A new study showing, you should really be using 2 spaces after a period. There, I just tried it and I kind like it! We have researchers from Skidmore College in Saratoga Springs, NY, to thank for this. They sought to settle the age-old debate using eye movement trackers and about 60 student test subjects. Both practices were put to test with the subjects tasked with reading passages as equipment noted how rapidly their eyes moved.
The researchers presented the students with sentences containing two spaces after a period vs. one. And the same using passages containing commas. Afterwards, students were tested to see how well they understood what they read.
The study found that subjects' eyes lingered for less time between sentences where a double-space was used after periods. But didn't affect how well they retained what was read.