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OCR for page 3
INTRODUCTION
Discovering what the users of a computer software system do
know and should know are important goals in current research on
human-computer interaction. Research on the kinds of knowledge
people have when they use computers, including the concept of
a mental mode} of the system, is one of the major topics that is
bringing the field of human-computer interaction from the tra-
dition of human factors closer to that of experimental/cognitive
psychology. Traditional human factors work has focused principal
attention on behavior and performance itself, and has avoided the
problem of describing the conceptual causes and effects of that
behavior. On the other hand, while academic cognitive psychol-
ogy does concern itself with theoretical interpretations of mental
processes, it has focused on narrowly restricted mental processes,
such as particular aspects of learning, memory, problem solving, or
planning, and has studied them in the context of highly controlled
and contrived laboratory tasks. The study of knowledge represen-
tations of users of computer-based systems affords an opportunity
to explore both the theoretical base of behavior as well as specific
behaviors in tasks that involve many different cognitive processes
in concert.
Because a number of researchers are concerned with mental
representations, and because this topic has an impact on cognitive
psychology and software human factors, there is an emerging need
to clarify the concepts underlying knowledge representation and
mental models as they apply to human-computer interaction. We
intend to fill this need by reviewing relevant current research
and presenting a preliminary framework of the kinds of mental
representations of procedures people might have.
MODELS OF WHAT, HEED BY WHOM?
Several key distinctions need to be recognized in discussing
mental representations and mental models in human-computer in-
teraction. For example, various individuals are concerned with
using or designing a piece of software, and they hold different
conceptions of it. These individuals include the user, the software
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OCR for page 4
engineer, the human factors analyst, and the cognitive psycholo-
gist. Furthermore, there are different aspects of the system to be
known: the task, knowing what the goal is and in general what
subtasks need to be accomplished to achieve the goal; the system
interface, knowing how to accomplish the sequence of subtasks in
this system, given the data presentation and interaction languages
of this system; and the system architecture, knowing the way the
data are stored, the internal processes the interactions invoke, and
in general how the system works.
Confusion has surrounded the term mental mode! because
different authors have referred to different owners of the models
(the user, the software engineer, etc.) and are not clear as to what
the mode] actually represents (the task, the architecture, etc.~.
For example, some researchers and human factors analysts
acknowledge that it is important to know the way users themselves
are built and work, what their memory limits are, their common
strategies in problem solving, their individual differences, and so
on, in order to build useful, usable software. A system that requires
the user to remember a list of 100 codes that represent areas of the
country or the types of transactions that are required (as in some
airline or automobile reservation systems) is predictably difficult
because our mode! of the user includes a long-term memory that
is confused by similar meaningless items. These researchers have
sometimes used the term mental mode' to refer to the model that
they, as researchers, have of the user's mental architecture.
Similarly, software engineers have ideas about what the user
wants to do and how the system itself is structured that dictate
how they will program the system and how it will operate to serve
the users' needs. Engineers have mental models of their design.
This highlights another distinction, that between descriptive
and prescriptive representations. Researchers want to be able to
analyze what the user currently knows so they can explain why
he or she is having difficulty, which aspects are learned and which
are confused, and so on. In this case, they are using a descriptive
model, one that tells us what the user knows. Designers, however,
want to construct a mode! of what the user should know. This
representation could be used to analyze, for example, whether a
proposed system will be too difficult to learn or where the errors
might be. And, in designing commands and screen presentations,
designers would like to invoke a mode} in the user that fits the
dialog; they would like to get the user to build a mental model
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Representative terms from entire chapter:
mental models
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