Where’s the evidence to justify two spaces?

We’re still scratching our heads trying to figure out what prompted APA to revert back to two spaces at the end of sentences. Combing three likely sources for why they made this change, so far we’ve found the following:

  1. The Manual, itself, doesn’t appear to provide any rationale. In fact, in the introductory chapter, in which changes are enumerated chapter by chapter, no mention is made of the change to two spaces.
  2. On APA’s website, there’s a section devoted to pointing out changes (http://apastyle.apa.org/manual/whats-new.aspx). Here’s what they say about the change to two spaces: “Punctuation—return to two spaces after the period at the end of the sentence recommended for ease of reading comprehension.”
  3. On APA’s blog devoted to the Manual, they have said the change will make manuscripts easier to read: “this new recommendation will help ease their reading by breaking up the text into manageable, more easily recognizable chunks” (http://blog.apastyle.org/apastyle/2009/07/on-two-spaces-following-a-period.html).
  4. On the APA blog, they  say:
  5. The question of whether one space or two should follow end punctuation has been hotly debated for quite some time, and it is no surprise that writers from both camps harbor equally compelling reasons for the approach they have always used, were taught, or have adopted.

  6. On the APA blog, they say: “improved readability was the impetus behind the new ‘two spaces after a period’ style recommendation” (http://blog.apastyle.org/apastyle/2009/06/apa-style-who-we-are.html).

So, based on these statements, it appears that some combination of making manuscripts easier to read or easier to comprehend was the primary rationale for the change. And the only reference to an empirical justification for the change is the claim that both those who advocate for one space and those who advocate for two spaces “harbor equally compelling reasons.”

During times when many disciplines that recommend the APA’s Publication Manual are advocating evidence-based decisions, it’s noteworthy, we think, that these discussions of the rationale for using two spaces at the end of sentences (and after colons) do not appear to be based on scientific examination of the hypothesis that two spaces makes manuscripts more readable. We have to admit that we haven’t employed the most rigorous search methods in seeking evidence, but we’ve searched for studies comparing readability when one or two spaces follow sentence-ending punctuation, and we simply haven’t found any studies of the hypothesis.

We’d welcome assistance from the leadership of the revision of APA’s Publication Manual in locating the evidence undergirding this change. It’d save us some additional head scratching, and neither of us has much hair to protect his scalp from more scratching.



Filed under Comments, Notes, Research

25 responses to “Where’s the evidence to justify two spaces?

  1. We produce PerfectIt, an MS Word add-in that helps professionals to proofread faster. In response to user requests, we added a feature to our most recent version in order to convert two spaces at the end of a sentence into one. We have never had any requests to convert one space into two.

    More details and a free download are at:

  2. There’s a small blooper at the start of your post that you might want to correct: “…prompted APA to revert back to two periods… .” I’m pretty sure that you meant “two spaces.” 😉

    • danhallahan

      Thanks, Katharine. Yes, that’s what I meant. I thought I’d made that correction much earlier, but I guess I neglected to hit the “save” button. In any case, it’s correct now.

  3. Oh, for heaven’s sake! This is utterly ridiculous. The people at the APA manual should be, well … I won’t say what I think should be done to them. Those with sensitivity to readability and visual impact have spent the last 10 years or more educating colleagues and clients to the fact that two-spaces-between-sentences creates rivers of white space through a document, looks clunky and is a holdover from the days of typewriters, when there was no such thing as word processing and proportional spacing. This step backward on the part of the APA makes me very glad that I rarely work with that style. Recant, recant!

  4. P.S. Thank you for this blog – what a great idea, and a great service to colleagues!

  5. Katharine, thanks for the help. We thought we’d already caught that mistake, but we must not have pressed the make-it-happen button after editing.

  6. Frank

    I agree completely with Ruth’s assessment of the APA change.

    Furthermore, they seem to be confusing readability, which has to do with the difficulty of the vocabulary and sentence structure in a given document, and legibility, which has to do with font size and style, page layout, and punctuation.

  7. Holly Lane

    I suppose I’m one of the few to cheer this change. My eyes have a notable preference for reading text with two spaces after the periods. I find text without such spacing to be more tiring to read and more challenging to comprehend. I cringed when the rule changed to one space and have rebelled ever since. Every manuscript I have submitted for publication has had two spaces after every period. In fact, I have even made my graduate students violate APA’s one-space rule in papers they submitted to me, because I really don’t want to read their papers without two spaces.

    I realize that I am hypersensitive to the visual impact of text, but certainly I can’t be alone in my preference. Since many of you don’t seem to notice an advantage to having two spaces, how about if you one-spacers consider it an example of universal design and make those two spaces to help out those of us for whom it does make a difference?

    • hme

      I agree wholeheartedly with Holly.
      Of all the nonsense I’ve had to endure with the APA guide, this is the first time I was happy my department uses it. Thank you, thank you.

    • You are not alone, Holly; and, I suspect, not hypersensitive. I too MUCH prefer to read writing with more whitespace between sentences. Artists might refer to this as “negative space” which is very important in achieving balance. I would see 7 additional spaces as excessive, but not 1.

    • ~Dessa~

      I agree with Holly. One space after a period hurts my eyes. I need the two spaces for my brain to comprehend that a sentence has ended and a new one is beginning.

    • Jim Oz

      What an irresponsible lecturer. It’s hard enough attempting to master APA without a recalcitrant teacher ‘encouraging’ poor academic rigour.

  8. John Thompson

    So the Publication Manual “recommends” two spaces after a sentence and distinguishes between draft and final copy. Interesting since the Publication Manual itself (4.01 on p. 88) makes no such differentiation. It states: “Space twice after a punctuation marks at the end of a sentence.” Am I missing something? Might be nice if the APA devoted more than one sentence to this topic. But when the publication goes from 439 pages in the 5th edition to only 272 pages in the 6th edition, I guess there are space constraints and something has to be left out. Interesting that the edition cuts 167 pages (38% fewer pages) without a corresponding reduction in sale price. Looks like the APA is following the policies my local supermarkets whose shelves are filled with clever packaging hiding the fact that you’re getting less for the same (or higher) price, which is a hidden price increase.

    If the issue is to make it a bit easier for editors reviewing draft copy, then why don’t we go the extra mile and include a few more assists such as:

    • Minimum 14 point font
    • Only Times Roman font, or a font with “hands” and “feet”
    • Increased margins so editors don’t have to move their eyes too far either right or left

    What’s next? The APA “recommends” placing the right quotation mark inside the punctuation?

    It would seem that in light of any definitive research on the topic, the APA (and its followers) would have been better served by sticking with the 5th edition: “Space once after all punctuation as follows…after punctuation marks at the ends of sentences” (5.11, p. 290). Of course, perhaps that seemingly definitive sentence really was just a recommendation, too, similar to J.R. just dreaming everything.

  9. Jennifer

    I am so grateful to find other people who were as surprised as I was to find this backwards move in the new APA style manual. I sent the following in an email to them right away (though I did not receive a response back):

    Hello! I really appreciate the work that has gone into the new APA style guide. As a psychology doctoral student, as well as a freelance editor, I know I will be using it frequently. However, I was really disturbed by the change back to the old method of using two spaces following punctuation at the end of each sentence. It appears to be taking editing backwards into the typewriter era. From what I understood, the reason that we switched to a single space was that the double space was only necessary because of old-fashioned printing techniques, now rendered obsolete with the use of modern technology. Kids in school are now taught to use a single space after ending punctuation marks, and it appears to be accepted fairly uniformly in different style guides. I just finally got all of my clients to switch to using one space, and am not looking forward to having to re-educate everyone to use two spaces. Why has the APA chosen to go backwards to an outdated method?

    Is the publication manual itself and the examples used within it showcasing the double space? From what I can see it appears that both the manual and the sample papers are using a single space after sentence punctuation. As far as clarity goes, the spaces in a text that have double spaces after sentences are fairly distracting to the eye, particularly in a society that is used to seeing text evenly spaced. If the publication manual itself and the examples in the text are using the single space because it is easier to read, why should the people following the APA style guidelines now have to use double spacing?”

    • danhallahan


      Thanks for your post. I think if you surf around our site, you’ll get a sense of why APA says they switched back to two spaces. They claim that it’s easier to read material using two spaces after a period. However, we’ve asked several times for any empirical evidence that this is true. So far, no one’s answered our query.

      Btw, you bring up a point that I don’t think too many folks have mentioned. If the future generation of APA users are now being taught to use one space in K-12, they’ll have quite an adjustment to make once they reach college or graduate school. But I predict that by then APA will have switched back to one space.

  10. John Thompson

    The way I understand it is that APA is “suggesting” two spaces in draft copies, but not saying that for final copies. To say APA is waffling and inconclusive in this change is a big understatement. I contacted the appropriate APA personnel and, frankly, got the corporate defensive runaround. The 6th edition is so messed up that APA is providing free replacement copies with a revised 6th edition to those like me who purchased the “original” 6th edition. Hope someone is being held accountable for this situation.

  11. Passing by

    To all law firms that still believe that two spaces after a period (or “full stop”) is the status quo, it might be useful to have them review Supreme Court rulings, or Federal legislation, or briefs filed by the U.S. Solicitor General: they use only one space.

    That’s pretty conclusive; and not surprising at all because the GPO Style Manual 30th edition 2008 by the U.S. Government Printing Office reads (*):

    “Leading and spacing — 2.49. A single justified word space will be used between sentences. This applies to all types of composition.”


    (*) to determine the form and style of U.S. Government Printing authorized by by the U.S Congress

  12. Dina

    OMG! In an area of professionals do we really need to have a huge book devoted to the proper way to design papers. I am so exhausted from the minute details necessary to function in life. I think we all know what looks, sounds and reads appropriately. As an instructor I do not care about one or two spaces between sentences. I think the content is important and where we should direct our focus. As an example, I have an international student who does not speak or write proper English but his content surpasses the English speaking students. A paper containing valuable information is worth more then a paper full of APA perfections. Oh, and what is with length…I don’t know about you but I’m tired of writing and reading papers filled with junk just to meet expected page length. Say what you have to say and be done. Can’t we make that a rule? (I say with a big smile)

  13. James Iz

    I have a headache (stop)
    I want to go to bed (stop)
    I hate the APA full stop (stop)
    Sigh (stop)

  14. I am aware that this two-spaces conversation has fallen by the way side for some time however the 1-space, 2-space conversation continues to raise its head at the graduate level of many higher education institutions. My students ask about it and I am challenged at an institutional level as well as a pure logic level.
    I come at this from a word-processing and design perspective and I know that word-processing software is designed to compensate appropriately for a period and one space as a result of the inherent design rules built into the word-processor and the scalable or proportional fonts. Thus 2 spaces after creates irregular spacing in a document over time because there is a constant spacing adjustment taking place within the software based upon the letters and characters used and how the software is designed to calculate horizontal space.
    Sadly we continue to challenge the wisdom of software design without fully understanding the impact these challenges have on our finished documents. Yes you get more visual space with 2 spaces after but it is irregular and inconsistent. Complex software design algorithms have been built into word-processors to compensate for the way fonts and space work with the software. Horizontal spacing constantly adjusts and spacing is not a rigid visual element as with the use of a typewriter. This may only be one tiny aspect of style but I guess we have to ask what it is that we are after by doing one over the other?

    • Jennifer Hutmire

      I am so glad to see that someone is still taking up this cause. I have continued to find it extremely irritating from my perspective as a doctoral student, an editor, and a mother of three sons. My children, as well as all of the other children I know, are taught in school now to use one space after a period, as are the clients that I edit for. It makes no sense to tell them that for EVERY other type of assignment they do in different subjects they need to put one space after a period, UNLESS they happen to be doing something that is for a publication that uses APA style or for a teacher that wants them to use APA style. It would be one thing if all of the styles were changing back to the more archaic two spaces after a period (though I am glad they are not), but it is very confusing to have everyone else using the one space rule and APA to be on a completely different punctuation rule. I actually have held out and not inserted extra spaces yet in my current draft of my dissertation proposal, hoping that they will soon realize it was a mistake to change the rule and revert before I need to submit it.

  15. rickla

    If you’re a teacher or an editor, I suggest using a sentence like this somewhere in your guidelines: “Follow APA (6th edition) style, except for the following:…”
    The modifications I insert after the colon are: Use one space after punctuation marks, including periods; Include issue numbers in journal article references, even when pagination is continuous through a volume. (This second one is to assist readers in actually finding the article easily (what a novel concept!), since, both on library shelves and on journal websites, articles are organised by issue, and we shouldn’t be making readers go through an initial step of finding out what issue contains a given page range.

  16. I can’t speak for the APA, but I do know a bit about this topic.

    In terms of strict evidence-based reasons, there’s been a few studies but really nothing conclusive. It’s probably too complex an issue for any simple analysis. For example, would you judge something as more readable based on how fast you read it? Or how few mistakes? Or how much you retain? Or how easy it is to find your place again? Or more space to mark up the text? Do you look at experienced readers? New readers? Readers learning a new language? Also, some studies have looked at accessibility issues and reached opposite conclusions. It seems entirely possible that some readers benefit from clearer segmentation, while others become fixated on the gaps and it disrupts their reading.

    There’s a lot of misconceptions on this issue. It’s worth noting that before the printing press sentences were marked off in extra large initial letters, often of a different color. In early days of movable type with blackletter, sentence separations were usually space-period-space (and were often still hand-illuminated). When roman fonts were introduced, wider sentence spacing became standard in English, from the mid or late 1500s through 1950.

    Despite unfortunate myths about typewriters, we actually lost wide sentence spacing because of technological limitations of the industrialized printing processes, primarily the Linotype and the use of less skilled labor to save typesetting costs.

    Given the actual history, it’s hard to say that human beings got it wrong for 400 years, and have only got it right in the last 60. I suspect that wider spacing has benefits that people reject today simply because they’re not used to seeing it. I’ve spent a lot of time reading old, widely spaced 19th century texts. I became use to the look very quickly and I now prefer it. I definitely find it easier to skim texts when I can immediately spot the sentences.

    But setting aside issues of aesthetics and ill-defined readability, there’s a modern technical reason to advocate for two spaces: it’s the only unambiguous way to mark off sentences. When periods are used in abbreviations or initials they can be open to ambiguous interpretation in as much as five percent of sentences. In the computer era, this is significant, since there’s a greater likelihood that our text will live on digitally, and be interpreted by computers, whether it’s for machine translation, text-to-speech, or other automated analyses that might be possible in the future.

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