Jumpscare is our natural reaction to danger that has been throughout our evolution. If a predator suddenly jumps against us, do we not have time to think about what the appropriate reaction would be, we simply react automatically to get away. It has always been better to react even it was nothing then not react, and it suddenly was dangerous.

Got it💯 why do intense sounds get us jumping on our chair? When the same scene maybe without music ain't scare that much?

Jumpscares in movies and videos are meant to startle and surprise us. Our brains release chemicals like adrenaline and cortisol in response to unexpected events, as a way to prepare us to react to potential threats. Even though we know there is no actual danger, our brains still react as if there is a threat.

Thank you very much!

This is because we often detect a sound before we see the predator, so the sound is mostly what triggers us, while when we first are looking at the danger, is it too late.

There’s a difference between being scared/fear versus being startled.

A big cat won’t fear a kitten and will never feel threatened by it but the kitten can jump the cat and startle it.