Q. Please explain your recommendation for using one space after a period in light of this article: James Hamblin, “The Scientific Case for Two Spaces after a Period,” The Atlantic, May 11, 2018.
A. As The Atlantic article reports, a small study conducted at Skidmore College found that spacing between sentences does influence how people read and that some people read faster if there are two spaces rather than one. But the results weren’t definitive, as the study’s conclusion admits:
Punctuation spacing had no effect on the likelihood of regressing back to the punctuation region after leaving it, did not affect comprehension, and only increased overall reading speed for participants who already type according to this two-space convention (who only showed a 3% increase in overall reading speed). Thus, while period spacing does influence our processing of text, we should probably be arguing passionately about things that are more important.
See Rebecca L. Johnson, Becky Bui, and Lindsay L. Schmitt, “Are Two Spaces Better than One? The Effect of Spacing following Periods and Commas during Reading,” Attention, Perception, & Psychophysics 80 (2018): 1510. We agree with that conclusion—except maybe for the part that discourages passionate arguing about small things. For another look at this issue, including some historical background, see “One Space or Two?,” at CMOS Shop Talk.