Hci activity#2

Activity #2
Human In HCI
•Understanding how people interact with computers
•Human characteristics in Design
•Human consideration in Design
•Human Interaction speeds
Human Computer Interaction(HCI)- Itec 332

In thisActivity you will :
Understand the human factors to be considered for
designing and building interactive computer
systems.
Understand important characteristics in design
 Identify capabilities and limitations of human in
HCI
2 Compiled by: DesalegnAweke. Human Factors in HCI

Introduction
 The journey into the world of interface design and the screen
design process must begin with an understanding of the system
user, which is the most important part of any computer
system.
 Understanding people and what they do is a difficult and often
undervalued process but very critical because of the gap in
knowledge, skills, and attitudes existing between system users
and developers that build them.

Cont’d
 To create a truly usable system, the designer must always
do the following:
Understand how people interact with computers.
Understand the human characteristics important in design.
Identify the user’s level of knowledge and experience.
Identify the characteristics of the user’s needs, tasks, and jobs.
Identify the user’s psychological characteristics.
Identify the user’s physical characteristics.
Employ recommended methods for gaining understanding of
users

Understanding how people interact with
computers
 Understanding people and what they do is a difficult and often
undervalued process but very critical because of the gap in
knowledge, skills, and attitudes existing between system users
and developers that build them.
 To understand how people interact with computers, we need to
know the following concepts and recognizes their effects.
These are:
Why People HaveTrouble with Computers
Responses to Poor Design
People andTheirTasks

Why People Have Trouble with Computers
Human Factors in HCICompiled by: DesalegnAweke.6
 Design decisions, therefore, have rested mostly on the designers’
intuition concerning the user’s capabilities and the designer’s
wealth of specialized knowledge.
 Consequently, poorly designed interfaces have often gone
unrecognized.
 A system that appears perfectly useful to its designers but one
that the user is unable or unwilling to face up to and master.
 What makes a system difficult to use in the eyes of its user?

Cont’d
 The following factors makes a system difficult to use in the eyes of its
users.
Use of jargon.Systems often speak in a strange language
 Learning to use a system often requires learning a new language.
Non-obvious design. Complex or novel design elements are not
obvious or intuitive, but they must nevertheless be mastered
Fine distinctions.Different actions may accomplish the same
thing, depending upon when they are performed, or different
things may result from the same action.

Cont’d
Disparity in problem-solving strategies: People learn best by
doing.
 Human problem solving can best be characterized as “error-
correcting” or “trial and error”
Design inconsistency
 The same action may have different name
 The same command may cause different things to happen.
 The same result may be described differently
 The same information may be ordered differently on
different screens.

Response to poor Design
 People remember the one thing that went wrong, not the many
that go right.
 Errors, and other problems that befuddle one, lead to a variety of
psychological and physical user responses.
Psychological:Typical psychological responses to poor design are:
 confusion
Annoyance
Frustration
Panic or stress
Boredom

Cont’d
 Confusion.Detail overwhelms the perceived structure
 Annoyance. Inconsistencies in design, slow computer reaction times,
difficulties in quickly finding information, outdated information
 Frustration.An inability to easily convey one’s intentions to the
computer, or an inability to finish a task or satisfy a need can cause
frustration.
 Panic or stress.Unexpectedly long delays during times of severe or
unusual pressure may introduce panic or stress
 Boredom.Boredom results from improper computer pacing (slow
response times or long download times) or overly simplistic jobs.

Cont’d
 These psychological responses diminish user effectiveness because
they are severe blocks to concentration.
 Thoughts irrelevant to the task at hand are forced to the user’s
attention, and necessary concentration is impossible.
 The result, in addition to higher error rates, is poor performance,
anxiety, and dissatisfaction.

Cont’d
Physical- Psychological responses frequently lead to, or are
accompanied by, the following physical reactions.
Abandonment of the system.The system may be rejected
Partial use of the system.Many aspects of many systems
often go unused.
Indirect use of the system.An intermediary is placed
between the would-be user and the computer
Modification of the task.The task is changed to match the
capabilities of the system.

Cont’d
Compensatory activity.Additional actions are performed to
compensate for system inadequacies.
Misuse of the system.The rules are bent to shortcut
operational difficulties.This requires significant knowledge of
the system and may affect system integrity.
Direct programming.The system is reprogrammed by its
user to meet specific needs.This is a typical response of the
sophisticated worker.

Cont’d
 These physical responses also greatly diminish user efficiency
and effectiveness.
 They force the user to rely upon other information sources, to
fail to use a system’s complete capabilities, or to perform
time-consuming “work-around” actions.

People and Their Tasks
 The user in today’s office is usually overworked, fatigued, and
continually interrupted.
 All computer users do tend to share the following:
 They tend not to read documentation,
They do not understand well the problems the computer can aid in
solving, and
They know little about what information is available to meet their
needs.
 Moreover, the users’ technical skills have often been greatly
overestimated by the system designer, who is usually isolated
psychologically and physically from the users’ situation.

Cont’d
 The user, while being subjected to the everyday pressures of the
office and home, frequently does not care about how technically
sophisticated a system orWeb site is.
 He or she wants to spend time using a computer, not learning to
use it.
 His or her objective is simply to get some work done, a task
performed, or a need satisfied.
 Today, many users have also learned to expect certain level of
design sophistication. It is in this environment our system will be
placed.

Human characteristics in design
 Human are complex organisms with a variety of attributes
that have an important influence on interface and screen
design.
 Important human characteristics to be considered in design
are perception,memory,visual acuity, foveal and peripheral vision,
sensory storage,information processing,learning,skill,and
individual differences.

Perception
 Perception is our awareness and understanding of the elements and
objects of our environment through the physical sensation of our
various senses, including sight, hearing, touch, taste, smell, and so
forth.
 Perception is influenced, in part, by experience.
 Imagine using a personal computer (PC) with a mouse and a
keyboard.The application you are using has a graphical interface,
with menus, icons and windows.
 In your interaction with this system you receive information primarily
by sight, from what appears on the screen.

Cont’d
 Comparing the accumulated knowledge of the child with that of an
adult in interpreting the world is a bright example of the role of
experience in perception.
 Perceptual characteristics include the following:
Proximity. Nearby objects tend to be grouped together.
Similarity. Similar items tend to be grouped together if they share
a common visual property, such as color, size, shape, brightness, or
orientation.
Matching patterns. Human respond similarly to the same shape
in different sizes.The letters of the alphabet, for example, possess
the same meaning, regardless of physical size.

Cont’d
 Succinctness. We see an object as having some perfect or simple
shape because perfection or simplicity is easier to remember.
 Closure. Our perception is synthetic; it establishes meaningful
wholes. If something does not quite close itself, such as a circle,
square, triangle, or word, human see it as closed anyway.
 Unity. Objects that form closed shapes are perceived as a group.
 Continuity. Shortened lines may be automatically extended
 Balance. We desire stabilization or equilibrium in our viewing
environment.Vertical, horizontal, and right angles are the most
visually satisfying and easiest to look at.

Cont’d
 Expectancies. Perception is also influenced by expectancies;
sometimes we perceive not what is there but what we expect to be
there.
Missing a spelling mistake in proofreading something we write is often
an example of a perceptual expectancy error; we see not how a word is
spelled, but how we expect to see it spelled.
 Context. Context, environment, and surroundings also influence
individual perception.
For example, two drawn lines of the same length may look the same
length or different lengths, depending on the angle of adjacent lines or
what other people have said about the size of the lines.

Cont’d
 The goal in design, then, is to utilize our perceptual
capabilities so a screen can be structured in the most
meaningful and obvious way.

Human Memory
 Much of our everyday activity relies on memory
 As well as storing all our factual knowledge, our memory
contains our knowledge of actions or procedures.
figure 1 A model of the structure of memory

Cont’d
 Minimize the need for a mighty memory.
 To reduce user memory loads, reduce the need for mental
integration, and expand working memory, thus enhancing
system usability include:
Presenting information in an organized, structured, familiar, and
meaningful way.
Placing all required information for task performance in close
physical proximity.
Giving the user control over the pace of information
presentation.

Sensory Storage
 Sensory storage is the buffer where the automatic processing of
information collected from our senses takes place.
 It is an unconscious process, large, attentive to the environment,
quick to detect changes, and constantly being replaced by newly
gathered stimuli.
 In a sense, it acts like radar, constantly scanning the
environment for things that are important to pass on to higher
memory.
 Repeated and excessive stimulation can fatigue the sensory storage
mechanism and cause noise.
 Eliminating interface noise will ensure that important things will be
less likely to be missed

Visual Acuity
 The capacity of the eye to resolve details is called visual acuity.
 It is the phenomenon that results in an object becoming more
distinct as we turn our eyes toward it and rapidly losing distinctness
as we turn our eyes away—that is, as the visual angle from the point
of fixation increases.
 The eye’s sensitivity increases for those characters closest to the
fixation point(0) and decreases for those characters at the extreme
edges of the circle
 Patterns for fill-in areas of screens (bars, circles, and so on.) must
be carefully chosen to avoid this visual distraction.

Foveal and Peripheral Vision
 Foveal vision is used to focus directly on something; peripheral vision
senses anything in the area surrounding the location we are looking
at, but what is there cannot be clearly resolved because of the
limitations in visual acuity
 The performance on a foveal window deteriorates when there are
peripheral windows, and the performance degradation is even
greater if the information in the peripheral is dynamic or moving.
 Care should be exercised in design to utilize peripheral vision in its
positive nature, avoiding its negative aspects.

Information Processing
 The information that our senses collect has to be processed in
some meaningful way in order to do something.
 There are two levels of information processing going on within
us.
First, the highest level of information processing, is identified
with consciousness and working memory.
 It is limited, slow, and sequential, and is used for reading
and understanding.
 You are utilizing this higher level now reading this
handout.

Cont’d
Second, the lower level of information processing
 The limit of its capacity is unknown.
 This lower level processes familiar information rapidly, in
parallel with the higher level, and without conscious effort.
 We look rather than see, perceive rather than read. Repetition
and learning results in a shift of control from the higher level to
the lower level.
 Both levels function simultaneously, the higher level performing
reasoning and problem solving, the lower level perceiving the
physical form of information sensed.

Cont’d
 You’ve probably experienced this difference in working with
screens
 If you’re new to a system, or if a screen is new to you, you rely on
its concrete elements to make that determination, its title, the
controls and information it contains, and so forth.You consciously
look at the screen and its components using this higher-level
processing.
 As you become experienced and familiar with screens, however, a
newly presented screen can be identified very quickly with just a
momentary glance.Your reasoning and problem solving continues
unhindered; your lower-level information processing has assumed
the screen identity task.

Mental Models
 As a result of our experiences and culture, we develop mental models
of things and people we interact with.
 A mental model is simply an internal representation of a person’s
current understanding of something.
 Mental models are gradually developed in order to understand
something, explain things, make decisions, do something, or interact
with another person.
 If the system conforms to the mental models a person has developed,
the model is reinforced and the system’s use feels more “intuitive.”
 If not, difficulties in learning to use the system will be encountered.
 This is why in design it is critical that a user’s mental models be to
identified and understood.

Movement Control
 Once data has been perceived and an appropriate action
decided upon, a response must be made; in many cases the
response is a movement
Time taken to respond to stimulus: reaction time plus
movement time.
 In computer systems, movements include such activities as
pressing keyboard keys, moving the screen pointer by pushing
a mouse or rotating a trackball, or clicking a mouse button
 Speed and accuracy of movement are important
considerations in the design of interactive systems, primarily
in terms of the time taken to move to a particular target on a
screen.

Cont’d
 For example, the target may be a button, a menu item or an
icon.
 The time taken to hit a target is a function of the size of the
target and the distance that has to be moved.
 Particularly important in screen design is Fitts’ Law (1954).
This law states that:
The time to acquire a target is a function of the distance to and
size of the target.

Cont’d
This simply means that the bigger the target is, or the closer
the target is, the faster it will be reached.The implications in
screen design are:
Provide large objects for important functions.
Take advantage of the “pinning” actions of the sides, top,
bottom, and corners of the screen
 This affects the type of target we design.
 Since users will find it more difficult to manipulate small
objects, targets should generally be as large as possible and the
distance to be moved as small as possible.

Learning
 Learning is the process of encoding in long-term memory
information that is contained in short-term memory
 Our ability to learn is important—it clearly differentiates people
from machines.
 A design developed to minimize human learning time can greatly
accelerate human performance.
 People prefer to stick with what they know, and they prefer to jump
in and get started.
 Unproductive learning time spent is something frequently avoided.
 people are very sensitive to even minor changes in the user
interface, and that such changes may lead to problems in
transferring from one system to another

Cont’d
 Moreover, just the “perception” of having to learn huge
amounts of information is enough to keep some people from
using a system
 Learning can be enhanced if it:
Allows skills acquired in one situation to be used in another
somewhat like it.
Design consistency accomplishes this.
Provides complete and prompt feedback.
Is phased, that is, it requires a person to know only the
information needed at that stage of the learning process.

Skill
 The goal of human performance is to perform skillfully.
 To do so requires linking inputs and responses into a
sequence of action
 Skills are hierarchical in nature, and many basic skills may be
integrated to form increasingly complex ones.
 Lower-order skills tend to become routine and may drop out
of consciousness.
 Increasing reaction time decreases accuracy in unskilled
operator but not in skilled operator
 System and screen design must permit development of
increasingly skillful performance.

Individual differences
 We should be aware of individual differences so that we can account
for them as far as possible within our designs.
 We all differ in looks, feelings, motor abilities, intellectual abilities,
learning abilities and speed, and so on.
 In a keyboard data entry task, for example, the best typists will
probably be twice as fast as the poorest and make 10 times fewer
errors.
 Individual differences complicate design because the design must
permit people with widely varying characteristics to satisfactorily
and comfortably learn the task or job, or use theWeb site.

Cont’d
 In the past this has usually resulted in bringing designs down to
the level of lowest abilities or selecting people with the
minimum skills necessary to perform a job.
 But technology now offers the possibility of tailoring jobs to the
specific needs of people with varying and changing learning or
skill levels.
 Multiple versions of a system can easily be created.
 Design must provide for the needs of all potential users.

Human consideration in design
 The human characteristics described above are general
qualities we all possess.
 There are also other human aspects in which people may
vary greatly.
 These are also important and must be identified in the
design process.These are:
The User’s Knowledge and Experience
The User’sTasks and Needs
The User’s Psychological Characteristics
The User’s Knowledge and Experience

The user’s knowledge and experience
 The knowledge possessed by a person, and the experiences
undergone, shape the design of the interface in many ways.
 The following kinds of knowledge and experiences should be
identified.
Computer Literacy
System Experience
Application Experience
Task Experience
Other System Use
Education
Reading Level
Typing Skill
Native Language and Culture

Cont’d
Computer Literacy
Are the users highly technical such as programmers or experienced
data entry clerks?
Do they have moderate computer experience or none at all?
System Experience
Are users already familiar with the interaction requirements of the
new system, somewhat familiar, or not familiar at all?
Various schemes have been proposed to classify the different and
sometimes changing characteristics of people as they become more
experienced using a system.
Words to describe the new, relatively new, or infrequent user have
included naive, casual, inexperienced, or novice

Cont’d
Application Experience
Have users worked with a similar application (for example, word
processing, airline reservation, and so on)?
Task Experience
Are users experienced with the task being automated? If it is an
insurance claim system, do users have experience with paying
claims?
Other System Use
Will the user be using other systems while using the new
system? If so, they will bring certain habits and expectancies to
the new system

Cont’d
The more compatibility between systems, the lower the learning
requirements for the new system and the higher the productivity
using all systems.
Education
What is the general educational level of users?
Reading Level
For textual portions of the interface, the vocabulary and
grammatical structure must be at a level that is easily understood by
the users
Typing Skill
A competent typist may prefer to interact with the system
exclusively through the keyboard, whereas the unskilled typist may
prefer the mouse.

Cont’d
Native Language and Culture
Do the users speak English, another language, or several other
languages?
Are there cultural or ethnic differences between users?
 In conclusion, most of these kinds of user knowledge and
experience are independent of one another, so many different
user profiles are possible. It is also useful to look ahead,
assessing whether future users will possess the same qualities.

The User’s tasks and Needs
 The user’s tasks and needs are also important in design.The
following should be determined:
Mandatory or Discretionary Use
The mandatory user must learn to live comfortably with a
computer, for there is really no other choice.eg. Flight
reservation,
Use of the computer or system is not absolutely necessary
for discretionary user.eg. ATM, library Information system
Frequency of Use
Is system use a continual, frequent, occasional, or once-in-a-
lifetime experience?
Frequency of use affects both learning and memory

Cont’d
Task or Need Importance
How important is the task or need for the user?
For less important things, ease of learning and remembering
are preferred, because extensive learning time and effort will
not be tolerated.
Task Structure
In general, the less structure, the more flexibility should exist
in the interface.
Highly structured tasks require highly structured interfaces.

Cont’d
Social Interactions
The design must accommodate the social interaction
User decision-making required by the interface should be
minimized and clear eye-anchors built into the screen to
facilitate eye-movements by the user between the screen and
the other person.
PrimaryTraining
Will the system training be extensive and formal, will it be
self-training from manuals, or will training be impossible?
With less training, the requirement for system ease of use
increases.
Job Category

The user’s psychological characteristics
 A person’s psychological characteristics also affect one’s
performance of tasks requiring motor, cognitive, or perceptual
skills.These factors are:
 Attitude and Motivation
Is the user’s attitude toward the system positive, neutral, or
negative? Negative attitude results in slower learning
Is motivation high, moderate, or low?
Poor feelings, however, can be addressed by designing a system to
provide more power, challenge, and interest for the user, with the
goal of increasing user satisfaction.
 Patience
Is the user patient or impatient?
Users doesn’t tolerate slow response times, and inefficiencies in
navigation for web

Cont’d
 Stress Level
System navigation or screen content may have to be
redesigned for extreme simplicity in situations that can
become stressful.
 Expectations
What are user’s expectations about the system orWeb
site?Are they realistic? Is it important that the user’s
expectations be realized?
 Cognitive Style
People differ in how they think about and solve problems.

The user’s physical characteristics
 The physical characteristics of people can also greatly affect
their performance with a system.
 Age
Age can have an affect on both computer and system usage.
With age, the eye’s capability also deteriorates, affecting
screen readability. Memory ability also diminishes.
 Hearing
As people age, they require louder sounds to hear, a
noticeable attribute in almost any everyday activity

Cont’d
 Vision
Older adults read prose text in smaller type fonts more slowly than
younger adults
 Cognitive Processing
Brain processing also appears to slow with age.Working memory,
attention capacity, and visual search appear to be degraded.
 Gender
A user’s sex may have an impact on both motor and cognitive
performance.
Women are not as strong as men, so moving heavy displays or controls
may be more difficult.
Significantly more men are color-blind than women, so women may
perform better on tasks and screens using color-coding.

Cont’d
 Handedness
A user’s handedness, left or right, can affect ease of use of an
input mechanism, depending on whether it has been optimized
for one or the other hand.
Ease of use promotes use.
 Disabilities
Blindness, defective vision, color-blindness, poor hearing,
deafness, and motor handicaps can affect performance on a
system not designed with these disabilities in mind.
People with special needs must be considered in design.This is
especially true for systems like theWeb that permit unlimited
user access.

Summary of User/Task Considerations in design

Summary…

Human interaction speeds
 The speed at which people can perform using various
communication methods has been studied by a number of
researchers
 Typical interaction speeds for various tasks are stated as
Reading
Listening.
Speaking.
Keying
Hand printing

Table showing Average Human Interaction Speeds

Methods for Gaining an Understanding of Users
 Use the following techniques to gain an understanding of
users, their tasks and needs, the organization where they work,
and the environment where the system may be used.
Visit user locations, particularly if they are unfamiliar to you.
Talk with users about their problems, difficulties, wishes, and
what works well now.
Observe users working or performing a task to see what they do,
their difficulties, and their problems.
Learn about the work organization where the system may be
installed.

 In general, the most important principle in interface and
screen design is to Know your user, client, or customer
Thank you!

Hci activity#2

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