Methodology II: Cognitive Dimensions and the Gulfs - Foundations for Designing User-Centered Systems - page 335

Jones et al. 2003 ). This was done by initially focusing on the cognitive require-
ments of the user, using the CDs and the Attention Investment model of
abstraction use (Blackwell 2002 ). The Cognitive Dimensions approach has also
been used to understand issues that arise for programmers when solving complex
systems integration problems and with contemporary, mash-upprogramming
practices with APIs (application programming interfaces) (see Jones et al. 2010 for
an example).
12.4 What is Omitted by the Cognitive Dimensions?
The CDs do have some limitations. This approach does not offer a complete way to
create an interface design, and it may not always be applicable. Those aspects of a
system that are of particular interest may not be covered by the dimensions noted,
for example.
Even for the existing CDs, there are areas where they could be expanded. The
current list includes error proneness, for example, but does not directly address the
quality of feedback and support for error recovery. The CDs also focus on usability
issues, and do not currently address issues related to user acceptability—does the
system fit in with the way users do the task or want to do the task, and so on.
The CDs are an attempt to provide a way for designers to discuss issues related
to usability. If we had a rich enough vocabulary to adequately describe the sources
of poor usability, then the problems could be solved simply by reducing or
eliminating each of these sources. The real benefit of the CDs is as a tool that can
highlight the trade-offs inherent in interface design in a way that can be easily
understood by designers.
As their name suggests, the CDs focus on the cognitive aspects of interfaces.
They do not address design trade-offs related to the other aspects of users that we
have introduced—anthropometric, behavioral, and social aspects—in any great
depth. The CDs approach, however, suggests that a similar approach to under-
standing design trade-offs could be used for these other aspects of usability. The
physical dimensions of a device will typically be related to the features that can be
provided, for example, iPods versus iPads. Similarly, other aspects can be put into
this framework. For example, social aspects could be included such as how the size
of a social network will influence the usability of devices designed for commu-
nicating with others.
12.5 Norman's Seven Stages of Action
In his book The Design of Everyday Things, Norman ( 1988 , 2013 ) describes the
process of how users interact with systems to achieve their goals as a series of
activities (see Table 12.2 ). This process is an approximate theory of action: all of