Human-Computer Interaction
Introduction
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Human-Computer Interaction:
Aims
• Knowledge of HCI
• Some practical analysis and design
skills
• Practical implementation of GUIs
• Enable you to assess how HCI may be
incorporated into software lifecycle
• Personal transferable skills
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Lecture Overview
• Background and aims of HCI
• Usability
• Rise in importance of
• Interactive Systems
• Graphical User Interface (GUI)
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Human Computer Interaction - HCI
Association for Computing Machinery (ACM)
defines human-computer interaction as
"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.”
Goal of HCI
Basic goal of HCI is to improve interactions
between users and computers by making
computers more usable and receptive to user's
needs. Specifically, HCI is concerned with:
• methodologies and processes for designing interfaces
(i.e., given a task and a class of users, design best
possible interface within given constraints, optimising for
a desired property such as learnability or efficiency of
use)
• methods for implementing interfaces (e.g. software
toolkits and libraries; efficient algorithms)
• techniques for evaluating and comparing interfaces
• developing new interfaces and interaction techniques
• developing descriptive and predictive models and
theories of interaction
Course Outline:
HCI and the Software Lifecycle
User object modelling
System design spec. (inc. Interface design spec.)
User’s conceptual model design / Interaction style
Interaction design / Presentation design
Design
U s e r P a r t i ci p a t i o n
Requirements spec. (inc. usability specs.)
Analysis
Systems Analysis (inc. user and task analysis)
Definition
Problem statement
Prototype (inc. online help)
Evaluation (Analytical, Empirical)
Implementation
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The Parts of User Interface Development
Development of the User Interface
Behavioural
Constructional
Development of
the interaction
component
Development of
the interface
software
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Disciplines
Contributing
to Human
Computer
Interaction
Computer
Science
Artificial
Intelligence
Sociology
Cognitive
Psychology
Human
Computer
Interaction
Graphic
Design
Ergonomics and
Human Factors
Central Aim and Approach of HCI
Aim: To optimise performance of human
and computer together as a
system
Approach: User-Centred
• Users should not have to adapt to the
interface: the interface should be intuitive
and natural for them to learn and to use.
• “Talking to users is not a luxury, it’s a
necessity”
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User Centred Design
Work
People
Technology
Environment
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User Centred Design
• User-Centred Design (UCD) or Pervasive Usability is a
design philosophy and a process in which needs,
wants, and limitations of end users of a product are
given extensive attention at each stage of design
process.
• UCD can be characterized as multi-stage problem
solving process that not only requires designers to
analyse and foresee how users are likely to use a
product, but also to test the validity of their
assumptions with regards to user behaviour in real
world tests with actual users.
• Chief difference from other product design
philosophies is that UCD tries to optimise the product
around how users can, want, or need to use the
product, rather than forcing the users to change their
behaviour to accommodate the product.
User Centred Design Principles
• Early focus on users and tasks
• Structured and systematic information gathering
(consistent across the board)
• Designers trained by experts before conducting data
collection sessions
• Empirical Measurement and testing of
product usage
• Focus on ease of learning and ease of use
• Testing of prototypes with actual users
• Iterative Design
• Product designed, modified and tested repeatedly.
• Allow for the complete overhaul and rethinking of design
by early testing of conceptual models and design ideas.
Software Quality (ISO 9126)
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Functionality
Reliability
Usability
Efficiency
Maintainability
Portability
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Requirements Gathering
User Requirements
Functional
Data
Usability
Learnability
Throughput
Flexibility
Attitude
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Usability
Bailey’s Human Performance Model
Usability
For specified user and specified task
• Learnability
• Ease of learning
• User retention over time
• Throughput • High speed of user task performance
• Low user error rate
• Flexibility
• Freedom of object / action selection
• User expertise levels
• Attitude - subjective user satisfaction
Usability Testing
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Participatory Design
Paper Prototyping / Storyboarding
Cognitive Walkthroughs
Usability Testing
Heuristic Evaluation
Usability Testing
Focus Groups
Participatory Design
Surveys
Heuristic Evaluation
Set Benchmarks
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Usability Testing
Heuristic
Evaluation
Follow-up Studies
Compare To
Benchmarks
Source: Based Upon Rubin, et al. “Handbook of Usability Testing: How to Plan, Design, and Conduct Effective Tests”
When It Goes Wrong
Rubin et. al. * have identified five reasons
why products, especially technology
focused ones, are typically hard to use.
These are:
• Focus on the device or system during
development
• Changing and adapting target
audience
• Trivialising designing usable products
• Non-integrated working of specialist
teams both internally and with each
other
• Design and implementation does not
always match.
* “Handbook of Usability Testing: How to Plan, Design, and Conduct Effective Tests ”
by Rubin, Chisnell and Spool
Microsoft and Quicken
• 1995 - Microsoft tries to purchase Quicken
from Intuit for $1.5 billion
• Reason for attempted purchase: Quicken
more usable than Microsoft’s own product
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Mitchell Kapor (Designer of Lotus 1-2-3)
Quotes from A software Design Manifesto 1990
“The lack of usability in software and the poor design
of programs are the secret shame of the software
industry.”
“One of the main reasons most computer software is
so abysmal is that it’s not designed at all, but merely
engineered….”
“... implementors often place more emphasis on a
program’s internal construction than on its external
design.”
(Reprinted in ‘Bringing Design to Software’, T. Winograd, 1996, Addison
Wesley)
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Usability
Transparency
Relationship between
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•
•
user’s goals
required actions
results
must be meaningful,
not arbitrary
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Problems with ATMs
• Older people make much less use of ATMs
• 24 year olds : average 7 visits to an ATM per month
• Use drops off among those over 45
• 65+ years : two-thirds NEVER use an ATM
• Senior citizens often put off by ATMs because
they find the machines complicated,
inconvenient and intimidating.
• Buttons that didn’t line up with commands
• Dimly lit screens hard to read in the glare of
daylight
• Sometimes confusing menu choices
Source: http://cnn.com/TECH/9712/04/t_t/atms.seniors/index.html
Reporting on research by W. Rogers and A. Fisk, Georgia Institute of Technology
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Problems with ATMs (Continued)
• Researchers and banks expected ATMs to be
intuitively easy to use
• Testing among senior citizens found only 20
percent correct operation
• For example, one man tried to withdraw $30. He entered
the amount he wanted incorrectly because the directions
-- calling for "multiples of 10" -- confused him
• Usability suggestions:
• Simpler on-screen instructions
• More "undo" buttons
• Banks should provide training for any customers who
need it
• A "large percentage" of people they surveyed said
they would use ATMs if trained
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Example:
Lack of
Transparency
Old UU phones:
Call Diversion Instructions
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Poor interface may cause:
• Increased mistakes in data entry and system
operation
• Inaccessible functionality
• User frustration: low productivity and/or
under utilisation
• System failure because of user rejection
Nearly half of entire software development
effort relates to the user interface.
(Myers and Rosson, 1992)
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Rise in Importance of Usability
Research machines
1950s
Mathematicians
Scientists
Machine reliability
users do programming
Mainframes
1960’s
&
1970’s
Data-processing
professionals
Users of output (business
managers) grow
disenchanted with delays,
costs and lack of flexibility
Minicomputers
1970’s
Engineering and
other non-computer
professionals
Users must still do must
programming; usability
becomes a problem
Microcomputers
1980’s
Almost anyone
Usability is the major
problem
Shackle, 1991
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ENIAC 1943: Research Machine
(U.S. Army Photo)
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IBM Mainframe 1960s
(Photograph courtesy of the IBM archives)
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Minicomputers: 1970s and
1980s
U.S. Army Photograph, courtesy of Michael John Muuss,
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Microcomputers: 1970s - 1990s
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Desktop & Multimedia Internet Ready PCs
Towards Pervasive / Ubiquitous Computing:
2005 - . . .
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The Leading Trend in Software
“Rise of GUI. The
pervasiveness of graphical
user interfaces is a clear sign
that all software of the future
must address the users’
needs for ease of use.”
IEEE Software, Nov 1990
A very rich
design medium
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Browser the ‘New’ Graphical
User Interface
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Windows 8 – Pervasive
Computing But Less Control
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Benefits of GUIs over Text
Interfaces
• User completes tasks faster
• Lower frustration e.g.
• Less ‘modal’ operation
• Easy interleaving tasks
• Perceived lower fatigue
• Better able to self-teach - Reduced
training costs
• Better able to learn more capabilities of
applications
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Recommended Further Reading
Recommended Further Reading
© Gary Larson
Recommended Further Reading
Advanced Common Sense SM http://www.sensible.com
Lecture Review
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HCI and other subject areas
User-centred
Usability
Faster CPUs / bigger disks support
highly interactive systems
• Interactive systems pervasive
• Benefits of GUIs
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