The pros of bullet lists is that by their nature, people tend to write less text. That concision is very useful on a poster, I admit.
But I want to argue there are more negatives to using bullets that positives.
First, my experience with looking at PowerPoint slides is that people are inconsistent in how they type bullet lists. For example, people often punctuate some bullet points with a period, but leave others without a period. When people write sentences in paragraphs, they will put a period at the end of every sentence.
Second, the size and spacing of bullet points is often badly done in software. Even PowerPoint, the culprit that made bullets ubiquitous, doesn’t scale well when you move outside of the standard slide sizes. Here’s a quick mock-up for a four foot wide poster with a bulleted list (click to enlarge):
Under this default scheme, the bullets are too far from the text. The spacing between lines and points is also a little dodgy. Microsoft Publisher, which I use a lot for posters, handles bullets even more poorly.
Third, bullets destroy narrative. Edward Tufte has made a thorough analysis (from The Cognitive Style of PowerPoint, excerpt quoted here):
Lists can communicate three logical relationships: sequence (first to last in time); priority (least to most important or vice versa); or simple membership in a set (these items relate to one another in some way, but the nature of that relationship remains unstated). And a list can show only one of those relationships at a time.
Bullet lists may be more concise, but they are impoverished compared to sentences in paragraphs. Sentences can express many more relationships.
Fourth, readers are trained to read sentences in paragraphs. It is the most common thing we read, and is how we expect to absorb complicated ideas.
This is not to say that bulleted lists are useless. They are completely appropriate for short lists. A poster, though, should be more than just short lists. For example, I feel okay about using a bulleted list for a quick summary of my case again bullet points:
- Bullets are used inconsistently
- Bullets are poorly typeset
- Bullets show relationships poorly
- Readers are used to sentences
I don’t think I would convince anyone of my argument if that list were all I posted.
The Zen of Presentations, Part 41: Consistency
Photo by David Stillman on Flickr; used under a Creative Commons license.