1.2 Understanding, Usefulness, and Usability

Discovery of what would be useful occurs in the research cycle because
development also functions as an opportunity to learn. Artifacts are not just
objects; they are hypotheses about the interplay of people, technology and work.
With this perspective of complementarity between research and design,
prototypes function as tools for discovery to probe the interaction of people,
technology and work and to test the hypothesized, envisioned impact of
technological change.

Many commentators note that design begins with analysis and problem
definition. This phase is concerned with understanding the nature of the
problem to be solved and the field of practice, the domain, in which it resides.
Design activity then progresses to a divergent phase of ideation, ending in the
selection of a single idea or set of ideas. Ideas, at this point, are means of
achieving the desired ends; they are how the product will work. The final
product is then produced through a gradual refinement phase, during which it is
evaluated to ensure it meets its requirements. Each of these three phases builds
on the others: analysis supports ideation, and the final product is an embodiment
of the selected idea and is evaluated based on how it solves the problem
identified in the analysis phase.

Rather than view design as this phased, sequential process, we believe that the
design process draws on research bases and past experience in a creative,
iterative fashion. With this view, the traditional stages in design are transformed
to parallel levels of knowledge bases from which we can draw on
opportunistically during the iterative design process. Rather than phases, the
traditional stages represent tracks that proceed in parallel but produce different
"products": a model of error and expertise in the domain, aiding concepts for
what will be useful to practitioners, and the fielded system (Figure 4).

Figure 4. Three parallel design tracks


1.2.1 Understanding. For practice-centered design, the problem definition is more
than merely learning about the field of practice and talking to the practitioners;
the designer must understand the nature of errors that occur and how
experienced practitioners develop and maintain expertise. By understanding the
demands that practitioners must meet in order to be successful, we can identify
constraints on productive design directions. For example, if we know that
intelligence analysts should never miss evidence that a nuclear weapon has been
tested, system designs that hide information that is infrequently reviewed are not
likely to meet the demands.

1.2.2 Usefulness. The usefulness track is where innovation occurs; during this
phase, designers generate creative ideas for what might help users. It is
intertwined with domain modeling, because testing ideas adds new knowledge
to the designer's model of error and expertise, which can in turn lead to new
ideas for how to aid performance. At this level, evaluations are aimed at the
underlying generalizable aiding concept rather than the specific implementation.
In order to do this, evaluation scenarios need to be crafted in ways to discover
further requirements about what might be useful rather than refining the
product to be more usable and consistent with existing infrastructures.

1.2.3 Usability. During prototype refinement, a series of decisions are made that
continually narrow an idea into a fieldable product. At the same time, there is a
growing resource and psychological commitment to a single concept. Design
activity concerns making commitments to how specific aspects of the product
will look or work. The depth of activity is often impasse driven, i.e., additional
information search, evaluation, or consulting with human-computer interaction
(HCI) specialists occurs when the design team confronts some impasse or gap in
their knowledge. HCI specialists can draw on knowledge of principles and
techniques to enhance usability. Usability tests are designed around cases that
instantiate target scenarios that were derived from the understanding of the
demands of the field of practice.

In order to advance as a science, we also can view each design process as an
opportunity to add back to the three research bases. Any embodiment of a
design concept, whether a crude prototype, refined prototype, or released
system, affords the opportunity to add back to these research bases
simultaneously: by improving our models of error and expertise, by discovering
requirements for what would be useful, and by identifying principles and
techniques to enhance usability.



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