design principles in infovis

In an attempt to organize my thoughts, here are several principles to consider when designing visualizations for specific task types.

1) Information scent - How does the user know how to find the information he seeks? What directs his browsing choices? How does he know what to look for? How does he know when he's found it?

2) Cost structure - How do we optimize the cost of knowledge access? How do we make commonly needed information immediately accessible to the user?

3) Information density and the useful field of view (UFOV) - What is the locus of attention? How much information can be processed within a given area? When looking at a tree of information, the UFOV depends on the nature of the task. If the task is to answer a question about the tree's structure, the UFOV might be the whole tree or a certain sub-tree. If the task is to answer a question about a tree node's attributes, the UFOV should be centered on the node itself.

4) Navigation/browsing - What actions does the user have to take to retrieve information? Is this done in the simplest way possible? Is the act of navigation too intrusive? Does it strain the user's cognitive abilities? Is the user forced to recall information, or can they simply recognize it in the interface?