UNIT – 4: DESIGN PROCESS
1. INTERACTION DESIGN BASICS
Interaction design is about creating
interventions in often complex situations using
technology of many kinds including PC
software, the web and physical devices.
1.1 WHAT IS DESIGN? So what is design?
A simple definition is: achieving goals within
constraints. This does not capture everything
about design, but helps to focus us on certain
things:
Cont…..
Goals What is the purpose of the design we are
intending to produce? Who is it for? Why do they
want it?
Constraints What materials must we use? What
standards must we adopt? How much can it cost?
How much time do we have to develop it? Are there
health and safety issues?
1.1.1 The golden rule of design
The golden rule of design: understand your materials
Cont…
For Human–Computer Interaction the obvious materials
are the human and the computer. That is we must:
understand computers: limitations, capacities, tools,
platforms
understand people: psychological, social aspects,
human error.
1.1.2 To err is
human It might sound demeaning to regard people as
‘materials’, possibly even dehumanizing. This is
particularly obvious when it comes to failures.
1.1.3 The central message – the user This is the core of
interaction design: put the user first, keep the user in the
centre and remember the user at the end.
1.3 THE PROCESS OF DESIGN Often HCI
professionals complain that they are called in too late. A
system has been designed and built, and only when it
proves unusable do they think to ask how to do it right!
1.4 USER FOCUS
As we’ve already said, the start of any interaction
design exercise must be the intended user or users.
This is often stated as: know your users
1.5 SCENARIOS
Scenarios are stories for design: rich stories of
interaction. In addition used to
Communicate with others
Validate other models
Express dynamics
Time is linear
1.6 NAVIGATION DESIGN
As we stressed, the object of design is not just a
computer system or device, but the socio-technical
intervention as a whole. Imagine yourself using a
word processor.
1.6.1 Local structure
knowing where you are? knowing what you can do?
knowing where you are going – or what will happen?
knowing where you’ve been – or what you’ve done?
1.6.2 Global structure
hierarchical organization This is typically organized
along functional boundaries
1.6.3 Global structure
dialog The arrows show the general flow
between the states.
1.6.4 Wider still
Style issues We should normally conform to platform
standards
Functional issues On a PC application
Navigation issues We may need to support linkages
between applications.
1. 7 SCREEN DESIGN AND LAYOUT
A single screen image often has to present
information clearly and also act as the locus for
interacting with the system.
1.7.1 Tools for layout
Grouping and structure
1.7.2 User action and control Entering information
Knowing what to do Affordances
1.7.3 Appropriate appearance Presenting information
Aesthetics and utility Making a mess of it: colour and
3D Localization / internationalizatio
2. HCI IN THE SOFTWARE PROCESS
2.1 THE SOFTWARE LIFE CYCLE
One of the claims for software development is that it
should be considered as an engineering discipline
2.2.1 Activities in the life cycle
The graphical representation is reminiscent of a
waterfall, in which each activity naturally leads into
the next.
2.2.2 Validation and verification
Throughout the life cycle, the design must be
checked to ensure that it both satisfies the high-level
requirements agreed with the customer and is also
complete and internally consistent. These checks are
referred to as validation and verification, respectively.
2.2.3 Management and contractual issues
The life cycle described above concentrated on the
more technical features of software development.
2.3 USABILITY ENGINEERING
The ultimate test of a product’s usability is based on
measurements of users’ experience with it.
2.3.1 Problems with usability engineering
The major feature of usability engineering is the
assertion of explicit usability metrics early on in the
design process which can be used to judge a system
once it is delivered.
2.4 ITERATIVE DESIGN AND PROTOTYPING
2.4.1 Techniques for prototyping
2.4.2 Warning about iterative design
2.5 DESIGN RATIONALE
Design rationale is the information that explains why
a computer system is the way it is, including its
structural or architectural description and its
functional or behavioral description.
2.5.1 Process-oriented design rationale Various
positions are put forth as potential resolutions for the
root issue
2.5.2 Design space analysis
The design space is initially structured by a set of
questions representing the major issues of the design.
2.5.3 Psychological design rationale
People use computers to accomplish some tasks in
their particular work domain.
3. DESIGN RULES
3.1 INTRODUCTION
One of the central problems that must be solved in a
user-centered design process is how to provide
designers with the ability to determine the usability
consequences of their design decisions.
3.1 PRINCIPLES TO SUPPORT USABILITY
4. IMPLEMENTATION SUPPORT
4.1 ELEMENTS OF WINDOWING SYSTEMS
4.2.1 Architectures of windowing systems
USER INTERFACE MANAGEMENT SYSTEMS
4.5.1 UIMS as a conceptual architecture
Portability
Reusability
Multiple interfaces
Customization
Presentation The component responsible for the
appearance of the interface, including what output
and input is available to the user.
Dialog control The component which regulates the
communication between the presentation and the
application.
4.5.2 Implementation considerations
Menu networks
Grammar notations
State transition diagrams
Event languages
Declarative languages
Constraints
Graphical specification
5. EVALUATION TECHNIQUES
5.1 WHAT IS EVALUATION?
Ideally, evaluation should occur throughout the design
life cycle, with the results of the evaluation feeding
back into modifications to the design.
5.2 GOALS OF EVALUATION Evaluation has three
main goals: to assess the extent and accessibility of the
system’s functionality, to assess users’ experience of
the interaction, and to identify any specific problems
with the system.
5.3 EVALUATION THROUGH EXPERT ANALYSIS
5.3.1 Cognitive walkthrough
Walkthroughs require a detailed review of a sequence of
actions.
5.3.2 Heuristic evaluation
A heuristic is a guideline or general principle.
5.3.3 Model-based evaluation
A third expert-based approach is the use of models.
5.3.4 Using previous studies in evaluation Experimental
psychology and human–computer interaction between
them possess a wealth of experimental results and
empirical evidence
5.4.1 Styles of evaluation
Before we consider some of the techniques that are
available for evaluation with users,
5.4.2 Empirical methods: experimental evaluation One
of the most powerful methods of evaluating a design or
an aspect of a design is to use a controlled experiment.
This provides empirical evidence to support a particular
claim or hypothesis. It can be used to study a wide
range of different issues at different levels of detail.
Participants ,Variables , Hypotheses, Experimental
design ,Statistical measures
6. UNIVERSAL DESIGN Universal design is about designing
systems so that they can be used by anyone in any circumstance.
Multi-modal systems are those that use more than one human
input channel in the interaction.
These systems may, for example, use:
Speech
non-speech sound
touch o handwriting
gestures.
Universal design means designing for diversity, including:
people with sensory, physical or cognitive impairment o
people of different ages of people from different cultures and
backgrounds.
7. USER SUPPORT Users have different
requirements for support at different times.
User support should be: – available but
unobtrusive – accurate and robust – consistent
and flexible. User support comes in a number of
styles: – command-based methods – context-
sensitive help – tutorial help – online
documentation – wizards and assistants –
adaptive help. Design of user support must take
account of: – presentation issues
