Visual foraging of highlighted text: an eye-tracking study
The wide availability of digital reading material online is causing a major shift in everyday reading activities. Readers are increasingly skimming instead of reading in depth. Highlights are increasingly used in digital interfaces to direct attention toward relevant passages within texts. In this paper, we study the eye-tracking behavior of subjects using both keyword highlighting and a new highlighting technique called ScentHighlights, introduced recently . In this first eye-tracking study of highlighting interfaces, we show that there is direct evidence of the von Restorff isolation effect  in the eye-tracking data, in that subjects performed better when a fact is isolated (highlighted) against a homogeneous background. Users with the ScentHighlights condition paid more attention to highlighted areas and are more accurate than with other interfaces. In addition to confirming the von Restorff effect, we found that there is great variation in subject differences in reading strategies among subjects, even in the presence of strong cues such as highlights. Some readers scan for highly profitable regions first, while others read sequentially despite the presence of strong highlight cues. The results point to future design possibilities in highlighting interfaces.
Chi, E. H. ; Gumbrecht, M. ; Hong, L. Visual foraging of highlighted text: an eye-tracking study. In Proceedings of 12th HCI International Conference; 2007 July 22-27; Beijing, China. Berlin: Springer; 2007; LNCS 4552: 589--598.