At a Remembrance parade today, a cannon was set off to mark the beginning of a two minute silence. As it went off, the crowds quite comically jumped in sync, from the shock it gave them. I’ve seen very similar reactions in other scenarios, such as a jump-scare in a horror film.
Seeing the in-sync crowd jump today made me wonder.. what is it, in the human body, that make us jump when we get a shock?