If fear is a response to a perceived danger, why do humans and other animals sometimes freeze up or faint when afraid, becoming more vulnerable?



As I understand it, fear is essentially a warning system to alert you that you are in danger, and encourage you to take action (the Fight or Flight reflex). That being the case, why is it so common for people to freeze up, faint, or become catatonic, when these responses prevent them from reacting to the threat, and places them in more danger?

Same applies to other animals. Fainting Goats, obviously, rabbits will sometimes suffer fatal heart attacks in response to fear, etc.

In: Biology

I’ve come to learn this through my own mental health struggles. A fear stimuli leading to panic which leads to action to stop whatever is causing the fear – this is what you’d think normally happens. But when the fear stimuli perceived by the brain is evaluated as having no escape, like let’s say an oncoming car or in another case being in a traumatic situation, the body instead goes numb or dissociated or faints as a way to reduce the pain of what it perceives as not just something scary but certain death.

For example, if a lion was to walk into your room rn instead of acting you’d freeze up. It’s just the brain has evaluated that it’s going to go through extreme pain and death so it numbs your senses / makes you faint as a way of coping.

Some predators won’t actually attack prey which has fallen over that they didn’t kill or attack themselves.

The majority flee. A minority freeze in place.

The herd survives just fine overall.

It’s kind of a variant on “I don’t have to outrun the bear, I just have to outrun you”

I’d like to know more about this too. I always thought that it’s just our lizard brains backfiring in today’s changed environment.

I used to struggle learning to backflip and to this day I think the only thing holding me back was fear. After I froze mid-air a few times and landed on my neck, I started to be afraid of being afraid. It was very bizarre realizing your fear could’ve killed you, but when you think about it, we weren’t made to backflip around.

When sensing fear, the reptilian part of the brain tipycally goes with one of two options: fight or flight. When none of the two options seem viable, the fallback reaction is freezing in place, or fainting in extreme circumstances, because you’re constantly switching between the two options, of which none seem good enough. Imagine you’re unarmed and out on an open field and a cheetah is attacking you. You might freeze in place because you know there’s no chance to outrun it (flight option), let alone fight it with your bare hands (fight option).

Freezing in place is often a good survival strategy. You may have noticed a predator, but that doesn’t mean it has noticed you. Taking off would be very conspicuous, and the predator would *definitely* notice you, and may chase you. If you stay very still, it may wander past you.

Fainting is a side effect and not a desirable effect. When your body reacts strongly to fear, it dumps a load of chemicals into your blood, increasing your heart rate, blood pressure, glucose levels in your blood, etc. Blood is often drawn *away* from your brain so that your muscles can get more energy and oxygen. If your response is too strong, your heart beats to erratically and suddenly your brain isn’t getting enough oxygen. Maybe the “freeze” part is a bit too strong and your breath catches, too. You try to move too quickly and your body just can’t keep up, so you pass out.

It isn’t *meant* to happen, but sometimes it does. Our ancestors that didn’t have a strong enough fear response died as a result. Too strong a response may also get you killed, but there will always be random variation so that some people just react more strongly than would otherwise be safe or healthy.