Ironically, WaPo's own introduction explains why the one-space convention only arose in a variable-width context. For the study to not test their findings with

Ironically, WaPo's own introduction explains why the one-space convention only arose in a variable-width context. For the study to not test their findings with a variable-width font, seems pretty silly. "Letters of uniform width looked cramped without extra space after the period. Typists learned not to do it. But then, at the end of the 20th century, the typewriter gave way to the word processor, and the computer, and modern variable-width fonts. And the world divided. Some insisted on keeping the two-space rule. They couldn't get used to seeing just one space after a period. It simply looked wrong. Some said this was blasphemy. The designers of modern fonts had built the perfect amount of spacing, they said. Anything more than a single space between sentences was too much."