Some representations are better than others, as shown by research in cognitive psychology. Studies of knowledge representation usually start with performance on some cognitive task and try to determine the kind of representation--whether it is linguistic, spatial, propositional, or whatever. A different approach is to start with the representation and see how it affects performance. The representation is literally given to participants--in the form of a chart, tree diagram, etc. The representations are varied, and hence the name alternative representations.
Research on alternative representations has shown that certain representations are better than others for certain everyday cognitive tasks, such as interpreting a bus schedule and determining which prescription medicine to take when (Day, 1988). Different kinds of representation may be more effective for persons of differing personalities (Albu, Toma, & Pitariu, 1998). This suggests that learning alternative ways of representing knowledge could be a valuable practical skill.
One practical test of what comprises a good representation of, say, a journal article would be whether it allows one to give an impromptu speech on the topic in question, perhaps taking sides for or against a particular position. Here is a variety of kinds of alternative representations, arranged in (what experience suggests to be) approximate descending order of usefulness for a situation similar to giving an impromptu speech.
- Flow charts, often used by debators, are excellent tools for representing arguments in which there are initial positions, responses, and rejoinders.
- Maps can show not only how to get from place to place but also from concept to concept.
- Structural models are a very sophisticated kind of graph useful for representing correlational and covariance structures.
- Graphs and tables can be used to integrate many different kinds of variables.
- Logical syllogisms and their associated Venn diagrams, the favorites of philosophers, have an important place in representing exact conceptual relations.
- Hypertext networks allow users to traverse great bodies of information in the order of the users' interests. Such networks can be hierarchically organized, as in a tree, but numerous other possible organizations exist. Yielding information on an as-needed basis is this medium's strength.
- Tree diagrams are quite good for chunking information and representing it non-sequentially.
- Outlines are good for chuncking information and representing it sequentially.
- Questionnaires and exams can put abstract concepts into concrete form but only provide data in need of explanation rather than explaining anything themselves.
- Lists are a bit better than text but are probably only satisfactory if the number of items is equal to or less than the "magic number" seven plus or minus two.
- Text is almost never the optimal kind of representation if one cannot make continuous reference to the text, either by reading it or rehearsing it in memory.