The role of extrafoveal vision when interpreting boxplots

Abstract Boxplots are widely used in descriptive statistics but they are challenging to learn. Particularly the interpretation of the box area often leads to a systematic error, the area bias, when students assume a proportional relation between area and frequency, while the box area represents the interquartile range and thus a measure of variability. By analyzing eye-tracking data, research was able to identify systematic differences in gaze patterns depending on the assumed solution strategy that was used by an individual. While previous studies suggested—based on initial results—that extrafoveal perception and simultaneous processing might occur when boxplots are displayed in close spatial proximity, this aspect has not been the focus of systematic investigation so far. In the present study, we therefore test whether the application of a schema leads to fewer transitions between and fewer, but on average longer fixations on schema-relevant areas when the boxplots are in closer proximity. $N= 27$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>N</mml:mi> <mml:mo>=</mml:mo> <mml:mn>27</mml:mn> </mml:math> university students participated in the study. Eye movement data were collected and evaluated in a generalized linear mixed model. Differences in line with the hypotheses regarding the number of transitions and the number of fixations were found for some but not all schemas. The findings provide initial indications that some, but not all, boxplot components may be perceived extrafoveally and processed simultaneously.