I used to ride motorcycles really fast on country roads. (Foolishly, but that’s another story.) One day, I was slicing through a sweeping blind turn, back tire sliding and front tire on the edge of traction, when for some reason I backed off the throttle.

I didn’t think about slowing down. I didn’t decide to slow down. I just did.  Which meant, seconds later, I was able to dodge two cars sitting crumpled and smoking in the middle of the road.

As we waited for the state trooper to arrive, I half-listened to the drivers argue about who was at fault and thought about how lucky I was to have slowed when I did.

But I couldn’t figure out why I had slowed — until the state trooper who investigated the accident showed me a scattering of gravel on the edge of the road and a few faint skid marks.