I learned this from acting. When we work on a script, we put triggers in on purpose. We take something from our own past and put it where the character experiences something similar. It's called substitution.
Then when the other character says the line, it triggers our original response, and it matches the character's.
That is exactly what your body is doing all day.
Someone brushes past you, and it tags on to the time someone knocked you over, or the time your dad hit you.