Human factors in simple and complex systems
Chapter 1 – Historical foundations of human factors
This book is about what we know about human cognitive, physical, and social characteristics
and to show how this knowledge can be brought to bear on the design of machines, tools, and
systems that are easy and safe to use.
In everyday life, we interact constantly with instruments, machines and other systems. Every
system has a purpose or a goal -> lighting system for illuminating a room. The ability of a system
also depends on human components; can we reach the light switch? So the total efficiency of
the system depends on both the performance of the inanimate component and the performance
of the human component.
- Electronic and digital equipment
How well modern electronic equipment work is often limited by the human component. In the
early 90’s people had VCR’s and almost half of the people didn’t know how to correctly use it. It
might be thought that usability concerns only apply to older people who may not be as familiar
with technology, but young adults who are more technologically sophisticated still have
problems with these kinds of devices.
- Computer technology
The first generation of modern computers, introduced mid-1940s, was extremely large, slow,
expensive and available mainly for military purposes. The ASCC was the first computer,
afterwards much smaller computers came out. These were more affordable and available to a
wider range of users at businesses – and easier to program.
In the late 1970s, the first desktop-sized personal computers (PCs) became widely available. It
was still difficult to use for most, but some were willing to learn. It used a pointing device to
locate objects on the screen -> mouse, first called an X-Y position indicator.
With the development of the Internet and the World Wide Web around 1990, the individual PC
became a common household accessory.
- Healthcare systems
Over the past 15 years, healthcare has become a major research focus of human factors
specialists. Among the technological advances in healthcare are electronic medical records,
which allow the sharing of medical information among many parties, including possibly patients,
but for which the interfaces must be usable by all potential users.
- Cyber security
In addition to usability, privacy and security on the Internet is a huge problem in general and for
medical records in particular. An unsecured computer system or website can be damaged,
either accidentally or intentionally, when an unauthorized person tampers with it, which may
lead to severe financial problems. Increases in cyber security usually come at the cost of
decreased usability. Most people do not want to perform the additional tasks required to ensure
a high degree of security. The desire to allow people control over their private online data has
resulted in the introduction of a new term Human-data interaction: to characterize the complex
interactions between humans, online software agents, and data access.
, - Serious accidents resulting from major system failures
Examples:
1. Space shuttle Challenger: exploded during launch, resulting in 7 deaths. There were
design flaws and relaxed safety regulations
2. Three mile island nuclear power plant: malfunctioning pressure valve. Poorly designed
warning displays and control panels contributed to the escalation of a minor
malfunction into the worst accident in power history.
3. Singapore Airline jumbo jet: attempted to take off on a runway that was closed for
construction, striking concrete barriers and catching fire. 81 deaths.
These disasters can be traced to errors in both the machine components and the human
components of the systems.
- What is human factors and ergonomics?
When enigeers design machines, they evaluate them in terms of their reliability, ease of
operation and error-free performance.
- Definition
Human factors: the study of those variables that influence the efficiency with which the human
performer can interact with the inanimate components of a system to accomplish the system
goals -> also called ergonomics. The scientific definition:
“ergonomics/ human factors is the scientific discipline concerned with the understanding of
interactions among humans and other elements of a system and the progression that applies
theory, principles, data, and other methods to design in order to optimize human well-being and
overall system performance.”
Embodied in the definition of human factors is the importance of basic human capabilities like
perceptual abilities, attention span, memory and physical limitations. These must be taken into
account in new designs.
- Basic human performance
The study of human performance involves analyses of the processes that underlie the
acquisition, maintenance, transfer and execution of skilled behavior. There are many human
limitations on performance that cannot be overcome. The human factors specialist must
consider basic human performance capabilities in order to wisely use the freedom that is
available in the design of the machine component of the system.
- Human-machine systems and domains
of specialization
The entire human-machine system is embedded
within the larger context of the work
environment, which also influences the
performance of the system.
The environment is not just physical aspects of a
workspace, it also consists of social and
organizational variables that make work easier or
,harder. Macroergonomics is used to describe the interactions between the organizational
environment and the design and implementation of a system. the total system performance
depends on the operator, the machine, and the environment in which they are placed.
- Historical antecedents
The major impetus for the establishment of human factors as a discipline came from
technological developments during WWII. As weapon and transport systems became
increasingly sophisticated, great technological advances were also being made in factory
automation and in equipment for common use.
- Psychology of human performance
The study of human performance emphasized basic human capabilities involved in perceiving
and acting on information arriving through the senses. Research on human performance dates
to the mid-19th century with different work relevant for human factors. Many of these concepts
and methods developed to study human performance are
still part of the modern human factors toolbox:
1. Sensory psychophysics: Weber and Fechner
founded the study of psychophysics. They
investigated the sensory and perceptual
capabilities of humans. Weber examined people’s
ability to determine that two stimuli differ in
magnitude ->
a. Weber’s law: states that the absolute
amount of change needed to perceive a difference
in magnitude increases with intensity, whereas the
relative amount remains constant.
Fechner formalized the methods and constructed the first
scales for relating physical magnitude to psychological
magnitude
2. Speed of mental processing: Helmholtz established a
method for estimating the time for transmission of a nerve impulse. The importance of
this finding was to demonstrate that neural transmission is not instantaneous, but takes
measurable time. It served as a basis for
Donders, who developed chronometric methods.
He reasoned that, when performing a speeded
reaction task, a person must make a series of
judgements. Now it is called the subtractive logic
and provides the foundation for the notion that
mental processes can be isolated.
3. Study of attention: Wundt advocated that mental events play a causal role in human
behavior. He held that our mental representation of the world is a function of experience
and the way our mind organizes that experience.
4. Learning and skill acquisition: Ebbinghaus applied experimental rigor successfully to the
study of learning and memory.
- Human performance in applied settings
, Considerable applied work important to modern human factors was conducted prior to WII.
1. Job specialization and productivity: Babbage proposed in his book methods for
increasing the efficiency with which workers could perform their jobs. He advocated job
specialization, with the idea that this would enable a worker to become skilled and
proficient at a limited range of tasks. F. Taylor was one of the first people to
systematically investigate human performance in applied settings. He is best
remembered for developing a school of thought referred to as scientific management.
He made 3 contributions to enhance productivity:
a. Task analysis: in which components of a task are determined
i. Time-and-motion study: a technique where a workers movements are
analyzed across time to determine the best way to perform a task
b. Pay for performance: a piecework method, by which the amount of
compensation to the worker is a function of the number of pieces completed.
c. Personnel selection: fitting the worker to the task
2. Early human factors journals: two journals were published that foreshadowed the future
development of human factors
- Biomechanics and physiology of human performance
A major accomplishment of this field was the development of procedures that allowed a
dynamic assessment of human performance
➔ So, a great deal of research conducted prior to the middle of the 20th century laid the
foundation for the field of human factors. Psychologists developed research methods
and theoretical views that allowed them to investigate various aspects of human
performance; industrial engineers studied many aspects of human performance in job
settings with an eye toward maximizing its efficiency; biomechanists and physiologists
developed methods for examining physical and biological factors in human performance
and principles relating those factors to work. The important point is simply that without
the prior work in these areas, human factors specialists would have had no starting point
to address the applied design issues that became prominent in the latter half of the 20th
century.
- Contemporary human factors
Human factors grew as a profession over the years. The value of human factors analysis is also
apparent in our everyday lives -> automobiles are designed for human comfort.
Chapter 3 – Reliability and human error in systems
Human error is common, like medical errors. Systems can be small or large. Within each system
we can identify one or more operators, people in charge, implementing policy, etc. A primary
mission of the human factors specialist is to minimize human error and so to maximize system
performance. Because large-scale systems may involve many people. A term that describes this
process is human-systems integration.
- Central concept in human factors; the system
A system operators for the purpose of achieving a goal. The system approach has its basis in
systems engineering, which is an engineering approach that provides an understanding of the
Chapter 1 – Historical foundations of human factors
This book is about what we know about human cognitive, physical, and social characteristics
and to show how this knowledge can be brought to bear on the design of machines, tools, and
systems that are easy and safe to use.
In everyday life, we interact constantly with instruments, machines and other systems. Every
system has a purpose or a goal -> lighting system for illuminating a room. The ability of a system
also depends on human components; can we reach the light switch? So the total efficiency of
the system depends on both the performance of the inanimate component and the performance
of the human component.
- Electronic and digital equipment
How well modern electronic equipment work is often limited by the human component. In the
early 90’s people had VCR’s and almost half of the people didn’t know how to correctly use it. It
might be thought that usability concerns only apply to older people who may not be as familiar
with technology, but young adults who are more technologically sophisticated still have
problems with these kinds of devices.
- Computer technology
The first generation of modern computers, introduced mid-1940s, was extremely large, slow,
expensive and available mainly for military purposes. The ASCC was the first computer,
afterwards much smaller computers came out. These were more affordable and available to a
wider range of users at businesses – and easier to program.
In the late 1970s, the first desktop-sized personal computers (PCs) became widely available. It
was still difficult to use for most, but some were willing to learn. It used a pointing device to
locate objects on the screen -> mouse, first called an X-Y position indicator.
With the development of the Internet and the World Wide Web around 1990, the individual PC
became a common household accessory.
- Healthcare systems
Over the past 15 years, healthcare has become a major research focus of human factors
specialists. Among the technological advances in healthcare are electronic medical records,
which allow the sharing of medical information among many parties, including possibly patients,
but for which the interfaces must be usable by all potential users.
- Cyber security
In addition to usability, privacy and security on the Internet is a huge problem in general and for
medical records in particular. An unsecured computer system or website can be damaged,
either accidentally or intentionally, when an unauthorized person tampers with it, which may
lead to severe financial problems. Increases in cyber security usually come at the cost of
decreased usability. Most people do not want to perform the additional tasks required to ensure
a high degree of security. The desire to allow people control over their private online data has
resulted in the introduction of a new term Human-data interaction: to characterize the complex
interactions between humans, online software agents, and data access.
, - Serious accidents resulting from major system failures
Examples:
1. Space shuttle Challenger: exploded during launch, resulting in 7 deaths. There were
design flaws and relaxed safety regulations
2. Three mile island nuclear power plant: malfunctioning pressure valve. Poorly designed
warning displays and control panels contributed to the escalation of a minor
malfunction into the worst accident in power history.
3. Singapore Airline jumbo jet: attempted to take off on a runway that was closed for
construction, striking concrete barriers and catching fire. 81 deaths.
These disasters can be traced to errors in both the machine components and the human
components of the systems.
- What is human factors and ergonomics?
When enigeers design machines, they evaluate them in terms of their reliability, ease of
operation and error-free performance.
- Definition
Human factors: the study of those variables that influence the efficiency with which the human
performer can interact with the inanimate components of a system to accomplish the system
goals -> also called ergonomics. The scientific definition:
“ergonomics/ human factors is the scientific discipline concerned with the understanding of
interactions among humans and other elements of a system and the progression that applies
theory, principles, data, and other methods to design in order to optimize human well-being and
overall system performance.”
Embodied in the definition of human factors is the importance of basic human capabilities like
perceptual abilities, attention span, memory and physical limitations. These must be taken into
account in new designs.
- Basic human performance
The study of human performance involves analyses of the processes that underlie the
acquisition, maintenance, transfer and execution of skilled behavior. There are many human
limitations on performance that cannot be overcome. The human factors specialist must
consider basic human performance capabilities in order to wisely use the freedom that is
available in the design of the machine component of the system.
- Human-machine systems and domains
of specialization
The entire human-machine system is embedded
within the larger context of the work
environment, which also influences the
performance of the system.
The environment is not just physical aspects of a
workspace, it also consists of social and
organizational variables that make work easier or
,harder. Macroergonomics is used to describe the interactions between the organizational
environment and the design and implementation of a system. the total system performance
depends on the operator, the machine, and the environment in which they are placed.
- Historical antecedents
The major impetus for the establishment of human factors as a discipline came from
technological developments during WWII. As weapon and transport systems became
increasingly sophisticated, great technological advances were also being made in factory
automation and in equipment for common use.
- Psychology of human performance
The study of human performance emphasized basic human capabilities involved in perceiving
and acting on information arriving through the senses. Research on human performance dates
to the mid-19th century with different work relevant for human factors. Many of these concepts
and methods developed to study human performance are
still part of the modern human factors toolbox:
1. Sensory psychophysics: Weber and Fechner
founded the study of psychophysics. They
investigated the sensory and perceptual
capabilities of humans. Weber examined people’s
ability to determine that two stimuli differ in
magnitude ->
a. Weber’s law: states that the absolute
amount of change needed to perceive a difference
in magnitude increases with intensity, whereas the
relative amount remains constant.
Fechner formalized the methods and constructed the first
scales for relating physical magnitude to psychological
magnitude
2. Speed of mental processing: Helmholtz established a
method for estimating the time for transmission of a nerve impulse. The importance of
this finding was to demonstrate that neural transmission is not instantaneous, but takes
measurable time. It served as a basis for
Donders, who developed chronometric methods.
He reasoned that, when performing a speeded
reaction task, a person must make a series of
judgements. Now it is called the subtractive logic
and provides the foundation for the notion that
mental processes can be isolated.
3. Study of attention: Wundt advocated that mental events play a causal role in human
behavior. He held that our mental representation of the world is a function of experience
and the way our mind organizes that experience.
4. Learning and skill acquisition: Ebbinghaus applied experimental rigor successfully to the
study of learning and memory.
- Human performance in applied settings
, Considerable applied work important to modern human factors was conducted prior to WII.
1. Job specialization and productivity: Babbage proposed in his book methods for
increasing the efficiency with which workers could perform their jobs. He advocated job
specialization, with the idea that this would enable a worker to become skilled and
proficient at a limited range of tasks. F. Taylor was one of the first people to
systematically investigate human performance in applied settings. He is best
remembered for developing a school of thought referred to as scientific management.
He made 3 contributions to enhance productivity:
a. Task analysis: in which components of a task are determined
i. Time-and-motion study: a technique where a workers movements are
analyzed across time to determine the best way to perform a task
b. Pay for performance: a piecework method, by which the amount of
compensation to the worker is a function of the number of pieces completed.
c. Personnel selection: fitting the worker to the task
2. Early human factors journals: two journals were published that foreshadowed the future
development of human factors
- Biomechanics and physiology of human performance
A major accomplishment of this field was the development of procedures that allowed a
dynamic assessment of human performance
➔ So, a great deal of research conducted prior to the middle of the 20th century laid the
foundation for the field of human factors. Psychologists developed research methods
and theoretical views that allowed them to investigate various aspects of human
performance; industrial engineers studied many aspects of human performance in job
settings with an eye toward maximizing its efficiency; biomechanists and physiologists
developed methods for examining physical and biological factors in human performance
and principles relating those factors to work. The important point is simply that without
the prior work in these areas, human factors specialists would have had no starting point
to address the applied design issues that became prominent in the latter half of the 20th
century.
- Contemporary human factors
Human factors grew as a profession over the years. The value of human factors analysis is also
apparent in our everyday lives -> automobiles are designed for human comfort.
Chapter 3 – Reliability and human error in systems
Human error is common, like medical errors. Systems can be small or large. Within each system
we can identify one or more operators, people in charge, implementing policy, etc. A primary
mission of the human factors specialist is to minimize human error and so to maximize system
performance. Because large-scale systems may involve many people. A term that describes this
process is human-systems integration.
- Central concept in human factors; the system
A system operators for the purpose of achieving a goal. The system approach has its basis in
systems engineering, which is an engineering approach that provides an understanding of the
