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Design activities begin
once a set of requirements has been established. Broadly
speaking, there are two types of design: conceptual and
physical. The former is concerned with developing a conceptual
model that captures what the product will do and how it
will behave, while the latter is concerned with details
of the design such as screen and menu structures, icons,
and graphics. The design emerges iteratively, through repeated
designevaluationredesign cycles involving users.
For users to effectively evaluate the design of an interactive
product, designers must produce an interactive version of
their ideas. In the early stages of development, these interactive
versions may be made of paper and cardboard, while as design
progresses and ideas become more detailed, they may be polished
pieces of software, metal, or plastic that resemble the
final product. We have called the activity concerned with
building this interactive version prototyping and construction.
There are two distinct circumstances for
design: one where you're starting from scratch and one where
you're modifying an existing product. A lot of design comes
from the latter, and it may be tempting to think that additional
features can be added, or existing ones tweaked, without
extensive investigation, prototyping or evaluation. It is
true that if changes are not significant then the prototyping
and evaluation activities can be scaled down, but they are
still invaluable activities that should not be skipped.
In Chapter 7, we discussed some ways to
identify user needs and establish requirements. In this
chapter, we look at the activities involved in progressing
a set of requirements through the cycles of prototyping
to construction. We begin by explaining the role and techniques
of prototyping and then explain how prototypes may be used
in the design process. Tool support plays an important part
in development, but tool support changes so rapidly in this
area that we do not attempt to provide a catalog of current
support. Instead, we discuss the kinds of tools that may
be of help and categories of tools that have been suggested.
The main aims of this chapter are to:
- Describe prototyping and different
types of prototyping activities.
- Enable you to produce a simple
- Enable you to produce a conceptual
model for a system and justify your
- Enable you to attempt some aspects
of physical design.
- Explain the use of scenarios and
prototypes in conceptual design.
- Discuss standards, guidelines,
and rules available to help interaction designers.
- Discuss the range of tool support
available for interaction design