Advances in graphical technology have now made it possible for us to interact with information in innovative ways, most notably by exploring multimedia environments and by manipulating 3-D virtual worlds. Many benefits have been claimed for this new kind of interactivity, a general assumption being that learning and cognitive processing are facilitated. We point out, however, that little is known about the cognitive value of any graphical representations, be they good old-fashioned (e.g. diagrams) or more advanced (e.g. animations, multimedia, virtual reality). In our paper, we critique the disparate literature on graphical representations, focussing on four representative studies. Our analysis reveals a fragmented and poorly understood account of how graphical representations work, exposing a number of assumptions and fallacies. As an alternative we propose a new agenda for graphical representation research. This builds on the nascent theoretical approach within cognitive science that analyses the role played by external representations in relation to internal mental ones. We outline some of the central properties of this relationship that are necessary for the processing of graphical representations. Finally, we consider how this analysis can inform the selection and design of both traditional and advanced form of graphical technology.

Scaife and Rogers review in this article literature on the use of graphical representations in educational environments. The authors argue that despite the vast body of empirical studies in the field little is known about why and how graphics facilitate learning.
The authors have found many shortcomings of empirical studies on graphical representation: assumptions merely based on intuition, lack of integration of theoretical concepts, non-systematic analyses. They distinguish between static diagrams, animations and virtual realities. Static diagrams often depend on prior knowledge about conventions and icons, e.g. diagrams of electronic circuits use a very specific notation. Animations tend to arrest the learners’ attention and thus distract them from verbal explanations. Virtual reality represents the real-world in a very realistic way but often lacks natural interactivity. Moving real-world objects is fairly different from moving an object using a joystick.
To ameliorate the situation the authors propose an analytic framework consisting of three characteristics of graphical representations:

1. computational offloading: graphics reduce the learners’ cognitive load, the "knowledge in the world" needs not to be memorized by the learner,
2. re-representation: graphics represent abstract structures in a way that is easier to comprehend, and
3. graphical constraining: graphics constrain the number of options in problem-solving tasks.

Another deficiency of empirical studies is that their findings fail to benefit the designers of educational material. The results are too specific to be generalized and used in another context. The authors deduce several design rationales from the reviewed literature: explicitness, visibility, cognitive tracing, interactivity, et cetera. Cognitive tracing for example means offering learners annotate and highlight graphical representation, trivial for diagrams but a challenge for virtual reality. Scaife and Rogers provide a useful overview on the use of graphical representations in educational environments and outline a sound theoretical framework. They illustrate potential benefits of graphics and criticise overestimation of virtual reality. However, they are not critical enough concerning static diagrams. For example the benefits of diagrams in geometry exercises might result from hidden clues in the diagram or constraints that are not expressed in the verbal version. [from http://www.elearning-reviews.org/]