Psychology: Another Science of Common Sense?
(1996), The Psychologist, 9, (7), 300-303.
What is Engineering Psychology
The Need for a Psychology of Engineering
Demand-Resource Theory in Engineering
Perspectives on Engineering
The Future of Engineering Psychology?
"The reasonable person adapts them self to the
world: the unreasonable one persists in trying to adapt the world to them self .
Therefore, all progress depends upon the unreasonable person." (George
What is Engineering Psychology?
Whilst Engineering is concerned with improving equipment from the point of
view of mechanical and electrical design and Psychology is concerned with the
study of the mind and behaviour, Engineering Psychology is concerned with
adapting the equipment and environment to people, based upon their psychological
capacities and limitations (Blum, 1952) with the objective of improving overall
system performance (involving human and machine elements). As Sanders &
McCormick (1987) put it, "... it is easier to bend metal than twist
arms", by which they mean that the design of the device to prevent errors
is likely to be more successful than telling people not to make errors.
According to Wickens (1992) the role of Engineering Psychology is distinct from
both Psychology and Engineering in that it arises from the intersection of the
two domains. He also distinguishes Engineering Psychology from Ergonomics (see
note 1) to suggest that "the aim of engineering psychology is not simply to
compare two possible designs for a piece of equipment ... but to specify the
capacities and limitations of the human ... from which the choice for a better
design should be directly deductible" (pp. 3-4, Wickens, 1992 cites Poulton,
Ergonomics is distinct from Engineering Psychology in that it is
mutidisciplinary (incorporating Psychology, Engineering, Physiology,
Environmental and Computer Science), but the boundaries are fuzzy and
Ergonomics shares the overall goals of Engineering Psychology. The
objectives of Ergonomics (cf. Human Factors) are shared by Engineering
Psychology, which are to optimise the effectiveness and efficiency with
which human activities are conducted as well as to improve the general
quality of life through "increased safety, reduced fatigue and stress,
increased comfort [and] ... satisfaction." (Sanders & McCormick, 1992,
It is difficult to delineate the genesis
of both Engineering Psychology and Ergonomics, but both can be traced back to a
general interest in problems at munitions factories during the First World War (Oborne,
1982). Machines that were designed to be operated by men seemed to have
production-related problems when operated by women. These difficulties were
resolved when it was realised that the problems were related to equipment design
rather than the people operating them, i.e. they were designed to be operated by
men and not women. The mis-reading of altimeters by pilots in the Second World
War stimulated further interest in Engineering Psychology. A study by Grether
(1949) illustrated that the traditional three needle altimeter (where the three
pointers read 10,000s, 1,000s and 100s of feet respectively) not only took
pilots over 7 seconds to interpret but nearly 12 percent of the readings
contained errors of a 1000 feet or more. Grether showed conclusively that
superior designs could dramatically reduce both reading time and error rates.
This study, perhaps more than any other, indicates the importance of Psychology
in the design of devices. Despite this evidence, it is sometimes difficult to
gain acceptance from the Engineering community, and to change design, as the
following quote from an accident report in 1958 (some 9 years after Grether's
original study) shows:
"The subsequent investigation ... showed that the captain had misread
his altitude by 10,000 feet and had perpetuated his misreading error until the
aircraft struck the ground and crashed."
Rolfe (1969) p.16
The Need for a
Psychology of Engineering
We are all familiar with the frustrations that accompany
one's use of technology in the home and at work. Norman (1988) provides an
abundance of examples on this subject. The Information Technology revolution has
led to computers pervading almost every aspect of our lives from programming
Video Cassette Recorders (VCRs) and Microwave Ovens, to withdrawing cash from
Automatic Teller Machines, to purchasing rail tickets, to performing most
aspects of our work. Yet why do these devices, which are supposed to make our
lives easier, seem to thwart our best intentions? One reason is that users of
these devices perceive the problem to be with themselves rather than with the
technology. People often blame themselves when failing to comprehend the
manufacturer's instructions or when errors occur (Reason, 1990). Also, the
problems are usually of a small, relatively trivial and individual nature, and
do not affect other people. These problems are often only minor hassles compared
to major events, such as incidents in the aviation and nuclear industries. On
the face of it there is little comparison between errors with VCRs and errors on
the flightdeck of an aircraft. However, Reason (1990) argues that at the basic
level of interfacing human thought processes with technology there are many
similarities. Despite the obvious differences in training, level of skill and
knowledge in operating VCRs and aircraft, basic error types such as 'mode error'
(i.e. errors that occur when devices have different modes of operation and the
action appropriate for one mode has different consequences in other modes:
Norman, 1986) have been found to occur in both environments.
There has been some concern in recent years about safety
(Stanton, 1996). The incidents at Three Mile Island (in the USA) and Chernobyl
(in the former USSR) are often cited in the press and technical literature. A
recent near-incident at a nuclear utility in the UK has seemingly reinforced
this concern. Whilst these nuclear power plants employ different technologies
there is one common factor to these, and other, incidents: namely human beings.
Reason (1990) reports that 92% of all significant events in nuclear utilities
between 1983-1984 were caused by people and of these only 8% were initiated by
the control room operator.
Thus, the scope of
Engineering Psychology needs to consider all aspects of the
human-technology system. Consideration of the human element of the
system has been taken very seriously since the publication of the
President's commissions report on Three Mile Island (Kemeny, 1979) which brought serious problems to the
forefront. The summary of the main findings of the report highlights a series of
"human, institutional and mechanical failures." It was concluded that
the basic problems were people-related, i.e. the human aspects of the systems
that design, build, operate and regulate nuclear power. Some reports have
suggested 'operator error' as the prime cause of the event. However, the
failings at Three Mile Island included:
- deficient training which
left operators unprepared to handle serious accidents;
- inadequate and confusing
operating procedures that could have led the operators to incorrect actions;
- design deficiencies in the
control room, for example in the way that information was presented and
controls were laid out;
- serious managerial problems
within the Nuclear Regulatory Commission.
None of the deficiencies explain the root cause of the
incident in terms of 'operator error', which is an all too familiar explanation
in incidents involving human-technology systems. Reason (1987), in an analysis
of the Chernobyl incident, suggested two main factors of concern. The first
factor relates to the cognitive difficulties of managing complex systems: people
have difficulties in understanding the full effects of their actions on the
whole of the system. The second factor relates to a syndrome called
'groupthink': small, cohesive and elite groups can become unswerving in their
pursuit of an unsuitable course of action. Reason cautions against the rhetoric
of "it couldn't happen here" because, as he argues, one of the basic
system elements (i.e. people) is common to all nuclear power systems.
Demand-Resource Theory in Engineering Psychology
Solutions to the problems raised in people interacting with
technology come in two main forms; either to reduce demand or to increase
resources in situations of work overload or vice versa in situations of work
underload. The dual concepts of demands and resources are prevalent in
Engineering Psychology and particularly pertinent when considering the
capacities and limitations of people in technological environments. Wickens
(1992) proposes a theory of multiple pools of attentional resources in relation
to different information processing demands - speech and text utilise a verbal
information processing code and draw upon a different pool of attentional
resources to tones and pictures which utilise a spatial processing code. Wickens
argues that when the attentional resources assigned to the verbal processing
code are exhausted, workload demands may be increased further by using the
alternative spatial information processing code through the presentation of
tones or pictures (although these pools are not wholly mutually exclusive).
The concept of demands and resources provides a conceptual framework for
Engineering Psychology. Demands and resources could come from the task, the
device and the user. For example, user resources (e.g. knowledge, experience and
expertise) and demands (e.g. user goals and standards) interact with task
demands (e.g. task goals and standards) and task resources (e.g. instruction
manuals and training). This interaction is mediated by demands (e.g. device
complexity) and resources (e.g. clarity of the user-interface, which could
reduce demands) of the device being operated.
This is a familiar
concept in discussions of task workload, and it is implied that demand
resource imbalance can occur as both task underload and task overload,
both of which are detrimental to task performance. An illustration of the relationship between
demands and resources is provided by the Tale of Procrustes (Oborne, 1982). In
Greek mythology, Procrustes was an ingenious robber who conned travellers into
parting with their gold. His trick was very simple. He offered weary travellers
all the food and wine they wanted and they could either pay for what they had
consumed or accept his hospitality without payment and take a bed for the night.
Most travellers opted for latter, at which point Procrustes added one more
clause: that the traveller had to fit one of his two spare beds exactly. Most
accepted without question and ate and drank their fill. When it came time for
them to bed down for the night Procrustes showed them the two beds, one was very
long and the other very short. At this point Procrustes threatened to make them
fit the bed by either cutting off their legs to fit the short bed or stretching
them to fit the long bed. Most traveller opted to pay the exhorbitant bill
instead! Oborne (1982) suggests that the Procrustean approach often appears to
be taken by designers, who design tasks that either stretch people beyond their
physical and/or mental capacities or tasks that are physically and/or mentally
constrictive. Both ends of the spectrum result in a dissatisfactory outcome for
the individual, as well as poor performance of the system. So we end up paying
for poor design in terms of discomfort, errors, dissatisfaction and poor
performance. Some times the price can be counted in terms of human life.
Perspectives on Engineering Psychology
Three different perspectives on Engineering Psychology are
offered, Engineering Psychology as:
- Human Computer Interaction
- Cognitive Engineering
Shackel (1996) starts by distinguishing Psychology from
Ergonomics, to propose that Ergonomics is about fitting the device to the
individual. He argues that industrialisation has exacerbated many of the
problems associated with device use. First there is the problem of operating
industrialised systems. Second there is the problem of tailoring mass produced
devices to individual needs. Tailoring every device to everyone's needs may seem
like an impossible goal, but if we know what the range of needs are we may be
able to design flexibility into devices so that they meet most people's needs
most of the time. For example, in a relatively simple device, like a chair, we
can offer height and backrest adjustments. The challenge is either to offer the
same degree of customisation for other more complex devices, like computer
interfaces, or to design a standard interface that can be used by all.
Shackel argues that Ergonomics, like Psychology, suffers from being labelled
a Science of Common Sense. All too often, designers seem to prefer to consult
their own intuitions rather than a professional ergonomist. Device testing tends
to be very informal, only involving the designers themselves, rather than being
based upon a sample of the end-user population and subjected to the rigour of
statistical analysis. If, indeed, good design were common sense then we would
not witness the extent of disasters due to poor design in human terms (see
Reason, 1990). Shackel argues that a systematic and scientific approach to the
analysis and design of devices is needed. Even apparently well design devices
(such as the example given by Shackel) appear to benefit from this approach,
although performance problems are normally the indication of poor Ergonomics.
Shackel considers the role of Ergonomics in different kinds of work and this
shows the links between Engineering Psychology and Ergonomics (specifically both
concerned with human-machine interaction and system performance)
Payne (1996) argues that technology and Psychology have mutually beneficial
relationship, but that advances in either can exist without the other. Payne
thus suggests a situation of mutual benefit but not mutual dependence. However,
the one without the other may lead to a poorer outcome for both. Payne asks the
question of whether advances in Psychology lead to advances in technology or
vice versa? He suggests that we witness more of the latter, i.e. technological
insights offer new insights for psychology. For example, the development of the
Graphical User Interface (GUI: e.g. the use of Windows, Icons, Menus and
Pointing devices: WIMP) owes little to psychological theory, but has enabled
applied cognitive psychologists to develop greater explanations for the
phenomenon of why the GUI is easier to use than character-based user interfaces
(Norman & Draper, 1986). Payne argues that psychology is good at providing
explanations for this kind of phenomenon but has not yet revolutionised
technology. The WIMP/GUI interface might be considered to be a technological
revolution, not a psychological one, whereas Psychology can offer small
Payne cites two examples where Psychology has had modest success: in the
development of the SuperBook and the application of the GOMS model. In the first
example, on-line versions of books are generated automatically with
additional features that enable the book to be used with enhanced
functionality. This functionality was based upon psychological research
on human language to design a word search facility.
In the second example, the GOMS model (based on a
cognitive theory developed by Card, Moran & Newell, 1982) was used to
determine the effectiveness of a new workstation. The theory-driven evaluation
(i.e. "to specify the capacities and limitations of the human from which
the choice for a better design should be directly deductible" Wickens,
1992) led to the company rejecting the new design.
Payne also notes the problem of coupling between Cognitive Psychology
research and engineering concerns - this has led to a new, but related
discipline: Human-Computer Interaction (HCI) - which is more closely aligned to
engineering concerns than Cognitive Psychology. Payne indicates that HCI is
rather more unifying than Cognitive Psychology. The former is largely concerned
with whole tasks, such as the operation of a device, from a Video Cassette
Recorder to a Nuclear Power Station, whereas the latter tend to focus on
isolated processes such as perceptual categorisation, word recognition, etc.
Additionally, Payne suggests that Cognitive Psychology can benefit from
advances in technology. The study of human interaction with technology (which
Payne proposes is the domain of Human Computer Interaction) supplies Cognitive
Psychology with phenomena which require explanation. As in the earlier example
of the GUI, the success of the interface was poorly understood until Applied
Cognitive Psychologists addressed this conundrum. Development of theory in this
area could lead to prediction of new technology. Whereas, design in the absence
of theory leads to Psychology chasing technology.
Long & Dowell (1996) argue that operational problems (such as the
problems associated with the computerisation of the London Ambulance Service)
has led to a shift in emphasis from addressing technology to addressing
human-device interaction problems. According to Long & Dowell, the link
between Psychology and Engineering is more than a marriage of convenience, it
has become essential in the wave of technological advancement that requires
humans to interact with devices. As Shackel (this volume) suggests, the need to
address problems has led to the emergence and shaping of the discipline. Long
& Dowell argue for a problem-led approach and propose that the objective of
this discipline should be to get human-computer systems to work effectively.
Like Payne, Long & Dowell argue that the link between Cognitive Psychology
and Information Technology is far from straightforward and they suggest that
even Applied Cognitive Psychology fails to link these two disciplines together
(coupling). Rather, Long & Dowell argue for a separate and distinct
discipline of Cognitive Engineering which is analogous to the relationship that
Software Engineering shares with its allied disciplines of Computer Science and
Long & Dowell argue that this view proposes two different ways of
conceiving the link between Cognitive Psychology and Information Technology
(IT). The one-stream perspective suggests a direct link between Cognitive
Psychology, Applied Cognitive Psychology and IT whereas the two-stream view
suggests that Cognitive Psychology and Applied Cognitive Psychology exist in
parallel to Cognitive Engineering and Information Technology (this is similar to
the argument that Payne puts forward in favour of HCI). They are cautious about
the relationship between these two streams. However, they show that the
two-stream view is more realistic as developments in Cognitive Psychology do not
directly translate into developments in IT even when mediated by Applied
Cognitive Psychology. They suggest that this is because the initial developments
in Cognitive Psychology did not directly address a problem in IT, whereas the
focus of Cognitive Engineering is directly upon design problems in IT. Long
& Dowell show that Cognitive Engineering and Software Engineering are very
similar in principles, practices and approach but for one subtle and important
difference: Cognitive Engineering emphasises that the design focus is upon the
requirements of user populations whereas Software Engineering emphasises the
design in terms of the functioning of the computer.
The Future of Engineering Psychology?
The vision offered by the perspectives are of a
problem-driven focus of Engineering Psychology with concerns about the
performance of human-device systems. Technological advances are likely raise
issues in the areas of advanced transportation, co-operative work, teleworking,
health, pollution and leisure. Recent research effort has called for more
theory-based approach from the discipline, in the design practices and
processes, in the evaluation and understanding of the way in which devices
support human thought. There is an inextricable link between Engineering
Psychology and the Science of Technology and is up to Engineering Psychologists
to rise to these challenges.
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Card, S. K. Moran, T. P. & Newell, A. (1983) The Psychology of
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Engineering Psychology and Human Performance.
We would like to thank
Professor Stanton and 'The Psychologist' for permission to reproduce this article:
Professor Neville Stanton,
BSc, MPhil, PhD, C.Psychol, FBPsS, FErgs
Transport Research Group
School of Civil Engineering & the Environment
University of Southampton
SOUTHAMPTON SO17 1BJ
48 Princess Road East
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