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The theory explored by this experiment is that the smooth motion provided by zooming gives the user cues that help navigate the Pad++ presentation. However, the nature of the cues was not considered in detail. Darken and Sibert (1996) have researched the navigation of large virtual spaces, with their treatments being based on the presence or absence of virtual world design principles. Their work is based on the use of map and other information to navigate a virtual world that mimics 12,000 square kilometers of physical space, so it is not directly applicable to our work with Pad++. However, it is based on a theory of spatial knowledge that can potentially be applied to zooming interfaces. This theory organizes information into the following hierarchy:
This model of spatial knowledge can be used to improve the measurement of information retention.
In addition, our experiment examined a fixed task, so we were unable to determine whether the payoff from zooming interfaces increases as task complexity increases. It is worth considering task complexity as a second independent variable and doing a factorial design and using two way ANOVA. However, to do this we need to determine what the best way of measuring complexity is. We don’t have answers to this question, but it is important to consider that the complexity of a presentation using zooming interface such as Pad++ should not necessarily be measured in the same way as it would be when using a traditional window-based interface such as Netscape.