What makes an infographic successful? As designers, we want it to achieve a balance of two main things:

• Did the reader get the message we wanted them to get?
• Was the message memorable?

Doctoral student Michelle Borkin of Harvard's School of Engineering and Applied Sciences worked with collaborators to collect, analyze and present 2,070 single-panel visualizations from a range of publications and websites.

In the “largest scale visualization study to date,” they asked, “What Makes a Visualization Memorable?”

Caveat

Memorability is very important, but still just half the recipe.

The researches did not look at how well viewers understood the images, just how well they remembered them. Borkin’s next steps are to measure comprehension: that new study is already in progress.

This study represents the first step in their research, as they explore what makes an effective infographic, but it already raises questions about what designers have believed so far.

What they did

First, the team created a "visual taxonomy" of the images, identifying them by qualities like chart types, number of colors and presence of human-recognizable objects. They also classified attributes like the presence of non-essential decoration and “visual density” (a.k.a. clutter).

"Redesign Your Place" infographic designed for DMC Bologna, by Jacopo Ferretti

Then they chose 410 images that evenly represented the range of their sources (like news, science and the infographics site, visual.ly) as well as the range of qualities they’d identified. Using that group, they ran an online experiment (using Amazon’s Mechanical Turk) in which participants watched a stream of images and clicked a button whenever they saw one they believed had been shown before.

What they learned

To the surprise of the researchers, bar graphs and charts did poorly. It turns out (news flash) they all kinda look the same. The most memorable images contained "human recognizable objects." Think mundane stuff like photos or illustrations of bottles, animals and shoes, not to mention people.

"Who is Occupy Wall Street" infographic created for Fast Company, by Jess3

Other important points:

1. Color made a huge difference: the more, the better.
2. Images with more clutter were highly memorable. How much more memorable? A lot.
3. Images with lots of circles and rounded corner graphics also ranked high.

More about clutter

Plenty of psychology lab studies show that simple and clear visualizations are easier to understand. However, researchers have also found that “chart junk” (a term coined by Edward Tufte, so important it gets its own Wikipedia entry) can improve retention because it forces us to work harder at understanding a graph, resulting in better comprehension.

Again, understanding what makes an infographic memorable is only the first step to creating more effective presentations. According to Borkin, “Making a visualization more memorable means making some part of the visualization ‘stick’ in the viewer’s mind.” She emphasizes that we also need to learn how to make sure that what sticks is our intended message, and not the eye candy.