Summary Human Factors
„Human Factors in Simple and Complex Systems‟ by Robert W. Proctor & Trisha Van Zandt
Second Edition 2008
Chapter One: Historical Foundations of Human Factors
Every system has a goal. The total efficiency of the system depends on both the human
components as well as on the inanimate components of the machine. The efficiency of both
components determines whether and in what fashion the goal is met. Failing of either
components can lead to failure of the entire system.
One key component to an effective system is Usability. This was a major problem with early
on devices such as the VCR or stereo‟s in the „70s & „80s which were very hard to use
properly. With the increasing rate of development of computer technology usability is still an
important subject which always had to be taken into account. Development of the mouse and
the graphical interface greatly improved this. On the other hand, coming with internet,
security & privacy became major issues. Increased security means a decrease in usability
forcing men to find the perfect compromise.
One major accident that was a result of major system failure was the explosion of NASA
spaceship the Challenger. Design flaws, relaxed safety regulations a.o. were causes that
resulted in the accident. Luckily people learned from these mistakes, not only at NASA but at
many other organizations, and safety guidelines were established so accidents can be
prevented.
What is Human Factors?
When designing a machine both the adequacy of the machine and human performance has to
be taken into account. That‟s why these are considered as a single human-machine system and
are analyzed as a whole. The variables that are considered fall under the topic of Human
Factors(HF). “HF is a scientific discipline concerned with the interaction among humans and
other elements of a system”. Part of this is knowing the capabilities and limitations of humans
and the machine and using this knowledge when designing a system. HF had a broad field
where it can be applied, because every single system has to work properly. The basics of HF
are thus essential for success.
There is a lot of scientific data reporting the capabilities and limitations of a human being.
With these data we can predict how well people can perform simple and complex tasks.
Where engineers and human performance specialists analyze the machine and human
respectively. We have a lot of freedom in designing and improving machines but we can‟t
rely on extending the limits of a person. Thus, the HF specialist must consider the human
limitation in order to use the degrees of freedom in the design of the machine.
, The most simple representation of a system is
displayed in figure 1. As you can see the human
and the machine are a lot alike. They both have
a sensory system, processing system and an
action/display system. Important to understand
is that not only, the human, machine and the
interaction have to be taken into account. The
work environment, both physical and social, Figure 1
also has great influences on performance. We
call this macroergonomics. We will return to that later.
Historical Antecedents
The importance of human factor arose during WWII in which HF established itself as
a real discipline. But before that research was conducted by performance psychology,
industrial engineering and human physiology.
Sensory Psychophysics: Performance psychology started with Weber and Fechner who
were interested in the sensory and perceptual capabilities of a human being. Weber examined
the discriminability of two certain stimuli by a person which resulted in Weber‟s Law(
). In which I is the intensity of a stimulus and the change in intensity necessary in
discriminating them. This resulted in a certain constant K. Fechner formalized Weber‟s
methods resulting in Fechner‟s law( ( ) ). S here stands for the magnitude of
sensation. This is a psycophysical function relating physical intensity to psychological
sensation. The term psychophysical describes the research to basis sensory sensitivity.
Helmholz in order was important in research to the speed of mental processing. He
established a method to estimate the time for transmission of a nerve impuls. This meant that
neural processing was not instantaneous but takes time instead. Donders used this fact when
he developed chronometric methods which is now called substractive logic. The time it takes
to react on a single stimulus is compared to the time it takes to select a certain reaction. With
this method you could measure the decision making time and/or respond selection. This was
important in the human information processing, the approach that underlies most
contemporary research on human performance. The basic assumption here is that these
cognitive mechanisms are in a serial manner.
Attention: Wundt was one of the founders of modern psychology. He argued that
mental events are the cause of human behaviour and that mental representations are the
function of experience. Wundt called this voluntarism with respect to the voluntary aspects of
behaviour. This brings us to attention and the founder of it, William James. He stated:
Attention is the taking possession by the mind, of one of several possible objects or trains of
thoughts.
Learning and Skill acquisition: Ebbinghaus was the first to apply experimental rigor
successfully in the study of learning and memory. His procedures and the theoretical issues
that he investigated provided the basis for a scientific investigation of higher mental function.
Bryan and Harter(1899) extended the research of learning and memory to skill acquisition.
They determined many factors which would later be called the perceptual-motor skills.
„Human Factors in Simple and Complex Systems‟ by Robert W. Proctor & Trisha Van Zandt
Second Edition 2008
Chapter One: Historical Foundations of Human Factors
Every system has a goal. The total efficiency of the system depends on both the human
components as well as on the inanimate components of the machine. The efficiency of both
components determines whether and in what fashion the goal is met. Failing of either
components can lead to failure of the entire system.
One key component to an effective system is Usability. This was a major problem with early
on devices such as the VCR or stereo‟s in the „70s & „80s which were very hard to use
properly. With the increasing rate of development of computer technology usability is still an
important subject which always had to be taken into account. Development of the mouse and
the graphical interface greatly improved this. On the other hand, coming with internet,
security & privacy became major issues. Increased security means a decrease in usability
forcing men to find the perfect compromise.
One major accident that was a result of major system failure was the explosion of NASA
spaceship the Challenger. Design flaws, relaxed safety regulations a.o. were causes that
resulted in the accident. Luckily people learned from these mistakes, not only at NASA but at
many other organizations, and safety guidelines were established so accidents can be
prevented.
What is Human Factors?
When designing a machine both the adequacy of the machine and human performance has to
be taken into account. That‟s why these are considered as a single human-machine system and
are analyzed as a whole. The variables that are considered fall under the topic of Human
Factors(HF). “HF is a scientific discipline concerned with the interaction among humans and
other elements of a system”. Part of this is knowing the capabilities and limitations of humans
and the machine and using this knowledge when designing a system. HF had a broad field
where it can be applied, because every single system has to work properly. The basics of HF
are thus essential for success.
There is a lot of scientific data reporting the capabilities and limitations of a human being.
With these data we can predict how well people can perform simple and complex tasks.
Where engineers and human performance specialists analyze the machine and human
respectively. We have a lot of freedom in designing and improving machines but we can‟t
rely on extending the limits of a person. Thus, the HF specialist must consider the human
limitation in order to use the degrees of freedom in the design of the machine.
, The most simple representation of a system is
displayed in figure 1. As you can see the human
and the machine are a lot alike. They both have
a sensory system, processing system and an
action/display system. Important to understand
is that not only, the human, machine and the
interaction have to be taken into account. The
work environment, both physical and social, Figure 1
also has great influences on performance. We
call this macroergonomics. We will return to that later.
Historical Antecedents
The importance of human factor arose during WWII in which HF established itself as
a real discipline. But before that research was conducted by performance psychology,
industrial engineering and human physiology.
Sensory Psychophysics: Performance psychology started with Weber and Fechner who
were interested in the sensory and perceptual capabilities of a human being. Weber examined
the discriminability of two certain stimuli by a person which resulted in Weber‟s Law(
). In which I is the intensity of a stimulus and the change in intensity necessary in
discriminating them. This resulted in a certain constant K. Fechner formalized Weber‟s
methods resulting in Fechner‟s law( ( ) ). S here stands for the magnitude of
sensation. This is a psycophysical function relating physical intensity to psychological
sensation. The term psychophysical describes the research to basis sensory sensitivity.
Helmholz in order was important in research to the speed of mental processing. He
established a method to estimate the time for transmission of a nerve impuls. This meant that
neural processing was not instantaneous but takes time instead. Donders used this fact when
he developed chronometric methods which is now called substractive logic. The time it takes
to react on a single stimulus is compared to the time it takes to select a certain reaction. With
this method you could measure the decision making time and/or respond selection. This was
important in the human information processing, the approach that underlies most
contemporary research on human performance. The basic assumption here is that these
cognitive mechanisms are in a serial manner.
Attention: Wundt was one of the founders of modern psychology. He argued that
mental events are the cause of human behaviour and that mental representations are the
function of experience. Wundt called this voluntarism with respect to the voluntary aspects of
behaviour. This brings us to attention and the founder of it, William James. He stated:
Attention is the taking possession by the mind, of one of several possible objects or trains of
thoughts.
Learning and Skill acquisition: Ebbinghaus was the first to apply experimental rigor
successfully in the study of learning and memory. His procedures and the theoretical issues
that he investigated provided the basis for a scientific investigation of higher mental function.
Bryan and Harter(1899) extended the research of learning and memory to skill acquisition.
They determined many factors which would later be called the perceptual-motor skills.
