Intra, Extra, Read all about it! How Readers Interpret Visualizations with Intra- and Extratextual Information

A reader’s interpretation of a visualization is informed by both intratextual information (the information directly represented in the visualization) and extratextual information (information not represented in the visualization but known by the reader). Yet, we do not know what kinds of intra- and extratextual information readers use or how they integrate it to form meaning. To explore this area, we conducted semi-structured interviews about four real-world visualizations. We used thematic analysis to understand the types of information that participants used and diffractive reading to reveal how participants blended intra- and extratextual information. Our thematic analysis showed that participants utilized a broad assortment of information from both expected and unexpected sources. Additionally, our diffractive reading exposed three ways that participants incorporated intra- and extratextual information: to decide what to look at, to make (in)accurate assumptions about what the visualization showed, and to discover insights beyond what was directly encoded.