Two-level artificial-landmark scrollbars to improve revisitation in long documents

Navigating to previously-visited pages is a trivial yet fundamental task in linear control-based document viewers. These widgets e.g., scrollbars often do not work well particularly for long documents. Existing solutions try to tackle this issue with bookmarks, search, history, and read wear but limited in terms of effort, clutter, and interpretability. To improve the revisitation support in long documents, we investigated the use of artificial landmarks similar to the visual augmentations available in physical books: coloring on page edges or indents cut into pages. We developed several artificial-landmark visualizations to represent page-locations in the scrollbar for many hundreds of pages long documents, and tested them in studies where participants visited multiple locations in long documents. Results indicate that using two columns of landmark icons significantly improved revisitation performance and preferred by users. Our two-level artificial-landmark augmented scrollbars can be a new way to support spatial memory development of long documents - and can be used either in isolation or in congregation with current techniques.