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 ... )
Comerford, Doreen, "Knowledge Structures: An End to the Redundancy And the Confusion" (1997). Link Foundation Modeling, Simulation and Training Fellowship Reports. 44.