I was out dirt riding my XT250 today, flying down double track, and thought about all the mental processing going on without me even thinking about it. There I was, buzzing along at 40 to 60 mph, picking my lines through the sand with ruts, dodging roots and mud holes, scanning for jeeps and other bikes and deer, so I am looking 10 feet ahead, 30 feet and maybe 75 or 100 feet away, while modulating the throttle, the gearbox, shifting weight, and also thinking about where I am overall and where I am going. There is also the calculations of how fast you can go around a turn if something should be coming the other way or something being IN the turn. That is a lot of high speed mental processing going on without me even being aware of it. It must keep your brain sharp. Its habit, I tend to do it on the street as well, but its not as intense.