Typography Papers - 9 is out now. It includes an article on Readability by Peter Enneson and myself. We are delighted to be in such good company: Articles by Gerard Unger, Eric Kindel, James Mosley, Paul Luna, Titus Nemeth, and Maurice Göldner.
Our article is the completion of work on the history of 'readability' that I first gave at TypeCon, and discussed further here: http://typophile.com/node/83684.
The core of the story is that the concept of 'readability' as ease of reading continuous text was developed by scientist Matthew Luckiesh in research done in the late '30s in collaboration with Linotype. Luckiesh found that the difficulty of reading text could be measured by the increase in blink rate over time. At the time, this was contested by researcher Miles Tinker, and an acrimonious dispute ensued. The upshot was that Luckiesh's concept lived on in typography, but his name was lost. In experimental psychology it was largely forgotten. However, a fatigue researcher, John Stern, reviewed the dispute in the '90s, and concluded that Luckiesh was largely right all along
What is new in this complete version is first, we found that Harry Gage at Linotype was an important collaborator, without whom the most important results wouldn't have been discovered. Second, we report at the end on current research that seem to reinforce the importance of blink rate. It turns out that during blinks the whole visual system is briefly shut down Our hypothesis is that this allows for refreshment of chemicals that the nerves in the brain need to do the visual processing. This would explain why when type is less easy to read, increased blinking is an understandable compensation.
The important thing for typography is that Luckiesh was able to discriminate some effects that nobody else has done, especially the fact that bold type is less readable, even though it can be read at nearly the same speed.