Analysis, Design and Evaluation of Man–Machine Systems. Proceedings of the 2nd IFAC/IFIP/IFORS/IEA Conference, Varese, Italy, 10–12 September 1985

346 Pages·1986·47.97 MB·English

by  G. Mancini

IFAC PROCEEDINGS SERIES
Editor-in-Chief
JANOS GERTLER, Department of Computer and Electrical Engineering,
George Mason University, Fairfax, Virginia, USA
GERTLER & KEVICZKY {General Editors): A Bridge Between Control Science 8c Technology
{Ninth Triennial World Congress, in 6 volumes)
Analysis and Synthesis of Control Systems {1985, No. 1)
Identification, Adaptive and Stochastic Control {1985, No. 2)
Large-scale Systems, Decision-making, Mathematics of Control {1985, No. 3)
Process Industries, Power Systems {1985, No. 4)
Manufacturing, Man-Machine Systems, Computers, Components, Traffic Control,
Space Applications {1985, No. 5)
Biomédical Applications, Water Resources, Environment, Energy Systems, Development, Social
Effects, SWIIS, Education {1985, No. 6)
BARKER 8c YOUNG: Identification and System Parameter Estimation (1985) {1985, No. 7)
NORRIE 8c TURNER: Automation for Mineral Resource Development {1986, No. 1)
CHRETIEN: Automatic Control in Space {1986, No. 2)
DA CUNHA: Planning and Operation of Electric Energy Systems {1986, No. 3)
VALADARES TAVARES 8c EVARISTO DA SILVA: Systems Analysis Applied to Water and Related
Land Resources {1986, No. 4)
LARSEN 8c HANSEN: Computer Aided Design in Control and Engineering Systems {1986, No. 5)
PAUL: Digital Computer Applications to Process Control {1986, No. 6)
YANG JIACHI: Control Science 8c Technology for Development {1986, No. 7)
MANCINI, JOHANNSEN 8c MARTENSSON: Analysis, Design and Evaluation of Man-Machine
Systems {1986, No. 8)
GELLIE, FERRATE 8c BASANEZ: Robot Control "Syroco '85" {1986, No. 9)
JOHNSON: Modelling and Control of Biotechnological Processes {1986, No. 10)
NOTICE TO READERS
If your library is not already a standing/continuation order customer or subscriber to this series, may we recommend that you place a
standing/continuation or subscription order to receive immediately upon publication all new volumes. Should you find that these volumes no longer
serve your needs your order can be cancelled at any time without notice.
Copies of all previously published volumes are available. A fully descriptive catalogue will be gladly sent on request.
ROBERT MAXWELL
Publisher
IFAC Related Titles
BROADBENT & MASUBUCHI: Multilingual Glossary of Automatic Control Technology
EYKHOFF: Trends and Progress in System Identification
ISERMANN: System Identification Tutorials (Automatica Special Issue)
ANALYSIS, DESIGN AND EVALUATION
OF MAN-MACHINE SYSTEMS
Proceedings of the 2nd IFAC/IFIP/IFORS/IEA Conference, Varese, Italy,
10-12 September 1985
Edited by
G. MANCINI
JRC Ispra Establishment, CEE, Varese, Italy
G. JOHANNSEN
University of Kassel, FRG
and
L. MARTENSSON
The Royal Institute of Technology, Stockholm, Sweden
Published for the
INTERNATIONAL FEDERATION OF AUTOMATIC CONTROL
by
PERGAMON PRESS
OXFORD · NEW YORK · BEIJING · FRANKFURT
SÄO PAULO · SYDNEY · TOKYO · TORONTO
U.K. Pergamon Press, Headington Hill Hall, Oxford OX3 OBW, England
U.S.A. Pergamon Press, Maxwell House, Fairview Park, Elmsford, New York 10523, U.S.A.
PEOPLES REPUBLIC Pergamon Press, Qianmen Hotel, Beijing, People's Republic of China
OF CHINA
FEDERAL REPUBLIC Pergamon Press, Hammerweg 6, D-6242 Kronberg, Federal Republic of Germany
OF GERMANY
BRAZIL Pergamon Editora, Rua Eça de Queiros, 346, CEP 04011, Sâo Paulo, Brazil
AUSTRALIA Pergamon Press Australia, P.O. Box 544, Potts Point, N.S.W. 2011, Australia
JAPAN Pergamon Press, 8th Floor, Matsuoka Central Building, 1-7-1 Nishishinjuku, Shinjuku-ku,
Tokyo 160, Japan
CANADA Pergamon Press Canada, Suite 104, 150 Consumers Road, Willowdale, Ontario M2J 1P9, Canada
Copyright © 1986 IFAC
All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in
any form or by any means: electronic, electrostatic, magnetic tape, mechanical, photocopying, recording or other
wise, without permission in writing from the copyright holders.
First edition 1986
Library of Congress Cataloging in Publication Data
Analysis, design & evaluation of man-machine systems.
(IFAC proceedings series; 1986, no. 8)
Proceedings of the 2nd IFAC/IFIP/IFORS/IEA Conference
on Analysis, Design, and Evaluation of Man-Machine
Systems.
Includes index.
I. Man-machine systems—Congresses. I. Mancini, G.
II. Johannsen, G. III. Martensson, L. (Lilian),
1943- IV. International Federation of Automatic
Control. V. IFAC/IFIP/IFORS/IEA Conference on Analysis,
Design, and Evaluation of Man-Machine Systems
(2nd : 1985 : Varese, Italy) VI. Title: Analysis,
design, and evaluation of man-machine systems.
VII. Series.
TA167.A54 1986 620.8'2 86-91458
British Library Cataloguing in Publication Data
Analysis, design & evaluation of man-machine
systems.—(IFAC proceedings series; 1986, v. 8)
1. Man-machine systems
I. Mancini, G. II. Johannsen, G.
III. Martensson, L. IV. Series
620.8'2 TA 167
ISBN 0-08-032566-1
These proceedings were reproduced by means of the photo-offset process using the manuscripts supplied by the
authors of the different papers. The manuscripts have been typed using different typewriters and typefaces. The
lay-out, figures and tables of some papers did not agree completely with the standard requirements: consequently
the reproduction does not display complete uniformity. To ensure rapid publication this discrepancy could not be
changed: nor could the English be checked completely. Therefore, the readers are asked to excuse any deficiencies
of this publication which may be due to the above mentioned reasons.
The Editors
Printed in Great Britain by A. Wheaton & Co. Ltd., Exeter
2nd IFAC/IFIP/IFORS/IEA CONFERENCE ON ANALYSIS,
DESIGN AND EVALUATION OF MAN-MACHINE SYSTEMS
Organized by
Commission of the European Communities, Joint Research Centre,
Ispra Establishment, 21020 Ispra (Va), Italy
Sponsored by
International Federation of Automatic Control (IFAC)
Technical Committee on Systems Engineering
Technical Committee on Social Effects of Automation
Technical Committee on Economic and Management Systems
Co-sponsored by
International Federation for Information Processing (IFIP)
International Federation of Operational Research Societies (IFORS)
International Ergonomics Association (IEA)
International Program Committee
G. Johannsen (Co-chairman), FRG F. Margulies, Austria
L. Martensson (Co-chairman), Sweden U. Pellegrini, Italy
M. Bartoli, Italy W. R. Perkins, USA
W. J. Edwards, Australia J. Rasmussen, Denmark
F. Filippazzi, Italy E. T. van Ravenzwaaij, Netherlands
R. Genser, Austria J. E. Rijnsdorp, Netherlands
M. Gomolinski, France W. Rohmert, FRG
M. Griffon-Fouco, France H. H. Rosenbrock, UK
V. G. Grishin, USSR W. B. Rouse, USA
G. Guida, Italy M. L. Schneider, USA
R. Haller, FRG R. Seifert, FRG
M. Manganut, Romania B. Shackel, UK
J. Hatvany, Hungary T. B. Sheridan, USA
V. De Keyser, Belgium Su Shi-quan, PRC
N. Malvache, France H. Tamura, Japan
G. Mancini, Italy T. Terano, Japan
Local Organizing Committee
G. Mancini (Chairman) F. Filippazzi
A. Amendola M. P. Moretti
P. C. Cacciabue A. Manara
S. Farfaletti-Casali R. Volcan
PREFACE
The field of man-machine interaction in technologi tional Program Committee has made a careful selec
cal systems is moving very rapidly and deserves an tion of papers for the Conference. Two types of
ever-increasing interdisciplinary contribution of papers have been distinguished: Survey and Techni
research and development. More and more computers cal.
are used as the basic component of interfaces and
support systems. This forces the human personnel The Conference program has been subdivided into
(one person or a group of persons) to fulfill many four main sessions:
tasks in cooperation with intelligent machinery. 1) Automation and Operator
2) System Concept and Design
Various aspects of man-machine interaction were 3) Man-Machine Interface
reflected in the different sessions of the Confe 4) System Operation
rence. Task issues of interest are among others:
controlling, monitoring, decision making, fault We hope that the results will be beneficial to
management, maintenance, problem solving, planning all engineers and scientists in automatic control,
and learning. information processing, operational research, and
ergonomics, who are actively working or strongly
The aim of the Conference was to present, and dis interested in the field of man-machine systems.
cuss, recent advances in theory, experimental and
analytical research, and application. The Interna The Editors
Copyright © IFAC Man-Machine Systems, KEYNOTE ADDRESS
Varese, Italy, 1985
FORTY-FIVE YEARS OF MAN-MACHINE
SYSTEMS: HISTORY AND TRENDS
T. B. Sheridan
Massachusetts Institute of Technology, Cambridge, MA 021139, USA
ABSTRACT intense struggle of men and machines. Governments
built laboratories to study the vision and hearing
The field of man-machine systems - the performance and measure the body dimensions of the
analysis and synthesis of systems in which both population of soldiers, sailors, and pilots that
human and machine interact closely - is a young would be the machine operators. The critical
and barely recognized discipline with an tasks themselves were subject to activity or task
unrelenting array of new challenges. Following a analysis to ensure that every one knew what the
brief review of history and highlights, this paper tasks were, who would do them - when, where, and
will characterize some current trends which have in what order. A great deal of empirical data
profound implications: (I) The removal of the poured forth from these laboratories, some of
human element up ("super") and away ("tele") from which continued to exist after the war.
direct and local physical interaction with the
process or product; (2) analytical engagement with At this time "man-machine systems" was
systems having multiple decision-makers with essentially synonomous with "human factors
partially overlapping databases and engineering". It was all quite empirical. No one
multi-incompatible objectives; (3) a new had much time to develop theory, for there were
acceptance of reported mental events (as many applications that needed immediate attention.
contrasted to physically observable behavior) and That period is sometimes disparaged as "knobs and
fuzzy relations (as constrasted to exclusive-set dials", but indeed some of the great empiricists
probablistic events); and (4) an emerging of this era such as Grether, Fitts and Chapanis
equivalence and transformability relation between have set a high standard for behavioral
computer-based decision aids and normative models experimentation and have challenged the theorists
of human performance. All of these have been who followed. For example, Fitts' law, a simple
driven, for reasons to be mentioned, by the generalization of his experiments on
computer in its various forms as automatic speed-accuracy trades in arm movements (Fitts and
controller and decision aid or expert system. Peterson, 1964), like Fechner's empirical law of
sensory judgements originated most of a century
HISTORY: FROM A TO B TO C . earlier, has provoked continuing (and healthy)
controversy.
It is always difficult to pinpoint the
intellectual beginnings of a discipline. In the U.S. during Era A the machines most
Inspiration surely came from synthesizers like affected by the new human factors perspective were
Leonardo, and from generalizers like Weber. The aircraft, both civilian and military, and weapons
technologists of the early 20th century such as systems of various kinds. This was natural
Edison, Bell and the Wrights forced us to realize because military funds in military laboratories
the tremendous importance of human-machine were used to do the research. The Detroit
interaction and the need for putting human sensory automobile manufacturers, General Motors, Ford and
and motor characteristics in quantitative form. Chrysler set up human factors groups. The
The early industrial engineers, such as telephone industry did the same. Mostly, however
Frederick Taylor, may be credited with encouraging the domestic sector, including factories, chemical
systematic analysis of the relation of man to plants, power stations and the home, remained
machine on the production line. The two great unaffected.
wars brought awareness of the need for systematic
analysis and synthesis of man-machine systems, for In Europe, by contrast to the U.Si,
here human operators were called upon to operate industrial productivity had been depleted, and
complex communication and control equipment such there was need to get industry moving again.
as aircraft, tanks, submarines, ships, radars, Ergonomics (literally "work science") including
sonars and ordnance. the professional society and journal with this
name, was born in the U.K. In the same period the
With some trepidation about Human Factors Society and its journal were begun
oversimplification I categorize the history of in the U.S. Pioneering research groups were set
man-machine systems into three fifteen-year eras, up by Barlett in Cambridge, U. K., by Fitts in
with the first beginning in 1940. Columbus, Ohio, by Chapanis in Baltimore,
Maryland, and by Taylor and Lyman in Los Angeles.
Era A: Acuity, Anthropometry and Activity
Analysis (1940-55) Era B: Borrowed Engineering Models (1955-70)
The first few years of this period saw most During the Second World War important new
developed nations of the world locked in an theories were developed to solve pressing
engineering problems: the theory of control
(applied to gun aiming and the stabilization of
aircraft, ships and tanks); the theory of signal
The historical review which follows is limited
detection (applied to detection of enemy aircraft
mostly to the relevant literature in English.
2 T. B. Sheridan
and submarines through use of radar and sonar apply with remarkable invariance to immediate
respectively) and the mathematical theory of memory of a variety of simple stimuli.
communication. In these engineering developments Another normative theory developed elsewhere,
was born what is now known as systems engineering that of Bayesian updating of probablistic
or systems theory, hypotheses, was rapidly adapted by the applied
behavioral scientists. Edwards (1963) showed how
The new system theory was an instant fashion. human decision-makers as users of evidence were
Non-engineers, for example operations researchers too conservative. He challenged the community of
(with their new applied mathematical tools such as man-machine systems engineers with his
linear programming), proclaimed their own special "probablistic information processor" - wherein
brands of systems analysis. Today the term knowledgeable humans would enter contingent
"systems" is generic, demanding only that system probabilities but a computer would perform the
components be identified in terms of inputs, final calculations on a normative basis and take
outputs and transfer equations. action. The military strategists did not evidence
great enthusiasm for this idea.
The first major borrowings from physical
engineering to apply to human engineering came As with control theory and information
just before 1950 - to apply linear control theory theory, the success of the engineering theory of
(by then well established in the engineering signal detection gave rise to human performance
world) to the human operator. Tust in (1944) is models, most notably that of Swets, Tanner and
generally reputed to have been first with his Birdsall (1955), leading to the normative model of
study of manual control in gun aiming. James, an "ideal observer" or expected value maximizer
Nichols and Phillips (1947) first published their (Tanner, Clarke and Birdsall, 1960).
analysis of manual tracking in a book that is a
classic in control theory. Taylor and Birmingham It was curious that Era B was to such a great
(1948) published perhaps the first "quickening" extent driven by engineering. There was already
studies. Ellson and Wheeler (1949) first pointed in place some elegant psychophysical technique
out the "range effect" in manual control - the (Stevens, 1951) and a modicum of mathematical
tendency to overshoot small inputs and undershoot learning theory (Bush and Estes, 1959), but
large ones. neither of these had the impact on the design of
man-machine systems as did the engineering
There followed in rapid succession a number of theories of control, communication, decision and
studies to refine the human operator model. signal detection. During Era B, for example, what
Notable among these were studies by Elkind (1954), is now the world's largest engineering society,
who refined the human operator model as a function The Institute of Electrical and Electronics
of input bandwidth, and by McRuer and Krendel Engineers, initiated publication of Transactions
(1957) who generalized upon a variety of published on Human Factors in Electronics, shortly
research and refined the model further as a afterwards changed to Transactions on Man-Machine
function of both input and controlled element. Systems, and then Transactions on Systems, Man and
Sheridan (1960) and Young et. al. (1964) first Cybernetics. Other engineering societies in both
showed how human operators adapt to suddenly Europe and the U.S. also became active in this new
changing plant parameters. Bekey (1962) showed field.
how a sampled-data model could give results
similar to the continuous dynamic model and also In the Soviet Union and Eastern Europe
accommodate to special spectral characteristics of interest in man-machine systems emerged in a
operator "noise". somewhat different way. Though B. Lomov and
others pioneered engineering psychology in the
A landmark report by McRuer et. al (1965) set USSR, and even though the Soviets already had
forth the now accepted "simple crossover model". their share of top control theoreticians, it was
This was an important engineering achievement in the ideas of N. Weiner's cybernetics (by Weiner's
that it provided a simple two-parameter model own definition "communication and control in the
which was easy to understand and widely useful. animal and the machine") that caught the
Even more important was the exposition of a new imagination there. I was privileged to attend the
principle in man machine systems - that since the first IFAC World Congress in Moscow in 1960, at
human operator adapts to his task environment it which time the American Professor Weiner was
is man-plus-controlled-element (i.e. the forward honored to the point of reverence.
loop) that tends to be invariant (and therefore Thus it was really in the period 1955 - 1970
should be modeled), not the human operator by that "man-machine systems" came into its own as a
himself. This principle of man-plus-machine discipline with a quantitative systems-theoretical
invariance is still to be appreciated by many. base. This was in contrast to the broader and
more empirical "human factors". (Many today
Optimal control theory had barely been would subsume the former as a subset of the
codified when Baron and Kleinman (1969) published latter).
their optimal control model of the human operator,
refinements of which continue to be developed Era C; Computers and Cognition (1970-1985)
today for ever more complex control problems.
Without question during the recent fifteen
A few years following the publication of year period the dominant influence has been the
Shannon's mathematical theory of communication digital computer. The computer's first use was
(1949) the information channel model of the human simply as a machine for solving equations
operator became popular. A contest developed ("crunching numbers"). Gradually because of speed
among the investigators - to determine the and cost improvements it emerged as a real-time
behavioral factors which enabled or constrained simulator of aircraft, nuclear power plant and
the transmission of bits-per-second. This other environments such that operators could be
included the work of Hake and Garner (1951) on trained, "accidents" could be made to happen, and
scale reading, Hick (1952) and Crossman (1953) on researchers could follow the fine grain detail of
choice reaction time, and Fitts (1954) on operator performance under task stress, which
speed-accuracy tradeoffs in voluntary limb previously they had not been able to do. More
movements. In 1956 Miller published his famous recently the computer has become the basis of
"magical number 7 +_ 2" paper in which Shannon's decision aids or "expert systems" in various
communication channel hypothesis was shown to decision contexts such as drug therapy, drilling
Forty-five Years of Man-Machine Systems 3
of oil wells, configuring computer systems and Now human pilots have less to do - at least with
military planning. respect to those aspects of their behavior
amenable to modeling. They have been elevated to
One of the impacts of the computer on "flight managers". (Other workers also are being
analysis and synthesis of man-machine systems has replaced by automatic machinery, but not always
been the acceptance of "cognition" as a viable due to advances in modeling).
entity worthy of scientific discourse.
Particularly striking has been the recognition of FOUR CURRENT TRENDS*.
cognition by engineers in the context of
applications (e.g. as exemplified by the phrase Discussed below are four interrelated trends
"cognitive engineering"). Artificial intelligence which I have observed over recent years which seem
and "expert systems" have caught the imagination to be making subtle but profound changes in the
of many, and have given new life to studies of ways we view our subject and do our work. They
perception, memory and thinking. are not trends in the technology per se, though
clearly the progress in computer speed and memory,
The new motivation to study man-computer parallel computation, new sensors, and high
systems has come from two directions. First, bandwidth communication are the technological
application-oriented engineers have sought to drivers for these intellectual trends. (Often in
introduce the computer and aid human operators the past technology has driven intellectual change
wherever possible. This includes the human rather than the reverse).
operators who program and oversee robots for the
assembly line, and those who control teleoperators 1. Super- and tele-; new roles for the human
for space, undersea and nuclear applications. operator
This also includes, now as not in the past, the
large cadre of office workers in the service The prefixes "super" and "tele" may be used
sector, who mostly have been abandoned by human to characterize the first trend - the removal of
factors when they typed and shuffled papers. Now the human operator up and away in physical
office automation, word processing and business relation to the process, product or ultimate
software and computer graphics are receiving great object of attention.
attention from a new breed of man-computer systems
researchers - whose orientation is less toward "Supervisory control" means that a person is
control and instrumentation, more toward setting initial conditions for, intermittently
production rules, frames and list processing. adjusting and receiving information from a
computer which itself closes a control loop with a
The other motivation to study human-computer controlled process by means of artificial sensors
interaction comes from those who develop computers and effectors. Typically (Figure 1) the human
and artificial intelligence. Starting two decades supervisor must: (1) plan the task execution, (2)
ago with almost a disdain for real humans and real teach or program instructions to the computer, (3)
human problems, there has evolved an acceptance monitor the automatic execution of the
that human cognitive and neuromuscal capabilities instructions, (4) intervene to assume control in
still provide a challenge to emulate, whether it case of failure, reinstruct in case of task
is visual or tactile pattern recognition, speech completion, or perform maintenance or repairs, and
recognition, language translation, manipulation or (5) learn from experience - so as to make better
body mobility. plans in the future. The high-level
human-interactive computer should (1) have an
What has also evolved during the most recent adequate knowledge base with regard to the task to
era of the history of man-machine systems is be accomplished, (2) be able to simulate
criticism of that term as being sexist, where by alternative control strategies, (3) have some
implication the female of the species is excluded. means to detect or anticipate failures, (4) have
Alas, the English "man" lacks the inclusiveness of some means to remember, recall or correlate past
the German "mensch", while the terms "human" and performance data, and (5) provide a flexible human
"person" continue to lack acceptance in the interface including graphic displays and command
technical context. language, including some capability for helping
the operator edit commands and avoid inappropriate
Necessarily the above characterizations of ones.
the three 15-year periods since 1940 are greatly
simplified, for each type of activity continues At a "lower" level of a supervisory control
on. The empirical human-factors activity to system one or many (multiplexed) task-interactive
refine displays and controls is as extensive today computers serve in real time as automatic
as ever. For example nuclear power plant control controllers or robots - autonomous for periods of
rooms, long neglected in the U.S. with respect to time appropriate to the task, instructions,
human-factors, were precipitously thrust into the resource constraints and the will of the
human-factors limelight by the accident at Three supervisor. In terras of the well known Rasmussen
Mile Island (Keraeny, 1979). (1976) trichotomy of knowledge-based, rule-based
and skill-based behavior, the skill-based and
The borrowing of theoretical engineering gradually more of the rule-based behavior are "off
models for modification into man-machine models, loaded" to the computers (see Sheridan, 1984).
which began so successfully in the late forties, Knowledge-based along with some of the rule-based
also continues. This, for example, is evidenced decisions are usually retained by the supervisor.
by the continuing annual meetings of Bayesian
decision-making modelers, manual control modelers The complementary "tele" prefix refers to the
and the like. (The American "Annual Manual", in ever greater tendency for the human operator to
its 22th year with no professional society to control remotely. Television and other forms of
sponsor it, now has a European counterpart, and telecommunication have been available for some
has recently spawned an "Annual Mental"). time. The latter coupled with mechanical control
technology have produced "teleoperators", which
In one sense the success of man-machine
modeling has contributed to putting the human
operator out of business. As what pilots did in Support for this research was provided by the
flying airplanes became better understood, that Office of Naval Research under contract
knowledge was immediately applied to autopilots. N00014-83-K-0193.
4 T. B. Sheridan
HUMAN SUPERVISOR 1
1
y
CONTROL INSTRUCTIONS,, HIGH-LEVEL FEEDBACK, HUMAN INTERACTIVE SYSTEM
REQUESTS FOR ADVICE ADVICE (IN CONTROL ROOM OR COCKPIT)
Y
1 HUMAN INTERACTIVE COMPUTER
(COMBINES HIGH-LEVEL CONTROL
1 AND EXPERT ADVISORY SYSTEM) >
y ,v
1 4 \
\ MULTIPLEXED SIGNAL TRANSMISSION
(MAY INVOLVE BANDWIDTH
CONSTRAINTS OR TIME DELAYS)
1 1 Λ
,I^ TASK TASK 1 1 TASK
INTERACTIVE INTERACTIVE INTERACTIVE
1C OMP1UT ER COMPU2T ER 1 COMPUTER y- TASK INTERACTIVE SYSTEM
1 N (REMOTE FROM OPERATOR)
) 1, * t , * ί
1 TASK TASK TASK CONTROLLED PROCESS MAY BE
1 l 2 L N J CONTINUOUS PROCESS, VEHICLE,
ROBOT, OR ETC
Figure 1. Supervisory Control
are vehicles, manipulator arms or combinations of complex and high-stakes technological systems.
these which are controlled remotely by humans. However, though sociologists and training
"Telepresence" is achieved by head-mounted psychologies have had to cope with such teams in
displays which, as the human operator turns his the past, man-machine systems analysts have shied
head, drive the remote video camera and thus away. Now command and control systems in both
provide the operator a sense that he is physically military and civilian (air traffic control, fire
present at the remote site. Stereopis, remote fighting, police) sectors now seem to demand
binaural listening, and tactile and force feedback analysis, particularly where different decision
from the manipulator arm also contribute to a makers have access to different data bases which
sense of telepresence. overlap only partially, and where communications
between decision makers are impaired. (This
Teleoperation is being done to an increasing latter describes what is now called "distributed
degree in space, undersea and nuclear radiation decision-making").
environments, and there is much promise for such
technology in mining, construction and medicine. One might imagine that tackling this more
Supervisory control is already present to a large complex form of man-machine system would follow
degree in modern aircraft, chemical plants, steel naturally from having the problem of one-person,
mills and discrete parts manufacturing. one data-base, and a well defined objective
function in relatively good order. Unfortunately
Quite obviously "super" and "tele" control by the latter cannot be assumed. If anything, recent
humans are appropriately combined in many years have seen much evidence that people don't
applications where there is an arbitrary distance behave quite as the normative theory would have
between the human interactive and task interactive them behave in order to maximize subjectively
computer. Because spatial separation and expected utility. First, they have a difficult
time conceiving of action alternatives or possible
multiplexing typically lead to constrained
outcomes with which they are not familiar.
bandwidth and time-delay, the
Second, they are poor judges of uncertainty,
human-operator-to-computer communications with
having a very difficult time with odds-ratios
respect to any one task tend to be intermittent
which deviate from unity by more than two decades
packets or chunks. For a review of the current
either way. Third, they do not seem to use
states of teleoperators see Vertut and Coiffet
evidence in a rational way, often preferring to
(1984). Research needs in supervisory control are
search for confirmatory evidence for one
reviewed by Sheridan and Hennessy (1984).
hypothesis while ignoring other hypotheses for
Research needs certainly include improved models
which evidence is present. Fourth, they are very
of human supervisory control. However, both
unsure of their own utilities for consequences
because of its complexity relative to simple
they have not experienced. Nevertheless, against
manual control and because the human operator in
this background there is demand to engineer and to
this case may be the goal or criterion setter,
model distributed decision-making! Fischhoff
there is some question whether a useful predictive
(1985) has written an excellent review of this
model of supervisory control can ever be attained.
problem.
2. Multi-; people, databases and criteria
The formal problem of group or social choice
A second recent trend in man-machine systems is one that has received attention by
is toward systems with two or more people econometric theory. However the results are
cooperating, using multiple sources of data and/or discouraging, in the sense that there seems to be
multiple not-easily-commensurable criteria or no fair procedure by which three or more persons
objectives. Teams of operators have long piloted can rank-order alternatives and not some of the
aircraft and ships, nuclear power plants and other time encounter intransitivity (e.g. the first
Forty-five Years of Man-Machine Systems 5
person ranks three available alternatives ABC, the it seems to me it must exist apart from
second BCA, the third CAB). Arrow won a Nobel physiological processes or task performance.
prize for his work on this "impossibility theorem" Physiological events may be correlated with mental
(Arrow, 1951). The group decision problem will workload, but cannot be_ mental workload, because
not go away, however, and less than perfect they are not mental. In any case, whatever our
procedures must and are being developed. pangs of guilt, we in the man-machine systems
community have pursued mental workload with
enthusiasm. (How close we are to catching the
The multi-objective problem by itself has
beast is open to question).
also received attention from the decision
theorists (see Keeney and Raiffa, 1976). But
experience with extracting multi-objective utility The man-machine systems community's recent
functions from people has been less than pursuit of the "mental model" has been a somewhat
satisfactory. It seems that most people have different story. The idea that a person carries
difficulty with lotteries, especially where the in his head some representation of objects and
hypothetical probabilistic consequences are events in the external world is at least 2000
unfamiliar. What seems a much more acceptable years old. Thus it was natural that control
approach is "satisficing", wherein the judge engineers considered that a model of the
(subject) first specifies a "desired point in controlled process, continuously modified to some
attribute (objective) space with which he would be extent by its discrepancy from actual measurements
satisfied, and in what general vector direction he of a few available variables to force it into
would prefer to go if he could. The computer, correspondence with reality, would be a good way
having been given constraining equations for what to estimate ("observe") all other variables of the
is physically or economically achievable, returns process.
a judgement as to whether the desired point is
achievable, and if so what "better" point lies at After the process-model-in-the-automatic-
the outer boundary of achievability in the controller proved so useful to the engineers, it
direction of what is wanted, and if not what was easy for man-machine system modelers to
"best" point in the neighborhood j^ achievable. reinvent the process-model-in-the-head. For a
The judge can then iterate the procedure with a normative internalized model, insofar as the
new desired point, etc. until satisfied. external process is known, one simply assumes its
equations operate in the head perfectly (as did
In time the problem of social choice by Baron et. al. assumed in the optimal control model
multi-persons using different data sources, of the human tracker). However, once one seeks to
different-multi-objective criteria and noisy determine empirically what model is actually in
channels will become tractable to formal analysis, the head, how is the knowledge represented there,
but just now it appears formidable. Recently some how accurate is it, etc. one takes on a problem of
interesting theory of two person decision with considerable difficulty, since one is right back
noisy channels is being developed, based on to the difficulties of inferring "intervening
information theory. The computer-based decision variables" of the "mind". Refering to Figure 2,
aid is already figuring heavily in the it can be said in this case that the researcher
has a second order inference problem, namely he
distributed-decision or command and control
must infer in his head a model of the operator's
system, and its use will not make analysis of such
model of the environmental objects or events
systems easier.
(which may or may not be similar to those same
objects or events as seen by himself or other
3. Revisitation of the Mind-Body Problem
human observers), then produce a public model for
the user.
The discrepancy between mind and body has
puzzled philosophers for a long time. Descartes'
"cogito ergo sum" may have been his way to bridge One bright hope for the cognitive modeler and
the gap, but following the rise of logical expert system designer appears to be the
positivism and a physics of the early 1900's that development of fuzzy sets (Zadeh, 1984). One can
demanded observable, repeatabie experiments the be quite sure that real human operators do not
cognitive psychologists of the day went into full ahere to floating point precision and boolean
retreat. The behaviorists claimed science on logical algorithms without any overlap between
their side, and so too, I believe, would they meanings or encodings of stored symbols (in
today claim systems engineering with its emphasis whatever form). Fuzzy sets appear inherently
on identifiable inputs, outputs and transfer appropriate for describing heuristic production
functions ("and don't mess with Mr. in-between" as rules encoded in natural language using terms such
the old ditty goes). Man-machine systems, I as "fast", "medium", "little", "red" and "mostly",
assert, was born in the behaviorist tradition. which map on physical quantities with varying
degrees of membership (applicability, relative
truth).
When the cognitive psychologists emerged from
the woods riding triumphant atop the digital
The decision aid or expert system can only be
computer, the man-machine systems researcher was
presented with a dilemma. Should one espouse the as smart as the rules given to it by legitimate
new liberated order, tolerant of "intervening human experts. Real human experts think and
variables" which can only be inferred, or should express themselves mostly in heuristics and fuzzy
one adhere to the rigid old dogma? Along with sets rather than precise equations and algorithms.
many of my colleagues, I have felt caught up in
this dilemma. 4. Decision aids and normative models
Subjective scaling of aircraft handling The trends described in the preceding three
qualities (Cooper-Harper ratings) or of sections suggest difficulty in man-machine
preferences (utility functions) has not seemed too modeling of the new computer-interactive system
compromising since, after all, there is a because of (1) system complexity, (2) the
closed-form analysis that can be performed increased evaluative role of the human operators
separately - with the subjective numbers only an (which means the objectives of the tasks are not
exogenous input. given from outside, and the task is therefore
specifiable to the analyst only partially), and
Where the behaviorist scruples really have to (3) the lack of observability of cognitive events.
be compromised is in confronting "mental workload"
(Moray 1979). Insofar as this phenomenon exists There is one respect, however, in whch the