A graph reading behavior: Geodesic-path tendency

The end result of graph visualization is that people read the graph and understand the data. To make this effective, it is essential to construct visualizations based on how people read graphs. Despite the popularity and importance of graph usage in a variety of application domains, little is known about how people read graphs. The lack of this knowledge has severely limited the effectiveness of graph visualizations. In attempts to understand how people read graphs, we previously observed that people have geodesic-path tendency based on subjective eye tracking data. This paper presents two controlled experiments. One is to approve the existence of the geodesic-path tendency. The other is to examine the effects of this tendency on people in reading graphs. The results show that in performing path search tasks, when eyes encounter a node that has more than one link, links that go toward the target node are more likely to be searched first. The results also indicate that when graphs are drawn with branch links on the path leading away from the target node, graph reading performance can be significantly improved.