system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we put our hands in front of our mouth when we gasp? Is it to instantly protect the mouth?
gpt
A gasp and the hand-over-the-mouth are actually two separate gestures.

A gasp is a reflex.  When we are startled, either physically or emotionally, we draw in air.   This reflex comes from the moment of our birth, when it is very important that we gasp for air.   We gasp, our lungs inflate, we live.   Reflexes never leave us, so a gasp is carried on throughout our lives.

The hand-over-the-mouth is what is called a *self-silencing* gesture.  It’s literally the same motion that a person uses to clap a hand over a toddler’s mouth when they start telling grandma how old she looks.

We do this to ourselves to tell ourselves to be quiet.  Another self-silencing gesture you’ll see (or notice yourself doing) include pressing fingers to the lips in a ‘shh’ motion.  There’s also self-comfort (hugging yourself, rocking back and forth) and a whole variety of other physical gestures like this that manifest when we are trying to control ourselves - consciously or otherwise.