Interface Ergonomy
KSTU, OshTU
Quality factors (utility, usability, learnability,
observability).
• Usability
–
(English, Usability - literally, "the use of" "the ability to be
used", "utility")
–
a concept in micro-ergonomics, degree of ergonomics, the
handiness of the object for use by users in achieving certain
objectives in some context.
Usability
Usability is defined by 5 quality components:
• Learnability: How easy is it for users to accomplish basic
tasks the first time they encounter the design?
• Efficiency: Once users have learned the design, how
quickly can they perform tasks?
• Memorability: When users return to the design after a
period of not using it, how easily can they reestablish
proficiency?
• Errors: How many errors do users make, how severe are
these errors, and how easily can they recover from the
errors?
• Satisfaction: How pleasant is it to use the design?
Learnability
Obtaining knowledge is difficult. Establish a process
that can identify several structural components.
• The subject of knowledge - the active component of
the process of knowledge, the one who knows. The
subject knowledge can be not only a specific
individual, but also a social group, class and society.
• The object of knowledge - what are the aims of the
subject knowledge of cognitive interest. The object
of knowledge can serve nature, man and society.
Observability. Principles to support usability(1)
Observability (2)
Observability:
allows the user to evaluate the internal state of the
system by means of its perceivable representation at
the interface.
Observability (3)
Observability
Example: Iphone perfectly applies observability
• By simply looking at the interface, the user can
easily evaluate the internal state of the system.
Physical, cognitive and software ergonomy
• Ergonomics (from the Greek ergon- meaning work,
and nomos- meaning law)
• A scientific discipline which studies human
conditions of its activities related to the use of
machines.
• The object of study of ergonomics is the "manmachine-environment", as a complex functioning
whole in which the leading role belongs to man.
Objectives of ergonomics
• The design of the "man-machine";
• Designing the workspace;
• Designing the environment in accordance with the
requirements of the operator;
• Designing work situations
Areas of ergonomics
Physical ergonomics
Cognitive ergonomics
Organizational
ergonomics
Physical ergonomics
Physical
ergonomics
considers
anatomical,
anthropometric, physiological and biomechanical
characteristics and their impact on human physical
activity.
The issues include working postures, handling,
repetitive movements, work leading to
musculoskeletal disorders, workplace layout, safety
and health.
Negative impact
• Prolonged stay in a sitting
position
• Eye strain
• Overloading joints of the
bones
• Exposure to electromagnetic
radiation of the screen
• Internet addiction, gambling,
stress
Proper organization of the workplace
• Monitor and keyboard on the
desktop should be carefully
positioned
• The monitor should be at least 5060 cms from the eyes
• The monitor must be absolutely
clean
• A well lit environment
• Centre of the screen should be at
eye level
Recommendations
• Properly organized place to work at the computer.
• Ensure good posture.
• Take regular breaks to rest and to exercise
• Ensure hygienic workplace (room ventilation, wet
cleaning, ....)
Findings
Focusing on user characteristics, the study of perceptual and
cognitive capabilities and limitations of man revealed patterns
of human interaction with the automated system.
Considering the processes and patterns of perception,
information processing and decision making, cognitive
psychology has identified the factors that determine the
success of the task by the operator.
However, only analysing processes perception and human
information processing is not enough to design a good
ergonomic interface.
It does not determine the composition and sequence of on-screen
information.
This led to the emergence of a number of interface design
methodologies based on a cognitive approach.
Cognitive ergonomics
It is necessary to study the user to create interfaces
that might work well.
Cognitive ergonomics is associated with thought
processes such as perception, memory, reasoning, and
motor response, and their role in the interaction of
man with other system elements.
Cognitive Psychology - The locus of attention
(Kolmogorov)
• At any time, a person can focus on only one item. This object,
memory, item, idea or concept becomes the locus of
attention.
• The concept of locus represents a place or region.
• In cognitive psychology any task performed by a person
without the participation of consciousness becomes
automaticity.
• The task that is not an automaticity is a locus of attention.
• The simultaneous execution of two non-automatic tasks
leads to reduced effectiveness of the implementation of each
(as a result of competition for the attention of the region).
Perceptual memory
• Most human perception fades over
time.
• People that have read or heard a
message five seconds before will not
necessarily be able to remember the
content.
• Implications for interface design: If
that message is important, it must
remain on the screen until it is not
longer needed.
User Interface
User Interface — a variety of
interfaces, in which one party is
represented by a person (user), the
other - the machine / device.
It represents a set of tools and
methods by which the user interacts
with the different, often complicated,
machines, devices and equipment.
The term is usually used to refer to
the interaction between the device
operator and the software.
Interface development - Methodology
Activity-Centered Design, ACD.
This methodology considers the "human-computer" as a complex
activity, related to concepts and ideas. Activity theory is the basis of
this approach. i.e. the computer is a tool by for the person to perform
different tasks, and human activity affects the interface.
Goal-oriented design
This methodology (developed by Alan Cooper), is based on the
assumption that a thorough study and understanding of the user's
goals, solves the problem of "cognitive friction".
Cognitive friction: introduced by Cooper. Characterized by a
complex relationship of man to things (such as a computer) as
another person.
Methodology development of interfaces
User-Centered Design
This justifiable popular methodology is
used not only for software development.
Concerned with the study of the needs
and capabilities of end users, and how a
product may be adapted to these needs.
Related to software being a product that
people want to use.
Design criteria.
There are a number of recommendations from the experts in
the design of the user interface.
• Jef Raskin, an expert in computer interfaces, in his book «The
Humane Interface», (2000), (and based on the laws of
robotics of A. Asimov) formulated the two laws of user
interface development:
First Law: The computer does not have to hurt your work
or, through inaction, allow harm to be done to your work.
Second Law: The computer does not have to waste your
time or require you to work more than is necessary.
Standardization
• In 1992, the International Organization for
Standardization, ISO introduced a group of
standards, one of which is:
– ISO 9241 “Ergonomic requirements for office work with
visual display terminals” (VDTs).
• In 2006, they received a more general name
“Ergonomics of Human System Interaction”.
Some of the standards ISO 9241:(1)
• ISO/TR 9241-100:2010 Ergonomics of humansystem interaction. The introduction of the
standards for ergonomics software
• ISO 9241-110:2006 Ergonomic requirements
associated with the use of video terminals for
institutional works. The principles of dialogue
• ISO 9241-129:2010 Ergonomics of human-system
interaction. Software Guide
• ISO 9241-143:2012 Ergonomics of human-system
interaction. Forms
Some of the standards ISO 9241:(2)
• ISO 9241-151:2008 Ergonomics of human-system
interaction. Guide to the World Wide Web user interface
• ISO 9241-154:2013 Ergonomics of human-system
interaction. Application of interactive voice response
(IVR)
• ISO 9241-171:2008 Ergonomics of human system. Guide
to the availability of software
• ISO 9241-210:2010 Ergonomics of human-system
interaction. Some concentrate on the person designing
interactive systems
8 “Golden" rules of Schneiderman (1)
Ben Shneiderman, an American researcher in the field
of human-computer interaction, in his book
«Designing the User Interface» formulated 8 "golden"
rules, which can be summarized as follows:
1. Be consistent: Use the same action, the names of
control elements in identical or similar situations.
8 "golden" rules Schneiderman (2)
2. Consider the possibility
of expert users: they find
alternative ways of
working by using the
"hot" keys, macros, etc.
3. Use feedback: the
program must respond to
every action of the
operator.
8 "golden" rules Schneiderman (3)
4. Create a complete dialogue: create consistent operator
actions into logical groups with a beginning, middle and
end. At each stage, to provide feedback.
8 "golden" rules Schneiderman (4)
5. Use simple error handling: as far as possible, design your
system so that the user can avoid serious mistakes, and if
an error is detected offer simple and clear mechanisms for
its resolution.
8 "golden" rules Schneiderman (5)
6. Provide a simple mechanism to undo: this reduces users
anxiety members since they know that the wrong actions
can be undone. This may be the reversibility of a one-time
event, a data entry or a group of actions.
8 "golden" rules Schneiderman (6)
7. Create the impression
that the user has control:
design the interface so
that the user is the
initiator of action, not a
slave.
8 "golden" rules Schneiderman (7)
8. Reduce short-term memory load: features of human
memory impose restrictions on the number, and size
of information or actions to do.
Thank you!