Knowledge Structures: An End to the Redundancy And the Confusion
Abstract
Situation awareness (SA) is most commonly defined as "the perception of the
elements in the environment within a volume of time and space, the comprehension of
their meaning, and the projection of their status in the near future" (Endsley, 1995, p.
36). While researching this construct, we were continuously faced with several terms
that, like SA, have themselves never been uniformly defined. For example, the
following terms have, in some way, been associated with the construct known as SA:
device model, domain model, mental model, script, schema, and "the picture" among
others (c.f., Mogford, 1994; Endsley, 1995; Garland & Hopkin, 1994; Fracket~ 1988).
These terms not only appear to be related to SA, but at an intuitive level they appear to
be related to one another. How they are related to one another and how they are
different from one another has yet to be plainly stated.
Ultimately, in order to understand the construct called SA, two courses of action
must be taken: (1) terms such as those presented in the list above must be properly
defined, and (2) SA should be examined in relation to these constructs only after this
first action has been carried out. The present paper is an attempt at the first order of
action. It is apparent within the literature pertaining to SA, the human factors literature
in general, and psychology literature as a whole that many of the aforementioned terms
are overused, confused, and misused. In addition, many of the ideas associated with
each of these terms are unnecessarily redundant. Perhaps the lack of communication
between the branches of psychology is responsible for much of this disarray. In the
following attempt to define terms like those listed above, literature from several areas
Knowledge Structures
within psychology is represented. In not limiting the ideas to those of the human
factors community, the commonalities and distinctions among these terms might
become more apparent, and the reader might be able to obtain "the big picture"
(whatever that might be).
Unlike SA, the constructs which will be explored here are not novel to the field of
psychology. In fact, some date back to the first half of the century (e.g., Bartlett, 1932).
However, to date, the literature has never been compiled in a single document. There
have been a few attempts at discussing and distinguishing two of these constructs. For
example, Brewer (1987) attempted to distinguish schemata from mental models, and
Wilson and Rutherford (1989) touched on the same distinction. Although the
distinction between schemata and mental models is important, there are many other
constructs which present difficulty (e.g., the frame vs. the schema, the script vs. the
schema, etc ... ). Therefore, a document which summarizes these ubiquitous constructs
might be beneficial to all, in that it might improve communication. In the following
pages then, the following constructs will be explored in terms of their similarities and
differences: schema, mental model, frame, script, plan and prototype. Other terms will
also be addressed where appropriate (e.g., perceptual set, domain model, motor
schema, etc ... )