Introducing User-Centered Systems Design - Foundations for Designing User-Centered Systems - page 22

turned off, but did not interrupt the pilots, possibly because of the high social status
accorded to the pilots. This type of cultural issue, where someone knows some-
thing that could help a team or a project and does not raise the issue, is a well
documented problem. How to adjust appropriately the social dynamics to fix
problems like this remains an important and interesting problem.
Another example comes from a nuclear power plant in Europe. A reporting
system was set up to allow staff to report incidents (near misses) so that the
company could learn from them to try and prevent the same thing happening
(Masson 1991 ). This was all working fine, and management and staff had settled
into using the system. Staff were happy to report incidents and were not blamed
when the incidents did occur. The management then decided that they would
change the (negotiated) culture, in which the emphasis had been on reporting
incidents, to one that focused on incidents as a measure of safety, and decided that
the shift that reported the least incidents would be regarded as the safest shift and
would receive some reward.
The net effect was that staff stopped reporting incidents in a bid to make their
shift appear to be the safest. In the end a new incident reporting system had to be
developed, and all the data about the unreported incidents was lost because the
management had unwittingly changed the culture from one that was designed to
use reported problems as a way of learning and improving safety to one that was
effectively designed to reward the lack of reporting of problems.
1.5 Simulating User Characteristics: Cognitive
Architectures
One of the main aims of this topic is to help you to develop a better understanding
of why users do things the way they do. Understanding the way users think and
behave will help you design systems that support users. The ABCS framework,
described above, provides one way of organizing this information about user
characteristics. It is also possible to encapsulate relevant details in a model. For
example, if one is interested specifically in human information processing, cog-
nitive architectures provide a convenient way of modeling human information
processing under different conditions, because they include mechanisms that are
specifically designed for modeling human cognition.
Figure 1.5 is a schematic of the major components of a computer model of a
user. The major components in this model are designed to mimic the major
components of users. The top box, ACT-R, refers to a simplified form of the ACT-
R cognitive architecture (Anderson and Lebiere 1998 ). (There are other archi-
tectures, but they are similar for our purposes.) In this instance the architecture has
been combined with an extension that allows it to interact effectively with the
external world. So the combined cognitive architecture takes the bitmap from a
computer screen and, in a process approximating vision, computes the objects and
some of their features in the image and puts the results into a perceptual buffer.