Summary: Putting It All Together - Foundations for Designing User-Centered Systems - page 375

however, that it will enable them to communicate with human factors engineers,
and develop a shared understanding of the issues as they affect system develop-
ment and use.
We conclude our discussions with a brief summary of what we have presented
in this topic. You will want to organize it yourself in some meaningful way to be
able to make effective use of all the information about users that we have pre-
sented. How you decide to organize it will partly depend on how you intend to use
it. You might find the metaphors in Chap. 12 , those of the Gulfs and Cognitive
Dimensions, to be useful. There are also methods and techniques that can help you.
A few of these have been implemented as computer programs that are fairly easy
to use, and encapsulate summaries of user behavior that can be applied in a range
of ways. These models are just one way of applying what we know about humans
to system design; they can also be used to help teach designers and developers
about users as a sharable representation.
We finish by describing how you can take forward what you have learned here and
incorporate it into system development. We would contend that you should always
apply this knowledge, because a lack of knowledge about users nearly always con-
stitutes a risk to system development. We illustrate this argument using an extended
version of the Risk-Driven Incremental Commitment Model (Pew and Mavor 2007 ).
14.2 Organizing What We Have Learnt About Users
If your aim is to build systems that are both useful and usable then the best way
forward in many cases is to focus on particular people doing particular tasks in
particular contexts. The knowledge that we have provided you will help. Whether
a system can be described as usable or not depends on factors such as the shape
and size of the users (anthropometric factors), external body functioning and
simple sensory-motor concerns and motivation (behavioral factors), internal
mental functioning (cognitive factors), and external mental functioning (social and
organizational factors). It therefore makes sense to consider organizing your
knowledge about these different factors in terms of the types of user characteristics
that we introduced early in the topic: Anthropometric; Behavioral; Cognitive; and
Social—the ABCS. You should be aware that there are other factors too, which we
have not addressed in this summary such as legal liability, and physiological
factors which will often also be important.
14.2.1 Anthropometrics
Users vary. One obvious way they can vary is in physical size, as Chap. 3 noted.
Different people of the same age and gender may have different heights and
different weights, for example. Users also change over time as they develop and