https://www.theatlantic.com/science/archive/2018/05/two-spaces-after-a-period/559304/
A new study proves that half of people are correct. The other is also correct.
I love the ending of the original study: “we should probably be arguing passionately about things that are more important.”
But I don’t love the first author’s quote in the Atlantic article: “Our data suggest that all readers benefit from having two spaces after periods.” Why, then, does their peer-reviewed article end with: “Punctuation spacing… did not affect comprehension, and only increased overall reading speed for participants who already type according to this two-space convention…”?
The above quote about two-spacing benefiting all readers, from what I can tell, is related only to eye tracking. It feels disingenuous to claim everyone benefits from two-spacing when arguably more important factors, such as comprehension and reading speed, are unaffected by spacing or slightly affected for only a subset of participants.
It’s worth noting, too, that this article and study are from 2018 and the most recent version of the APA manual (7) recommends only one space after punctuation. I was worried all my recent writing was breaking form.
I remember taking typing (on manual typewriters!) in high school before the personal computer.
I don't know if it was then, or 20 years later when I was taking a desktop publishing course, but I remember being told that, just like dashes, spaces come in 2 widths. The en-space, which goes between words, and the em-space, which goes between sentences. (There are other widths used in kerning, the spacing between letters.) The two-space convention of typing was an approximation of that.
This part I know I got from that desktop publishing course: As a result, the two space convention should be followed only when working with monospaced fonts, proportional fonts that don't offer an em-space, or software that isn't smart enough to use the correct space in the appropriate places and you're too lazy to do it by hand. (I used find and replace for that last case when em-spaces were available.)
Now, I can't say I really care. :)
I don't even remember when, why or how I learned this. Regardless, I think it's easier to read. Especially in paragraphs with several sentences, including where it makes a clear distinction from other punctuation.