Which Factors Determine Visual Scanning Strategies?

One of the most important question in modeling
visual attention is how the parameters of the
visual scene influence the visual scanning pattern
of the viewer. Despite the high variability of
scan paths, some basic regularities can be found.
I use the paradigms of comparative visual search
and visual tagging to investigate these 
regularities. Effects of color and form entropy
and item density are found and incorporated in
two different models of comparative search behavior.
The first approach is a simple random-walk model,
and the second one is a more adequate three-level
model of comparative visual search.