Storytelling and Visualization

Memory refers to the faculty by which things are remembered; the capacity for retaining, perpetuating, or reviving the thought of things past according to the Oxford English Dictionary. Memorability is an important goal of storytelling. A good visualization technique engages the viewer's attention and increases a story's memorability.

All papers in this section evaluate the effects of visualization on memorability. Bateman et al.  explore the effects of embellishment on comprehension and memorability. Saket et al. illustrate that map-based visualization can improve accuracy of recalled data comparing with node-link visualization.

Borkin et al. develop an online memorability study using over 2000 static visualizations that cover a large variety of visualizations and determine which visualization types and attributes are more memorable. They investigate a domain at the interface between human cognition and visualization design.

A visualization taxonomy classifies static visualizations according to the underlying data structures, the visual encoding of the data, and the perceptual tasks enabled by these encodings. It features twelve main visualization categories and several popular sub-types for each category. Borkin et al. run memorability tests via Amazon's Mechanical Turk with 261 participants and gather memorability scores. The result in memorability comparison test demonstrates that there is memorability consistency with scenes, faces, and also visualizations, thus memorability is a generic principle with possibly similar generic, abstract features. The result in visualization attribute tests illustrates that higher memorability scores were correlated with visualizations containing pictograms, more color, low data-to-ink ratios, and high visual densities.

Borkin et al. show that visualizations are intrinsically memorable with consistency across people. Visualizations with low data-to-ink ratios and high visual densities (i.e., more chart junk and "clutter") were more memorable than minimal, "clean" visualizations.

Memorability for Linear Visualization

The literature here shows and tests visual designs in linear order. Users are asked to compare the visual designs (e.g., standard bar charts) verses embellished bar charts. In other words, users are tested on their ability to recall one visual design at a time in linear fashion.

Bateman et al. examine whether embellishment is useful for comprehension and memorability of charts. Bateman et al. compare plain and embellished charts, and conclude that a user's accuracy in describing the embellished charts is no worse than for plain charts and that their recall after a two-to-three week gap is significantly better.

Fourteen embellished charts are selected from Nigel Holmes' book Designer's Guide to Creating Charts and Diagrams, and converted to plain charts. See Figure 30. Twenty participants are presented a chart on a slide, alternating between embellished and plain versions. Participants are required to perform two tasks (reading and describing task and recall task) after five-minutes and after 2–3 weeks. The eye-gaze and task performance of participants are recorded for analysis. This study shows that there is no significant difference between plain and embellished versions for interactive interpretation accuracy and recall accuracy after a five-minute gap, but after a long-term gap, recall of both topic and detail of chart (categories and trend) is significantly better for embellished charts. Participants saw the value in message more often in Holmes' charts than in the plain charts.

Figure 30. Bateman et al. compare two different levels of graphical embellishment of the same data. The top graph is an embellished image but still retains the recognisable features of a bar chart. The bottom image replaces the bars with a silhouette of a person next to a drink where the height of the drink corresponds to the height of the original bar. This method also uses the addition of color to emphasize the data.

Previous studies have suggested that minor decoration in charts may not hamper interpretation, and work in psychology has shown that the use of imagery can affect memorability, but there is very little work that looks at how chart imagery can affect the way people view information charts.

Borkin et al. present the first study incorporating eye-tracking as well as cognitive experimental techniques to investigate which elements of visualizations facilitate subsequent recognition and recall. They design a three-phase experiment (See Figure 31) and evaluate the performance of recognition and recall. The conclusion includes visualizations with more memorable content can be memorable 'at-a-glance'. Titles and text are key elements in a visualization and help recall the message. Pictograms do not hinder the memory or understanding of a visualization. Redundancy facilitates visualization recall and understanding.

Figure 31. Borkin et al. design three-phase experiment to evaluate viewer performance of recognition and recall.

Borkin et al. is based on previous work on perception and memorability of visualization and eye-tracking evaluation visualization.

Memorability for Parallel Visualization

In this subsection, users are presented with a large number of relation data in parallel (as opposes to one at a time). Users are tested on their ability to process relationship data in parallel (all relationships simultaneously). This is distinct from memorability for linear visualization where recall focuses on one visual design at a time in linear order.

Saket et al. illustrate that different visualization designs can effect the recall accuracy of data being visualized. Compared to a node-link diagram, a map-based visual design is more effective.

Two datasets are examined. A book dataset (small) and LastFM dataset (large) are transformed into a node-link diagram and node-link group (map-based). See Figure 32. Three phrases are performed to examine the difference between node-link diagram and map-based visualization. In phase 1 participants examine two kinds of visual design without task with unlimited time. Phase 2 asks participant to study two kinds of visualization with six tasks in a required time. Phase 3 asks participants to recall what they read in phase 1 and 2, complete 6 tasks similar to phase 2, and 3 new addition tasks. The result of the experiment illustrates that recalling map-based diagrams is more accurate than recalling node-link diagrams, but no faster. The participants spent more time on map-based visualizations than node-link visualizations.

Figure 32. Saket et al. show two visualization of the same data: node-link diagram and map-based diagram.

Saket et al. is based on previous work of visualization memorability and a recalling experiment.