IEEE VIS 2024 Content: What Does the Chart Say? Grouping Cues Guide Viewer Comparisons and Conclusions in Bar Charts

What Does the Chart Say? Grouping Cues Guide Viewer Comparisons and Conclusions in Bar Charts



 Chase Stokes -

 Andrew Lovett -

 Steven Franconeri -

 DOI: 10.1109/TVCG.2023.3289292

 Room: Bayshore II

2024-10-16T18:45:00ZGMT-0600Change your timezone on the schedule page
2024-10-16T18:45:00Z

Exemplar figure, described by caption below — When designing simple bar charts depicting the revenue of two companies A and B in two regions East and West, one can group the bars spatially by company such that West A and East A are closer together, and West B and East B are close together. One can also add color to the bars, such as coloring the two A bars the same color, and the two B bars the same color. We compared the spatial proximity cue against the color cue, and found people to prioritize the spatial proximity cue when making comparisons. That is, they are more likely to group bars that are next to each other, even if they have different colors, to be compared to bars further away. They are less likely to group bars that further away from each other even if they have the same color.

Fast forward

Keywords

comparison, perception, visual grouping, bar charts, verbal conclusions.

Abstract

Reading a visualization is like reading a paragraph. Each sentence is a comparison: the mean of these is higher than those; this difference is smaller than that. What determines which comparisons are made first? The viewer's goals and expertise matter, but the way that values are visually grouped together within the chart also impacts those comparisons. Research from psychology suggests that comparisons involve multiple steps. First, the viewer divides the visualization into a set of units. This might include a single bar or a grouped set of bars. Then the viewer selects and compares two of these units, perhaps noting that one pair of bars is longer than another. Viewers might take an additional third step and perform a second-order comparison, perhaps determining that the difference between one pair of bars is greater than the difference between another pair. We create a visual comparison taxonomy that allows us to develop and test a sequence of hypotheses about which comparisons people are more likely to make when reading a visualization. We find that people tend to compare two groups before comparing two individual bars and that second-order comparisons are rare. Visual cues like spatial proximity and color can influence which elements are grouped together and selected for comparison, with spatial proximity being a stronger grouping cue. Interestingly, once the viewer grouped together and compared a set of bars, regardless of whether the group is formed by spatial proximity or color similarity, they no longer consider other possible groupings in their comparisons.