The thing is, having worn one of those racing helmets, I never even noticed the helmet, all you realy see is a bit of a black ring around your vision at first, but after a while, you don't even notice it.
I finnished an entire trail run (in good time to) on my dirt bike and didn't even notice the helmet untill the end when I took it off. The effect you get from wearing them wouldent even show up on a monitor, because you see the sides of the helmet as much as the top and bottom, its just a fuzzy black box around your vision, its not realy a small slot across.
Now that I ride vintage though, I wear a bell bubble helmet, one of the old helmets with the clip-on visor. Almost identical to the ones they used in 70's F1.