Table Of ContentHUMAN FACTORS IN INFORMATION TECHNOLOGY 7
Series Editors:
Hans-Jörg Bullinger Peter G. Poison
FbG-IAO Institute of Cognitive Science
Stuttgart University of Colorado
FRG Boulder, Colorado, USA
Assistant Series Editors:
Klaus-Peter Fähnrich
Jürgen Ziegler
FhG-IAO, Stuttgart, FRG
NORTH-HOLLAND
AMSTERDAM · NEW YORK · OXFORD · TOKYO
Mental Models and
Human-Computer
Interaction 2
Edited by
M. J. TAUBER
Universität Paderborn
Paderborn, FRG
D.ACKERMANN
ETH-Zentrum
Zürich, Switzerland
199'i
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Library of Congress Cataloging-in-Publication Data
Mental models and human-computer interaction 2 / edited by M.J.
Tauber, D. Ackermann.
p. cm. — (Human factors In information technology ; 7)
"An edited report of the 8th Interdisciplinary Workshop in
Informatics and Psychology ... held in Schärding (Austria) in June
1989"—Pref.
Includes bibliographical references and index.
ISBN 0-444-88602-8
1. Human-computer interaction—Congresses. I. Tauber, Michael J.
II. Ackermann, D. (David) III. Interdisciplinary Workshop in
Informatics and Psychology (8th : 1989 : Schärding, Austria)
IV, Series.
QA76.9.H85M47 1991
004· .or 9~dc20 90-7995
CIP
ISBN: 0444 88602 8
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PREFACE
This is the second volume of "Mental Models in Human-Computer
Interaction" and is published as an edited report of the "8th Interdisci
plinary Workshop in Informatics and Psychology" which was held in
Schärding (Austria) in June 1989. The workshop allied researchers and
practitioners from different continents and different fields to discuss
their results. Mental Models are a very convincing idea, well supported
by intuition and to some degree supported by research. The concept of
mental models has many roots and goes even back to early philosophy.
Nowadays, the interest in this concept has more practical reasons: men
tal models are seen as crucial in systems design. There is the hypothesis
that knowing more about cognition during work on systems would sup
port decisions in design and in consequence help to produce better
interfaces and worksystems. Other researchers focus on a different
view, they use the computer and its facilities as a research modelling
tool in cognitive science.
In his opening address of the "6th Interdisciplinary Workshop on
Informatics and Psychology" (see "Mental Models and Human-
Computer Interaction I"), Thomas Green pointed to the fact, that in
mental models research we have to face some of the central and crucial
questions of cognitive science and cognitive psychology. A lot of
research is going on in these fields but it seems unlikely that all the
difficult issues will be solved in the near future and that we have a uni
fying theory of mental models and their role in action control.
Meanwhile, interface design has to go on based on all the scrappy
knowledge we have. Is there a way to construct a theory from all these
parts of this puzzle? Thomas Green convincingly argued for "limited
theories" based on single research questions. They can be unified by
linking together the questions we wish to answer. Each explanatory
concept can then be kept within its proper bounds by using it only
when we are addressing the type of question for which it is intended.
It seems that each researcher taylors his own definition according
to the investigated task and according to his own demands and intui
tions and the concept "Mental Model" has become very ambiguous.
Preface
VI
Jens Rasmussen summarized recent approaches in his overview paper
presented at the ah-eady mentioned 6th workshop and pointed to the
fact, that for planning human-computer interaction during actual work it
is necessary to consider the interaction between several modes of cogni
tive control which are based on quite different kinds of mental
representations. We have to know more about the identification of the
content and structure of such mental representations during complex
tasks especially between mental processes across cognitive levels and
through time during actual work in order to support decision making
and work by modem information technology.
The papers in this volume concentrate more on design issues, their
theoretical background and the application of the concept in Human-
Computer Interaction (HCl). Nevertheless, there are also contributions
on theoretical topics and methodological questions. They have to be
seen in our interpretation as "limited theories" in a field where we still
miss important knowledge about cognitive processes. These (limited)
theories should be seen not as competitive but as complementary as
Titchener declared for psychological theories already in 1899. This
maxim of tolerance and mutual understanding should be observed much
more in our discussions than in the past.
The Content of the Book
The contributions of the workshop are arranged in 5 sections.
Many contributions can be assigned to different headings as they are
influenced by different theoretical backgrounds and their results contri
bute to different fields. In consequence the assignment has to be to
some extent arbitrary. Some papers address the same or similar topics
and may even contradict each other. They should be interpreted as lim
ited theories contributing to the scientific debate.
The opening address of Gerhard Fischer has its own section:
"From Theory to Design". The complexity of reality calls for more and
more powerful but complex systems but there are three fundamental
problems to solve: We have to comprehend the complexity of the
intended worksystem, describe it by models and finally build the
required powerful and usable system. Starting with a theoretical
analysis of the involved different models and the results of a field
study, Fischer formulates the requirements for "cooperative problem
solving systems" where the system supports decision making and
Preface vii
problem solving. The designer needs new methodologies to construct
such systems. He suggests "integrated knowledge-based design environ
ments" as promising directions toward making complex systems more
comprehensible. The importance of his opening address lies in the fact
that he tries to unify different limited theories and link them together to
a whole perspective for design.
In the second section "Methodological Aspects" of mental models
will be discussed. It is unusual to present scientific results in the form
of a discussion between two researchers. In the case of the paper by
Rutherford and Wilson, we feel that the form of a dialogue between to
"opponents" of different disciplines is apt to outline current tendencies
in the use of the concept and difficulties in understanding the subtleties
of the different perspectives.
Sasse addresses more concrete problems asking "How to t(r)ap
users' mental models". Analyzing several experimental studies, she con
cludes that they suffer from two methodological shortcomings: (1) there
is the over-interpretation of performance data and (2) she identifies a
lack of ecological validity. Based on five experimental studies she sug
gests a constructive-interaction technique. Nevertheless, the existing
methods still remain snapshots of users' models at a certain point in
time.
Adaptable and adaptive systems are discussed in the scientific
community for some time based on the assumption, that really adaptive
systems will improve cooperative interaction between human and com
puter. Diane Murray summarizes the state of the art in the field of
"Modelling for Adaptivity". Based on a new taxonomy derived from
literature the prerequisites for adaptable systems are identified. The
paper ends discussing the key-question "how are adaptive systems to be
built?". An ongoing project how to produce a development environment
for the creation and testing of the suggested "Embedded User Models"
in the context of a "User Modelling Shell" is outlined.
The section continues with a paper by Visser and Moráis address
ing key techniques in knowledge elicitation. Based on studies on pro
grammers and programming they analyze mainly four data collecting
methods such as interviews, results of activity, real time observations
and observations in controlled situations. Each method is appropriate
viii Preface
to gather specific information. In consequence, they recommend a com
bination of methods in order to combine the advantages and cancel out
the inconveniences of the single methods.
The representation of mental models is decisive in research and
there are many attempts to solve this question. Each of them such as
the "Command Language Grammar" by Moran or the well known
GOMS model by Card, Moran and Newell have their advantages but
also their shortcomings. Arend extends the GOMS model adding the
concepts of schemata and unit to enable the model to deal with con
sistency and learning. With his extended GOMS* model he analyzes
the task of academic scheduling to test the power of his extensions.
It is difficult to describe semantic and procedural aspects with the
same formalism. Beringer and Wandmacher attempt to solve this prob
lem. Inspired by object-oriented programming, they suggest an object-
based formalization of conceptual tool knowledge which tries to
integrate a high level semantic description as well as the procedural
level. Their approach is illustrated by some examples from a
spreadsheet program.
"Empirical results" are included in the third section. Brazier and
van der Veer outline a framework for the design of the user interface
with special regard to consistency between mental models and the con
ceptual model of the system. Starting with a pilot study they describe
design decisions and the process of system development.
An evaluation study of an on-line library system is presented by
van der Velden and Arnold. Their approach is based on action theory in
the sense of Hacker. The conceptual model of the system did not fit the
common usage profiles and the authors formulate many recommenda
tions to improve the system.
Performance is the main focus of Dewier and Karnas in their con
tribution about the role of experience in text-editing tasks. They com
pare "naive" and "experts" and point out for example, that the fact that
a text editor is a dynamic device compared with paper explains many
of the difficulties of novices. For experts they advocate some sort of
standardization of text editors.
Another important question is addressed by Metzler, Wetzenstein-
Ollenschläger and Wandke: It would by very helpful if we had methods
to decide in early stages of the design process if the intended solution
Preface ix
will be "user-friendly". Modelling of user behaviour seems to be a
promising solution. The authors examine existing models of user
behaviour such as the GOMS model, Cognitive Complexity Theory and
Task Action Grammars. They apply the criteria of psychological test
theory and demonstrate experimentally that the existing predictive
models are not yet applicable to practical design solutions.
The final paper presents new aspects in program understanding.
Detienne outlines different psychological mechanisms involved in pro
gram understanding. According to her findings, understanding activity
has to be interpreted as depending on the match between the program
characteristics and the characteristics of the programmer's knowledge.
Furthermore, she points to the necessity that beside cognitive capacities
and knowledge structures influences of task and programming should
also be taken into account.
Most of the contributions in this book have stressed the impor
tance of mental models. In the forth section on "Mental Models in
Design" three different approaches of the use of mental models in
design are presented. Information retrieval in bibliographic online data
bases is a difficult design problem. Wettler and Glöckner-Rist analyzed
strategies of end users and of professional searchers in order to identify
the cognitive processes and structures which govern the transformation
of problem descriptions into expressions of query languages of online
information systems. The results of their psychological analyses will be
used to develop a retrieval system that is easy for the end user to
operate.
Karat and Bennett pick up the thread of user modelling in design.
Based on an approach of David Kieras called "Natural GOMS
Language" (NGOMSL), they investigate the opportunities of this
approach specifying interfaces. Comparable functions of two well
known operating systems are taken as examples to test the approach.
They conclude from their experience that the discussions during the
modelling provided valuable insights and that they need further experi
ence to sort out how much of the insight they gained was due to the
skills of the individual analyst, how much was a product of the particu
lar interactions in their group meetings and what has to be attributed to
the discipline of the methodology.
The simulation of cognitive processes is one possibility but you
can also simulate the system for usability testing as Innocent did. He
Preface
reports a pilot study where the use of a telephone device is simulated
on the system, the task and the user level implemented in PROLOG on
a Macintosh. He concludes that the simulations may enable faster test
ing of specific design alternatives.
Plan recognition is a complex process not only for psychologists
but also in Artificial Intelligence (fifth section). Technically, someone's
intentions should be identified by means of a formal method for analyz
ing actions. In spite of its argued and potential implications for HCl,
especially for adaptive systems, plan recognition is still limited to a few
experimental systems. Desmarais, Giroux and Larochelle discuss the
current state of the art outíining the main directions. In an experimental
study with a well known text editor they compare different parsing stra
tegies. Not only theoretical interests promote research in plan recogni
tion but also practical needs. Intelligent help systems for example are
only possible if the user's intentions can be identified properly.
Hoppe and Plötzner outline two methods for analyzing sequences
of user's actions based on task-oriented parsing. The first method is
semi-automatic as it still requires a high degree of analytical under
standing by the user. In the second method the authors try to optimize
their approach. Examples illustrate their work.
The psychological process of constructing a mental model is simu
lated by Schmalhofer and Kühn. The information processing of
different learning methods were modelled on a LISP-system. Their
results illustrate how knowledge from related domains, hypothesis, and
heuristic strategies might be used for forming a mental model.
Plan recognition is one challenge in the field but another is to
identify and support learning processes. In order to investigate these
processes, Opwis, Stumpf and Spada constructed a microworld simulat
ing the dynamics of elastic impacts in classical mechanics. With this
system, a student can design and simulate his own experiments accord
ing to his understanding of the process. Their basic idea is to achieve
more consistency between the representation of the domain expertise
and the knowledge acquisition processes going on while the domain is
explored.
Learning processes can be explained by "assimilation" and
"accommodation" in the sense of Piaget. Riekert uses an object-oriented
representation technique to describe processes of assimilation and
Preface xi
accommodation. He points out the possibilities for constructing systems
whose knowledge bases are to be extendable by the end user.
What have Aristotelian Syllogisms to do with mental models?
Quite a lot according to Lansky's work. Johnson-Laird did some empir
ical research to find a psychological explanation for the human ability
of syllogistic reasoning. The presented approach based on the theory of
graphs is an attempt to approximate an "optimal" model of inference
and simulated in micro-PROLOG.
There are some aspects and results which can not be reported here.
The discussion of the papers during the workshop and afterwards in the
pubs of Schärding. The workshop is not a conference as usual, it is a
very specific place to meet with plenty of time to exchange ideas, to
challenge established views, to debate different theoretical backgrounds
and experimental results but the limits of our research and their com
plementary aspects have to be kept in mind discussing and interpreting
the current state of the art.
Michael J. Tauber, David Ackermann
Paderborn and Zürich, May 1990
