Page 123 -

92 Chapter 3 Understanding users

3.4 Conceptual frameworks for cognition
In the previous section we described the pros and cons of applying knowledge of
people's coping strategies in the physical world to the digital world. Another ap-
proach is to apply theories and conceptual frameworks to interaction design. In this
section we examine three of these approaches, which each have a different perspec-
tive on cognition:
mental models
information processing
external cognition

3.4.1 Mental models
In Chapter 2 we pointed out that a successful system is one based on a conceptual
model that enables users to readily learn a system and use it effectively. What hap-
pens when people are learning and using a system is that they develop knowledge
of how to use the system and, to a lesser extent, how the system works. These two
kinds of knowledge are often referred to as a user's mental model.
Having developed a mental model of an interactive product, it is assumed that
people will use it to make inferences about how to carry out tasks when using the
interactive product. Mental models are also used to fathom what to do when some-
thing unexpected happens with a system and when encountering unfamiliar sys-
tems. The more someone learns about a system and how it functions, the more
their mental model develops. For example, TV engineers have a "deep" mental
model of how TVs work that allows them to work out how to fix them. In contrast.