Hypermedia presentations are not similarly constrained. Users can be provided with static and dynamic presentations and non-linear navigation facilities. One answer, that of basing the design primarily on the printed counterpart and intuitions, is what is found in most current hypermedia manuals. Another answer, the one we are pursuing in our research, is to develop a model of comprehension of machines from multimodal presentations and to use this model to drive the design of hypermedia manuals. The model we have developed views comprehension as a constructive process in which an individual uses prior knowledge, information presented in the external media, and skills of reasoning and visualization to build a mental model of a machine.
Comprehension proceeds in stages.
The first stage involves the decomposition of the machine's illustration into elementary visual units that represent various components. The second stage is that of constructing a static mental model of the machine. This involves various processes. One must internally represent the spatial relations that exist between components. Thus, this second stage involves building various kinds of representational and referential connections among visual and verbal information and prior knowledge.