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:
- 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.
- 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.”
- 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).
- On the APA blog, they say:
- 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).
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.
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.