ergonomics

Ergonomics (or human factors) is the scientific discipline concerned with the understanding of interactions among humans and other elements of a system, and the profession that applies theory, principles, data, and methods to design in order to optimize human well-being and overall system performance (definition adopted by the International Ergonomics Association in 2000).

Overview

Ergonomics, also known as human engineering or human factors engineering, the science of designing machines, products, and systems to maximize the safety, comfort, and efficiency of the people who use them. Ergonomists draw on the principles of industrial engineering, psychology, anthropometry (the science of human measurement), and biomechanics (the study of muscular activity) to adapt the design of products and workplaces to people's sizes and shapes and their physical strengths and limitations. Ergonomists also consider the speed with which humans react and how they process information, and their capacities for dealing with psychological factors, such as stress or isolation. Armed with this complete picture of how humans interact with their environment, ergonomists develop the best possible design for products and systems, ranging from the handle of a toothbrush to the flight deck of the space shuttle.

Ergonomists view people and the objects they use as one unit, and ergonomic design blends the best abilities of people and machines. Humans are not as strong as machines, nor can they calculate as quickly and accurately as computers. Unlike machines, humans need to sleep, and they are subject to illness, accidents, or making mistakes when working without adequate rest. But machines are also limited-cars cannot repair themselves, computers do not speak or hear as well as people do, and machines cannot adapt to unexpected situations as well as humans. An ergonomically designed system provides optimum performance because it takes advantage of the strengths and weaknesses of both its human and machine components.

Ergonomists contribute to the design and evaluation of tasks, jobs, products, environments and systems in order to make them compatible with the needs, abilities and limitations of people (IEA, 2000).

Domains

The IEA divides ergonomics broadly into three domains:

Physical ergonomics deals with the human body's responses to physical and physiological loads. Relevant topics include manual materials handling, workstation layout, job demands, and risk factors such as repetition, vibration, force and awkward/static posture as they relate to musculoskeletal disorders (see repetitive strain injury).

Cognitive ergonomics, also known as engineering psychology, concerns mental processes such as perception, attention, cognition, motor control, and memory storage and retrieval as they affect interactions among humans and other elements of a system. Relevant topics include mental workload, vigilance, decision making, skilled performance, human error, human-computer interaction, and training.

Organizational ergonomics, or macroergonomics, is concerned with the optimization of sociotechnical systems, including their organizational structures, policies, and processes. Relevant topics include shift work, scheduling, job satisfaction, motivational theory, supervision, teamwork, telework and ethics.

Applications

Designing with people in mind often requires advanced technology, such as computer-aided design/computer-aided manufacturing (CAD/CAM) programs and robots to simulate human responses. Other ergonomic tools may be relatively simple. Ergonomists frequently use two- or three-dimensional mannequins that represent particular dimensions of the human body, such as seated height, or arm length or reach. Using such tools, ergonomists create products and workstations that fit 90 percent of the possible users. To help evaluate the tools and systems people use in the course of their day, ergonomists use simulations-replicas of workstations, aircraft, and other scenarios together with observations of people operating equipment and products in the replicated environment.

Workplace Illness and Accident Prevention

One of the primary goals of ergonomics is prevention of workplace illness and accidents. According to the United States Bureau of Labor Statistics, more than 60 percent of the workplace illnesses reported each year are associated with repetitive stress injuries (RSI). These injuries result from continuous repetition of the same motions, for instance screwing or twisting items on an assembly line. The injury may be exacerbated by awkward postures, such as bending or reaching. One prime example of a repetitive strain injury is Carpal tunnel syndrome, which is a painful and often debilitating swelling of the tendons in the wrist. Carpal tunnel results from overuse of the hands and wrists. It is particularly common in people who must bend or overextend their arms while performing a repetitive task, such as typing on a computer keyboard, cutting meat, or tripping knobs and levers. Frequent, unassisted heavy lifting, such as lifting patients to move them in and out of hospital beds, is one of the leading causes of work-related back injuries. Another frequent cause of work-related back pain is a result of sedentary jobs, such as sitting at a computer workstation everyday, which tends to strain the structures in the lower back, upper back, and neck. Noise-induced hearing loss resulting from continuous exposure to excessive noise is another type of RSI, as are headaches and eyestrain due to improper workplace lighting.

Ergonomists work to eliminate these problems by designing workplaces, such as computer workstations or assembly lines, with injury prevention in mind. They position tools and machinery to be accessible without twisting, reaching, or bending. They design adjustable workbenches, desks, and chairs to comfortably accommodate workers of many different sizes, preventing the need to continuously lean or overextend the arms. Ergonomists also determine and design safe workplace environmental conditions, such as correct temperature, lighting, noise, and ventilation to ensure that workers perform under optimal conditions.

Ergonomists also seek to increase worker efficiency and productivity when designing workspaces. They place those pieces of equipment used most frequently in closest proximity to the worker and arrange systems in ways that are convenient and easy to use. Well-designed workspaces ensure that workers perform their jobs in optimal comfort, without experiencing the unnecessary physical and mental fatigue that can slow work performance, reduce accuracy, or cause accidents.

Other ergonomists design the individual tools or equipment a worker uses. Specially curved computer keyboards encourage typists to hold their wrists in a position that is less likely to cause carpal tunnel syndrome. To protect the eyes from incessant glare, ergonomically designed computer monitors are equipped with glare reduction screens. Ergonomically designed chairs distribute a person's body weight evenly to avoid back and neck strain. These chairs adjust to a user's height to ensure that the feet rest flat on the ground. In factories and assembly lines, ergonomically designed knobs and levers are positioned appropriately so as not to require reaching, and these knobs and levers also require minimal force to trip.

By employing the best possible design for safety systems, ergonomists minimize workplace accidents. Ergonomists consider the way humans interpret information, their reaction speed, and how both of these factors are influenced by the stress of an emergency. Warning signals, such as lights, buzzers, and sirens, must be easy to interpret. Control devices must be easy to identify and use, particularly in workplaces such as aircraft, vehicles, and nuclear power plants, where quick, accurate reactions are imperative to public safety. A poorly designed control panel was a factor during the near meltdown of the nuclear generating station at Three Mile Island, Pennsylvania, in 1979.

Maximizing Job Performance and Efficiency

Some ergonomists practice in the area of job design. These professionals help employers assess both the individual tasks necessary to perform a particular job and the skills needed to accomplish each task. By grouping like tasks and skills, jobs can be redesigned to maximize efficiency. An office telephone receptionist, for example, may perform a number of other tasks as varied as filing, sorting mail, and bookkeeping. Grouping these responsibilities, which can all be performed in the vicinity of the office telephone system, makes use of the receptionist's time when there are no telephone calls. Ergonomists help employers evaluate different ways of organizing workdays to increase worker productivity, ensuring that workers have adequate breaks and rest periods, as well as a well-defined set of tasks.

An ergonomist may use similar skill-analysis principles to help an employer identify the best candidate for a particular job. By working with the employer to define the physical, mental, and social skills needed to perform a job, ergonomists can determine the necessary qualifications and help employers with personnel selection. Job task and skill analysis is also used to determine the most effective ways to train employees. Training for astronauts and pilots, for example, may include simulations developed by ergonomists. Training simulations, such as computer virtual reality training, teach trainees how to deal with dangerous scenarios, such as accidents, without exposing them to the dangers of a real accident. Ergonomists also design virtual reality simulations for medical doctors, enabling them to practice diagnostic and surgical skills on computer-simulated patients, thereby not endangering the health of a live patient.

Information Design

Cognitive ergonomists specialize in information design-the best way to present complex information. These professionals study the way the human brain processes information. Using this knowledge and the principles of graphic design, cognitive ergonomists develop signs, maps, instruction manuals, and even computer programs and Internet sites that are easy to use, or intuitive. The work of cognitive ergonomists is particularly evident in public transportation buildings, such as airports or train stations. These buildings are often large, complex, and difficult to navigate. Cognitive ergonomists develop clear, easy-to-understand navigation aids, such as signs and maps, to help people find their way to their gate as simply and efficiently as possible. Color-coded subway maps, for example, help subway riders navigate with relative ease through a complicated maze of interconnected underground tunnels.

Cognitive ergonomists also work with manufacturers to design the instruction manuals packaged with consumer products. They evaluate the tasks required to assemble or operate the goods, and present the tasks as a set of sequential, easy to follow instructions. When designing instruction manuals, cognitive ergonomists must consider not only the way the brain processes information, but also the way people expect to receive instructional information. As they develop and learn, humans grow accustomed to receiving different types of information in particular formats. When information does not conform to its customary format, people may find it difficult to follow or understand.

Consumer Product Design

Ergonomic design makes consumer products safer, easier to use, and more reliable. In many manufacturing industries, ergonomists work with designers to develop products that fit the bodies and meet the expectations of the people who will use them. An ergonomically designed toothbrush, for example, has a broad handle for easy grip, a bent neck for easier access to back teeth, and a bristle head shaped for better tooth surface contact. The shaving razor has undergone a similar design revolution. The bent-handled, easy-grip models popular today are more comfortable to use and have a better shaving performance than the straight-edged razors of days gone by.

Ergonomic design has dramatically changed the interior appearance of automobiles. The steering wheel-once a solid, awkward disk-is now larger and padded for an easier, more comfortable grip. Its center is removed to improve the driver's view of the instruments on the dashboard. Larger, contoured seats, adjustable to suit a variety of body sizes and posture preferences, have replaced the small, upright seats of early automobiles. Equipped with seatbelts and adjustable headrests that prevent the neck from snapping backward in the event of a collision, modern automobile seats are not only more comfortable, they are also safer. The principles of ergonomic design affect other features of the automobile as well. The center-mounted rear windshield brake light, now a required component of all new automobiles, is an ergonomic innovation that saves lives.

Perhaps the most compelling ergonomic innovations of our time, improvements to computer user interfaces have changed the way the world uses computers. Graphical user interface (GUI) is a computer display format that enables the user to choose commands, start programs, and see lists of files and other options by pointing to pictorial representations on the screen. By taking into account the way humans interact with machines, computer scientists developed a GUI that is intuitive and easy to use. This innovation made computers, once the cryptic and complex tool of an elite group of scientists and mathematicians, accessible to almost anyone.

Ergonomic improvements to computer hardware and software are ongoing. The mouse, a hand-shaped input device, enables users to give the computer commands with the click of a button. In the future, keyboards and mice, already ergonomically shaped to reduce the occurrence of carpal tunnel syndrome, may be entirely replaced by voice-activated input systems. Many computer users already use verbal commands, touch the screen, or use pencil-like instruments to enter their commands, rather than typing them on a keyboard or clicking with a mouse.

Ergonomics profession

The term ergonomics (Greek ergon, "work"; nomos, "laws"), first appeared in a Polish article published in 1857, but the modern discipline did not take shape until half a century later. The study of human factors did not gain much public attention until World War II (1939-1945). Accidents with military equipment were often blamed on human error, but investigations revealed that some were caused by poorly designed controls. The modern discipline of ergonomics was born in the United Kingdom on July 12, 1949, at an interdisciplinary meeting of those interested in human work problems in the British navy. At another meeting, held on February 16, 1950, the term ergonomics was formally adopted for this growing discipline.

Today in the United States, ergonomics professionals belong to the Human Factors and Ergonomics Society (HFES), an organization with over 5,000 members interested in topics ranging from aging and aerospace to computers. The HFES is active in developing national and international technical standards to help improve the design of products and workplaces. Ergonomists also work with the United States Occupational Safety and Health Administration (OSHA) to develop ergonomic guidelines, standards, and regulations to ensure the safety and comfort of American workers. About 40 percent of HFES members have degrees in psychology or an associated behavioral science, about 30 percent have degrees in engineering or design, and others have diverse backgrounds in subjects ranging from computer science to medicine. Over 60 universities in the United States now offer graduate or undergraduate degrees in human factors and ergonomics.

History

Italian Bernardino Ramazinni (1633-1714) became the first physician to write about work-related injuries and illnesses in his 1700 publication, "De Morbis Artificum (Diseases of Workers)". Ramazinni was ostracized by his fellow doctors for visiting the workplaces of his patients in order to identify the causes of their disorders. The term ergonomics (from the Greek words ergon [work] and nomos [natural laws]) first entered the modern lexicon when Wojciech Jastrzębowski used the word in his 1857 article Rys ergonomji czyli nauki o pracy, opartej na prawdach poczerpniętych z Nauki Przyrody (adapted from a previous version of this page).

Later in the 19th century, Frederick Winslow Taylor pioneered the "Scientific Management" method, an approach that sought the single best method to perform a job and its tasks. By incrementally reducing the size and weight of coal shovels until the optimum shovelling rate was reached, Taylor tripled the amount of coal that workers could shovel in a day. Frank and Lilian Gilbreth, in the early 1900s, expanded Taylor's methods to develop "Time and Motion Studies" that aimed to improve efficiency by eliminating unnecessary steps and actions. By applying this approach, the Gilbreths reduced the number of motions in bricklaying from 18 to 4.5, allowing bricklayers to increase their pace of laying bricks from 120 to 350 bricks per hour.

World War II marked the advent of highly sophisticated machines and weaponry, creating previously unseen cognitive demands on operators in terms of decision-making, attention, situational awareness and hand-eye coordination. It was observed that perfectly working aircraft, flown by the best-trained pilots, still crashed. In 1943, Alphonse Chapanis, a lieutenant in the U.S. Army, showed that "pilot error" could be greatly reduced when more logical and differentiable controls replaced confusing designs in airplane cockpits.

In the decades since the war, ergonomics has continued to flourish and diversify. The Space Age created new human factors issues such as weightlessness and extreme G-forces. To what extent could these environments be tolerated and what effects would they have on the mind and body? The Information Age has spawned the field of human-computer interaction (HCI) while the growing demand for and competition among consumer goods and electronics has resulted in more companies including human factors in product design.

Foundations

Ergonomics draws on many disciplines in its study of humans and their environments, including anthropometry, biomechanics, engineering, kinesiology, physiology and psychology.

Typically, an ergonomist will have a BA or BS in Psychology, Industrial/Mechanical Engineering or Health Sciences, and usually a MA, MS or PhD in a related discipline. Many universities offer Master of Science degrees in Ergonomics, while some offer Master of Ergonomics or Master of Human Factors degrees.

Applications

The more than twenty technical subgroups within the Human Factors and Ergonomics Society, HFES, indicate the range of applications for ergonomics. Human factors engineering continues to be successfully applied in the fields of aerospace, aging, health care, IT, product design, transportation, training, nuclear and virtual environments, among others. Kim Vicente, a University of Toronto Professor of Ergonomics, argues that the nuclear disaster in Chernobyl is attributable to plant designers not paying enough attention to human factors. "The operators were trained but the complexity of the reactor and the control panels nevertheless outstripped their ability to grasp what they were seeing [during the prelude to the disaster]."

Human factors issues arise in simple systems and consumer products as well. Some examples include cellular telephones and other handheld devices that continue to shrink yet grow more complex (a phenomenon referred to as "creeping featurism"), millions of VCRs blinking "12:00" across the world because very few people can figure out how to program them, or alarm clocks that allow sleepy users to inadvertently turn off the alarm when they mean to hit 'snooze'. A user-centered design (UCD), also known as a systems approach or the usability engineering lifecycle aims to improve the user-system fit.

Resources

Books
Ergonomics for Beginners - Jan Dul and Bernard Weerdmeester - A classic introduction on ergonomics - Original title: Vademecum Ergonomie (Dutch) -published and updated since 1960's.
Bodyspace - Stephen Pheasant - A classic exploration of ergonomics.
The Human Factor - Kim Vicente - Full of examples and statistics illustrating the gap between existing technology and the human mind, with suggestions to narrow it.
The Design of Everyday Things - Donald Norman - An entertaining user-centered critique of nearly every gadget out there (at the time it was published).
Evaluation of Human Work - Wilson & Corlett - A practical ergonomics methodology. Warning: very technical and not a suitable 'intro' to ergonomics.
Engineering Psychology and Human Performance - Wickens and Hollands - Discusses memory, attention, decision making, stress and human error, among other topics.
The Measure of Man & Woman - Henry Dreyfuss Associates - A human factors design manual that has controversial elements.

Peer-Reviewed Publications
(between brackets mean ISI impact factor 2001-2003)

Ergonomics (0.747)
Applied Ergonomics (0.738)
Human Factors (0.723)
International Journal of Industrial Ergonomics (0.395)
Human Factors and Ergonomics in Manufacturing (0.311)
Travail Humain (0.260)
Theoretical Issues in Ergonomics Science (-)
International Journal of Occupational Safety and Ergonomics (-)
17th cent. writings of Ramazzini, father of Occupational Medicine

See also

• Human factors
• Human computer interaction
• Systems engineering
• Environmental design
• Cognitive load
• Carpal tunnel syndrome
• Back injury
• Repetitive strain injury
• Industrial noise

External links

Organizations

• IEA International Ergonomics Association
• FEES Federation of European Ergonomics Societies
• The Ergonomics Society (Europe) Links
• HFES Human Factors and Ergonomics Society (USA)
• ACE Association of Canadian Ergonomists
• Board of Certification in Professional Ergonomics (BCPE).

Websites

• About Ergonomics
• Bad Human Factors Designs
• ErgoWeb list-server and online forum
• Office Ergonomics Training

Projects

• Virtual Reality and Human Factors Applications for Improving Safety (2005-2009)