Scientists' and non-scientists' mental representation of scientific diagrams

Diagrams are an ubiquitous means of depicting information. As well as being a valuable professional tool for both thinking and communicating, diagrams are widely used to help students learn various disciplines. However, in this context diagrams are used not only with the expectation that they will enrich the students’ knowledge of the discipline, but also with the assumption that diagrammatic information is inherently easier to process than other presentations. This research arose from theoretically motivated doubts about the capacity of those without expertise in a particular discipline to process diagrams more easily than other presentations. It was set within the general expert-novice framework and based upon a theoretical position that diagram processing is not driven directly by the diagrammatic data but rather is mediated by an individual’s mental representation of those data. It gauged the processing capability of those without discipline expertise by comparing the way professional scientists represented diagrams mentally with the way they were represented by non-scientists. The scientists and diagrams used as illustrative examples in this research were professional meteorologists and weather maps respectively. If nonscientists’ mental representations of given diagrammatic material differ with regard to important fundamentals from those of scientists, they may not be able to process the material effectively without considerable support. The results indicated fundamental differences between the way diagrams were represented mentally by the scientists and non-scientists. The nature and extent of these differences indicated that the non-meteorologists lacked a suitable basis for processing the diagrams in a way that would help them learn about the discipline. Their mental representation was impoverished, fragmentary and mainly based upon superficial visuospatial characteristics of weather map diagrams’ pictorial constituents. It was largely without the fundamental domain-specific meteorological dimension that was the basis of the scientists’ mental representation and was lacking in organisation, detail and scope. Whereas the scientists’ mental representation set the information from a particular weather map diagram in a much broader temporal and spatial meteorological context, the non-scientists’ mental representation was limited to the particular diagram under consideration and lacked the scientists’ highly interrelated and hierarchical structure between different types of information. This research shows that the task of processing diagrams may not be as different from the task of processing other types of presentation as might be supposed. It indicates that as with other forms of presentation such as text and mathematics, individuals lacking experience in a discipline will have a limited capacity to make effective use of diagrammatic presentation. An inference from this research therefore is that diagrams cannot be regarded simply as an alternative form of presentation that is easier to process than other modes. Rather, the indications are that specific instructional support for students would be required with regard to the context, subject-matter principles and type of organisational structure that are the basis of the types of diagram which characterise a particular discipline. An improved realisation of the instructional potential of diagrams would require a change from the largely informal and somewhat haphazard manner by which students typically learn how to use diagrams at present, to more formal and systematic approaches. The development of such approaches requires further research to increase understanding of the nature of diagram processing and determine how this understanding may be translated into effective pedagogical strategies