Integrating Physical and Cognitive Ergonomics

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Integrating Physical and Cognitive Ergonomics
Ranjana K. Mehta
To cite this article: Ranjana K. Mehta (2016) Integrating Physical and Cognitive Ergonomics,
IIE Transactions on Occupational Ergonomics and Human Factors, 4:2-3, 83-87, DOI:
10.1080/21577323.2016.1207475
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INTRODUCTION
Integrating Physical and Cognitive
Ergonomics
Ranjana K. Mehta
Department of Environmental and
Occupational Health, Texas A&M
University, 1266 TAMU, College
Station, TX 77843, USA
The field of human factors and ergonomics (HF/E), since its inception, has
been instrumental in developing methods, tools, and solutions when consider-
ing cognitive and physical systems independently. However, every human
action is orchestrated by mind (and brain) and body interactions. To compre-
hensively understand how humans (from the neck up and down) interact with
their environments, it is necessary to employ approaches that effectively iden-
tify, assess, and facilitate development of controls and remedial measures that
address these mind-body interactions. The study of physical ergonomics is con-
cerned with human anatomic, anthropometric, physiological, and biomechani-
cal characteristics as they relate to physical work systems. The study of cognitive
human factors is concerned with mental processes, such as perception, memory,
reasoning, and motor response, as they affect interactions among humans and
other elements of a system. Most work systems involve some level of mental or
cognitive processing in addition to physical efforts, so that ideally physical and
cognitive demands should be considered together when examining human
behavior at work. High cognitive demands can influence physical capabilities,
and physical demands can influence cognitive processing. So, while HF/E is a
highly multidisciplinary field that considers humans relative to some aspect of
their work environment, efforts are needed to integrate physical and cognitive
subsystems during evaluation and (re)design when considering the human in
the context of the work situation. The goal of this special issue is to contribute
to the growing body of scientific literature on integrating physical and cognitive
ergonomics that brings researchers closer as an interdisciplinary HF/E field. The
breadth of topics covered includes studies that focus on quantifying human
behavior when interacting with physical and cognitive subsystems, applied
research that proposes predictive tools to assess multidimensional work
demands, theoretical positions and new methodologies that challenge how we
currently examine these interactions, and finally, evidence that highlights busi-
ness outcomes of the interplay between physical and cognitive processes.
Mental workload, fatigue, and stress, stemming from an overloaded cogni-
tive subsystem, have been shown consistently to affect several aspects of
human physical capabilities. For example, cognitive distractors and social
stress can alter biomechanical strategies during controlled processes such as
upper extremity and low back exertions ( Marras, Davis, Heaney, Maronitis, &
Allread, 2000; Mehta & Agnew, 2011; Mehta, Nussbaum, & Agnew, 2012) as
Corresponding author. E-mail:
rmehta@tamu.edu
2157-7323 � 2016 “IIE” 83
IIE Transactions on Occupational Ergonomics and Human Factors, (2016), 4: 83–87
Copyright� “IIE”
ISSN: 2157-7323 print / 2157-7331 online
DOI: 10.1080/21577323.2016.1207475
well as automated processes such as walking
(Beauchet et al., 2003; Osofundiya, Benden, Dowdy,
& Mehta, 2016). Neuromuscular performance, such as
muscular fatigue and recovery, also deteriorates with
mental fatigue and workload (Yoon et al., 2009;
Mehta & Agnew, 2012). Mechanistic investigations
have revealed cardiovascular, endocrinal, neuromuscu-
lar, and perceptual pathways through which “non-bio-
mechanical” work factors affect worker functional
capacity. These include, but are not limited to, recruit-
ment of same motor units during separate physical
and mental work (Lundberg et al., 2002), increased
neuromotor noise (Gemmert & Galen, 1997;
Bloemsaat, Meulenbroek, & Galen, 2005) resulting in
impaired motor coordination (Mehta & Agnew, 2011;
Mehta et al., 2012; Mehta, 2015), altered detection,
labeling, and attribution of sensations (Sauter & Swan-
son, 1996), and interference at the dorsolateral pre-
frontal cortex that is involved in cognitive processing
and isometric motor contractions (Mehta &
Parasuraman, 2014; Mehta, 2016).
The impact of exercise on cognitive functions, based
on type and duration, is also well established and docu-
mented (reviewed in Tomporowski, 2003). Physical
exercise influences the amount of attentional resources
devoted to a given cognitive task, which follows an
inverted U-shaped behavior of differences in physical
intensity (Kamijo et al., 2004; Yanagisawa et al., 2010).
Previous evidence has also demonstrated that the tim-
ing of cognitive tasks during exercise can regulate cog-
nitive performance during dual-task scenarios
(Audiffren, Tomporowski, & Zagrodnik, 2009). But
what about modality of information processing? HF/E
design strategies have regularly exploited sensitizing
both auditory and visual systems for signal detection
and information dissemination to enhance stimulus
salience. In this issue, Pankok, Zahabi, Zhang, and
Kaber (2016) examined the effect of physical exertions
on concurrent cognitive task performance with differ-
ent modalities of information presentation. Using tra-
ditional ergonomic techniques to assess physical
exertions during running, the authors reported that in
occupations where workers are heavily physically chal-
lenged, presenting cognitive information through
visual modality may result in faster processing of inhi-
bition responses than through auditory channels.
Because Pankok et al. (2016) simulated physical
exertions in a controlled lab environment using a tread-
mill, the ecological validity of physical demands may
be questioned. Indeed, it is possible that cognitive pro-
cesses during running differ when one runs on a tread-
mill (and indoors) versus on a natural outdoor terrain.
This, in fact, was examined in the next article in this
issue by Blakely, Kemp, and Helton (2016). The
authors sought to understand whether differences in
natural terrain characteristics impacted cognitive and/
or running performance. The study was conducted in
naturalistic settings, in even and uneven natural ter-
rains, and a tone-counting working task at two diffi-
culty levels was employed to manipulate cognitive
demands. Decrements in running performance were
found as the cognitive load increased. Moreover, cogni-
tive performance declined with increasing workload
(i.e., greater cognitive difficulty and an uneven terrain).
Findings reported by Pankok et al. (2016) and
Blakely et al. (2016) have important implications for
warning signal designs in high stress scenarios. This is
particularly true in scenarios that are associated with
running/exercise and are extremely physically challeng-
ing, such as those experienced by law enforcement and
military officers. One might inquire if the aforemen-
tioned relationships were true for physical tasks that
require greater postural stability. Maintaining balance
and posturalstability, both seated and standing, are
critical in minimizing the risk of falls in industrial set-
tings, such as construction and oil and gas operations.
The third article in this issue, by Cullen and Agnew
(2016), investigated the effects of a multimodal dual-
task paradigm (seated balance and auditory discrimina-
tion tasks) on performance, physiological, and subjec-
tive measures of workload. Contrary to the authors’
hypotheses, the balance task did not affect the perfor-
mance of the auditory task, and the presence of the
auditory task led to better balance performance with
unstable seating. While performance measures
remained unchanged, and physiological workload indi-
cator was only sensitive to the auditory task, subjective
workload measures showed the greatest sensitivity to
changes in workload due to both balance and the audi-
tory task difficulty levels. As such, the authors under-
score the need for employing multiple metrics of
workload to better evaluate how operators interact with
their multitasking environment.
The fourth article in this issue, by Murata (2016),
employed multiple metrics, both behavioral and physi-
ological, to predict subjective drowsiness during a sim-
ulated driving task. Driver fatigue and drowsiness is a
critical HF/E challenge and current research
Mehta 84
(to practice) efforts have focused on real-time monitor-
ing systems that can accurately predict driver drowsi-
ness to avoid accidents. Murata (2016) integrated
several behavioral measurements, such as neck bending
angle, back pressure, and foot pressure, as well as physi-
ological measurements, such as electroencephalogra-
phy, heart rate variability, and blink frequency, to
develop a model that offered»97% accuracy to predict
subjective drowsiness. The author successfully
employed an integrated approach using key informa-
tion from different operator subsystems (cognitive and
physical) during simulated driving tasks, through tradi-
tional ergonomics and human factors assessments as
well as more recently developed neuroergonomic
methods. The feasibility of obtaining different meas-
urements, which vary in the level of technology
requirements, intrusiveness, and precision offered, was
also discussed in the context of developing real-time
monitoring systems for tracking driver drowsiness. The
objective of the next article in this issue, by Ye and Pan
(2016), was to predict subjective recovery time, which
can facilitate efficient physical and mental work shift
schedules, using parameters that are feasible to obtain
in naturalistic work environments. Their study built
upon existing evidence on the interactions between
physical and cognitive work demands to develop an
estimation tool that utilized gender, relative body mass
index, heart rate, perceived functional ability, and
physical activity rating score, to predict when during
the course of physical recovery workers can safely and
effectively resume cognitive work.
One of the common discussion points raised in the
aforementioned studies presented in this issue is the
need for a better understanding of the impact of phys-
ical and cognitive stressors on various human subsys-
tems. Neuroergonomics, the study of brain and
behavior at work, is one of the numerous scientific
impacts that Raja Parasuraman made on HF/E
(Parasuraman, 2003; Parasuraman & Rizzo, 2007; Para-
suraman & Wilson, 2008). The two Methods, Models,
& Theories articles presented in this issue expand on
this new subdomain of HF/E and as such aim to con-
tribute to Raja’s legacy. Hancock, Volante, and
Szalma (2016) present an extension to Parasuraman’s
vigilance taxonomy (Parasuraman & Davies, 1977), in
an attempt to defeat vigilance decrements, by empha-
sizing the need for simple design characteristics such
as cuing and knowledge of results. Rather than rede-
signing existing poor designs, the authors recommend
that the design of interfaces be informed such that
real-world, operationally critical vigilance-inducing dis-
plays are never created in the first place. At the same
time, displays should be designed in such a fashion
that operators do not experience visual fatigue when
working. Richter, Crenshaw, Domkin, and Elcadi
(2016) present the utility of unique neuroergonomic
research in quantifying visual effort, which has the
potential to advance visual fatigue research in the
emerging domain of visual ergonomics. The authors
provide compelling arguments and supporting evi-
dence that both the cognitive processes of the visual
system and the biomechanical functions of the neck/
shoulder area are impacted during visual fatigue devel-
opment. The study further demonstrated the utility of
functional near infrared spectroscopy (fNIRS) to
uncover underlying neural mechanisms of visual
fatigue. Another application of fNIRS is discussed
subsequently by Cheng, Ayaz, Sun, Tong, and Onaral
(2016). Their study employed fNIRS to examine func-
tional connectivity (FC) between motor-related brain
regions and high-level cognitive brain regions during
distal upper extremity movements. Results of this
study indicate that movement intention that requires
collective neural efforts from cognitive-and motor-spe-
cific regions, during the transition period between rest
and hand movement, can be accurately captured
through FC changes. These findings have strong-
implications for improving the precision and latency
of anticipation-based brain-computer interfaces, for
neuroergonomic research related to human system
integration and automation, and various neurorehabi-
litation approaches.
The final article in this issue, by Garrett et al. (2016),
provided a unique perspective on the business impact
of integration of physical and cognitive ergonomics.
Standing desks have gained recent attention as a work-
place intervention to minimize sedentary behavior and
improve physical activity among employees. Garrett
et al. (2016) examined productivity over time between
a group of standing desk users and a seated control
group in a call center, and reported significant improve-
ments in productivity with standing desk usage. The
authors emphasize that sustainability of office (physi-
cal) ergonomics solutions relies on whether these inter-
ventions consider cognitive impact on work, such as
productivity and task interruption challenges.
The nine articles in this issue highlight studies that have
combined facets of physical and cognitive ergonomics to
85 Introduction
better understand and assess human capabilities at work.
However, integration of physical and cognitive ergonom-
ics can simply be facilitated with how we design studies,
analyze, and report study findings. For example, when
investigating cognitive performance of different warning
signal designs, studies should consider physical activity
levels of the participant pool, physical environmental
impact, and psychomotor requirements of the task. Simi-
larly, in studies that focus on traditional physical ergo-
nomic issues, such as lifting, the cognitive processes
associated with the different task features (e.g., known ver-
sus unknown weights), use of visual/auditory aids for
speed of work, etc., should be considered. Such integra-
tion efforts are even more critical when examining worker
fatigue, operator situation awareness, and decision mak-
ing, as well as understanding etiology of work-relatedmus-
culoskeletal disorders.
ACKNOWLEDGMENT: IN MEMORY OF
PROFESSOR RAJA PARASURAMAN
My most inspiring memory of Raja Parasuraman was
when he shared his joy of publishing his first “physical
ergonomics” article in 2014. After my initial surprise at
this reaction of pure academic joy from someone who
is truly a prolific scientist, I began to understand why.
Raja was an “interdisciplinarian.” Raja integrated the
field of human factors and ergonomics (HF/E) and
neuroscience to develop a thriving new field of neuro-ergonomics, the study of brain and behavior at work,
that has found home in several cognitive and physical
ergonomic investigations alike. Thus, recognizing the
mounting scientific evidence and the need for further
examinations on the interactions of physical and cogni-
tive demands on operator health and performance,
Raja took charge to co-develop this special issue on
“Integrating Physical and Cognitive Ergonomics.” He
inspired me, and many others, through his science, his
advice and mentorship, and (simply) his company. He
challenged us to question the status quo and bridge dis-
ciplines such that the true nature of how and why
humans and their various subsystems interact with
complex work systems can be understood. After all,
HF/E is a fusion of numerous (life) sciences. This spe-
cial issue is dedicated to Raja and his efforts of bringing
the HF/E community closer together through innova-
tion and integration in theories, approaches, and tools.
We miss you and hope to make you proud.
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87 Introduction