Science Just Settled One of Type Design’s Oldest Debates

From Fast Company:

Ever since the invention of movable type, the debate has raged: Are two spaces after a period better than one? The French said “Non!” from the beginning, using one space only. The British said “Aye!” and established their own two-space rule.

Now, three psychology researchers at Skidmore College are settling the debate with a study published in the journal Attention, Perception, & Psychophysics. Their study demonstrates that using two spaces makes reading “smoother.” In other words, your eyes spend a few milliseconds less on a period if it’s followed by two spaces rather than one. But before all you two-spacers out there start gloating like the annoying pestiferous bunch you are, here’s the caveat: The study also shows that it doesn’t actually make overall reading faster or your comprehension any better–unless you are a two-spacer to begin with.

The war of sentence spacing has been a long and tortuous one. Back in the 18th century, some printers used French-style single-spaced sentences and others the English double-space rule. It wasn’t until the mass printing era after World War II that most American books turned to single-spaced sentences to reduce costs and speed up production. The 1941 IBM Executive typewriter also introduced proportional spacing–which meant that each letter took only the horizontal space it needed instead of being monospaced. Things looked much better that way when using a typewriter, since it effectively eliminated the need for two spaces after every period. Today, computers and proportional fonts make the two-space rule absolutely useless–even while recalcitrant two-spacers continue to write eye-twitching emails using the English rule, claiming the rest of us rational people are wrong.

. . . .

The results are pretty conclusive: Reading speed wasn’t slowed down with either single or double space after a period. The two-spacers experienced a marginal speed improvement while reading double-spaced sentences.  Reading and comprehension was completely unaffected no matter the spacing rule they used. The paper argues, however, that readers spend “fewer milliseconds” looking at periods when there are two spaces after them, which they claim makes for a “smoother” reading experience. On the other hand, when they added an extra space after a comma, the reading speed diminished across the board.

Link to the rest at Fast Company

The ghosts of Mr. Schrupp’s high school typing class (hands-down, the most useful class PG ever took in high school, college or law school) still haunt PG’s relationship with the space bar.

Once in a while, he can master his thumb long enough to generate a single space after a period, but thumbs have a mind of their own and he’s back to two spaces a couple of lines later.

He hasn’t paid attention to what Word Autocorrect does with periods preceded by two spaces lately, so he may be either fashion-forward or out-of-date with respect to most of his punctuation.

9 thoughts on “Science Just Settled One of Type Design’s Oldest Debates”

  1. *squints* I thought this was only an issue with monospaced fonts. Most modern/proportional fonts kern the space after a period so that it’s slightly wider than the space between letters, don’t they?

  2. I seem to recall this question coming up on PV some time ago and I’m wondering whether there is anything new here or it is just the recycling of an old story. As far as I can see the report the OP mentions (though does not link to) dates back to May 2018 or earlier.

  3. I can’t imagine what anybody makes of a period preceded by two spaces… it must be lonely out there all by itself. 🙂

  4. It was my understanding that around or after the debut of Office 1997 or 2000, Microsoft adjusted the Word algorithm to automatically insert more space after a period on non-monospaced fonts, making the two-space practice redundant.

    • That’s what I thought, as well. Also the page design programs. Back when I was a typesetter, Atex inserted extra space between the ends of sentences as a matter of programming. Double-spacing on a computer keyboard stopped being an issue after I started working exclusively on keyboards and put away my typewriters.

  5. I always suggest that writers use two spaces after a period. Some publishers want two, and it’s spit simple to do a universal double space removal if they want two. Adding another space is another matter entirely.

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