Focusing on the analysis of the behaviour-shaping constraints, rather than on the
observed behaviour, makes Cognitive Work Analysis particularly useful for the
design of information systems. A mere description of an observed behaviour
presents various problems for designers. People's information behaviour is
informed by the mental models they have on the information world around them,
but some of these models can be incomplete or wrong. The design of information
systems should not be led by such models. Further, not all people have the same
mental model but a designer cannot know which models are complete and
correct. In addition, the information systems that are already in place, and their
limitations, greatly influence their users' mental models and their information
behaviour. As a general rule, however, designers try to create new, or improved,
systems, rather than replicating existing ones. Alternatively, by gaining an in-depth understanding of the factors that shape information behaviour, researchers
can determine what information behaviour patterns cantake place, or what
strategies canbe used, independently of how observed actors interact with
current systems. This frees the design from its dependence on the capabilities of
existing systems and their effectiveness in the process of human-information
interaction.
The analysis of goals and behaviour-shaping constraints creates a formative
model. Vicente explains that a formative model is, 'A model that describes
requirements that must be satisfied so that a system could behave in a new,
desired way' (Vicente 1999: 7). Unlike a descriptive model, which describes how
things are, or a normative, which explains how things should be, a formative
model portrays what is possible. The map Mary provides the hotel guests shows
constraints: the layout of streets, buildings on the way, direction one is allowed to
drive on each street, distance, and so on. Analysis of constraints makes it
possible to create maps. Similarly, designers of information systems would need
to know the lay of the landof information behaviour. Therefore, studies of
human information behaviour that uncover what users need, what is possible for
them to do, and what is not possible, would be most useful for systems design.