| The Design of Reliable HCI: The Hunt for Hidden Assumptions | | BIBAK | 3-15 | |
| Erik Hollnagel | |||
| The design of HCI is based on a number of assumptions. Some of these are
explicitly stated in design guidelines. Others are hidden in the design and
possibly even concealed for the designer. A particular instance is the
assumptions about the reliability of human performance -- and cognition -- and
about which things can go wrong. It is important for designers of HCI to know
more about human reliability, regardless of whether the HCI is for industrial
or academic applications. Lack of knowledge may deceive designers to rely on
their personal experience. That is, however, unlikely to constitute a valid
basis for the design and the resulting system is therefore likely to be
inadequate. This caution is pertinent for human reliability as well as for
the, unfortunately, many other aspects of man-machine interaction that do not
receive the attention they rightly deserve. Keywords: Design method, Reliability, Linked HCI, Human error | |||
| Beyond Human Computer Interaction: Designing Useful and Usable Computational Environments | | BIBAK | 17-31 | |
| Gerhard Fischer | |||
| Human-computer interaction has refocussed many research efforts within
computer science from a technology-centered view to a human-centered view. But
current research efforts and systems (both prototypes and those commercially
available) are just the beginning rather than the end. Conceptual frameworks
and computational environments are needed that will give domain workers more
independence from computer specialists. Just as the pen was taken out of the
hands of the scribes in the middle ages, the power of high-tech computer
scribes should be re-defined. To turn computers into convivial tools requires
that end users themselves can use, change and enhance their tools and build new
ones without having to become professional-level programmers.
This article explores a number of future themes transcending current views of human-computer interaction. It describes domain-oriented design environments as new prototypes of computational environments which are simultaneously useful and usable by focusing on humans and their tasks. Keywords: Human-computer interface design, Cooperative work, Domain oriented design | |||
| Precipitating Change in System Usage by Function Revelation and Problem Reformulation | | BIBAK | 35-47 | |
| Wai On Lee; Philip J. Barnard | |||
| Long term learning has been neglected in much of HCI research. Although
many workers have observed that users typically asymptote at mediocre levels of
expertise and make sub-optimal usage of system functionality, little detailed
research has been applied to examine such a phenomenon. Attempts to tackle the
problem in the past have focused on finding effective ways to reveal system
functionality to the users. In this paper, we examined the adequacy of such an
approach to effect change in users' function repertoire. The results showed
that to precipitate a permanent change, users have to be supported in
reformulating problems on the basis of their relevant features. The
implications of the results are discussed. Keywords: Change, Long-term learning, Intelligent help systems, Function revelation,
Problem reformulation | |||
| Icon Design and its Effect on Guessability, Learnability, and Experienced User Performance | | BIBAK | 49-59 | |
| Jackie Moyes; Patrick W. Jordan | |||
| A great deal of research has been conducted in order to find properties
which determine the success of an icon. The overwhelming majority of work has
indicated representational type as the most important property. This paper
contains a review of some of this work, and reports a study investigating the
effects of representational type on three components of usability;
guessability, learnability, and EUP. These effects were compared with those
for set compatibility. Results indicate that, whilst representational type
might strongly influence performance during the early stages of interaction, it
may be of less significance as the user reaches EUP. This is in contrast to
set compatibility which is of greatest influence during the learnability stage. Keywords: Usability, Set compatibility, Rule compatibility, Icon design, Guessability,
Learnability, EUP | |||
| Adapting to Interface Resources and Circumventing Interface Problems: Knowledge Development in a Menu Search Task | | BIBAK | 61-77 | |
| Wai On Lee | |||
| This paper examines knowledge development in an information search task
using two menu systems. We found that in a system where locational cues were
distinctive, subjects adapted to them by developing locational knowledge of
menu items. However, in a system where such cues were poor, users circumvented
the difficulty of menu selection by committing to memory part of the menu items
names. The results confirmed our hypothesis that users will adapt to interface
resources and circumvent interface problems in order to satisfy the demands of
the task. We conclude by examining the implications of the findings for
'display-based' expertise using a framework for the analysis of change in skill
development. Keywords: Information flow, Development of expertise, Locational knowledge, Specific
item knowledge | |||
| A Survey of Usability Engineering Within the European IT Industry -- Current Practice and Needs | | BIBAK | 81-94 | |
| Andrew Dillon; Marian Sweeney; Martin Maguire | |||
| The present paper reports on a survey of current practices in usability
engineering and requirements for support within European IT organisations.
Responses were obtained from 84 individuals working in nine European countries.
The data were analysed in terms of four themes; respondents' background, their
interpretation and appreciation of the concept of usability, current practice
with regard to usability evaluation, problems and requirements for support in
conducting usability evaluation. Results suggest widespread awareness but only
superficial application of Human Factors methods in Industry. Keywords: Usability engineering, Usability evaluation tools, Industrial survey,
Industrial practice, Usability laboratories, HCI guidelines, Standards | |||
| Modelling User Performance in Visually Based Interactions | | BIBAK | 95-110 | |
| Jon May; Lisa A. Tweedie; Philip J. Barnard | |||
| This paper outlines a general technique for analysing user performance in
visually based interactions. Such interactions are modelled as an evaluation
process in which the user compares the visual structure of an object with an
internally-generated propositional representation of the target. The content
and structure of this propositional representation is dependent upon the
context within which the target has been learnt and searched for previously.
The technique is used to frame a specific model of icon search, and an
experiment is described which tests the model against icon sets with different
visual structures, and by keeping one set of icons constant but changing the
context within which they are presented. The results provide general support
for the technique, with icon search times being affected both by the number of
icons which contain the 'psychological subject' of the target icon, and by the
depth to which the propositional representations must be evaluated before icons
can be rejected or accepted as the target. Keywords: Icons, Visual interaction, Visual search, Cognitive modelling, Display
design | |||
| Developing Runnable User Models: Separating the Problem Solving Techniques from the Domain Knowledge | | BIBAK | 111-121 | |
| Ann Blandford; Richard M. Young | |||
| Runnable models of computer users can serve as the basis for predictions
about the usability of interfaces. Both the construction and the running of a
user model can provide useful information to interface designers. To define
such a model, the designer must specify what users know about the interface
(relevant to the tasks they are to perform with it), how they will use that
knowledge in their operation of the device, and what background knowledge they
can be assumed to have. In this paper we report on work which allows these
different components of the user model to be specified independently, and
automatically integrated to generate a set of Soar productions which constitute
a runnable model. Keywords: Predictive modelling, User models, Interface design, Cognitive architecture | |||
| PowerTools: New Generation Data Presentation Tools | | BIBAK | 125-142 | |
| Eugenio Zabala; Richard W. Taylor | |||
| This paper introduces the PowerTools data presentation toolset and its
application. PowerTools is the name given to a set of diverse data
presentation systems, integrated under the Common Tool Control (CTC) program.
At present, the system is made up of two visualisation tools (Maritxu and The
Cave) and a sonification tool (SRT, Sonic Representation Tool). The system was
originally developed to aid the understanding and optimisation of parallel
computer systems. It is now being applied to problems in which quantity,
variation and complexity of data is problematic (e.g. Control and Stock
Markets).
The visualisation tools have been designed to deal with large quantities of complex multivariate dynamic data. They exploit pre-attentive vision's ability to discriminate the data sub-sets that require attentive analysis. Maritxu is highly scalable and has been designed for data set comparison; The Cave portrays data evolution through time. SRT generates a sound track driven by the input data set and has been designed to represent multiple dynamic data items simultaneously. Keywords: Data presentation, Visualisation, Sonification, Applied psychology | |||
| A Generic User Interface Constructor for Planning and Scheduling Applications | | BIBAK | 143-156 | |
| Jan van Putten; Nardie Scharenborg; Auke Woerlee | |||
| This paper describes a generic user interface construction tool for planning
and scheduling applications. By means of predefined graphical representations,
a user interface can easily be defined for any data model associated to a
planning or scheduling problem. The set of predefined representations
currently contains: a tabular view, a map, a Gantt chart and a bar chart. A
planning or scheduling application is constructed by choosing the underlying
data model and subsequently defining one or more graphical representations
where particular elements of the data model are attached to the axes in those
representations. The Model View Control paradigm is applied in order to
guarantee that the representations show the actual contents of the data model,
that is, to preserve consistency. Keywords: Model based UIMS, Object orientation, Automated plan board, Planning and
scheduling | |||
| Objects, Invariants and Treacle: Animation in the Views System | | BIBAK | 157-171 | |
| Lon Barfield; Eddy Boeve; Steven Pemberton | |||
| With interactive computer systems there are times when the user or the
system can make some discreet change that takes the system from one distinct
graphic state to another. Usually the feedback provided is purely 'before and
after' in nature. 'Fill-in' animation gives continuity by providing the
intermediate states between the two different graphic states. Such animation
is already in use, but each program that uses it must implement its own special
case of it. The Views system is a computing environment that unifies many
aspects of computer use and application development. Within its framework
'fill-in' animation can be implemented in a general, system-wide way available
to all applications. Keywords: Computer graphics, Graphics methodology, Ergonomics of computer software,
User interfaces | |||
| A Method for Multimedia Interface Design | | BIBAK | 173-190 | |
| Peter Faraday; Alistair Sutcliffe | |||
| Multimedia (MM) interfaces are currently created by intuition. Development
of a method for analysis and design of MM presentation interfaces is described.
The study investigates task based information analysis, persistence of
information, attention and concurrency in presentation. The method gives an
agenda of issues and techniques for specification, and guidelines for media
selection and presentation scripting. Use of the method is illustrated with a
case study of shipboard emergency management. Keywords: Multimedia, Task analysis, Presentation, Design, Methodology | |||
| A Novel Device for Using the Hand as a Human-Computer Interface | | BIBAK | 191-202 | |
| Christoph Maggioni | |||
| Making today's complex computer applications easier and more intuitive to
use and to learn is one of the main issues in research on human-computer
interaction. Investigating the diverse mechanisms of natural human
communication and mapping these to multimodal human-machine interfaces should
lead to qualitative improvement in human-machine communication and thus
significantly increase the usability of computers. Two central observations
regarding human communication and behavior can be made: people have a natural
ability to move and act in their three-dimensional environment, and they
naturally use gestures as a means of communication. Three-dimensional
representations of real environments form a new means of communication between
man and machine, making explicit use of mechanisms which humans have learned
and experienced during their whole lives in moving themselves and manipulating
objects. We present a novel three-dimensional input device that allows
applications to be controlled by gestures of the human hand. Hand position and
orientation are obtained using a video camera and image processing techniques.
The system works in real-time and is integrated into a three-dimensional
environment. Our input device has proven to be very reliable and is more
natural to use than other conventional computer input devices systems. Keywords: Input device, Image processing, Gesture recognition | |||
| Reusing User Interface Designs: Experiences with a Prototype Tool and High-Level Representations | | BIBAK | 203-216 | |
| T. T. Carey; M. S. Ellis; M. Rusli | |||
| A library of user interface design exemplars is being constructed to aid
designers in learning from and reusing existing artifacts. Reuse concepts from
software engineering have been applied to the design of the library.
Experiments are underway to test usage-oriented design representations for
incorporation in the library. Several scenarios of potential use are
suggested. Keywords: Software reuse, Design rationale, User interface design, Toolkits | |||
| Beyond Hacking: A Model Based Approach to User Interface Design | | BIBAK | 217-231 | |
| S. Wilson; P. Johnson; C. Kelly; J. Cunningham; P. Markopoulos | |||
| This paper discusses the role of models in the design of user interfaces,
with particular emphasis on integration across different modelling stages. We
are concerned with bridging the gap between psychologically motivated modelling
approaches to HCI and implementation oriented interaction models, to produce a
task-informed user interface design process. An early version of a UIDE which
provides support for the role played by models in the design process is
described and exemplified through models taken from a case study. We conclude
with an assessment of our experiences and a discussion of how the work will
proceed. Keywords: User interface design, Task modelling, User modelling, UIDE | |||
| Specifying and Prototyping Dynamic Human-Computer Interfaces for Stochastic Applications | | BIBAK | 233-246 | |
| C. W. Johnson | |||
| Formal methods are increasingly being used to support the software
engineering of complex systems. A number of limitations restrict the utility
of these techniques for the design of human-computer interfaces. Firstly,
formal notations often abstract away from the temporal properties that affect
usability. Secondly, specifications fail to consider the stochastic, or
probabilistic, behaviours that characterise human-computer interaction with
distributed and concurrent applications. This paper proposes techniques to
overcome these limitations. It is argued that temporal logic provides a means
of representing sequential and concurrent properties of interaction. It is
also demonstrated that logic can be used to explicitly represent assumptions
about operator responses to high and low risk events. In order to support the
validation of these assumptions we have implemented a tool which exploits Monte
Carlo techniques to directly derive prototype simulations from temporal logic
specifications of interactive systems. Keywords: Formal methods, Prototyping, Monte Carlo simulation | |||
| Interface Semantics and Users' Device Models: Identifying Evaluation Issues for Direct Manipulation Design | | BIBAK | 249-265 | |
| M. V. Springett; A. S. Grant | |||
| This paper proposes that evaluation of direct manipulation (DM) interfaces
requires a richer analysis than is provided by current methods. We begin by
considering the strengths and weaknesses of contemporary evaluation approaches
when applied to examples of DM dialogue breakdowns. In the light of this
analysis we go on to discuss the necessary focus of future DM evaluation
methods. In particular, we focus on the importance of presentational factors
in DM interface design. We consider the role of metaphor and feature
presentation in synthesis with users' representations of tasks. An analysis of
the interface's role in the formation of users' device models is then proposed,
and its potential use in evaluation discussed. Keywords: Direct manipulation, Evaluation, Task model, User's device model | |||
| User-Centred Evaluation of Explanation Facilities in Information Systems | | BIBAK | 267-276 | |
| H. Johnson | |||
| This paper argues that explanation facilities will become common place in
future interactive systems. As a result, a major concern for HCI researchers
is to establish the utility and quality of explanation provision currently
provided by a range of information systems, such as intelligent tutoring,
expert or knowledge-based systems, etc. Although there has been much research
in the area recently, there are still three problems which need to be
addressed. First, there is a lack of unifying theory; secondly, there are no
criteria by which to judge the resulting explanations; and finally, there are
very few empirical studies which demonstrate the claimed improvements. In this
paper we are particularly concerned with developing criteria for evaluation and
also considering why evaluation is important and how evaluation of explanation
provision in information systems might occur. Keywords: Evaluation, Evaluation criteria, Explanation, Information systems | |||
| Critical Incidents and Critical Themes in Empirical Usability Evaluation | | BIBAK | 279-292 | |
| John M. Carroll; Jurgen Koenemann-Belliveau; Mary Beth Rosson; Mark Kevin Singley | |||
| Empirical usability evaluations (particularly 'formative' evaluations) hinge
on observing and interpreting critical incidents of use: the causes of such
critical incidents can often be found in the immediate contexts of their
occurrence and can guide specific design changes. However, it can also happen
that the causes of a critical incident are temporally remote from its context
of occurrence or distributed throughout the user's prior experiences. We
propose augmenting critical incident methods by analysis of what we call
'critical threads': sets of causally related user episodes that, taken
together, define major usability themes. Keywords: Evaluation methodology, Formative evaluation, Usability evaluation, Design
rationale, Psychological design rationale, Claims analysis | |||
| The Development of DRUM: A Software Tool for Video-Assisted Usability Evaluation | | BIBAK | 293-309 | |
| Miles Macleod; Ralph Rengger | |||
| The development is reported of a practical software tool which supports
video-assisted observational evaluation of usability. The Diagnostic Recorder
for Usability Measurement (DRUM) helps evaluators to organise and analyse
user-based evaluations, and to deliver measures and diagnostic data. This
paper reports DRUM's rationale, theoretical background, requirements capture
and collaborative iterative development. It outlines DRUM's functionality and
manner of use. DRUM runs on Apple Macintosh, drives a range of video machines,
and supports management of evaluation data, task analysis, video mark-up and
logging (with find and replay of logged events), analysis of logged data and
calculation of metrics. Keywords: Usability, Observational evaluation, Tools, Video, Protocol analysis,
Usability engineering, Usability metrics | |||
| The Three-Dimensional Graphical User Interface: Evaluation for Design Evolution | | BIBAK | 311-331 | |
| A. G. Sutcliffe; U. K. Patel | |||
| The design of a three-dimensional interactive graphical user interface for a
medical knowledge based system is described. A prototype of the design has
been developed and evaluated. The evaluation study investigated usability, and
individual differences in patterns of interaction. We found that there are
individual differences in the way users explore three dimensional
visualisations, and that usability is dependent on both the morphology
(visualisation) and manipulations (interface functionality). While
three-dimensional graphics can help reduce representational complexity, other
forms complexity are intrinsic to the medium and require design solutions.
Implications of these findings for design evolution are discussed. Keywords: Three-dimensional graphics, Visualisation, Usability, Evaluation,
Morphology, Manipulation | |||
| A Formal Approach to the Presentation of CSCW Systems | | BIBAK | 335-352 | |
| C. W. Johnson | |||
| It is a non-trivial task to develop appropriate presentation strategies for
Computer Supported Cooperative Work (CSCW) systems. Some applications, such as
communications environments, must be presented to all the members of a group.
Other information is only relevant for those users who are engaged in
particular activities. Representing a design in terms of bitmaps and device
primitives can obscure such requirements. This paper argues that formal,
mathematically based, specification techniques can represent images that are
distributed amongst multiple, concurrent operators. A limitation of this
approach is that formal specifications provide little impression of what it
would be like to interact with a CSCW system. The Prelog prototyping tool has
been developed to overcome this limitation. Prelog can be used to derive
prototypes from logic specifications of multi-user applications. Prelog is
intended to support the early stages of development when it may not be possible
to analyse systems within their eventual working context. It also supports the
later stages of development because Prelog displays can be incorporated into
final implementations using either the C or Ada programming languages. Keywords: CSCW, Formal methods, Prelog, Graphics programming | |||
| Theory-Based Negotiation Frameworks for Supporting Group Work | | BIBAK | 353-365 | |
| Beth Adelson | |||
| In this paper we begin by presenting a taxonomy of impasses in group work
situations. The taxonomy includes factors such as goal conflicts and resource
limitations. We then present a prescriptive theoretical framework designed to
support negotiation during these impasses. We also describe Negotiation Lens,
a system which embodies the framework by supporting the actions prescribed by
the theory. We then analyze the adequacy of the framework which stresses a
collaborative form of negotiation. From this analysis we suggest a line of
research which would lead to an expanded taxonomy. We hypothesize the expanded
taxonomy would include interpersonal factors such as inequalities in the power
of negotiating parties. We then discuss the framework and tools which would be
useful given this expanded view of causes of group work impasses. Lastly we
suggest the relevance of these factors to other classes of groupware. Keywords: Group work, CSCW, Interaction architectures, Organisational and societal
issues | |||
| Autonomous Support for Group Working: The Aide de Camp Project | | BIBAK | 367-382 | |
| F. P. Coenen; I. Finch; T. J. M. Bench-Capon; M. J. R. Shave | |||
| Computer networking and the genre of software, collectively referred to as
groupware, enabled by such networks have been with us for some time. The
potential advantages to be gained cannot be overstated. There are also
disadvantages associated with the technology. In particular the introduction
of computer networking and groupware has significantly increased the work load
of individual network users, especially those charged with the administration
of the cooperative tasks that the software supports. In this paper we describe
the Aide de Camp system. This is a decentralised communications management
system that actively addresses the administration of cooperative tasks. This
is achieved through the development of two key concepts, collaborative mail
filtering and the use of autonomous agents to administer cooperative tasks.
Both are described and the advantages gained illustrated through the use of a
number of examples taken from applications currently under investigation. Keywords: Group work, Autonomous agents, Work-flow, Task scripting language,
Cooperative (mail) filtering language | |||
| A Study of Turn-Taking in a Computer-Supported Group Task | | BIBAK | 383-394 | |
| Andy McKinlay; Rob Procter; Oliver Masting; Robin Woodburn; John Arnott | |||
| Synchronous computer-supported cooperative work (CSCW) tools are intended to
provide opportunities for remotely located groups to work together in a manner
akin to groups meeting face-to-face. Little is understood, however, of what
may influence the effectiveness of group work performed under these
circumstances. One likely factor is the way in which 'floor control', or turn
management is supported, and its impact on group coordination. This paper
describes an experiment designed to examine the impact of different turn
management protocols on the performance of groups using a CSCW tool. The
results are compared with the performance of a group working face-to-face.
Finally, the implications for coordination in synchronous CSCW are discussed. Keywords: Computer-supported cooperative work, Conversation analysis,
Computer-mediated communications, Turn management | |||
| A Longitudinal Study of Transfer between Programming Languages by Experienced Programmers | | BIBAK | 397-410 | |
| Jean Scholtz | |||
| This study reports on a longitudinal study of experienced programmers
transferring to a new language. Our previous research studied the initial
efforts of experienced programmers transferring to a new language. This work
showed that transfer, even within the same language paradigm, presents
difficulties. In particular, transfer to a dissimilar language poses problems
in plan selection even for experienced programmers. In our longitudinal study
we found that these problems did not disappear with increased exposure to the
language. With few exceptions subjects reused the plans that they first
developed rather than searching for a more appropriate solution. We believe
that there is a definite need for tools that aid the programmer in their
initial efforts at learning a new language. Without outside intervention
programmers may be very slow to exploit language capabilities. Keywords: Transfer between programming languages, Plan selection, Programming
meta-knowledge | |||
| Expertise and Display-Based Strategies in Computer Programming | | BIBAK | 411-423 | |
| Simon P. Davies | |||
| This paper reports two studies which explore the development of
display-based problem solving strategies in the context of computer programming
tasks. These studies suggest that expertise in programming is dependent upon
the development of strategies for effectively utilising external displays. In
this context, it appears that novices rely extensively upon working memory to
generate as much of a solution as possible before transferring it to an
external source. In contrast, experts make extensive use of an external
display to support problem solving. These results are discussed in terms of a
framework which emphasises the role of display-based problem solving and its
contribution to strategy development. Finally, consideration is given to the
implications of these findings for the design of programming support tools and
languages. Keywords: Programming, Expertise, Display-based problem solving, Strategy development | |||
| MRE: A Flexible and Customisable Program Visualisation Architecture | | BIBAK | 425-439 | |
| Mike Brayshaw | |||
| In this paper we will look to extend basic visual metaphors to produce
higher level descriptions of program execution that allow users to express
their own perspectives on a task. We shall show how this can be done by
adapting a model of event recognition using agents, demonstrate how these
agents are useful in their own right, and then embed such definitions within
templates to generate new visualisations. The aim is thus to bring increased
flexibility and expressibility to programmers in order to aid software tool
based problem solving, enable them to build increasingly abstract models of
their domain, and debug programs from this particular perspective level. The
above will be presented within the context of an overall debugging model, and
its integration demonstrated. Keywords: Program visualisation, Agents, Customisation | |||
| Why HyperTalk Debugging is More Painful than it Ought To Be | | BIBAK | 443-462 | |
| Marc Eisenstadt | |||
| As part of a series of investigations on the nature of programming and
debugging environments, this paper looks in detail at what it's like to work
with an apparently 'modern' and 'friendly' environment: HyperCard. I kept a
detailed diary of several lengthy debugging sessions, and then analysed the
problems and difficulties I experienced. Eight fundamental problems were
observed in the use of HyperTalk's debugging facilities: indirect access to
troublesome source code; disruptive intermediate actions required; poor
interpreter access during breaks; poor monitoring of built-in functions; no
coarse-grained view of execution; no data flow analysis; no control flow
analysis; deceptive view of inner states. The paper discusses the broader
implications of these eight problems, as well as possible ways to alleviate the
problems. Keywords: Debugging, Programming, Programming environment, Hypertext | |||
| Towards Cognitively Salient Relations for Hypertext Navigation | | BIBAK | 463-477 | |
| Henry Bloomfield; Peter Johnson | |||
| The difficulties involved in the navigation of computer-based information
spaces have been widely documented. This paper discusses the navigation
problems and argues that some of these will be alleviated by the use of a set
of domain-independent, semantically 'rich' relationships to define links
between pieces of information.
The background to this area is summarised and an experiment to support the theoretical work in identifying a set of relationships is reported. Finally, the implications, benefits, and possible applications of such a set of relationships are discussed. Keywords: Hypertext, Navigation, Link-types, Text comprehension | |||
| Combining Systems and Manuals | | BIBAK | 479-488 | |
| Harold Thimbleby | |||
| Like many interactive systems, hypertext is operated by button pressing. It
is therefore possible to combine an interactive system with its own hypertext
manual. Numerous advantages follow: adaptive intelligent interactive help;
correct documentation, in natural or mathematical language; automatic
generation of conventional manuals optimised for various tasks; and detailed
analysis.
This paper motivates the approach, and describes a representative system, Hyperdoc. Hyperdoc enables research questions about good user interfaces and good user manuals to be investigated. Keywords: Hypertext, Manuals, Finite state machines | |||