HCI_usable_user_interface_productivity in HCI

© Dr. Khalid Nazim S.A. B.E., M. Tech, MBA[IT], PhD, LMISTE, LMCSI, MIE
Assistant Professor,
Department of Computer Science & Information,
Majmaah University, Az- Zulfi Campus, KSA.
CSI 522: Human Computer Interaction
© 2017 Dr. Khalid Nazim Abdul Sattar

Chapter Objectives
 To maximize the benefit of one good idea by repeating its
benefit in many other designs.
 To understand the primary objective of an interactive
system to achieve particular goals in some application
domain.

It doesn’t have to be that way
You can design user interfaces that
Are pleasant and convenient for your users
Let them accomplish their goals
The key: think about your users
Learn about them
Watch them work, in their workplace
Interview them, also in their workplace

Benefits of Usable User Interfaces
 Gaining a competitive edge
 Reducing development and maintenance costs
 Improving productivity
 Lowering support costs

Reducing development
and maintenance costs
Learn about users first, and you will avoid
1. Implementing features users don’t want
2. Creating features that are annoying or inefficient
3. High cost of making changes late in the development
cycle

Improving productivity
Productivity means employees become more
efficient because the system supports their
tasks in an easy way.

Goals of HCI
To develop or improve the
 Safety
 Utility
 Effectiveness
 Efficiency
 Usability
 Appeal
. . . of systems that include computers

Safety
 Safety of Users—think of
 Air traffic control
 Hospital intensive care
 Safety of Data—think of
 Protection of files from tampering
 Privacy and security

Utility and effectiveness
Utility: what services a system provides
e.g. Ability to print documents
Effectiveness: user’s ability to achieve goals, e.g.
1. How to enter the desired information
2. How to print a report
Utility and effectiveness are distinct
A system might provide all necessary services, but if users
can’t find the services items, the system lacks effectiveness

Efficiency
A measure of how quickly users can
accomplish their goals or finish their work
using the system.

Usability
Definitions
1. “a measure of the ease with which a system can
be learned and used, its safety, effectiveness
and efficiency, and attitude of its users towards
it” (Preece et al., 1994)
2. “the extent to which a product can be used by
specified users to achieve specified goals with
effectiveness, efficiency and satisfaction in a
specified context of use” (ISO 9241-11)

Usability
1. Ease of learning !
2. Ease of use !
3. Appeal/ attitude !
1. How well users like the system
2. First impressions
3. Long-term satisfaction

? How can we measure usability?
? How can we develop a system to ensure usability?
 Paradigms
Usually based on new technology
E.g. WIMP interface
 Principles
Independent of technology
Usability

Principles to support usability
Learnability
 The ease with which new users can use the
system effectively.
Flexibility
The multiplicity of ways the user and the system exchange information.
Effectiveness
 the level of support provided to the user to achieve
successfully its goals.

User-Centered Development Methodology
1. Traditional software engineering methods
arose in 1960s and 1970s
a. Systems were not highly interactive
b. End-user were computer specialists
c. Issues concerning end-user and
usability were not at all important
d. user interface design not considered
explicitly
2. Now:
a. Most end-users are not computer
specialists
b. Usability vital for success

1. Traditional System-Centered design:
a. Emphasis on the functionality,
b. UI is added at the end
c. Emphasis on correct software rather than on ease of use
d. User has to adapt himself to the system
2. Things are changing: User-Centered design
a. UI more important
b. Emphasis on end-users’ tasks,
c. Early end-user participation: in analysis and design
d. Evaluation by end-users
e. Consequences:
a. more work for UI-designer and UI-programmer

Fields of HCI

Usability Paradigms and Principles
1. Designing for maximum usability is
the goal of design.
2. History of interactive system design
provides paradigms for usable designs.
3. Principles of usability are more
general means of understanding
usability.

Introduction
Concerns:
?How can an interactive system be developed to
ensure its usability?
?How can the usability of an interactive system be
demonstrated or measured?
Approaches:
a.Paradigms for usability:
examples of successful interactive techniques
a.Principles for usability:
theoretically driven from psychological,
computational and sociological knowledge.

Paradigms for usability
Historical perspective on interactive system design
1. Time-sharing
40s and 50s – explosive technological growth
60s – need to channel the power
J.C.R. Licklider at ARPA
single computer supporting multiple users

2. Video Display Units
a. more suitable medium than paper
b. 1962 – Sutherland's Sketchpad
c. computers for visualizing and manipulating data
d. one person's contribution could drastically change the history
of computing
Paradigms

3. Programming toolkits
a.Engelbart at Stanford Research Institute
b.1963 – augmenting man's intellect
c.1968 NLS/Augment system demonstration
d.the right programming toolkit provides
building blocks to producing complex
interactive systems
Paradigms

4. Personal computing
a.70s – Papert's LOGO language for simple
graphics programming by children
b.A system is more powerful as it becomes
easier to user
c.Future of computing in small, powerful
machines dedicated to the individual
d.Kay at Xerox PARC – the Dynabook as
the ultimate personal computer
Paradigms

5. Window systems and the WIMP interface
a.humans can pursue more than one task at a time
b.windows used for dialogue partitioning, to "change the topic“
c.1981 – Xerox Star first commercial windowing system
d.windows, icons, menus and pointers now familiar interaction
mechanisms
Paradigms

6. Direct manipulation
a.1982 – Shneiderman describes appeal
of graphically-based interaction
b.visibility of objects
c.incremental action and rapid feedback
d.reversibility encourages exploration
e.syntactic correctness of all actions
f.replace language with action
g.1984 – Apple Macintosh
h.the model-world metaphor
i.What You See Is What You Get
(WYSIWYG)
Paradigms

7. Language versus Action
a.actions do not always speak louder than words
b.DM – interface replaces underlying system
c.language paradigm
d.interface as mediator
e.interface acts as intelligent agent
f.programming by example is both action and
language
Paradigms

8. Hypertext
a.1945 – Vannevar Bush and the memex
b.key to success in managing explosion of
information
c.mid 60s – Nelson describes hypertext as
non-linear browsing structure
d.hypermedia and multimedia
e.Nelson's Xanadu project still a dream today
Paradigms

relating computing to other real-world activity is
effective teaching technique.
a.LOGO's turtle dragging its tail
b.file management on an office desktop
c.word processing as typing
d.financial analysis on spreadsheets
e.virtual reality – user inside the metaphor
Problems:
some tasks do not fit into a given metaphor
cultural bias.
The Metaphor

 Multimodality
1. a mode is a human communication channel
2. emphasis on simultaneous use of multiple channels for input
and output
 Computer Supported Cooperative Work
1. CSCW removes bias of single user/single computer system
2. Can no longer neglect the social aspects
3. Electronic mail is most prominent success

Principles to Support Usability
A structured presentation of general principles to apply during design of an
interactive system.
1. Learnability
the ease with which new users can begin effective interaction and achieve
maximal performance
2. Flexibility
the multiplicity of ways the user and system exchange information
3. Robustness
the level of support provided the user in determining successful achievement and
assessment of goal-directed behaviour

Principles of learnability
1. Predictability
determining effect of future actions based on past interaction history
operation visibility
2. Synthesizability
assessing the effect of past actions
immediate vs. eventual honesty
3. Familiarity
how prior knowledge applies to new system
guessability; affordance
4. Generalizability
extending specific interaction knowledge to new situations
5. Consistency
likeness in input/output behaviour arising from similar situations or task
objectives

Principles of flexibility
1. Dialogue initiative
freedom from system imposed constraints on input dialogue
system vs. user pre-emptiveness
2. Multithreading
ability of system to support user interaction for more than one task at a time
concurrent vs. interleaving; multimodality
3. Task migratability
passing responsibility for task execution between user and system
4. Substitutivity
allowing equivalent values of input and output to be substituted for each other
representation multiplicity; equal opportunity
5. Customizability
modifiability of the user interface by user (adaptability) or system (adaptivity)

Principles of Robustness
1. Observability
ability of user to evaluate the internal state of the system from its perceivable
representation
browsability; defaults; reachability; persistence; operation visibility
2. Recoverability
ability of user to take corrective action once an error has been recognized
reachability; forward/backward recovery; commensurate effort
3. Responsiveness
how the user perceives the rate of communication with the system stability
4. Task conformance
degree to which system services support all of the user's tasks
task completeness; task adequacy

Summary
Paradigms for usability:
the history of computing contains examples of creative insight that enhanced
interaction
Principles for usability:
repeatable design for usability relies on maximizing benefit of one good design
by abstracting out the general properties which can direct purposeful design
The success of designing for usability requires both creative insight (new
paradigms) and purposeful principled practice

HCI_usable_user_interface_productivity in HCI

More Related Content

Similar to HCI_usable_user_interface_productivity in HCI (20)

More from nazimsattar (20)

Recently uploaded (20)

HCI_usable_user_interface_productivity in HCI