As far as I know, yes. I have seen books for brain exercises that address that, for example: LePoncin, M.: Brain Fitness. New York, NY: Ballantine Books; 1990.
Yes, this especially as what you see is to a great part created by your mind from the raw data your eyes send it. If you train yourself to look around a lot (much more than normal or usual), you will find improvement in all the cerebral aspects of your sight. This is one of the 'secrets' of the martial arts.
Just how clear are we talking? Like being able to read a sign from the far side of your peripheral vision? Is there any proof of this?
Well, most of the color receptor cells are right around the fovia, which have no receptor cells at all so they produce no data input. All of the rest of the receptor cells are dark/light receptors - no color. If what you "saw" was the actual visual data from your eye receptor cells, there would appear to be 2 black spots about 8 inches across floating in the air about 6 feet out in front of you at all times. The area immediately around these spots would have color, the rest of your visual field would be blurred and colorless. Since your eyes "saccade" (move around a lot looking at different things in diverse places in your environment), your mind can assemble this information, simulate color where it thinks it should be, fabricate continuity over those fovial dark spots, accentuate edges and motion and thus present you with what appears to be a full color, in - focus clear picture of your surroundings. That picture though, is largely fabricated from that raw saccade data and the color is mostly false. With training exercises and persistence you should be able to read those signs peripherally though, if your wetware is up to par. Practice takes time to accomplish the goal set forward.
I used to find my peripheral vision improved markedly when I played a lot of squash. It was very much like being a martial arts exponent, I was extremely fit , lithe, flexible and hyper aware.
Good to see your still around Spud! On the topic, I have noticed that periphal vision can improve, yes!
Yes, there are. that is precisely where I learned those eye exercises, to avoid getting hit. The exercises work, your peripheral vision improves a lot as you pursue them.
But still, has anyone ever developed the ability to such an extent to be able to make out writing from the corner of their eyes?
From what I understand, peripheral vision evolved to be good at detecting motion - functioning as a sort of 'early warning' device: From Wikipedia, Peripheral vision: I'm sure it can be improved but only to an extent because the type of cells that make up clear vision, there's more of them in the center than on the edges. From wikipedia:
