising texts. Greater facilitative effects of the page-by-page presentation were observed in both tasks. The participants' reading task performance indicated that they built a better mental representation of the text as a whole and were better at locating relevant information and remembering the main ideas. Their revising task performance indicated a larger number of global corrections (which are the most difficult to make).
User Performance and Acceptance of a Speech-Input Interface in a Health Assessment Task BIBA 591-602
  Thomas W. Dillon; A. F. Norcio
Novice and expert nurses performed a hands-busy and eyes-busy task using a continuous speech-input interface. This study examined their performance and acceptance of the interface. Three factors were found to improve the user's performance: expertise in the domain, experience with the interface and the use of a small vocabulary. Experience with the interface corresponded with a higher degree of acceptance. Available vocabulary size and level of expertise did not affect acceptance.
Bulletin BIB 603-607
 

IJHCS 1997 Volume 47 Issue 5

The Effects of Motion and Stereopsis on Three-Dimensional Visualization BIBA 609-627
  Geoffrey S. Hubona; Gregory W. Shirah; David G. Fout
Previous studies have demonstrated that motion cues combined with stereoscopic viewing can enhance the perception of three-dimensional objects displayed on a two-dimensional computer screen. Using a variant of the mental rotation paradigm, subjects view pairs of object images presented on a computer terminal and judge whether the objects are the same or different. The effects of four variables on the accuracy and speed of decision performances are assessed: stereo vs. mono viewing, controlled vs. uncontrolled object motion, cube vs. sphere construction and wire frame vs. solid surface characteristic. Viewing the objects as three-dimensional images results in more accurate and faster decision performances. Furthermore, accuracy improves although response time increases when subjects control the object motion. Subjects are equally accurate comparing wire frame and solid images, although they take longer comparing wire frame images. The cube-based or sphere-based object construction has no impact on decision accuracy nor response time.
Evaluation of Verification Tools for Knowledge-Based Systems BIBA 629-658
  Alun D. Preece; Stephane Talbot; Laurence Vignollet
Validation has emerged as a significant problem in the development of knowledge based systems (KBS). Verification of KBS correctness and completeness has been cited as one of the most difficult aspects of validation. A number of software tools have been developed to perform such verification, but none of these are in widespread use. One of the reasons for this is that little quantitative evidence exists to demonstrate the effectiveness of the tools. This paper presents an experimental study of three KBS verification tools: a consistency checker, a completeness checker and a testing tool (for correctness). The tools are evaluated on their ability to reveal plausible faults seeded into a complex, realistic KBS application. The cost of using the tools is also measured. It is shown that each tool is independently effective at detecting certain kinds of fault and that the capabilities of the tools are complementary -- a result not revealed by previous studies.
The Epistemics of Accidents BIBA 659-688
  C. W. Johnson
Human intervention has played a critical role in the causes of many major accidents. At Three Mile Island, the operators isolated a reactor from its heat sink. The pilots of the Boeing 737 at Kegworth managed to shut down their one functioning engine. Staff continued to allow trains to deposit passengers in Kings' Cross after the fire had started. In retrospect, it seems impossible to predict all of the ways that human intervention might threaten safety. It is, therefore, important that we learn as much as possible from those accidents that do occur. This task is complicated because conventional accident reports contain many hundreds of pages of prose. They present findings drawn from many different disciplines: metallurgy; systems engineering; human factors; meterology. These findings are, typically, separated into a number of distinct chapters. Each section focuses upon a different aspect of the accident. This makes it difficult for designers to recognize the ways in which operator intervention and system failure combine during major failures. The following pages use formal methods to address these concerns. It is argued that mathematical specification techniques can represent human factors and system failures. Unfortunately, formal methods have not previously been used to analyse the factors that motivate operator intervention. This paper, therefore, argues that epistemic extensions of mathematical notations must be recruited in order to support the formal analysis of major accidents.

IJHCS 1997 Volume 47 Issue 6

Generating Queries and Replies During Information-Seeking Interactions BIBA 689-734
  Bhavani Raskutti; Ingrid Zukerman
Analysis of naturally occurring information-seeking dialogues indicates that they usually consist of a number of distinct discourse segments, such as a greeting segment, a request issued by a user, an optional clarification segment, a transfer of information segment and a final closing segment. The clarification interaction is often initiated by the information provider and it may be due to one of the following reasons: (1) there is confusion regarding the user's intentions, (2) there is insufficient information to formulate a plan to satisfy a recognized intention, or (3) there is difficulty in formulating a plan that satisfies a recognized intention. Once the information provider determines the user's intention and formulates a plan to achieve this intention, the information transfer phase is initiated to inform the user about the proposed plan.
   In this paper, we present a mechanism for generating queries during the clarification stage and answers during the information transfer stage. Given a hierarchical representation of the alternatives possibly intended by a user and the probabilities of these alternatives, our mechanism determines the hierarchy level at which a query must be directed and the query to be posed in order to determine the alternative intended by the user. Once the user's intentions are ascertained, the mechanism determines whether additional information is required and the manner in which queries may be posed to acquire this information. When a user's intentions cannot be satisfied by means of a single plan, our mechanism enters into a negotiation process to alter the user's specifications until a valid plan is formulated. In the final stages of the interaction, the mechanism determines the information to be transferred and generates an answer to effect the transfer. The mechanisms for negotiation and for the generation of queries and answers described in this paper have been implemented in a system called RADAR, a computerized information providing system that functions as a travel agent.
Accountability of Work Activity in High-Consequence Work Systems: Human Error in Context BIBA 735-766
  John C. McCarthy; Patrick G. T. Healey; Peter C. Wright; Michael D. Harrison
Organizational context is now accepted as a central concept in attempts to understand error in human-machine systems. However, accounts which emphasize the processes of everyday organizing, such as accountability and work activity, are needed in order to establish organizational requirements for design. In this article, we provide a framework for the consideration of organizational contexts of human error in high-consequence work systems, with a view to integrating empirical insights and supporting practical design work. We draw on computer-supported cooperative work conceptualizations of the process of everyday organizing, particularly the notion of "accountability for work activity" which is pivotal to our organizational account of error. The conceptual framework is characterized here as a set of dimensions which are expressive concerning the relationship between accountability and work activity in different contexts: (1) explicit-implicit; (2) global-local; (3) stable-transient and (4) dependent-independent. The framework is demonstrated with respect to everyday work practices in a radiology department and its analytical utility validated with respect to two documented aviation system failures. Applying the framework has enabled us to identify and define, in terms of the dimensions, a number of contexts for vulnerability in high-consequence systems: contexts for collusion, violation, deference, loss of control, buck passing and complacency. These are discussed in terms of requirements for error-tolerant design. In the final section of the article, links between the various contexts for vulnerability and the design process are explored.
Structure of Operators' Mental Models in Coping with Anomalies Occurring in Nuclear Power Plants BIBA 767-789
  Ken'ichi Takano; Kunihide Sasou; Seiichi Yoshimura
Accidents occurring in nuclear power plants cannot be depended upon to train experts of nuclear operators. Generally, this expertise is developed through the simulator training. In this training course, only limited varieties of malfunctions can be presented. Thus, it would be impossible for operators to cope with any other possible anomalies of diverse varieties. Operators have to reorganize knowledge and experiences obtained in the training. Of course, prescribed procedures are far from covering them. This paper presents the structure and contents of a "operator's mental model" and it can deal with flexible operations under any situation. Based on the record of the simulator experiments, in-depth analyses were conducted by interviewing with experienced operators in order to model operators' thinking patterns and also to arrive at the aims behind their actions and utterances. Summarizing the findings obtained, fundamental functions of the mental model in coping with anomalies resulted in the following: (1) suggesting suitable preventive measures by envisioning the ongoing (future) scenario of plant dynamics; (2) identifying causes by investigating symptoms and implying causal remedies to eliminate them or to avoid influences from them and (3) adopting immediate responses simply formulated by "if alarm A then action B". These functions, as well as the mental model itself, can be made available by getting information on plant status and operator's structured knowledge together. The substances and structures of the mental models could be proposed, including implications of how to create it for a specific event, and finally they were synthesized into a more generalized format.