Re: Making Presentations Accessible [Review Draft]

I have a thought about this exchange between Shawn and Liam on "Use an easy to read font face":

Liam: Sans is not *always* easier to read than serif - too much of a generalisation. Suggest mentioning a few commonly available fonts by name instead.
Shawn: um - I wonder if that would be more complicated on our end. Maybe just saying "Use an easy-to-read font face. Avoid fancy fonts that are difficult to read." is enough given the scope of this document/page?
Liam: Yes, much better.
Cliff's thought: I wonder if this be even better: "Use an easy-to-read font face, especially a font with a constant or nearly constant stroke width."
 
Here's my thinking: It seems to me that the main reason serif fonts are generally less readable than sans serif fonts has to do with stroke width. Especially among the older serif fonts, the stroke varies quite a bit. It's rather thin in the horizontal portions of characters and is much thicker on the vertical portions. By contrast, the older sans serif fonts have a stroke thickness that is uniform, or nearly so, throughout each character.
 
As a result, when the image is out of focus, text can still be readable in such a sans serif font while portions of the letters in a serif font have disappeared. Of course, the image is always out of focus for people with low vision, but we can simulate this experience by slowly taking a projected image of the same passage in three different fonts -- Times New Roman, Arial, and Georgia -- out of focus.
 
Times New Roman and Georgia are both serif fonts; Arial is sans serif.
 
The stroke width varies quite a bit in Times New Roman varies; the stroke width is constant or nearly constant in Georgia and Arial.
 
As you take the image out of focus, the passage in Times New Roman will become illegible when the passages in Georgia and Arial are both still readable. The passages in Georgia and Arial eventually become illegible at about the same time.
 
So a person at the back of the room could still read slides in Georgia or Arial when they couldn't read slides in Times New Roman. Either Georgia or Arial is a good choice; Times New Roman is not a good choice. By no means would I consider Times New Roman to be either "fancy" or "difficult to read," but if you were to clue me in to the importance of the stroke width, perhaps I would look at it more carefully and make a more careful choice.
 
Is this analysis on target?
 
Cliff Tyllick
Texas Commission on Environmental Quality
 
t: +1 (512) 239-4516
e: ctyllick@tceq.state.tx.us 
w: www.tceq.state.tx.us