| Visualizations of Web spaces may provide users the ability to identify relevant information from a set of Web pages, while gaining new insights or understanding of the space. A survey of existing Web visualization techniques suggested a taxonomy, which divides the techniques into four categories: distortion, three-dimensional layout, zoom, and expanding outline. This study tested three classes of visualization techniques (distortion, zoom, and expanding outline) to better understand which visualization techniques may better represent the underlying structure. The effects of different visualization techniques on user performance on information searching tasks, and the effects of different sizes of the Web spaces were studied. User mental models induced by different Web visualizations were also examined.; It was found that when users are not familiar enough with the visualization tools, the tools caused cognitive overloads and failed to augment users' performance. Improved performance was found with the expanding outline tool, which presented the most familiar interface to users, as compared to the other tools. Improved performance was also found with the small Web spaces over the large Web space. Subjects' mental models of the space were not affected by the visualization tool and the size of the Web space. The factors that caused cognitive overloads need further study, as well as other related topics such as visualization of search results, interactive visualization, and larger space visualization. |
