Fluorescent Flicker

So I have a dozen fluorescent fixtures in my house. The ballast in one of them failed a couple of years ago, and looking at the difficulty in obtaining and replacing the ballast, I bought a whole new light fixture, which in turn meant buying all new bulbs because the new fixtures use T-8 bulbs (the eight means the number of eighths of an inch in diameter, so T-8's are 8/8th's, or one inch in diameter) and the old bulbs are T-12's which draw more power, so you can't use T-12's in the new fixtures.

Now two more fixtures have failed and I have half a dozen spare T-12 bulbs, so I think I will go to the trouble to obtain new ballasts and install them. First place I go is Google to study up, and I come across this really bizarre statement in Wikipedia:

Flicker at mains frequency is more noticeable in the peripheral vision than it is in the center of gaze.

I would really like to know why that is. Someday I may even look into it.