Trajectories of Search - Mapping Scientific Frontiers: The Quest for Knowledge Visualization - page 153

Fig. 4.7 Legend for the visualization of foraging tails

center. If the user marks a document as relevant in a search session, this document
will be colored in blue. Upon the user visits a document, a dark circle is drawn
around the current document. The time spent on a document is denoted by a growing
green belt until the user leaves the document. If the user comes back to a previously
visited document, we will see a new layer of dark circle and an additional layer of
green belt will start to be drawn. One can choose to carry these discs grown from
one task into the next task and a red disc indicates how long the user has spent on it
in the previous task.
We expect to observe the following patterns concerning users' navigation
strategies:
Spatial-semantic models may reduce the time spent on examining a cluster of
documents if the spatial-semantic mapping preserves the latent semantic structure.
Spatial-semantic models may mislead information foragers to over-estimate the
profitability of a cluster of documents if the quality of clustering is low.
Once users locate a relevant document in a spatial-semantic model, they tend to
switch to local search.
If we use the radius of disc to denote the time spent on a document, the
majority of large discs should fall in the target area in the thematic spaces. Discs
of subsequent tasks are likely to be embedded in discs of preceding tasks.

4.1.5 Trajectories of Users

Because of the superior performance results with MST-based interfaces, we restrict
our discussions to navigation strategies associated with the use of the MST version
of the ALCOHOL thematic space. Figure 4.8 shows an overview map of the
ALCOHOL space. Documents relevant to Task A are marked with bright yellow
dots in the center. All the relevant documents are clustered in the branch located at
the lower right hand corner of the map, with the exceptional documents number 63