Department of Computer Science
Human Computer Interaction
Ephrem G.
(Lecturer, Electrical and
Computer Engineering)
2024/25 G.C
C hapte r O ne:
Introduction to Human-Computer Interaction
Human-Computer Interaction (HCI)
2
▪ HCI is the study of how humans interact with computer
systems.
▪ “HCI is a discipline concerned with the design, evaluation and
implementation of interactive computing systems for human
use and with the study of major phenomena surrounding
them”.
Human-Computer Interaction (HCI) (cont…)
3
▪ Many disciplines contribute to HCI, including computer
science, psychology, ergonomics, engineering, and graphic
design.
▪ HCI consists of three parts: the user, the computer itself, and
interactions
The Goals of HCI
4
The goals of HCI are:
◼ to produce usable and safe systems, as well as
functional systems
◼ understand the factors that determine how people use
technology
The Goals of HCI (cont…)
5
◼ develop tools and techniques to enable building
suitable systems
◼ achieve efficient, effective, and safe interaction
◼ put people first
HCI
6
◼ The Human: I/O channels, Memory, Reasoning and
problem solving;
◼ The computer: Devices, Memory, processing and
networks
◼ Interaction: Models, frameworks, Ergonomics, styles,
elements, interactivity, Paradigms
HCI (cont…)
7
◼ Ergonomics: the study of the physical characteristics of the
interaction:
◼ how the controls are designed, the physical environment in
which the interaction takes place, and the layout and
physical qualities of the screen.
◼ A primary focus is on user performance and how the
interface enhances productivity.
Why do we care?
8
▪ Computers (in one way or another) now affect every person
in our society.
▪ We are surrounded by unusable and ineffective systems!
▪ Its not the user’s fault!!
Why do we care? (cont…)
9
▪ Product success may depend on ease of use, not
necessarily command
▪ You will likely create an interface for someone at some
point Making things people love.
▪ Effortless interaction.
Interaction Techniques
10
▪ Scroll bars, buttons, text fields
▪ But also:
Drawing a new object in an editor
Copy-and-paste
Selecting a cell in a spreadsheet
Some Examples
11
✓ Visual Basic
✓ Physical controls
Interaction technique
12
▪ An interaction technique starts when the user does
something that causes a computer to respond, and includes
the direct feedback from the computer to the user.
▪ Interaction techniques are generally reusable across
various applications.
Interaction technique (cont…)
13
▪ Wikipedia’s definition: “An interaction technique, user
interface technique or input technique is a combination of
hardware and software elements that provides a way for
computer users to accomplish a single task.”
▪ Foley & van Dam, 1990: “An interaction technique is a way
of using a physical input/output device to perform a generic
task in a human-computer dialogue.”
The Era of HCI
14
The Past
The Era of HCI (cont…)
15
The Present: The Mobile, Pervasive and Ubiquitous Era
USERS
16
TECHNOLOGY
17
GOALS
18
Overview: Map of Human Computer Interaction
19
What Is Not An Interaction Technique?
20
◼ Whole applications (MS Word) dashboard
◼ widgets - small apps for the desktop output
◼ only (no interactions)
What Is Not An Interaction Technique? (cont…)
21
◼ Visualizations
But many come with specialized interactions, then they
might count?
◼ Animations
◼ Movies
Goals of HCI
22
▪ Allow users to carry out tasks:
▪ Safely (Reducing anxiety & fear of computer usage)
▪ Effectively (accuracy and completeness in achieving goals)
▪ Efficiently (resources used)
▪ Enjoyably (comfort, acceptability, happiness, pleasure)
Usability
23
▪ Combination of
▪ Ease of learning i.e., easy to learn, to use, to memorize
▪ High speed of user task performance i.e., Efficiency
▪ Low user error rate i.e., Effectiveness
▪ Subjective user satisfaction i.e., Enjoyable
▪ User retention over time i.e., Safety
Design Evaluation
24
▪ Both subjective and objective metrics
▪ Some things we can measure
▪ Time to perform a task
▪ improvement of performance over time
▪ Rate of errors by user
▪ Retention over time
▪ Subjective satisfaction
UI Design/ Develop Process
25
◼ User-Centered Design
◼ Active involvement of users
◼ Appropriate allocation of function between user & system
◼ Multidisciplinary design teams
UI Design/ Develop Process (cont…)
26
◼ Analyze user’s goals & tasks
◼ Determine what tasks and subtasks must be carried out
◼ Include tasks which are only performed occasionally.
◼ Functionality must match need or else users will reject or
underutilize the product
UI Design/ Develop Process (cont…)
27
◼ Create design alternatives
◼ Evaluate options
◼ Implement prototype
◼ Test
◼ Refine
◼ Implement
Know The Users
28
◼ Physical & cognitive abilities (& special needs)
◼ Classification of human cognitive processes:
◼ Long-term and semantic memory
◼ Short-term and working memory
◼ Language communication and comprehension
◼ Learning, skill development, knowledge acquisition and
concept realization, etc. …
Know The Users (cont…)
29
◼ They also suggest this set of factors affecting
perceptual and motor performance:
◼ Fatigue and sleep deprivation
◼ Perceptual (mental) load
◼ Fear, anxiety, mood, and emotion
Know The Users (cont…)
30
◼ Personality differences & Gender differences
◼ There is no set taxonomy for identifying user
personality types
◼ Two Fatal Mistakes for Designers:
✓ Assume all users are alike
✓ Assume all users are like the designer
Know The Users (cont…)
31
◼ No clear patterns have emerged
◼ Games
◼ Tend to be aimed at young males
◼ Highest demographic of online players older women
▪ Productivity tools
▪ Largely male designers
▪ Poor UI choices (KILL a process)
Know The Users (cont…)
32
▪ Cultural and international diversity
▪ Left-to-right versus right-to-left versus vertical input and
reading
▪ Date and time formats
▪ Numeric and currency formats
▪ Names
▪ Capitalization and punctuation
▪ Icons, buttons, colors
Know The Users (cont…)
33
◼ Users with disabilities
◼ Designers must plan early to accommodate users
with disabilities
◼ Early planning is more cost efficient than adding on
later
◼ Temporary disabilities (glasses, loud environments)
Know The Users (cont…)
34
◼ Elderly Users
◼ Including the elderly is fairly ease, designers should
allow for variability within their applications via
settings for sound, color, brightness, font sizes, etc.
Know The Users (cont…)
35
◼ Knowledge & skills
◼ The Beginner
◼ Just starting out, possibly not very technical
◼ Will need lots of hand-holding, at least to start
Know The Users (cont…)
36
◼ The Casual User
◼ Uses the system infrequently
◼ Uses short-cuts, occasionally needs help
About 8% of men have color blindness of some type,
and about 0.5% of women
Designing for Hardware Diversity
37
◼ Display technology runs a large range from large to
small, high/low resolutions
◼ Discuss Effectiveness, efficiency and satisfaction:
◼ Are all of these equally important?
◼ All the time?
Summary
38
HCI is an interdisciplinary field in which computer
scientists, engineers, psychologists, social scientists, and
design professionals play important roles.
The goal of HCI is to solve real problems in the design and
use of technology, making computer-based systems easier to
use and more effective for people and organizations.
Summary (cont…)
39
▪ Ease of use and effectiveness are critical to the success of
any systems that interact with people, including software
systems, home, office and factory appliances, and web and
phone applications.
Department of Computer Science
Human Computer Interaction
Ended!
Chapter One
2024/25 G.C
