Information Technology Reference
In-Depth Information
system. In this case common ground concerns only the software specialists so for-
mal models and specifications, which are not accessible to users, are appropriate.
However, for validation, representations need to support both concrete and abstract
views of requirements. Contrasting and integrating representations is part of the
answer, but Clark's action ladder points to further lessons.
Common ground is established not only through conversation but also by act-
ing in the world. This is manifest in prototypes where the consequence of action
and interaction are immediately apparent. Although interacting with prototypes is a
powerful means of analysis, it needs to be combined with specifications and models
for causal diagnosis of problems observed during testing prototypes. The causes of
incorrect or inappropriate actions need to be traced back to errors in specifications
or inadequate requirements. Models can be 'walked-through', and early designs can
be mocked-up as storyboards presented as interactive sequences, or designs can be
simulated as Wizard of Oz techniques. User hands-on testing, i.e. interaction with
RE artefacts and prototypes, plays a vital role in developing common ground since
perceiving the consequences of action is a powerful means of promoting understand-
ing. Facts described in a conversation may be accepted uncritically at face value, but
it is difficult to ignore the consequences of actions.
4.5 Communicating Requirements
The lessons so far for common ground may be summarised as the following set of
principles:
•
Iterative cycles or requirements analysis and design exploration build mutual
understanding about users' requirements and the space of possible solutions for
those requirements.
•
Common ground in RE involves integrating the abstract and concrete sub-spaces.
Juxtaposing abstract (models) and concrete presentations (scenarios, sketches,
storyboards) helps to bridge the gap.
•
Interaction with representations and especially prototypes helps to build mutual
understanding.
•
Negotiation and agreeing common ground requires special representations and
tools which support decision making, by depicting the choice space, and facili-
tating comparisons.
Concurrent use of several representations enables comparisons; for instance, sce-
narios, drawings, storyboards for specific information, with models, diagrams and
text specifications for abstract information, while the decision space is structured
using matrices and design rationale. Adding prototypes and simulations for the mer-
its of understanding interaction may seem to be the optimal solution. However, the
threads and tracks component of Clark's theory points towards a problem with mul-
tiple representations. There is no escape from the limitations of working memory
Search WWH ::
Custom Search