Visualizations that were visually dense proved memorable, as did those that used many colors. Other results were more surprising.
“You’d think the types of charts you’d remember best are the ones you learned in school—the bar charts, pie charts, scatter plots, and so on,” Borkin says. “But it was the opposite.”
Unusual types of charts, like tree diagrams, network diagrams, and grid matrices, were actually more memorable.
“If you think about those types of diagrams—for example, tree diagrams that show relationships between species, or diagrams that explain a molecular chemical process—every one of them is going to be a little different, but the branching structures feel very natural to us,” explains Borkin. “That combination of the familiar and the unique seems to influence the memorability.”
The best type of chart to use will always depend on the data, but for designers who are required to work within a certain style—for example, to achieve a recognizable consistency within a magazine—the results may be reassuring.
“A graph can be simple or complex, and they both can be memorable,” explains Oliva. “You can make something familiar either by keeping it simple or by having a little story around it. It’s not really that you should choose to use one color or many, or to include additional ornaments or not. If you need to keep it simple because it’s the style your boss likes or the style of your publication, you can still find a way to make it memorable.”
At this stage, however, the team hesitates to issue any sweeping design guidelines for an obvious reason: memorability isn’t the only thing that matters. Visualizations must also be accurate, easy to comprehend, aesthetically pleasing, and appropriate to the context.
“A memorable visualization is not necessarily a good visualization,” Borkin cautions. “As a community we need to keep asking these types of questions: What makes a visualization engaging? What makes it comprehensible?”