Great article here, and a super guide to how *not* to do design research:
Apparently defying Betteridge’s Law, the study claims to show that two spaces after a period are easier to read than one. On its face, this also seems to contradict my longstanding advice to put only one space between sentences.
Confidential to two-space researchers: you might consider making your paper available for free, as it may be the last time that a topic of your research overlaps with a widespread internet obsession. Because the study costs $39.95 for a PDF, I’m certain the social-media skeptics rushing to claim victory for two-spacing have neither bought it nor read it. But I did both.
True, the researchers found that putting two spaces after a period delivered a “small” but “statistically … detectable” improvement in reading speed—about 3%—but curiously, only for those readers who already type with two spaces. For habitual one-spacers, there was no benefit at all.
Incidentally, if you’re not familiar with the whole of Butterick’s Practical Typography, I heartily recommend it to you.