Your brain's alarm system

Your brain is always scanning for threat, mostly without you noticing. A sudden noise, a frown, an unknown number on your phone: circuits deep in the brain, including the amygdala, can set off a racing heart, tense muscles and narrowed attention in a fraction of a second, before you've consciously worked out what's going on.

That speed is the point. It's also why fear can arrive before any thought, and feel impossible to argue with.

Think of a smoke alarm. One that goes off for burnt toast is annoying. One that misses a real fire is a disaster. So smoke alarms are set to be oversensitive, and evolution did the same with us: missing a real threat cost far more than reacting to a false one.

So most false alarms aren't a sign that something is wrong with you. They're the system doing its job, a little too keenly.

You'll often read that the amygdala is the brain's "fear center". It isn't, quite. The circuits that detect threat and get your body ready are separate from the ones that produce the conscious feeling of fear. They usually fire together, but not always: your body can react before you feel afraid, and you can feel afraid of a thought with your body barely involved.

That gap matters. The feeling of fear is partly built from how you read what's happening, and that part you can work with.

Sam's heart pounds whenever his phone shows an unknown number, though he isn't in any kind of trouble. What's the most accurate way to see it?