Title: An Introduction to
1An Introduction to
Interaction Design
- Guohua Bai (Ph.D)
- Kalmar University
- Department of Technology
- 391 82 Kalmar
- gba_at_bth.se
- 46 733 967108
2The goals of the course
- The objective of the program to provide students
with knowledge, methods, and skills in creation,
design, and management of digital interactive
products for applications in social services,
business management, home, work environment, and
industries. - The goals of this course are
- Practical issues to Interaction Design Program
- Knowledge about the subject of different kinds of
interactive systems and general development
process - General Knowledge about human cognitive
behaviours such as social ability (team work),
memory, problem resolving, learning, decision
making, perception, visualisation, etc . - Introduction to task analysis, evaluation, and
methodologies of interaction design
3Contents
- The course comprises Introduction of the program,
theoretical lecturing, study visiting, and
practices within the area of interactive system
design. Introduction part will provide students
with specific knowledge about the overall
education program of interaction design. The
theoretical part is aiming at providing students
general knowledge about the subject of
interactive design. Through study visits students
will experience different kinds of practical
design problems as background for future study.
4Teaching, Examination
- Teaching
- The method of instruction is lectures, seminars
and compulsory practical assignments. - Examination
- Assessment of the student achievement is normally
made with the aid of a written and/or oral
examination, as well as presentation (least 80)
of compulsory assignments on either individual or
group basis. The following grades are awarded
Pass, or Fail. - Compulsory Moments
- (1) lectures and visits 1P (2) Theoritical
examination1P (3) project report 1P (4) Seminar1P
(5) Oral presentation technique 1P
5Literature
- Newman W. M. Michael G. L. (1995) Interactive
System Design, Addison-Wesley Pub.ltd. ISBN
0-201-63162-8 - Preece J (2002) Interaction design-beyond
human-computer interaction,John Wiley Son,ISBN
0-471-49278-7 - http//www.interaction-design.org/
- http//www2.iicm.edu/hci
6Lab. Task
1. Decide your acting role in the experiment
(designer,end-user, or project leader) 2. Find
your partners to form a group (each group should
be no more than two designers, two users, and one
project leader) 3. The user(s) in the group must
have a task to be supported by computer
system. 4. The designer(s) must be able to find a
quick prototyping tool (e.g., Visual Basic, C,
Progress, Excel) which can be used during the
prototyping process. (Cont.)
7Lab. Work (cont.)
5. Work in group to identify functional
requirements, interface design, etc. Documenting
all your communication (as a project diary). 6.
In the end of the course you have to analyze your
design process (via project diary) and write a
report (no less than 1500 words about the
reflection of the process). 7. On 22/09 and
23/09, each group will dispute (oral
presentation) your prototype (20 min. can be on
overhead projector or on computer demo.) to all
participants, and meanwhile acts as another
groups opponent (you have to read their report
first, and prepare at least three questions).
8Other Courses You Will Study
- Interaction Design 5p
- User Interface Design 5p
- User study for Interactive Systems Design 5p
- Research Methodology 5p
- Project work 5 p
- Thesis Work 10p
9What is Interaction Design?
- Desinging interactive products to support people
in their everyday and work lives. - The design of sapces for human communication and
interaction (interaction design is not software
design, just like architects is not a civil
engineer)
10Activities and technologies.
11Interaction Design and its Concerns
- The problem of objective (usability and context
of work) - The problem of development process (design
methodology) - The problem of human and computer (man-machine
fit)
Work and context
Organisational design Social ethical aspects
Work structure Task analysis
Human
Computer
Cognitive processes Communication Learning Ergonom
ics
Interface design Input and output
devices Dialogue Processing
Life-cycle design method Prototyping Participatory
design
Evaluation Usability test Implementation
Development Design
12Activities in interactive systems design
13Characteristics of Interaction Design
- Multidisciplinary knowledge (computer sciences,
psychology, ergonomics, arts, sociology, design) - Integrity of theories, methodologies, skills, and
experiences. - Multidisciplinary team work (computer supported
cooperative work, CSCW)
14Related studies
Systems Design
Cognitive Psychology
Ergonomics and Human Factors
Artificial Intelligence
Interaction Design
Linguistics
Computer Engineering
Social
Organizational Psychology
Philosophy
Sociology
15Normans Interaction Model
Goals
Expectation
Intention
Evaluation
Action Specification
Interpretation
Execution
Perception
Mental Activity
- Home work (1)
- Preeces book Chapter 1, ch.2
- Newmans book Ch.1
- Search Web by interaction design
Physical Activity
Seven-stage model of (individual) interaction,
from Norman (1986)
16Types of Interactive Systems and Design Focuses
- 1. Life-critical systems
- Examples control of air traffic, nuclear
reactor, power utilities, police or fire
dispatch, military operation, and medical
instruments - Characteristics High cost, high reliability and
efficiency, error free operation, long time
training. Subjective satisfaction is not
important. Retention is obtained by frequent use
of common function.
17- 2. Industrial and commercial uses
- Examples banking, insurance, order entry,
inventory management, airline and hotel
reservations, car rentals, credit card
management, point-of -sales terminals - Characteristics Cost must be in balance with
reliability, speed of performance, and error
rate high cost for training personals, so easy
of learning is important subjective satisfaction
is modest importance retention is obtained by
frequent use
18- 3. Office, home, and entertainment
- Examples word processing, automated transaction
machines, video games, education packages,
information retrieval, e-mail, tel-conference. - Characteristics Must be easy to learn, low error
rates subjective satisfaction is very important.
19- 4. Explorative, strategic, creative, and
co-operative systems - Example Business decision making, architecture
design, CSCW, artist program and music
composition - Characteristics Users are knowledgeable in task,
but novice in computer, high motivation and high
expectation, difficult to design, must be easy to
use, e.g., provide direct manipulation of objects
represented of their real world task. Trial-and
-error learning, participatory design.
20Understanding Users - Cognitive Theory and
Application
21Why do we need to understand users?
- Interacting with technology is cognitive
- We need to take into account cognitive processes
involved and cognitive limitations of users - We can provide knowledge about what users can and
cannot be expected to do - Identify and explain the nature and causes of
problems users encounter - Supply theories, modelling tools, guidance and
methods that can lead to the design of better
interactive products
22Cognitive Human
- The man in the computer - a standard figure
- The man in the reality of work - motive to
operation
Why ?
Activity
Motive
What
Goal
Action
Operation
Condition
How
23Attention
- Selecting things to concentrate on from the mass
around us, at a point in time - Focussed and divided attention enables us to be
selective in terms of the mass of competing
stimuli but limits our ability to keep track of
all events - Information at the interface should be structured
to capture users attention, e.g. use perceptual
boundaries (windows), colour, reverse video,
sound and flashing lights
24Human Memory
LTM
STM
SIB
- Long-term
- memory
- (Knowledge, mental model,
- experiences in
- episodic and
- semantic forms)
Visual Auditory Haptic Taste Smell
Short-term memory Working memory
Environment input
Control Processes Rehearsal coding Decisions Retri
val Strategies
Response Output
25Short-term Memory
- Short-term memory is the memory of the present,
used as working or temporary memory. - Information is retained in STM automatically and
is retrieved without effort. - However, the amount of information in STM is
severely limited 7 ?2 items. - STM is extremely fragile - the slightest
distraction and its contents are gone. For
example, STM can hold a seven digit phone number
from the time you look it up until the time you
use it, as long as no distractions occur.
26Long Term Memory (LTM)
- Long-term memory is the memory of permanent
knowledge, experience. - It takes time to put stuff into LTM and time and
effort to get stuff out. - Capacity is estimated at about 100 million items.
27Learning vs. Efficiency
28Forms of Representation
- Prepositional (linguistic), Pictorial, and
Auditory
Pictorial
Prepositional She is talking.
1 No discrete symbols 2 Implicit, no separate
symbol for relation 3 No clear rules of
combination or symbol types 4 Concrete
1 Discrete symbols 2 Explicit, needs symbol for
relation 3 Grammatical, clear rules of
combination for types of symbol 4 Abstract
29Types of Knowledge
- Experience (learning by doing, prototyping)
- Production rule (If . Then )
- Distributed network
- Recall and recognition
- Context
30Knowledge in the Head and in the World
- Not all of the knowledge required for precise
behaviour has to be in the head. It can be
distributed - partly in the head (memorise code)
- partly in the world (e.g., default input)
- and partly in the constraints of the world
(e.g, inactive fields to omit input).
31- Semantic and episodic knowledge
- Semantic knowledge mostly are in form of
concept, general fact, statement,
judgement. - Episodic knowledge's mostly are in form of
personal experience, time and location
specified. - Relationship (Vygovtskys theory)
- semantic network with nodes for various concepts
and links activation.
Nation
pencil
Cat
o.5
0.1
Europa
Dog
0.3
Fish
Frankrike
Italien
Marseille
Paris
Rom
Milano
huvudstad
32Communication (1)
- Communication means exchange of information
between system and environment, within the system
in order to control the systems function with
respect to change of environment (by way of
feedback.) (Winner). - Any viable system includes communication
channels to knit the entire system together into
one coherent whole and to ensure that the
sub-units are working together appropriately and
contributing to the objectives of the whole.
33Communication (2)
- The ultimate significance of communication is
that it serves to bind societies together, "World
State. - Communication is a key point to understand
processes of humans perception, attention,
memory, language, learning, problem solving, and
decision making. - Shannons Communication model (syntactic and
technical problem of communication).
34Face-to-face communication
HCI - Support communication
35A Mental Model of Communication
36- Task and Context Analysis
- Task Analysis
- Context Analysis
37 Task Analysis
- A task is a human activity designed to achieve
some goals, e.g., Checking credit, checking
order, shipping product, etc. - The output of task analysis is a hierarchical
task model (general structure), and a task
scenarios (Concrete case) . - The Input of task analysis can be Observation of
users at work, Interview or workshop, analysis of
business documents, analysis of proposed system.
38Process of Task Analysis
- 1. Identify Tasks Observation, interview,
analysis documents and business activities - 2. Select task scenarios sample from real
representative business process. - 3. Analyse and model tasks by GOMS model, HTA.
- 4. Describe task context work environment,
social/interpersonal task context, constraints or
pressure, errors made, organisation types
(dynamic, stable, market, production, services.. - 5. Identify subtasks requiring computer support
manual(Unstructured task), interaction(semi-struct
ured tasks), automatic (well structured). Also
consider what is the benefit for using computer,
and cost/benefit analysis. - 6. Express scenarios as actions on user objects
what concrete objects involved, attributes used,
relation types. - 7. Validate task model and scenarios task
performers check, observing other scenarios, ask
managers, and other operators. - Sources Redmond-Pyle, D. (1995) Graphical User
Interface Design and Evaluation, Prentice Hall,
London.
39Example of a Task Analysis
- Identified Task
- Help desk for customers query of booking train
tickets
40Identify tasks
- Resolve customer query identify the customer,
listen to their query, attempt to resolve it and
record details of the query - Provide query status
- Reproduce the problem
- Update known problem
- Provide customer information
- Provide problem information
- Monitor advisor workload
- Monitor unresolved queries
- Sources Redmond-Pyle, D. (1995) Graphical User
Interface Design and Evaluation, Prentice Hall,
London.
41Select task scenarios
- Scenario 1 resolve by using system support
- Scenario 2 need further information
- Scenario 3 resolve without system support
42 Task Scenarios
- A task scenario is an example of a task. It must
be representative, realistic, usable for HCI
design, consistent with task model. - Example of task scenario (book a train ticket)
- Operator answer phone
- Customer Id like three tickets to Stockholm on
4th April - Operator checks train departure list, note time
- Operator We have three tickets to Stockholm on
4th April, time 1000 am. Price 600 Kr/ per. - CustomerOk, we take it
- Operator How do you pay?
- CustomerVisa
- Operator put into list, ..
43 Task Model
Hierarchic Task Description (Buy a train ticket)
A hierarchic Diagram
(Buy a train ticket)
- 1. Find time of next train
- 1.1 study list of train departures
- 1.2 mentally note time and platform number of
next train - 2 Purchase ticket
- 2.1 stand in line at ticket counter
- 2.2 on reaching counter, state destination and
journey type - 2.3 receive quote for price of ticket
- 2.4 pay money
- 2.5 receive ticket and change
Find time of train
Study list
Note time
Purchase ticket
pay money
stand in line
state destination
get quote
receive ticket
44Goals, Operators, Methods and Selection Rules (P.
Johnson)
- Goals Symbolic structure that define a state of
affairs to be achieved and determine a set of
possible methods by which it may be accomplished. - Operators theses are elementary perceptual,
motor or cognitive acts whose execution is
necessary to change any aspects of the users
mental state or to affect the task environment
- Methods methods are descriptions of procedures
for achieving goals. They are conditional
sequences of goals and operators. - Selection Rules There are may be more than one
method for achieving a give goal. The selection
rules handle the process of choosing between
methods, in the form of IF X THAN M.
45 More to consider in task analysis
- Chose a scenario which frequently happen, time
critical, user errors significant (dangerous,
expensive, often) - Enrich the task model by asking
- what happens if
- some input info. is missing or incorrect?
- Someone else has borrowed the folder?
- Interruption from other urgent task?
- the users make an error?
- Subdivide task properly in details (logical
action level, not on computer system)
46Analyses and Model Tasks
Goal Customer satisfied Volume 60 per day Est.
Time 5-30 min. errors 1 in 20
0.
Resolve customer query
1.
2.
3.
4.
Identify customer
Identify problem
Advise customer
Log query
4.1
4.2
4.4
Set responsibility and action date
1.1
1.2
4.3
Associate query to problem
Record query info.
1.3
Identify customer organisation
Identify customer contact
Set status and priority
Check on maintenance
(Context information here)
47Describe Task Context and Identify Subtasks
Requiring Computer Support
Goal Customer satisfied Volume 60 per day Est.
Time 5-30 min. errors 1 in 20
0.
Resolve customer query
1.
2.
3.
4.
Identify customer
Identify problem
Advise customer
Log query
4.1
4.2
4.4
Set responsibility and action date
1.1
1.2
4.3
Associate query to problem
Record query info.
1.3
Identify customer organisation
Identify customer contact
Set status and priority
Check on maintenance
48Express Scenarios as Actions on Users Objects and
Valid Task Model and Scenarios
- Excise to identify objects based on the script of
scenarios. - Build up object model and relationship
- (ref.. object modelling)
49Context of Work
To understand anything, you need a model, not
just of the thing itself, but of the context in
which it operates.
What is this ?
and that?
50Context tells you what it is!
51The Organisational Aspects
- The Nature of Organisations
- People, technology, work, culture.
- The impact of Information Technology on
Organisation - Two lists of advantages and dis-advantages of
computerisation. - Methods for Organisational Analysis
- Scientific management (Taylor, 1911) Division of
labour, training unskilled workers, monitoring
working load. - Sociotechnical Systems Approach
- Activity Theory
- Ethnomethodology (details of work with
technology, social practices, participation,
evaluation of use technology) - CSCW and Organisational Consideration
- Source Preece J. (1994) Human Computer
Interaction, Addison-wesley, New York.
52Scientific Management
- Separation of planning and working
- Choose the best person for the job that have been
planned and designed - Determine how a task can be performed the most
efficiently - Train the workers
- Determine the best form of reward for the
different task - Monitor worker performance to ensure that the
prescribed methods are followed and the set goals
achieved
53The Sociotechnical Approach
- Step 1 Initial scanning briefing
- Step 2 Identification of unit operations
- Step 3 Identification of variances
- Step 4 Analysis of the social system
- Step 5 Workers perception of their roles
- Step 6 The maintenance systems
- Step 7 The supply and user systems
- Step 8 The corporate environment and development
plans - Step 9 Proposals for change
- (Source Mumford (1987) Sociotechnical system
design evolving theory and practice. In
computers and democracy, Bjerknes G., Ehn P. And
Kyng M., eds., pp. 59-77, Aldershot Avebury)
54Methodologies for Interactive System Design
- Why Important
- Difficult and Expensive, more than 75 work,
involves study of psychology, communication, task
analysis, etc. - Methodologies to Design
- Waterfall model and
- Prototyping Approach
- Participatory Design
55Introduction Who and what are involved in the
design
Tools User-Centred Design Methods Guideline Evalua
tion methods Software Tools Principles Prototyping
tools Experimentation Creative ideas
HCI Design Expertise
Design Team Managers System analysts Software
engineers programmers Graphic designers others
User Group
The product
Training
The design process
Application
Implementation
Hardware
In-house HCI group
Organization managers End user
Documentation
HCI Consultants
Software
Ergonomist expert
56Perspectives on Interface Design
- Design of Interface must consider
- 1 Functional Perspective Concerned with whether
or not the design is serviceable for its intended
purpose. - 2 Aesthetic perspective Concerned with whether
or not the design is pleasing in its appearance
and artistic design - 3 Structural Perspective the structure is
adaptive and currently useful
57Software Engineering Methods
- Software Engineering
- The development and use of principles, methods
and tools to design and develop, economically and
optimally, software systems that are
aesthetically pleasing, efficient, reliable and
usable for the purposes for which they were
designed. - Principles Include principles of usability,
design and construction, They should lead to the
formulation of criteria by which the quality of
the design can be tested. - Methods provide the process model for software
development - Tools languages, notations, semi-libraries and
toolkits.
58 Lifecycle or Waterfall Approach
59 Prototyping Approach
- Introduction
- The use of experimenting with prototypes has
become prominent due to a number of claimed
advantages in the case that users requirements
are difficult to specify. In principle users
should be highly motivated in acting since they
are provided with more chances to improve their
work, to verify if their needs are taken care of
and that the terms used in the interface,
functions of the designed system are consistent
with their work.
60- Participatory Design Approach
PD
The Scandinavian tradition of socio-technical
approach to the design of work and artefacts
61Usability Engineering
62Defining Usability
63- Usability Design Principles
- What are principles
- They apply to any user interface, more or less
independently of the supported activity, the
user, and the form of solution. - Why do we need Principles
- Because of varieties of tasks and new technique,
designers constantly involve in unfamiliar design
problems. Principles can provide a source of help
by referencing of general principles which are
based upon cognitive theory.
64Principles for DesignThe Windows Interface-An
application design GuideMicrosoft Press,
Redmond, Washington, 1992
- User Control Be interactive quickly (see limits
on response time) and easily, easy in and easy
out Customisation, good default support task
(activity) performance (not how to use computer) - Directness Manipulating objects directly (not
e.g., to type command), e.g., re-size a window by
dragging not by co-ordinates in dialog box.
65Bad design Indirect operation
66Bad Design- Indirectness
67Principles for Design
- Consistency Consistency with the real world (see
Avoid Breaking a Metaphor) and consistency within
and among applications in using of concepts,
linguistic, visual, and function. (priority of
consistency within application, if there is
conflict between consistency among app. and
within app.) - Clarity simple metaphor, unambiguous terms,
transparent function, process display. - Aesthetics pleasing appearance
68Avoid Breaking a Metaphor
- As a means of deleting files and documents, the
Macintosh trashcan is a perfectly intuitive
metaphor. - Unfortunately, the designers decided to extend
the trashcan metaphor to include the completely
counterintuitive function of ejecting diskettes - Ejecting a diskette on the Mac.
69Affordness
- Affordness are the the perceived and actual
properties of an artefact, which determine how it
might possibly be used. - Appearance indicates how to use something
- A chair affords (suggests) sitting.
- Knobs are for turning.
- Slots are for inserting things.
- A button affords pushing.
- A menu affords choosing.
- When affordness are taken advantage of, the user
knows what to do just by looking. - When simple things need pictures, labels, or
instructions, the design has failed!
70Constraints
- The difficulty of dealing with a novel situation
is directly related to the number of
possibilities. - Constraints are physical, semantic, cultural, and
logical limits on the number of possibilities. - Physical constraints such as pegs and holes limit
possible operations. - Semantic constraints rely upon our knowledge of
the situation and of the world. - Cultural constraints rely upon accepted cultural
conventions. - Logical constraints exploit logical
relationships. For example a natural mapping
between the spatial layout of components and
their controls. - Where affordness suggest the range of
possibilities, constraints limit the number of
alternatives.
71Cultural Constraints
- Beware that cultural constraints can vary
enormously, for example - Light switches
- America down is off
- Britain down is on
- Water taps
- America anti-clockwise is on
- Britain anti-clockwise is off
- The colour red
- America danger
- Egypt death
- India life
- China happiness
72Bad design affordability vs. constrains?
73The PC Cup Holder - Example of affordness vs.
constrains
- A supposedly true story from a Novell NetWire
SysOp - Caller Hello, is this Tech Support?''
- Tech Rep Yes, it is. How may I help you?''
- Caller The cup holder on my PC is broken and
I am within my warranty period. How do I go about
getting that fixed?'' - Tech Rep I'm sorry, but did you say a cup
holder?'' - Caller Yes, it's attached to the front of my
computer.'' - Tech Rep Please excuse me if I seem a bit
stumped, it's because I am. Did you receive this
as part of a promotional, at a trade show? How
did you get this cup holder? Does it have any
trademark on it?'' - Caller It came with my computer, I don't
know anything about a promotional. It just has
'4X' on it.'' - At this point the Tech Rep had to mute the
caller, because he couldn't stand it. The caller
had been using the load drawer of the CD-ROM
drive as a cup holder, and snapped it off the
drive. - This story was found at Greenberg(1997) and is
attributed there to George Wagner
g.wagner_at_sylvania.sev.org.
74Principles for Design
- Feedback immediate feedback to users action
(e.g., dragging, typing, clicking, moving etc.)
by visual, auditory response (see limits on
responses times) - Forgiveness allow trial and error learning
(learning by doing), regret or undo function,
error messages - Awareness of human strengths and limitations
e.g., human perception, recall and recognition,
memory, reasoning,
75Bad design too much contents, colors, flash
76Bad design bad clarity too much content, colors,
text graphics
77Bad design Unnecessary and confusing functions
(content)
78Other Principles
- Allow quick way for experienced user (see curve
of learning) - Provide navigation support (home, back, bookmark,
etc.) - Special action should be noticed with special
sound, colour,blink. - Do not use more than four different kinds of
colour in your system. - Use colour as information (red warning, green
ok) - Use white-black interface first (colour later)
79Other Principles
- The user should be required to know as little as
possible to use the system - Non-thought disruptiveness (working memory
consistency, see limits on response time) - All error message should be helpful and fully
self-explanatory - The dialogue should never put the user in a
situation where he does not know what to do next - The most possible selection should be made of
default option.
80Other Principles
- Consider Organization dynamics
- By using menus, natural language, diagrams,
window system (icon, fields, mouse), touch
screen, and panels selection to avoid using
computer language - The dialogue should completely avoid forcing the
user to remember mnemonics or an alien syntax
(short term memory limitation)
81Other Principles
- Graphics techniques should be used as help to
clear thinking (e.g., to choose proper icon to
indicate function, consequence, action, etc.) - Self teaching and computer aided instruction
that can be invoked at any point during the
interaction.
82Bad Design Keeping Unnecessary Design Items
Spinning logos
3D graphics
Large graphics
Music
83Bad design Splash Pages
84Typical Ways of Measuring Usability
- Learnability pick novice users of system,
measure time to perform certain tasks.
Distinguish between no/some general computer
experience. - Efficiency decide definition of expertise, get
sample expert users (difficult), measure time to
perform typical tasks. - Memorability get sample casual users (away from
system for certain time), measure time to perform
typical tasks. - Errors count minor and catastrophic errors made
by users while performing some specified task. - Satisfaction ask users' subjective opinion
(questionnaire, interview), after trying system
for real task.
85Ten Usability Heuristics (1)
- Visibility of system status
- The system should always keep users informed
about what is going on, through appropriate
feedback within reasonable time. - Match between system and the real world
- The system should speak the users' language, with
words, phrases and concepts familiar to the user,
rather than system-oriented terms. Follow
real-world conventions, making information appear
in a natural and logical order. - User control and freedom
- Users often choose system functions by mistake
and will need a clearly marked "emergency exit"
to leave the unwanted state without having to go
through an extended dialogue. Support undo and
redo. - Consistency and standards
- Users should not have to wonder whether different
words, situations, or actions mean the same
thing. Follow platform conventions. - Error prevention
- Even better than good error messages is a careful
design which prevents a problem from occurring in
the first place.
86Ten Usability Heuristics (2)
- Recognition rather than recall
- Make objects, actions, and options visible. The
user should not have to remember information from
one part of the dialogue to another. Instructions
for use of the system should be visible or easily
retrievable whenever appropriate. - Flexibility and efficiency of use
- Accelerators -- unseen by the novice user -- may
often speed up the interaction for the expert
user such that the system can cater to both
inexperienced and experienced users. Allow users
to tailor frequent actions. - Aesthetic and minimalist design
- Dialogues should not contain information which is
irrelevant or rarely needed. Every extra unit of
information in a dialogue competes with the
relevant units of information and diminishes
their relative visibility. - Help users recognise, diagnose, and recover from
errors - Error messages should be expressed in plain
language (no codes), precisely indicate the
problem, and constructively suggest a solution. - Help and documentation
- Even though it is better if the system can be
used without documentation, it may be necessary
to provide help and documentation. Any such
information should be easy to search, focused on
the user's task, list concrete steps to be
carried out, and not be too large.
87Apple Mac UI Design Principles
- 1. Use of Metaphors
- 2. Aesthetic Integrity
- 3. Consistency
- 4. Perceived Stability
- 5. Direct Manipulation
- 6. See and Point
- 7. WYSIWYG
- 8. Feedback
- 9. Forgiveness
- 10. User Control
88Users and Designers Conceptual System
89Designers Centred Design
- The design is based upon
- What can be built easily on this platform?
- What can I create from the tools available?
- What do I as a developer find interesting to work
on?
90User Centred Design
- The design is based upon a user's
- abilities and needs
- context
- work
- tasks
91Usability Engineering Lifecycle
- 1. Know the User
- 2. Competitive Analysis
- 3. Set Usability Goals
- 4. Parallel Design
- 5. Participatory Design
- 6. Co-ordinated Design of Total Interface
- 7. Applying Guidelines
- 8. Prototyping
- 9. Usability Evaluation (Inspection and Testing)
- 10. Iterative Design
- 11. Follow-up Studies
921. Know the User
- Observe Users in Working Environment Site
visits, unobtrusive observation. Don't believe
their superiors! - Individual User Characteristics Classify users
by experience (see Figure), educational level,
age, amount of prior training, etc. - Task Analysis Users' overall goals, current
approach, model of task, prerequisite
information, exceptions to normal work flow. - Functional Analysis Functional reason for task
what really needs to be done, and what are merely
surface procedures? - Evolution of User and Task Users change as they
use system, then use system in new ways.
93Categories of User Experience
942. Competitive Analysis
- Competitive analysis of software components
- Use existing interface framework as far as
possible (Motif, MS-Windows, Java AWT) - saves a
lot of work. - Use existing components and applications rather
than re-inventing the wheel. - Competitive analysis of competing systems
- Analyse competing products heuristically or
empirically. - Intelligent borrowing'' of ideas from other
systems.
953. Set Usability Goals
- Decide in advance on usability metrics and
desired level of measured usability - Financial impact analysis - estimate savings
based on loaded cost of users, compared to cost
of usability effort.
964. Parallel Design
- Explore design alternatives - designers should
work independently, then compare draft designs
(see Figure). - Brainstorm with whole team (engineers, graphic
designer, writer, marketing types, usability
specialist, one or two representative users).
97Parallel Design
98How to Brainstorm
- Meet away from usual workplace (different
building, hut in the mountains). - Use plenty of paper. Cover the walls with it!
- Draw. Scribble. Use lots of coloured pens.
- Three rules during brainstorming
- 1. No one is allowed to criticise another's
ideas. - 2. Engineers must not say it can't be
implemented. - 3. Graphic designer must not laugh at engineers'
drawings. - Only after brainstorming, organise ideas and
consider their practicality and viability.
995. Participatory Design
- Have access to pool of representative users.
- Guided discussion of prototypes, paper mock-ups,
screen designs with representative users.
1006. Co-ordinated Design of Total Interface
- Consistency across total interface
documentation, online help, tutorials,
videotapes, training classes as well as screens
and dialogues. By means of - Interface standards specific rules as to how
interface should look and feel. - Widget libraries shared code implementing
standard UI functionality. - Shared culture training, meetings, interface
evangelist''.
1017. Applying Guidelines
- Smith S. Mosier J. Design Guidelines for
Designing User Interface Software The MITRE
Corp., 1986. 944 guidelines ISBN 9992080418 - ftp//ftp.cis.ohio-state.edu/pub/hci/Guidelin
es - Brown C. Human-Computer Interface Design
Guidelines Ablex, NJ, 1988. ISBN 0893913324 302
guidelines - Mayhew D. Principles and Guidelines in
Software User Interface Design Prentice-Hall,
1991. ISBN 0137219296 288 guidelines
1028. Prototyping
- Perform usability evaluation as early as possible
in the design cycle by building and evaluating
prototypes. - Prototypes cut down on either the number of
features, or the depth of functionality of
features - Vertical Prototype in-depth functionality for a
few selected features. - Horizontal Prototype full interface features,
but no underlying functionality. - Scenario only features and functionality along a
pre-specified scenario (task) or path through the
interface. - These varieties of prototype are illustrated in
Figure.
103Dimensions of Prototyping
104Techniques for Implementing Prototypes
- Verbal prototyping verbal description of choices
and results. - Paper mock-ups printouts or sketches of screen
designs. - Wizard of Oz human expert operating behind
scenes. - Fake data similar data, images instead of video,
etc. Simple algorithms ignore special cases. - Prototyping tools e.g. HyperCard, ToolBook.
- UIMS (User Interface Management Systems)
interactive interface builders such as Visual
C.
1059. Usability Evaluation
- Usability Inspection
- Inspection of interface design using heuristics
and judgement (no user tests). - Usability Testing
- Empirical testing of interface design with real
users.
10610. Iterative Design
- Severity ratings of usability problems
discovered. - Fix problems new version of interface.
- Capture design rationale record reasons why
changes were made. - Evaluate new version of interface.
- design, test, redesign.
10711. Follow-Up Studies
- Important usability data can be gathered after
the release of a product for the next version - Specific field studies (interviews,
questionnaires, observation). - Standard marketing studies.
- Instrumented versions of software log data.
- Analyse user complaints, modification requests,
bug reports.
108Systems evaluation
- Objectives of Evaluation
- to determine the effectiveness or potential
effectiveness of the system - to provide a means for suggesting improvement
- The context of evaluation includes
- the users experience
- the type of task
- the system being used
- the environment in which the study takes place
109Measurable Human Factors to Evaluation
- Time to learn How long does it take for typical
members of the user community to learn how to use
some specified functions? - Speed to performance How long does it take to
carry out the specified task? - Rate of errors by users How many and what kinds
of errors do users make in carrying out the
specified task? - Retention over time How well do users maintain
their knowledge after an hour, a day, or a week? - Subjective satisfaction How much did the users
like using various aspects of the system? - (Ben Shneiderman, 1998, Designing the user
interface, Addison-Wesley)
110When to do evaluation
- Formative evaluation takes place before
implementation in order to influence the product
that will be produced - Summative evaluation takes place after
implementation with the aim of testing the proper
functioning of the final system.
111Methods, techniques and tools
- Analytic evaluation uses formal or semi-formal
interface description to predict user
performance. - Expert evaluation involves experts in assessing
an interface - Observational evaluation involves observing or
monitoring users behaviour while they are using
a system. - Survey evaluation seeks to elicit users
subjective opinions of the system. - Experimental evaluation uses scientific
experimental practice to test hypotheses about
the system.
112Evaluation at Stages of Design
Previous evaluation
Systems Engineering
Analysis
Formative evaluation
Design
Coding
Implementation, maintenance
Summative evaluation
113Analytic evaluation
- Task analysis and task structure (HTA)
- user interactions (input- process - output)
- users operation, scenarios
114Expert evaluation
- It is essential to select experts who have
knowledge of general principles for design and
experiences in design. - the experts should not have been involved
previous versions of the system under evaluation. - materials, interface presented to the experts
should be representative to the real users use
situation.
115Observational evaluation
- Direct observation observing users execution,
making notes. - video recording record visible aspects of users
activity, replayed and analysed (with users as
participatory evaluation) - software logging record dialogue between the
user and the system in time sequence of
user-computer interaction. - interactive observation a hidden operator who
simulates all the output from the system. - verbal protocols (think-aloud) record users
spoken thought while task performing couple with
video record
116Survey evaluation
- Structured interview easy to conduct, easy to
analyses, but important details of users
situation may not be recorded - questionnaires
- open question answers are free to users
- closed question answers are defined as multiple
choices - flexible interview
117Rating scales in closed questions
- Check list
- multi-point rating scale
Can you use the following text editing commands
? DUPLICATE PASTE
Dont know
yes
no
Rate the usefulness of the DUPLICATE command on
the following scale
Very useful
Of no use
118Rating scales in closed questions
- likert scale
- semantic differential scale
Computer can simplify complex problems
Rating the Diagram package on the following
dimensions
extremely
quite
slightly
neutral
slightly
quite
extremely
Difficult confusing dreary
Easy clear fun
strongly agree
slightly agree
slightly disagree
strongly disagree
agree
neutral
disagree
119Rating scales in closed questions
- Ranked order questionnaire
Place the following commands in order of
usefulness (use a scale of 1 to 4 where 1 is the
most useful)
Paste
Duplicate
Group
Clear
120Experimental evaluation
- In an experimental evaluation, evaluators
systemically manipulate the factors associated
with design (input or independent variables) and
study or measure the effects on users performance
(output or dependent variables). - Example to test if different rates of learning
(output) exist for three different type of
interfaces (input as command, ask/answer, window
based), this examination can be shown as this
figure
121Steps in experimental evaluation
- 1 Formulating your goal of evaluation or
hypotheses (based on principles) - 2 Developing predictions from the hypotheses
(possible results or output) - 3 Choosing methods to test your predictions
- 4 Identifying all the variables that might
affect the result of your examination - 5. Deciding which are the input variables,
output variables, and environment - 6 Selecting Subjects
- 7 Conduct evaluation (examination), Collecting
Data - 8. Conducting statistics or analysis, synthesis
- 9 Conclusion of your evaluation (according to
your hypotheses)
122Three criteria for a valid evaluation
- 1 The examiner must systematically
manipulate/observe one or more independent
variables in the domain under investigation - 2 The examination must be made under controlled
conditions, - such that all variables which could affect
the outcome of the - experiment are controlled
- 3 The examiner must measure output as a function
of the input variables.
123Hypotheses
- Hypotheses are conditional statements in the
form - If conditions then result
- The examination is set up to manipulate input
variables to observe their output. The final
result of the examination will either confirm or
reject the hypotheses. - Hypothesis example
- If users are provided a structured interface,
then they will learn quicker than unstructured
interface.
124Conditions for experimental evaluation
- System being observable To transform quality to
quantity - System being stableThe system must be able to
remain at some determined status under constant
experimental conditions. - System being controllable The system output
(dependent variables) must be sensitive to the
change of input (independent variables). - (The selected dependent variables and
independent variables must have an observable
cause-effect relationship. ) - You must have a goal for an experiment, e.g, to
test some predefined hypotheses, to gain more
information about problem space, to identify
variables in relation to a problem under
investigation.
125Evaluation measuring
- 1 Nominal Scale A classification of categories,
qualitative differences, no quantitative meaning
(e.g., group 1, group 2,......). - 2 Ordinal Scale Ordering according to
quantitative differences, though it does not
exactly tell how much the differences are (good,
bad, ..). - 3 Interval Scale Assigning an equidistant to
different status of measured phenomena (e.g.,
Fahrenheit temperature scale) - 4 Ratio Scale There is an absolute zero point
so we can make ratio calculation (e.g, distance,
mass, time)
126Subject selection
- A subject is the person who participates in the
examination. - Factors to consider in subject selection
- 1. the subject's previous experiences
- 2 the level of skill
- 3. the number of subjects needed (n gt 6).
- Single case study (n1) when
- Time is limited the type of subjects are in
short supply - general knowledge about human factors are of
- interest and when generalisation is not
important.
127Subject grouping
- Within-group design
- Group 1 Group 2
- With DSS No DSS
- s1 s1
- s2 s2
- s3 s3
- s4 s4
- s5 s5
- efficient in use of time and subject good for
testing learning. - carry-over effects
- Between-group design
- Group 1 Group 2
- With DSS No DSS
- s1 s6
- s2 s7
- s3 s8
- s4 s9
- s5 s10
- no carry-over effects (no order or experience
problem). - subjects costly carry-over effects.
- members in the same group must share the same
properties
128Subject grouping
- Mixed factorial design - An example
- Group 1
Group 2 - Interface style - picture Interface
style - text - Trials, 1,2,3,4.
Trials, 1,2,3,4. - s1
s5 - s2
s6 - s3
s7 - s4
s8 - efficient where carry-over effect are not great
and where measurement - of learning performance is important
- complicated when many input variables involved
(in this example, - two kinds of input variables Interface
Stylespicture, text (between - groups), and trials1,2,3,4 (within group or
repeated measure).
129Analysis and synthesis
- Analysis
- Dissect conceptually or physically
- Learn the properties or behaviour of the
separate parts - From the properties of the parts, deduce the
properties/behaviour of the whole.
- Synthesis
- Identify the system of which the unit in focus is
a part - Explain the properties or behaviour of the system
- Explain the properties or behaviour of the unit
in focus as a part or function of the system.
130Which methods and when?
- Differences among the five evaluation methods
Analytic Specification no users, tasks
Quantitative specified Expert Specificatio
n or Role playing, no qualitative prototype tas
k restrictions Observational Simulation or Real
users, no task Quantitative/ Prototype restric
tions qualitative Survey Simulation or Real
users, no task Quantitative/ prototype
restrictions qualitative Experimental Normally
full Real users, no task Quantitative/ prototy
pe restrictions qualitative
131Which methods and when?
- Advantages and disadvantages of the evaluation
methods
Method Advantages Disadvantages Analytic Usab
le early in design Narrow focus, lack of
diagnostic out few resources required put for
redesign, broad assumptions of users
cognitive operations, complex Expert Strongly
diagnostic, overview Restrictions in role
playing, no real of whole, few
resources behaviour of user, difficult finding
experts Observational Quickly highlights
difficulties Observation side.effect on users
rapid iterative design, verbal performance,
time and resources protocols useful for
design consuming in data analysis Survey Address
es users opinions Bias to users experience, low
response diagnostic, rating scales to rates,
complicated and lengthy analysis, quantitative
result, large group time consuming for
interview. Experimental Powerful method,
quantitative High resources demands,
knowledge data for analysis, reliability
and requirement high, difficult integration
in validity good, replicable. design
132Home work
133 Lifecycle or Waterfall Approach
134System Engineering Activities
- 1. Analysis of task, domain, users, hardware,
software, all at a general level. - 2. Establishing user requirements
- 3. Establishing system requirement
- 4. Allocation of requirements to software
- Purpose To identify the scope of the system and
general design area. - Output A general requirement document that
address each of areas mentioned above.
135Analysis Activities
- Tasks
- Users
- Domain
- Software
- Purpose To understand the information exchange,
domain entities, required function,
characteristics of interface, criteria of
evaluation. - Output A specific requirement document.
136Design Activities
- Data structures
- Software architecture
- Procedural detail
- User interface
- Purpose To translate the requirements
specification into a model for the software - Output A software design specification.
137Coding Activities
- Translation of design specification into
machine-runnable form. - Purpose To produce a runnable version of the
design specification. - Output A software based on requirement
specification.
138Testing Activities
- Logical testing of the software
- Testing of the functionality
- Testing of the usability
- Testing of the efficiency of the design and
implementation. - Purpose To assess the quality of the design and
the coding. - Output An assessment report on the design
quality and recommendations for redesign.
139Maintenance Activities
- Repairing any errors or faults in the design or
the coding. - Updating the design because of changes in the
requirement. - Updating of the design because of change in the
environment. - Purpose To allow the software to be adapted to
the changes. - Output Revised set of requirements, design and
software.
140Problems About the Iifecycle Model
- 1 Real projects are not sequential in the rigid
way that this model assumes, but in a different
order with iteration. - 2 It is not possible to elicit or identify all
the requirements at the start of the project
because of unpredictable changes. - 3 It is often expensive to correct design and
coding errors in the late process of testing and
maintenance.
141Advantage About the Lifecycle/Waterfall Model
- 1 It provides a comprehensive template (as of
DNA) in which many important aspects of design
can be placed. - 2 It provides generic steps that are found in
most software engineering paradigms. - 3 It is the most widely used model at least in
large software project. - 4 It is superior than unplanned design
(haphazard).
142 Prototyping Approach
- Introduction
- The use of experimenting with prototypes has
become prominent due to a number of claimed
advantages in the case that users requirements
are difficult to specify. In principle users
should be highly motivated in acting since they
are provided with more chances to improve their
work, to verify if their needs are taken care of
and that the terms used in the interface,
functions of the designed system are consistent
with their work.
143Types of Prototypes
- Throwaway prototype to initiate user interest,
develop builder skills, to reduce risk and
investment. - Evolving prototype Adaptive, prototype to be
product - Co-operative Prototype Participatory Design (PD)
- Embryonic Prototype Feedback Learning, organic
development.
144Model of Prototyping Approach
145Steps in Prototyping
- Requirements Gathering Designers and the
customer define the overall objectives of the
system, and some known requirements. - Quick Design Focuses on the design of interface.
- Build Prototype Choose the types of prototypes
and build quickly. - Evaluate and Refine Involving the designers, the
customers, and the users to experience the
prototype and elicit requirement more specific
than requirement gathering. - Engineer product Based on the prototype, the
final product is engineered