Category Archives: Science


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:

fabric-postersI 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.

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Insects from Gambier, Ohio

I spent a few hours over the weekend taking photographs at Kenyon College’s Brown Family Environmental Center in Gambier, Ohio. It was fun to be back in the area — I spent a good chunk of my childhood in Granville, Ohio, about 45 minutes away.

1. Robber fly (Asilidae; probably Dioctria hyalipennis). I watched it for awhile but didn’t see it take prey. Menacing little guy. Love the forked antennae.

Colin Purrington Photography: Insects &emdash; Robber fly (Dioctria hyalipennis)

2. Small flies on a milkweed (Asclepias syriaca) flower. It was quite the hangout.

Colin Purrington Photography: Insects &emdash; Small flies on milkweed flower

3. Milkweed plants (Asclepias syriaca), with a monarch butterfly caterpillar (it’s there). It was the only monarch I could find in the whole field. It didn’t seem to be eating, and I for the life of me I couldn’t find any evidence that it had been eating anywhere on the two milkweeds in the frame. Odd.

Colin Purrington Photography: Insects &emdash; Milkweed with monarch caterpillar

4. Helmeted squash bug (Euthochtha galeator), I think, on a milkweed leaf. This is a nymph, of course — adults grow up to look completely different.

Colin Purrington Photography: Insects &emdash; Helmeted squash bug (Euthochtha galeator) nymph

5. Wooly aphid caught on a spider web. These were flying all around, so it was nice to have one that was relatively stationary because I didn’t have a tripod with me.

Colin Purrington Photography: Insects &emdash; Wooly aphid stuck on spider web

6. Goldenrod gall caused by the midge, Rhopalomyia solidaginis (diptera).

Colin Purrington Photography: Insects &emdash; Goldenrod gall midge (Rhopalomyia solidaginis)

7. Goldenrod gall (with Eurosta solidaginus):

Colin Purrington Photography: Insects &emdash; Goldenrod gall (with Eurosta solidaginus)

8. Grape filbert gall (Schizomyia coryloides) growing on a grape vine (Vitis sp.). The namers of this species thought the gall looked like clusters of filberts (hazelnuts). I found a photograph of filbert fruit if you are curious, like I was. Coryloides is apparently a genus of extinct filbert, by the way. I’ve never seen one of these galls before, so this was a real treat.

Colin Purrington Photography: Insects &emdash; Grape filbert gall (schizomyia coryloides)

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Golden-backed snipe fly

This golden-backed snipe fly (Chrysopilus thoracicus) landed in one of my bird baths and drifted around for a few minutes on the surface tension. I’m not positive, but I think I’ve seen them do this in past years, too. I wonder whether they are looking for mosquito larvae, or perhaps adults. These flies have predaceous mouthparts, so they clearly hunt something. Sure wish somebody would PCR the gut contents of these things and let me know. Anyone ever seen them take something down?

Colin Purrington Photography: Insects &emdash; Golden-backed snipe fly (Chrysopilus thoracicus)

Here’s another one, albeit one with a damaged eye:

Colin Purrington Photography: Insects &emdash; Golden-backed snipe fly (Chrysopilus thoracicus) with dented eye

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Complimentary fumigation during flight to Galápagos Islands

Before arriving in the Galápagos Islands, you get to watch the cabin being fumigated with insecticide. Because the plane is full of Prius owners who listen to NPR, it was fun to watch peoples’ faces as they slowly realized what’s going on. The audio couldn’t pick up everyone’s conversations, but trust me, it was funny. They don’t ask, “Would anyone mind if we sprayed a little insectide right now?” They just start doing it.

I think the prior to the spraying the captain should have cued up a short video on what introduced insects can do to the islands. For example, showing the devastation of Philornis downsi. Then again, people might be eating …

By the way, when you step off the tarmac after the flight you walk over a spongy mat that has even more chemicals, suspended in a soapy liquid, to kill the things that might be hiding in your treads. Pro tip: watch your step after coming off the sponge mat … it’s incredibly slippery, and will make you wonder whether the airport planners have a firm grasp of basic safety protocols.

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