There are existing studies which show that people react faster when startled than when not. There's a nifty little online test to check your own response times: <a href="http://www.mathsisfun.com/games/reaction-time.html" rel="nofollow">http://www.mathsisfun.com/games/reaction-time.html</a><p>As far as I know this is the first test to show that startle response extends beyond reaction time, it's an interesting piece of data. It's worth noting that it's possible to force yourself into a state of mind similar to being startled, which may very well eliminate the advantage to "shooting" second.