Double or Single Space After a Period?

What is the greatest challenge facing authors, editors and publishers today?

Trade wars increasing the prices of books? Forget about it.

Amazon starting a publishing company? Small potatoes.

Brick & mortar bookstores in peril? Child’s play.

These things are peanuts compared to the REAL issue:

Double or single space after a period.

Raise this question around any author, editor or publisher and you will hear strong opinions, one way or the other. People are not ambiguous about how they feel about this hot-button issue.

Thankfully, we’re here to break it down for you.

Those of us who have been around a while will remember that this issue was not up for debate for decades. We were all taught that there are two spaces between each sentence, no question. We sat in front of our typewriters and pressed that space bar twice, with gusto.

As the millennium came to a close and the typewriter went the way of the dinosaur, replaced by fancy word processors - and then PCs - the issue of how many spaces after a period created a divide that has yet to be fully mended.

Old school authors and editors stuck with tradition and continued to use two spaces. The new guard said this was archaic and wrong, arguing that with all the snazzy new fonts available it made no sense to have that much space between sentences.

“Typing two spaces after a period is totally, completely, utterly, and inarguably wrong,” Farhad Manjoo wrote in Slate in 2011. “You can have my double space when you pry it from my cold, dead hands,” Megan McArdle wrote in the Atlantic the same year.

So where do you turn when you don’t know what to do?

Psychologists, of course.

Psychologies performed studies by measuring the speed at which people could read by clamping their heads into place and measuring eye movements to see which format provided smoother reading – one space or two.

The results showed that two spaces after a period showed smoother eye movement, but not by much.

This left the door open for other studies to argue that the advantage was so slight that it’s negligible, and one-space purists refused to conform.

Plus, they argued, it depends on the font. The aforementioned study was done using old-school courier font, which most resembles typewriters.

So, researchers Rebecca L. Johnson, Becky Bui and Lindsay L. Schmitt rounding up a study group of students and some eye-tracking equipment and set out to settle the issue. Again.

When a short paragraph was dictated to the (young) students to see how they naturally typed, 21 of the 60 students were two-spacers, and the rest - the majority - were one-spacers.

These same researchers then tracked how smoothly the students read text and used an Eyelink 1000 to record where they looked as they silently read 20 paragraphs written in a variety of styles, including one-space, two-space, and other combinations like two spaces after a comma.

The verdict?

Two spaces after the period work better.

Does this settle the debate? The answer is frustrating: perhaps. People don’t change habits – or their minds – easily, so one-space purists continued one-spacing their way through life, and two-spacers kept two-spacing away.

To further complicate this issue, we can add peer pressure to the mix. With emails and texts and social media posts all written with one-space after a period, what’s a person to do?

We all want to fit in, so inevitably most people use a single space. It just started to look weird with two spaces. The two-spacers began to give in, grumbling all the way.

We promised to break it down for you, and we did, but we are still left scratching our heads. In single spaces.

What is your opinion on this issue? Let us know in the comments. We could use the help.

This essay is part of a series on hot-button editorial issues faced today. Next up in the series? The Oxford comma.