I was asked on Twitter if I could clarify my views on text justification for conference posters, but decided I couldn’t come up with a good 140 character response. So here you go:
I recommend left-justified research posters for several reasons. First, I read in some typography/readability article (can’t find reference but will keep looking) that your brain subconsciously uses the ragged right edge to better gauge vertical reading position, allowing reader to more quickly travel through a paragraph. This matters less if you have good space between lines of text, but matters a lot if you’ve squished lines together to fit more on your poster (unfortunately, a very common scenario). Second, left-justified text has more predictable spaces within and between words, and that consistency makes sentences easier (faster) to read. Fully justified text can be especially awful when column widths are too small, and for smaller text boxes like figure and table legends. As an example of how awful those space problems can be, here’s an artificial dem on stration. These spacing issues are much bigger problems for people with dyslexia (20% of people, perhaps) and other reading disorders. That said, typesetting software such as InDesign have really good controls for minimizing the spacing problems of fully justified text. And some fonts (often the ones you have to actually purchase) are good at spacing themselves. Third, left-justified paragraphs suffer much less from the rivers and pigeonholes of white space that are sometimes created by full justification. These distracting visual elements are probably more of a problem for people or disciplines that are fond of big words, which coincidentally are those that love to have poster sessions. You can minimize rivers and pigeonholes by turning on automatic hyphenation, of course. In related news, Powerpoint doesn’t do auto-hyphenation, which makes it terrible for posters because you typically want to cram as much on a page as possible. Finally, errors in spaces between sentences (you just need one) are much easier to catch if you are using left justification.
But there are at least two reasons why you might reasonably ignore what I’ve written above. First, full justification looks so cool! If you want people to think you’re cool and professional, and you probably do, you might just go ahead and hit that button … because most viewers (and mentors, and poster judges) will also be similarly impressed. Unless they’re dyslexic, in which case they might hate you. A compounding problem is that justification looks cooler and cooler as you reduce font size … contributing to the word problem that plagues almost all conference posters. Second, there seems to be some research (again, I’m looking for citations I know I have somewhere) suggesting that full justification might increase a reader’s comprehension of the text. My guess is comprehension increases because one reads it more slowly. Changing the font every sentence might also increase comprehension in the same way, though I don’t recommend doing that. (Hyphenated paragraphs take longer to read, too.)
By the way, don’t center-justify text in figure legends and table captions. Many prestigious journals use centered text in this way, but I think they’d change to left justification if they could do so without admitting to prior foolishness.
As an aside, I recently purchased a Kobo eReader because I can specify left-justification. I couldn’t do that with my Kindle. I can also now read while floating in a pool (my Kobo is waterproof).
If for some reason the above didn’t bore you, please see more of the same at Designing conference posters. Drop me a note if you have actual data for any of the above speculation.