An introduction to human factors engineering

587 Pages·4.584 MB·English

by  Wickens, Christopher D., Gordon, Sallie E., Lee, John, Liu, Yili

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ISBN 978-1-29202-231-4 2
e
9 781292 022314
An Introduction to
Human Factors Engineering
Wickens Lee Liu Gordon-Becker
Second Edition
ISBN 10: 1-292-02231-0
ISBN 13: 978-1-292-02231-4
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book by such owners.
ISBN 10: 1-292-02231-0
ISBN 13: 978-1-292-02231-4
British Library Cataloguing-in-Publication Data
A catalogue record for this book is available from the British Library
Printed in the United States of America
1111222331470369247031011064839741
P E A R S O N C U S T O M L I B R AR Y
Table of Contents
1. Introduction to Human Factors
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 1
2. Design and Evaluation Methods
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 10
3. Visual Sensory Systems
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 41
4. Auditory, Tactile, and Vestibular System
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 71
5. Cognition
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 100
6. Decision Making
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 136
7. Displays
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 164
8. Control
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 198
9. Engineering Anthropometry and Work Space Design
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 223
10. Biomechanics of Work
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 249
11. Work Physiology
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 277
12. Stress and Workload
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 304
13. Safety and Accident Prevention
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 331
I
334444556914780738662673
14. Human-Computer Interaction
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 363
15. Automation
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 398
16. Transportation Human Factors
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 416
17. Selection and Training
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 446
18. Social Factors
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 472
19. Research Methods
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 486
References
Christopher D. Wickens/John Lee/Yili Liu/Sallie Gordon Becker 507
Index 573
II
Introduction to Human Factors
I
n a midwestern factory,an assembly-line worker
had to reach to an awkward location and position a heavy component for assembly.
Toward the end ofa shift,after grabbing the component,he felt a twinge ofpain in
his lower back.A trip to the doctor revealed that the worker had suffered a ruptured
disc,and he missed several days ofwork.He filed a lawsuit against the company for
requiring physical action that endangered the lower back.
Examining a bottle of prescription medicine,an elderly woman was unable to
read the tiny print ofthe dosage instructions or even the red-printed safety warning
beneath it.Ironically,a second difficulty prevented her from potentially encounter-
ing harm caused by the first difficulty.She was unable to exert the combination of
fine motor coordination and strength necessary to remove the “childproof”cap.
In a hurry to get a phone message to a business,an unfortunate customer found
herself“talking”to an uncooperative automated voice response system.After impa-
tiently listering to a long menu of options, she accidentally pressed the number of
the wrong option and now has no clue as to how to get back to the option she
wanted,other than to hang up and repeat the lengthy process.
WHAT IS THE FIELD OF HUMAN FACTORS?
While the three episodes described in the introduction are generic in nature and
repeated in many forms across the world,a fourth,which occurred in the Per-
sian Gulfin 1987,was quite specific.The USS Vincennes,a U.S.Navy cruiser,was
on patrol in the volatile,conflict-ridden Persian Gulf when it received ambigu-
ous information regarding an approaching aircraft.Characteristics of the radar
system displays on board made it difficult for the crew to determine whether it
was climbing or descending. Incorrectly diagnosing that the aircraft was de-
From Chapter 1 ofAn Introduction to Human Factors Engineering,Second Edition.Christopher D.Wickens,
John Lee,Yili Liu,Sallie Gordon Becker.Copyright © 2004 by Pearson Education,Inc.All rights reserved.
1
Introduction to Human Factors
scending, the crew tentatively identified it as a hostile approaching fighter. A
combination of the short time to act in potentially life-threatening circum-
stances,further breakdowns in communication between people (both onboard
the ship and from the aircraft), and crew expectancies that were driven by the
hostile environment conspired to produce the captain’s decision to fire at the ap-
proaching aircraft.Tragically,the aircraft was actually an Iranian passenger air-
line,which had been climbing rather than descending.
These four episodes illustrate the role of human factors. In these cases
human factors are graphically illustrated by breakdowns in the interactions be-
tween humans and the systems with which they work.It is more often the case
that the interaction between the human and the system work well,often exceed-
ingly so. However, it is characteristic of human nature that we notice when
things go wrong more readily than when things go right.Furthermore,it is the
situation when things go wrong that triggers the call for diagnosis and solution,
and understanding these situations represents the key contributions of human
factors to system design.
We may define the goalofhuman factors as making the human interaction
with systems one that
■ Enhances performance.
■ Increases safety.
■ Increases user satisfaction.
Human factors involves the studyoffactors and developmentoftools that facil-
itate the achievement of these goals.We will see how the goals of productivity
and error reduction are translated into the concept of usability, which is often
applied to the design ofcomputer systems.
In considering these goals,it is useful to realize that there may be tradeoffs
between them.For example,performanceis an all-encompassing term that may
involve the reduction of errors or an increase in productivity (i.e.,the speed of
production).Hence,enhanced productivity may sometimes cause more opera-
tor errors,potentially compromising safety.As another example,some compa-
nies may decide to cut corners on time-consuming safety procedures in order to
meet productivity goals.Fortunately,however,these tradeoffs are not inevitable.
Human factors interventions often can satisfy both goals at once (Hendrick,
1996;Alexander,2002).For example,one company that improved its worksta-
tion design reduced worker’s compensation losses in the first year after the im-
provement from $400,000 to $94,000 (Hendrick,1996).Workers were more able
to continue work (increasing productivity),while greatly reducing the risk ofin-
jury (increasing safety).
In the most general sense, the three goals of human factors are accom-
plished through several procedures in the human factors cycle, illustrated in
Figure 1, which depicts the human operator (brain and body) and the system
with which he or she is interacting. At point A, it is necessary to diagnose or
identify the problems and deficiencies in the human–system interaction of an
existing system.To do this effectively,core knowledge ofthe nature ofthe physical
body (its size,shape,and strength) and of the mind (its information-processing
2
Introduction to Human Factors
Performance
A Identification of Problems
Analysis
Techniques
Task
Statistics
Accident
Brain
System
Human
Body
DESIGN
B
Equipment
Task
Implement
Solutions
Environment
Selection
Training
FIGURE 1
The cycle ofhuman factors.Point A identifies a cycle when human factors solutions are
sought because a problem (e.g.,accident or incident) has been observed in the human–
system interaction.Point B identifies a point where good human factors are applied at the
beginning ofa design cycle.
characteristics and limitations) must be coupled with a good understanding of
the physical or information systems involved,and the appropriate analysistools
must be applied to clearly define the cause ofbreakdowns.For example,why did
the worker in our first story suffer the back injury? Was it the amount of the
load or the awkward position required to lift it? Was this worker representative
ofothers who also might suffer injury? Task analysis,statistical analysis,and in-
cident/accident analysis are critical tools for gaining such an understanding.
Having identified the problem, the five different approaches shown at point B
may be directed toward implementing a solution (Booher,1990,2003),as shown
at the bottom ofthe figure.
Equipment designchanges the nature of the physical equipment with which
humans work.The medicine bottle in our example could be given a more read-
able label and an easier-to-open top. The radar display on the USS Vincennes
might be redesigned to provide a more integrated representation of lateral and
vertical motion ofthe aircraft.
Task designfocuses more on changing what operators do than on changing
the devices they use.The workstation for the assembly-line worker might be re-
designed to eliminate manual lifting.Task design may involve assigning part or
3
Introduction to Human Factors
all of tasks to other workers or to automatedcomponents.For example,a robot
might be designed to accomplish the lift of the component.Of course,automa-
tion is not always the answer, as illustrated by the example of the automated
voice response system.
Environmental designimplements changes,such as improved lighting,tem-
perature control,and reduced noise in the physical environment where the task
is carried out.A broader view ofthe environment could also include the organi-
zational climate within which the work is performed.This might,for example,
represent a change in management structure to allow workers more participa-
tion in implementing safety programs or other changes in the organization.
Training focuses on better preparing the worker for the conditions that he
or she will encounter in the job environment by teaching and practicing the nec-
essary physical or mental skills.
Selectionis a technique that recognizes the individual differences across hu-
mans in almost every physical and mental dimension that is relevant for good
system performance.Such performance can be optimized by selecting operators
who possess the best profile of characteristics for the job. For example, the
lower-back injury in our leading scenario might have been caused by asking a
worker who had neither the necessary physical strength nor the body proportion
to lift the component in a safe manner.The accident could have been prevented
with a more stringent operator-selection process.
As we see in the figure, any and all of these approaches can be applied to
“fix”the problems,and performance can be measured again to ensure that the
fix was successful. Our discussion has focused on fixing systems that are defi-
cient, that is, intervening at point A in Figure 1. In fact, the practice of good
human factors is just as relevant to designing systems that are effective at the
start and thereby anticipating and avoiding the human factors deficiencies be-
fore they are inflicted on system design.Thus,the role of human factors in the
design loop can just as easily enter at point B as at point A.If consideration for
good human factors is given early in the design process,considerable savings in
both money and possibly human suffering can be achieved (Booher,1990;Hen-
drick, 1996). For example, early attention given to workstation design by the
company in our first example could have saved the several thousand dollars in
legal costs resulting from the worker’s lawsuit.Alexander (2002) has estimated
that the percentage cost to an organization of incorporating human factors in
design grows from 2 percent ofthe total product cost when human factors is ad-
dressed at the earliest stages (and incidents like workplace accidents are pre-
vented) to between 5 percent and 20 percent when human factors is addressed
only in response to those accidents,after a product is fully within the manufac-
turing stage.
The Scope of Human Factors
While the field of human factors originally grew out of a fairly narrow concern
for human interaction with physical devices (usually military or industrial),its
scope has broadened greatly during the last few decades.Membership in the pri-
4
Introduction to Human Factors
mary North American professional organization of the Human Factors and Er-
gonomics Societyhas grown to 5,000,while in Europe the Ergonomics Societyhas
realized a corresponding growth. A survey indicates that these membership
numbers may greatly underestimate the number ofpeople in the workplace who
actually consider themselves as doing human factors work (Williges,1992).
This growth plus the fact that the practice ofhuman factors is goal-oriented
rather than content-oriented means that the precise boundaries ofthe discipline
of human factors cannot be tightly defined. One way of understanding what
human factors professionals do is illustrated in Figure 2.Across the top of the
matrix is an (incomplete) list of the major categories of systems that define the
environments or contexts within which the human operates. On the left are
those system environments in which the focus is the individual operator.Major
categories include the industrial environment (e.g. manufacturing, nuclear
power,chemical processes);the computer or information environment;health-
care; consumer products (e.g., watches, cameras, and VCRs); and transporta-
tion.On the right are those environments that focus on the interaction between
Contextual Environment of System
Nature of Individual Group
Human Computer & Health Consumer
Components Manufacturing Information Care Products Transportation Team Organization
Visibility
Sensation
s
nt
e
on Perception
p
m
Communications
o
C Cognition &
an Decision
m
Hu Motor Control
Muscular
Strength
Other
Biological Factors
Stress
Training
Individual
Differences
Task Analysis
FIGURE 2
This matrix ofhuman factors topics depicts human performance issues against contextual environments
within which human factors may be applied.The study ofhuman factors may legitimately belong within
any cell or combination ofcells in the matrix.
5