Constrained Highlighting in a Document Reader can Improve Reading Comprehension

Highlighting text in a document is a common active reading strategy to remember information from documents. Learning theory suggests that for highlights to be effective, readers must be selective with what they choose to highlight. We investigate if an imposed user interface constraint limiting the number of highlighted words in a document reader can improve reading comprehension. A large-scale between-subjects experiment shows that constraining the number of words that can be highlighted leads to higher reading comprehension scores than highlighting nothing or highlighting an unlimited number of words. Our work empirically validates theories in psychology, which in turn enables several new research directions within HCI.