The fear response is one of those sorta-useful, sorta-not things we have now that evolution has pushed us to the point where most of our apex predators are either in zoos for our amusement or the subject of endangered species campaigns because we’ve become so good at killing them.
Now studies are showing that the reaction is as much about timing as it is about seeing something scary. Specifically, it’s about where you are in your heartbeat.
A quick explanation: a heartbeat has two phases. Systole is where your heart is contracting to move blood, and diastole is where your heart relaxes to fill with it. The interesting part comes in when researchers time-locked the display of fearful faces to the heartbeat of test subjects. During systole, subjects were better at spotting fearful faces.
In further research, this was done in an MRI. It found that during systole, the brain had a stronger fear response.
So, why is your fear response timed to your heartbeat? That’s the uncertain part. It could be a pure coincidence, or it could be some form of adaptation. For example, if you have a higher fear response during systole, that could prep you to, say, sprint away from whatever scared the crap out of you.
Either way, it illustrates the body and the brain exert a strange degree of control over each other. Also now you know when to terrify your friends.
image courtesy epSos.de on Flickr