Kasper Hornbaek, Erik Frøkjær
Reading electronic documents has become deeply integrated with the everyday activities of many people. Yet, reading electronic documents is complicated by a number of problems, including cumbersome navigation, lower tangibility of electronic documents compared to paper, unclear awareness of the length of documents, and lower reading speed caused by the poor resolution of most screens.
To study and develop better support for reading, we designed two information visualization interfaces for electronic documents. One interface shows an overview of the entire document alongside the detailed content. The other interface is a so-called fisheye interface, which collapses parts of the document that typically receive the least attention in order to facilitate an overview-oriented reading style and quick navigation. It was unclear, however, if these interfaces change how documents are read and whether the interfaces are more useful than a baseline, linear interface. To investigate that, 20 subjects were asked to read scientific documents and then write essays and answer questions about them.
To understand reading patterns, we introduced progression maps that illustrate the progression of the subjects' reading activity, and visibility maps that show how long different parts of the document are visible. These maps show that with the overview interface, subjects use the overview for jumping directly to interesting parts of the document and to already-visited parts of the document. However, subjects are slower at answering questions with the overview interface. From the visualizations of the reading activity, we find that subjects using the overview interface often explore the document further even when a satisfactory answer to a question has already been read. Thus, overviews may grab subjects' attention and possibly distract them.
With the fisheye interface, reading patterns show that subjects use more time on gaining an overview of the document and less time on reading the details. Thus, they read the documents faster, but afterwards made more errors in answering questions about the content of the document. We also show how subjects only briefly have visible the parts of the document that are initially collapsed in the fisheye interface, even though they express a lack of trust in the algorithm underlying the fisheye interface.
Our studies of reading patterns show that reading is profoundly changed with the information visualization interfaces. Consequently, further improvement of visualization of electronic documents is feasible, as are further use of progression and visibility maps to study and improve reading activity.
We find the most common form of electronic documents, the linear interface, inferior in usability compared with the overview and the fisheye interfaces. With the overview interface, for example, subjects get higher grades for their essays. Subjects also strongly prefer the overview interface. With the fisheye interface, subjects read documents faster. Information visualization interfaces are thus recommended to developers as usable interfaces for electronic documents.
By Kasper Hornbæk
Natural Sciences ICT Center
University of Copenhagen, Denmark
By Erik Frøkjær
University of Copenhagen, Denmark
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Figure 2. In progression maps, the horizontal axis shows time elapsed since the beginning of the task. On the vertical axis we plot the position within the document of the top line that the user can see; to the left is shown an overview of the contents of the document. At the top of the figure are indicated three reading modes, where reading follows different patterns: in initial orientation mode, subjects navigate nonlinearly through the document ; in linear read-through mode, subjects read through the document linearly from beginning to end, with occasional skips forwards and backwards; in review mode, subjects revisitnonlinearlywhat they presumably felt were the most important sections in the document.
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