Keith,
A few years ago I came across a kind of simple skill/talent check list for those interested in getting into car rallying. I was curious how it compared to what I felt were important skills in bike road racing. One of the things mentioned was reaction time with a test one could perform to see how they measured up. The test involved a friend holding a ruler by its end and the test subject placing his or her fingers as close to the ruler as they wished without touching it. At a random time the friend holding the ruler lets it go and the test subject catches it as quickly as they can by squeezing their fingers (no vertical movement of the hand is allowed). The place on the ruler where they actually catch it is then compared to where they were originally holding it. This is supposed to give a decent perspective on physical limitations of said individual in terms of how quickly they can respond to a visual input with their hands, which is understandably important for rallying.
I tested myself and found I scored quite poorly (don't remember the actual numbers, but it was somewhere below average and way way worse than what would be considered good enough for rallying). This got me thinking about my strengths and weaknesses on the track and appeared to explain some things. For example, I tend to do fairly well in situations I plan out, like executing a pass on a rider I'm somewhat familiar with. And conversely, I am usually quite lost in the chaos of a large group of riders going into T1 at the race start and tend to lose positions in those situations, while I'm watching others react faster than I. Some other things don't seem to fit well into this theory, such as that I usually am able to get pretty decent starts and feel quite comfortable in congested and aggressive urban traffic (think NYC).
What is your opinion on the importance of reaction time and other things that are somewhat biologically predetermined? Does anything help, such as street riding for those that don't see as much track time as they'd like? Are there other similar biological factors you can think of that may or may not relate to track performance? I'm of opinion that, even if it is a limitation, I'm able to work around it and still enjoy myself out-there (I won't be vying for Mat Mladin's job anytime soon though).