Reading patterns and usability in visualizations of electronic documents

Abstract

We present an exploration of reading patterns and usability in visualizations of electronic documents. Twenty subjects wrote essays and answered questions about scientific documents using an overview+detail, a fisheye, and a linear interface. We study reading patterns by progression maps that visualize the progression of subjects' reading activity, and by visibility maps that show for how long different parts of the document are visible. The reading patterns help explain differences in usability between the interfaces and show how interfaces affect the way subjects read. With the overview+detail interface, subjects get higher grades for their essays. All but one of the subjects prefer this interface. With the fisheye interface, 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 display lower incidental learning. We also show how subjects only briefly have visible the parts of the document that are not initially readable in the fisheye interface, even though they express a lack of trust in the algorithm underlying the fisheye interface. When answering questions, the overview is used for jumping directly to answers in the document and to already-visited parts of the document. However, subjects are slower at answering questions with the overview+detail interface. From the visualizations of the reading activity, we find that subjects using the overview+detail interface often explore the document further even when a satisfactory answer to the given question has already been read. Thus, overviews may grab subjects' attention and possibly distract them.