Planning on watching a scary movie or going out to a haunted house on Thursday? In honour of Halloween we thought it would be interesting to look at what actually happens in our brains when we get scared.
Bytesize Science talked with Abigail Marsh, professor of psychology at Georgetown University, to find out how the brain processes fear.
We feel fear because we see or hear something that makes us anticipate harm. Say you’re walking through a haunted house this Halloween and a spooky skeleton jumps out at you. That skeleton acts as a stimulus that triggers a signal in your brain.
The signal travels to the amygdala — a region near the base of the brain. The amygdala fires a brain chemical called glutamate out into two other regions of the brain. The first region makes us freeze or involuntarily jump. These reactions are so automatic because the signal is sent deep into the base of the brain to an area that we have little control over.
The second signal is sent to the hypothalamus and triggers our autonomic nervous system — the system responsible for the fight or flight instinct — when our bodies go into superman mode. It elevates our heart rate and blood pressure and pumps adrenaline throughout our bodies. That’s the rush you feel when scared.
We experience fear in three stages:
1. Freeze. This is the evolutionary response designed to keep us hidden from the potential predator we sense near us.
2. Run away. If we’ve already been spotted, the adrenaline coursing through our bodies helps us run away quickly.
3. Fight. If running away is no longer an option, that same adrenaline helps us fight off — or at least try to fight off — whatever threat we’re facing.
If we aren’t in a real life-threatening situation, luckily our bodies have a quick way of reversing this fear response. The parasympathetic nervous system is the counter to the fight or flight instinct — it reverses the flood of adrenaline and lowers our heart rate back to its normal state.
That’s why every time we jump during a scary movie our bodies are not suddenly coursing with adrenaline. After the initial reaction our brains recognise the threat is not real and the parasympathetic nervous system calms us down.
You can watch the entire interview with Marsh below for more:
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