Extensive Summary Human
Factors
Chapter 1: Introduction
Taylor is the father of Scientific Management. He focused on increasing productivity, but not safety
or satisfaction.
All systems include people and meeting their needs is the end goal of engineers and designers – if a
system doesn’t work for people, it doesn’t work – human factors engineering makes technology work
for people.
Goals and process of human factors engineering
Human factors engineering is a discipline that considers the cognitive, physical, and organizational
influences on human behavior to improve human interaction with products and processes. Human
factors engineering aims to improve human interaction with systems by enhancing:
- Safety: reducing risk of injury or death.
- Performance: Increasing productivity, quality, and efficiency.
- Satisfaction: Increasing acceptance, comfort, and well-being.
Design of high-risk systems must focus on safety, design of workplaces focuses more on
performance and design of consumer products focuses more on satisfaction.
Tradeoffs between safety, performance and satisfaction need to be made. However, human factors
interventions often can satisfy safety, performance and satisfaction simultaneously.
Using human factors interventions depends on knowledge of the mind, the physical body and the
social interactions that govern teams and organizations. Design should strive to accommodate all
people.
The human factors design cycle is in iterative process of creating, understanding and evaluating.
Task design focuses more on changing what operators do than on changing the devices they use.
Equipment design changes the physical equipment that people work with.
Environmental design changes the physical environment where the tasks are carried out.
Training enhances the knowledge and skills of people by preparing them for the job.
Selection changes the makeup of the team or organization by picking people that are best suited to
the job.
Team and organization design changes how groups of people communicate and relate to each
other, and provides a broad view that includes the organizational climate where the work is
performed.
Scope of human factors engineering
Fields closely related to human factors engineering include:
, - Engineering psychology is a discipline within psychology, and human factors is a discipline
within engineering. The ultimate goal of the study of human factors is system design. In
contrast, the ultimate goal of engineering psychology is to understand the human mind as it
relates to design.
- Cognitive engineering, focuses on the cognitive considerations, particularly in the context of
safety of complex systems.
- Macro ergonomics, addresses the need to consider not just the details of particular devices
or processes, but the need to consider the overall work system. It takes complex systems as
its focus and considers the design of teams and organizations.
- Human-systems integration, considers how designs must consider how people interact with
all systems.
- Human-computer interaction (HCI) is often linked to the field of user experience and tends
to focus more on software and less on the physical and organizational environment.
Systems thinking
Three elements of systems thinking are highlighted:
- Interconnection. Joint optimization: where the focus is on improving the performance of the
person and the technology, not just making the technology perform better. The
interconnections of complex systems mean that there is no single cause for most mishaps.
- Adaptation. Technology often has unanticipated consequences that result from people
adapting and changing their behavior in response to the technology – adaptation can lead
good technology to have bad outcomes.
- Environment. Affordances: opportunities for action presented by the environment. Properly
specified affordances lead people to effortlessly behave in an appropriate fashion. The
environment also determines the consequence of a behavior. Variability of the environment
means that designs need to be flexible and support variety of responses. Often engineering
solutions that strive to eliminate human error may improve routine performance, but
diminish flexibility needed to respond to unusual situations.
Scientific base of human factors engineering
Intuitions fail because people are not aware of how their minds and bodies operate: expectations
change what people see, attention makes people blind to events that happen right in front of them,
and default settings often make decisions for people. Intuition also fails to guide design because
designers often differ substantially from end users: they have different needs, priorities and
preferences. Designers might also have a deep familiarity with technology which leads to learned
intuition that might not be shared by those unfamiliar with for instance computer technology.
,Chapter 2: Design Methods
The concept of “design” is very broad and can include activities such as:
- Creating new products, systems and experiences.
- Improving existing products
- Ensuring safety in the workplace, car and home
- Implementing safety-related activities
- Developing performance support materials (e.g. checklists and instruction manuals)
- Guiding team and organizational design
Considering human factors at the start of the design smooths the design process.
System design processes
Generally design processes include iterative stages that reflect:
- Understanding the user’s needs; pre-design, front-end analysis.
- Creating a product or system; prototypes, pre-production models.
- Evaluating how well the design meets user’s needs.
Product lifecycle models are design processes that include product implementation, utilization,
maintenance, and dismantling or disposal.
Vee process is often used in large, high-risk systems where sequential development is possible and
verification, validation and documentation are critical. The Vee shape starts with a broad system
description and design requirements, which are decomposed into detailed requirements. In the Vee
process, the general specifications are well-defined at the start and emphasis is given to
documenting a successful implementation of those specifications.
Plan-Do-Check-Act (PCDA) cycle is commonly used to enhance workplace efficiency and production
quality. The cycle is trivial and does what its name states. With Act referring to improvements. The
cycle reflects the scientific management approach of Taylor in that each plan represents a
hypothesis of how the system or product might be improved.
Scrum process is more typical of consumer software products, such as smartphone and web
applications, where an iterative and incremental approach is needed to resolve uncertainty in design
requirements. The Scrum approach focuses on creating products and using those products to
discover requirements. “Sprints” which are short duration efforts, typically 24 hours to 30 days,
focus effort on quickly producing new iterations of the product. The Scrum approach is well-suited to
situations that demand high degree of innovation.
Vee process focuses on methodical implementation. PCDA guides incremental improvement and
Scrum focuses on fast iteration. Some areas, such as high-tech cars, are high-risk and the
requirements are not well known. In such cases a hybrid approach that combines elements of the
Vee, PCDA and Scrum might be necessary.
Integrating human factors into design process. Human factors methods trade accuracy for speed.
Understanding how to make this speed-accuracy trade-off is critical for inserting human factors
considerations into design. One must select human factors methods that fit the demands of the
design process.
, Human-centered design
The human-centered design of a system or product revolves around users: it must meet their needs
and be compatible with their abilities. Systems thinking is important, it focuses on the interaction
and relationship of parts. Systems thinking can avoid unintended consequences.
Human centered design process three stages:
- Understand users; observation of tasks
- Create prototype
- Evaluate prototype; heuristic evaluations/usability tests.
Heuristic evaluation is quick. Usability tests help understanding the users and their needs, in a more
detailed fashion, it takes longer and is usually iterative. This speed-accuracy tradeoff means that the
resources should match to the system being developed.
Questions to be asked before design solutions are created in a task analysis:
- Who are the users (also installers, maintainers, etc.)?
- Why do users need it and what are their preferences?
- What are the environmental conditions of product being used?
- What is the physical and organizational context?
- What major functions must be fulfilled by a person, team or machine?
- When must tasks occur, in what order and how long to they take?
In contrast to accident analysis, which typically focuses on system safety, time-motion studies
developed by Taylor, focuses on improving performance of manual work. Contextual inquiry
provides an understanding of users’ needs by going to users’ workplace or wherever the system
should be used, the investigator acts as an apprentice to learn.
How to perform a task analysis
Task analysis: a way of systematically describing human interaction with a system to understand how
to match the demands of the system to human capabilities. Task analysis has the steps:
- Define the purpose and identify the required data
- Collect task data
- Interpret task data
- Innovate from task data
These steps are described sequential, but in practice it is often iterative.
Step 1: Define purpose and identify required data
Cognitive components in conducting the analysis if any of the following characteristics are present:
- Complex decision making, problem solving, diagnosis or reasoning
- Much conceptual knowledge needed to perform tasks
- Large and complex structures that are highly dependent on this situation
- Performance depends on memory of information that needs to be retained for seconds or
minutes
