I have long wondered about some of the “rules” of presentation design. One of them which I used to mention in my own classes was the classic Serif vs. Sans Serif debate.
So according to Hoffman, et al. 2005, it turns out that the real key may be READABILITY. When asked about their preferences for projected fonts on screen, these were the top choices in order of preference. It is interesting that 3 of the 4 are, in fact, sans serif fonts, but don’t be so quick to throw out stylistic yet highly readable fonts like Times if they work for your presentation.
Hoffman B, White A, Aquino N. (2005) “Screen text readability: Ease, accuracy, and speed of some common computer typefaces.” IVLA Conference Proceedings
Exley K, Dennick R. (2009) Giving a lecture: From presenting to teaching. 2nd edition. New York, New York: Routledge