The answer? Large blocks of uninterrupted text.
In a web article from the olden days of 1997, Jakob Nielsen answers the question of How Do People Read on the Web? by responding:
People rarely read Web pages word by word; instead, they scan the page, picking out individual words and sentences. In research on how people read websites we found that 79 percent of our test users always scanned any new page they came across; only 16 percent read word-by-word. (Update: a newer study found that users read email newsletters even more abruptly than they read websites.)Likewise, many magazines have given up on paragraphs, choosing line breaks over indentation, and relying more upon bulleted lists, Top Ten lists, and text boxes to deliver content to readers.
In an amusing yet painfully truthful article titled Nation Shudders at Large Block of Uninterrupted Text, the Onion pokes fun at this phenomenon:
WASHINGTON—Unable to rest their eyes on a colorful photograph or boldface heading that could be easily skimmed and forgotten about, Americans collectively recoiled Monday when confronted with a solid block of uninterrupted text.
Dumbfounded citizens from Maine to California gazed helplessly at the frightening chunk of print, unsure of what to do next. Without an illustration, chart, or embedded YouTube video to ease them in, millions were frozen in place, terrified by the sight of one long, unbroken string of English words.
I'm totally open to suggestions.
(image from The Onion)