Local Density Guides Visual Search: Sparse Groups Are First and Faster

Visual search in an important aspect of many tasks, but it not well understood how layout design affects visual search. This research uses reaction time data, eye movement data, and computational cognitive modeling to investigate the effect of local density on the visual search of structured layouts of words. Layouts were all-sparse, all-dense, or mixed. Participants found targets in sparse groups faster, and searched sparse groups before dense groups. Participants made slightly more fixations per word in sparse groups, but these were much shorter fixations. The modeling suggests that participants may have attempted to process words within a consistent visual angle regardless of density, but that they were more likely to miss the target if the target was in a dense group. Furthermore, it was found that the participants tended to search sparse groups before dense groups. When combining densities in a layout, it may be beneficial to place important information in sparse groups.