Perception of content, structure, and presentation changes in Web-based hypertext

The Web provides access to a wide variety of information but much of this information is fluid; it changes, moves, and occasionally disappears. Bookmarks, paths over Web pages, and catalogs like Yahoo! are examples of page collections that can become out-of-date as changes are made to their components. Maintaining these collections requires that they be updated continuously. Tools to help in this maintenance require an understanding of what changes are important, such as when pages no longer exist, and what changes are not, such as when a visit counter changes. We performed a study to look at the effect of the type and quantity of change on people's perception of its importance. Subjects were presented pairs of Web pages with changes to either content (e.g., text), structure (e.g., links), or presentation (e.g., colors, layout). While changes in content were the most closely connected to subjects perceptions of the overall change to a page, subjects indicated a strong desire to be notified of structural changes. Subjects only considered the simultaneous change of many presentation characteristics as important.