I can't cite any particular studies, but it's my understanding that serifs, done right, are supposed to help with quick and easy recognition of letters and words. I'd be interested in seeing something that backs that up.
Whether that is so or not, here on Lingq for my target language of Russian I always use the serif font. In the sans fonts it is sometimes difficult when reading to distinguish between the letters п and л (p and l), as in "радиоактивный пепел". In the serif font the leading hook on л is much more apparent.
Thank you so much for your input, I will play around with it.March 15 at 00:38
And there's more to it than serifs. Many serif fonts have different and varying weights on the strokes that should be designed to aid legibility. Back to my Cyrillic "p" and "l" example, the serif font offered by Lingq uses the same weight for both vertical strokes of "п", but for "л" the left vertical stroke is thinner than the right vertical, further distinguishing the letters. But really, I only know enough about font design to know that it is a large and complex topic.
When reading on a computer screen, the screen resolution and rendering software will also have a big impact on legibility and eyestrain. Maybe one font or another would work better with a certain system in this regard, but I haven't heard of any particular examples that I can recall.
My example with these two letters is my main reason for choosing serif for Russian, but there is another. The mix of lower-case letters with ascenders and descenders in Latin-based alphabets aids the rapid, unconscious recognition of letters and word shapes -- it's been shown that we learn to recognize whole words without having to decipher each letter individually.
The Cyrillic alphabet has fewer ascenders and descenders. Or so I think; I haven't counted them. But the lower-case letters much more tend to be just smaller renditions of the capitals. AND YOU KNOW HOW READING TEXT IN ALL CAPS IS HARDER THAN READING LOWER CASE. The nuances that a serif font lends to letters makes them all more distinguished from each other, which, in my opinion, really helps with lower-case Cyrillic.
For English and other text in a Latin-based alphabet, however, I might not necessarily be so quick to recommend a serif font.March 15 at 15:23