100 Things Every Designer Needs to Know About People, 2nd Edition

13 It’s a Myth that Words in All Caps are Inherently Hard to Read

You’ve probably heard that words in uppercase letters are harder to read than those in mixed case or lowercase. You’ve probably even heard some kind of percentage cited, such as “between 14 and 20 percent harder.” The story goes that we read by recognizing the shapes of words and groups of words. Words in mixed case or lowercase letters have unique shapes. Words in all caps have the same shape—a rectangle of a certain size—so, in theory, they’re harder to distinguish (Figure 13.1).

Figure 13.1 The word shape theory

This explanation sounds plausible, but it’s not really accurate. ...