Food & Culture

Should You Put One or Two Spaces After a Period?

Back in the day of the typewriter, the rule was simple: put two spaces after each period. Letters were all the same width, so it made sense to give the sentences some breathing room. And then the computers came, along with different fonts, different software applications, and different operating systems. Thus, the typographical war between single-spacers and double-spacers began. It has raged on for decades, but science has finally stepped in to put a period at the end of the debate.

Spaces: The Final Frontier

Who makes the rules, anyway? Official rules for writing are contained in style guides (also called style manuals) and there are more than a dozen style guides in the U.S. alone. Together, the "Associated Press Stylebook" and "The Elements of Style" are among the most referenced style guides in the country for general writing, including here at Curiosity. Writers with specific needs sometimes rely on other guides, such as "The Chicago Manual of Style" for academic papers and certain editorial writing, or "MLA Handbook for Writers of Research Papers" (often referred to as "MLA" or "MLA Style") for academic papers. All of the aforementioned guides that address spacing after "terminal punctuation" — periods, question marks, and exclamation points — either recommend or require a single space after a period.

So ... problem solved, right? Not according to psychology researchers from Skidmore College. In an April 2018 study, they dug through decades of previous research that argued for one space or two. In the end, they wrote, "there has been no direct empirical evidence in support of these claims, nor in favor of the one-space convention."

To find the missing evidence, they asked 60 students to participate in an experiment. The students performed a typing task to assess the way they used spacing, followed by an experiment using eye-tracking software to measure how spacing affected their reading performance. The eye-tracking software recorded where the students looked while they read paragraphs written in various single-spaced and double-spaced styles, in addition to unconventional variations like double-spacing after commas but just single-spacing after periods. The results showed that putting two spaces after a period made reading easier — though some refuse to respect the science.

2018: A Double-Space Odyssey

Rebecca Johnson, the leader of the research team and an associate professor in Skidmore's department of psychology, told The Atlantic that their data suggested that "all readers benefit from having two spaces after periods." She explained that "increased spacing has been shown to help facilitate processing in a number of other reading studies. Removing the spaces between words altogether drastically hurts our ability to read fluently, and increasing the amount of space between words helps us process the text."

The study might sound like a slam dunk to double-space advocates, but there are a few caveats to the study. Chiefly among them is that the study used Courier New, a monospace font that was initially designed as a typewriter face for IBM and which you rarely see used on blogs or social media (but is used all the time in programming). To help the eye-tracking device, the participants were also strapped down when they read, preventing them from moving their heads naturally the way you would while reading. The difference in reading speed was also underwhelming, with only a 1-3 percent difference detected. That's not a huge advantage, and it was found in an admittedly small study of only 60 students at one (relatively diverse) university.

In fairness to the researchers, Johnson told Lifehacker that Courier New is standard for eye-tracking tests, because other tests on text spacing have found no significant difference between reading monospace and reading proportional fonts. The team also wrote that the major reason to use two spaces was to make the reading process smoother, not faster. This explains why reading comprehension was unaffected, regardless of how many spaces followed a period. But since everyone tended to spend less time staring at periods that were followed by a bit of extra white space, science has ensured that this debate will rage for another period of human history ... or two.

Do you want some extra help with your writing? Millions of students and professionals use Grammarly to check their papers, emails, and other important documents. If you choose to make a purchase through a link on this page, then Curiosity will get a share of the sale.

Written by Cody Gough May 17, 2018

Curiosity uses cookies to improve site performance, for analytics and for advertising. By continuing to use our site, you accept our use of cookies, our Privacy Policy and Terms of Use.