Not jumpy at all. Everyonce in a while something will catch me off guard, but most of the time I am pretty relaxed. I think my reflexes are pretty decent to good though.
Simple things like if I am about to walk through a closed door and someone opens it from the other side towards me my reflexes cause me to simply take a step back and I grab the door to keep it from hitting me.
I have had someone ask me if I was in martial arts before because the way I tend to move and react is pretty smooth.
Take what I say with a grain of salt, because that's all it is compared to the ocean of complexity when it comes to actions and real life.
I flip out if I see shadows that don't belong there. A paper bag that blew past behind me has been known to cause me to go into combat mode before.
Also people who ride up behind me on bicycles without warning. I want to strangle them because it causes my reflexes to kick in and my body can't decide to tackle them or flee and some times I nearly hurt myself trying to go in more than one direction...