HUMAN FACTORS ENGINEERING AND SYSTEMS DESIGN
1.1 Human Factors Engineering and the Systems Approach
in Today’s Environments 38
1.2 Brief History of the Systems Approach
and Human Factors Engineering 41
2 DEFINITION OF A SYSTEM 43
2.1 General System Characteristics 43
2.2 Person–Machine Systems 44
2.3 System Reliability 47
2.4 Human Reliability 47
3 SYSTEM DESIGN PROCESS 48
3.1 Approaches to System Design 48 3.2 Incorporating Human Factors
in System Design 50
3.3 Applications of Human Factors
to System Design Process 51
3.4 Test and Evaluation 54
4 CONCLUSIONS 54
REFERENCES 54
1 INTRODUCTION
1.1 Human Factors Engineering and the Systems Approach in Today’s Environments 1.1.1 Overview
Human factors is generally defined as the “scientific discipline concerned with the understanding of interac- tions among humans and other elements of a system, and the profession that applies theory, principles, data, and other methods to design in order to optimize human well-being and overall system performance” (Interna- tional Ergonomics Association, 2010). The focus of human factors is on the application of knowledge about human abilities, limitations, behavioral patterns, and other characteristics to the design of person–machine systems. By definition, a person–machine system is a system which involves an interaction between people and other system components, such as hardware, soft- ware, tasks, environments, and work structures. The sys- tem may be simple, such as a human interacting with a hand tool, or it may be complex, such as an avia- tion system or a physician interacting with a complex computer display that is providing information about the status of a patient. The general objectives of human factors are to maximize human and system efficiency, health, safety, comfort, and quality of life (Sanders and McCormick, 1993; Wickens et al. 2004). In terms of research, this involves studying human performance to develop design principles, guidelines, methodologies, and tools for the design of the human–system interface.
Research relevant to the field of human factors can range from basic, such as understanding the impact of aging on
reaction time, to very applied, such as the understanding if multimodal cues enhance visual search performance in dynamic environments such as air traffic control. In terms of practice, human factors involves the applica- tion of these principles, guidelines, and tools to the actual design and evaluation of real-world systems and system components or the design of training programs and instructional materials that support the performance of tasks or the use of technology/equipment (Hendrick and Kleiner, 2001). In all instances human factors is concerned with optimizing the interaction between the human and the other systems components.
Given the focus on human performance within the context of tasks and environments, systems theory and the systems approach are fundamental to human factors engineering. Generally, systems theory argues for a uni- fied nature of reality and the belief that the components of a system are meaningful only in terms of the general goals of the entire system. A basic tenet among systems theorists is that all systems are synergistic and that the whole is greater than the sum of its parts. This is in contrast to a reductionist approach, which focuses on a particular system component or element in isolation.
The reductionist approach has traditionally been the
“popular” approach to system design, where the focus has been on the physical or technical components of a system, with little regard for the behavioral component.
In recent years the increased incidence of human error in the medical, transportation, safety, energy, and nuclear power environments and the resultant horrific conse- quences as well as the limited success of many technical developments have demonstrated the shortcomings of this approach and the need for a systems prospective.
38 Handbook of Human Factors and Ergonomics, Fourth Edition Gavriel Salvendy Copyright © 2012 John Wiley & Sons, Inc.
As noted by Gorman and colleagues (2010), if there is a polarity between high technologies and humans that use them, errors can arise, especially if the system is asked to respond in a novel or unanticipated situation. A cogent example cited by the authors is the poor coordination of the system-level response following Hurricane Katrina.
Other examples include adverse patient outcomes, oil spills (e.g.,Exxon Valdez), and transportation incidents such as Flight 3407, the commercial commuter plane that crashed in the Buffalo, New York, area in 2009.
Implicit in the belief in systems theory is adoption of the systems approach. Generally, the systems ap- proach considers the interaction among all of the components of a system relative to system goals when evaluating particular phenomena. Systems methodology represents a set of methods and tools applicable to (1) the analysis of systems and system problems; (2) the design, development, and deployment of systems; and (3) the management of systems and change in systems (Banathy and Jenlink, 2004). As noted by Sage and Rouse (2009), today’s systems are often large scale and complex, and simply integrating individual subsystems is insufficient and does not typically result in a system that performs optimally. Instead, systems methodologies must be employed throughout the entire life cycle of the system. Further, systems engineering must use a variety of methodologies and analytical methods as well as knowledge from a multitude of disciplines.
Applied to the field of human factors, the systems concept implies that human performance must be eval- uated in terms of the context of the system and that the efficiency of a system is determined by optimizing the performance of the human and the physical/technical components of the system. Further, optimization of human and system efficiency requires consideration of all major system components throughout the design process. Unfortunately, there has been a long tradition in the design and implementation of systems that places the primary emphasis on the technology components of the system without equal consideration of the person component (Gorman et al., 2010). A basic tenet of human factors is that design efforts that do not consider the human element will not achieve the maximum level of performance. For this reason, a discussion of the role of human factors in system design and evaluation is central to a handbook on human factors engineering. This is especially true in today’s era of computerization and automation where systems are becoming increasingly large and complex and involve multiple components and interrelationships.
In this chapter we discuss the role of human factors engineering in system design. The focus is on the approaches and methodologies used by human factors engineers to integrate knowledge regarding human performance into the design process. The topic of system design is vast and encompasses many areas of specialization within human factors. Thus, we introduce several concepts that are covered in depth in other chapters of the handbook. Prior to discussing the design process, a summary of changes in today’s systems and a brief history of the systems approach are provided. Our overall intent in the chapter is to provide an overview
of the system design process and to demonstrate the importance of human factors to systems design. Further, we introduce new approaches to system design that are being applied to complex, integrated systems.
1.1.2 Changes in Work and Organizational Systems
Work organizations and social environments have changed enormously over the past decade, and these changes will continue as technology and demo- graphic/social patterns evolve. Technology by its nature is dynamic, and continual developments in technology are changing work processes, the content of jobs, where work is performed, and the delivery of education and training. These changes will continue as new technologies emerge and we continue to move toward a service sector economy. For example, telework, where work is performed outside of the workplace and oftentimes in the home, is increasing on both a full- and part-time basis. In addition, technology-mediated learning, or “e-learning,” is emerging as the preferred method for training employees (Czaja and Sharit, 2009).
Systems and organizations are also changing dramat- ically due to the growth of new organizational structures, new management practices, and technology. Changes include a shift from vertically integrated business orga- nizations to less vertically integrated, specialized firms.
Another shift is to decentralized management and col- laborative work arrangements and team work across distributed organizational systems. Because of the com- plexity of tasks involved in complex systems, multi- operator teams are often preferred as the skills and abilities of a team can exceed the capabilities and work- load constraints of individual operators (Salas et al., 2008). In these cases effective collaboration among the group members is challenging and requires a balance between efficiency and participatory involvement of as many stakeholders. In this regard, technology, such group support systems, has helped make it possible for organizations to use very large and diverse groups to solve problems. However, collaborative technology systems do not address all of the issues facing large groups such as meeting scheduling and information overload (de Vreede et al., 2010). Further, in many work domains, such as air traffic management and safety- critical domains, group members with different roles and responsibilities are distributed physically. There is also a shift towards knowledge-based organizations where intellectual capital is an important organizational asset.
Together, these changes in work structures and processes result in an increased demand for more highly skilled workers who have a broader scope of knowledge and skills in decision making and knowledge management.
Also, in many domains such as the military, health care, and communication, there is an increased concern with “systems of systems” where different systems orig- inally designed for their own purposes are integrated to produce a new and complex large system. The challenge associated with systems of systems has given rise to the discipline of human systems integration (HSI), which is a comprehensive multidisciplinary management and technical approach for ensuring consideration of
40 HUMAN FACTORS FUNCTION the person in all stages of the system life cycle. HSI
includes manpower, personnel, training, environment, safety, health, human factors engineering, habitability, and survivability. It is also concerned with the design process and the development of tools and methods that help to ensure that stakeholders and designers work together to ensure that the abilities, limitations, and needs of users are considered in all phases of the design cycle. HSI has been largely employed in military systems (Pew and Mavor, 2007; Liu et al., 2009).
The demographics of the population are also chang- ing. As depicted in Figure 1, the number of older adults in the United States is dramatically increasing. Of partic- ular significance is the increase in the number of people aged 85+ years. The aging of the population has vast implications for the design of systems. For example, increases in the number of older people coupled with a shrinking labor pool due to a decline in fertility rates will threaten economic growth, living standards, and pension and health benefit financing. To this end, current changes in pension policies favor extending working life, and many industries are looking to older workers to address the emerging problem of labor and skill shortages due to the large number of older employees who are leaving the workforce and the smaller pool of available work- ers. Many adults in their middle and older years are choosing to remain in the workforce longer or return to work because of concerns about retirement income, health care benefits, or a desire to remain productive and socially engaged. Together, these trends suggest an increase in the number of older workers in the upcoming decades (Figure 2). These trends are paralleled in other countries. In the European Union (EU), the aging of the workforce and supporting social structures are a major
concern, and a major goal for the countries in the EU is to increase the employment rate of people aged 55–64 years (Ilmarinen, 2009). Overall, these trends imply that organizations will need to focus on strategies to accom- modate an increasingly older workforce. Thus there is a great need for understanding the capabilities, limitations, and preferences of older adults with respect to current jobs, work scheduling, and training. There are also many unanswered questions regarding the impact of aging and an older workforce on team functioning and processes.
This is an important consideration given the current focus on collaborative work. The aging of the popula- tion also has implications for system design within other domains such as transportation and health care.
The number of women in the labor force has also been increasing steadily, which also has implications for job and workplace design. For example, many women are involved in caregiving for an older relative or friend.
Current estimates indicate that about 22% of adults in the United States are engaged in some form of care- giving. Most informal caregivers currently work either full time or part time, and these caregivers (∼59–75%) are typically middle-aged women at the peak of their earning power (Family Caregiving Alliance, 2010). As noted by Schulz and Martire (2009), increases in both labor force participation rates of women and the num- ber of people who need informal care raise important questions about how effectively the work and caregiver roles can be combined and what strategies can be used to optimize work and caregiving scenarios. Finally, due to the globalization of trade and commerce, many sys- tems include people from a variety of ethnic and cultural backgrounds. As noted by Strauch (2010), ethnic and
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65–74 Age group
Figure 1 U.S. historical and projected older adult population as percentage of the total population: 1900–2050 (Hobbs and Stoops, 2002; U.S. Census Bureau, 2008).
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Figure 2 Projected labor force participation rates of older adults, 1986–2016 (Toossi, 2007).
cultural values vary with respect to work practices, com- munication, and family. Cultural/ethnic values are also dynamic and change over time. If ethnic/cultural factors are not considered in systems design and operations, there may be breakdowns in system team performance and overall system efficiency. To date, there is limited information on how cultural factors affect issues such as team work, communication, and the overall opera- tions of systems. In general, all of the aforementioned issues underscore the need for a more human factors involvement in systems design.
1.2 Brief History of the Systems Approach