Is it better to have one or two spaces after a period? The first study that investigates this controversial issue is here, and supposedly gives the victory to the two spacers . But a closer look at the research suggests that the only reasonable interpretation is that double spacing after a period is still bad . It's ugly, it does not help when it comes to what matters most (reading comprehension), and the experiment that supports its benefits used an outdated font style.
The "two spaces" convention is left over from the days of typewriters. Typewriters allocate the same amount of space for each character, so a narrow character like "i" gets as much as a broader character like "w". (This is called "monospaced font"). With a typewriter, it makes sense to add extra space to make it clear that the prayer is over. However, the current word processing software makes the sources proportional, so we only need a space. Also, it looks better. The Chicago Manual of Style and the Modern Language Association Style Manual also adopt this position. However, the two spacers claim that their path improves readability, which is the same reason given by the American Psychological Association when it advocated two spaces.
But, as the authors of the new document point out, so far no investigations have been carried out to support this claim. They recruited 60 university students to solve the debate. First, students wrote passages to determine if they are from one space or two spacers. Then, they used eye tracking technology while reading paragraphs in which the number of spaces was manipulated. Then, they answered a question to assess reading comprehension.
The finding allegedly claimed by two spacers is that students who read the pages of two spaces were less likely to notice the scoring area, probably because the additional space made it clear that the sentence was over. This happened regardless of whether the students used one or two spaces. But the effect, the authors write, was small, and did not prevent people from rereading what they had already seen. Double spaces after a period failed to increase reading speed unless the student had two spacers. (And since we no longer use typewriters, people have started to see more and more)
It is not clear if readability really improved, although people observed the area near the period less: the two spaces after the periods did not help anyone to better understand the passage. In addition, the researchers used a monospaced source, and most computers use proportional sources, which means that researchers recognize that the findings "may differ" when dealing with other situations, such as those we encounter most frequently.
When the facts change, we should change our minds. But the facts here are simply not convincing enough to compensate for the horror of two spaces. Yes, the aesthetic choices are arbitrary and can change, but not without a good reason.
Finally, it is important to note that, in a more profound way, none of this, not a space or two, or "tabs versus spaces," nor the whole debate of the Oxford comma, really matters. We humans simply love to link too much to debates that are relatively unimportant. Before the division of a space / two spaces existed, there was a famous psychological experiment that created the false division between Kandinsky and Klee. Psychologist Henri Tajfel randomly selected a group of teenagers into two groups and told them it was because they preferred the paintings by Paul Klee or Wassily Kandinsky. Despite this random classification, the children came to define themselves as "Klee lovers" or "Kandinsky lovers". When asked to distribute money, they strongly favored their own group. To be fair, adolescents and adults are fortunately not the same, so the exact details of this study could be misleading. But this finding does not surprise anyone who has seen people too tired in front of the cake.
So, really, the best and most noble of all, the action that will help us to transcend our nature, is to free us from worrying so much about spaces after periods. The authors are right when they suggest that "we should probably discuss passionately about the things that are most important." But until we overcome human nature, two spaces are wrong.