Recently there's been some interesting research that indicates there are some personality traits that do indicate a higher propensity to being accident prone. For instance people who worry a lot or who are very talkative have difficulty focusing on the task at hand.
I have a data point to back that up--I remember when I was a kid riding with an uncle by marriage who was an airline pilot. He was totally focused on the task at hand--little talking, no radio, etc. So much so, in fact, that he needed a navigator lest he miss turns.
That leads me to conclude that the recent rise in motorcycle accidents is not solely due to older riders taking up the sport or returning to it, but also to the profusion of cell phones. I haven't had that many close calls in the few months I've been riding a motorcycle, but in every instance the driver who pulled out in front of me was talking on a cell phone.
I've told my two college age daughters that if I catch them talking on a cell phone (much less text messaging) while driving, I'll give them a choice as to whether I cancel their cell phone account or take them off of my auto insurgence.