A company called Walker Reading Technologies has produced research showing that the human brain is not "wired" to read text in the traditional way we print it, which is in blocks. In short, we're constantly filtering out text that surrounds what we're trying to actually read. This filtering impedes our comprehension of the material.
Supposedly, the optimal format is a series of "short, cascading phrases" that look really odd but are easier for the human brain to comprehend. Of course, Walker Research makes a product that reformats text in this manner automatically :-) Apparently the company has improved some test scores by simply putting tests in this new format. A major textbook publisher also has contracted Walker Research for help with online textbooks.
I'm skeptical about company-conducted research that conveniently provides an excuse for purchasing a product from the same company. But the theory is still interesting. NI does a lot of documentation "online," meaning shipped as HTML. And the very essence of our jobs depends on readers comprehending the material. Maybe this new theory means we'll someday
be writing documentation
Edit: A link to the ensuing Slashdot discussion.