Mike Scaife, Yvonne Rogers
The importance of considering external cognition in relation to internal cognitive processing is increasingly acknowledged. Adopting this stance, we examine the interplay between external and internal representations in terms of the value of various graphical representations (GRs) in mediating problem-solving and learning tasks. The objective of our analysis is to outline the relevant theoretical questions that need to be addressed in understanding the way GRs work. We present a detailed analysis of studies that have investigated cognitive processing for both 'good old-fashioned' GRs (diagrams) and more advanced technological representations (animations and virtual reality). A number of assumptions and fallacies are exposed, revealing a largely fragmented and poorly-understood account of how GRs work. We discuss alternative, theoretically-grounded characteristics that we take to be central to an understanding of the internal/external relationship of representations whilst also being of practical application to graphical design. These include computational offloading, re-representation, graphical constraining and interactivitity. Finally, we offer an analysis of advantages and disadvantages for different forms of GR.
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