It all happens in a flash.
Our brain shuttles the sensory data streaming in to the relevant processing areas as the amygdalae - the two small portions at the middle base of the brain - ignite and flood emotions towards the prefrontal cortex, responsible for organization and systematic thinking, and (if morality is called for) brush along the dorsolateral prefrontal cortex as the angular cingulated cortex - an elongated region on the frontal inside of the brain - magnifies the emotions and moral confusion while our autonomic functions rise from the increased stress. The medulla oblongata - located at the brainstem - then quickens our breathing rate and heartbeat (and adds slight nauseousness if digestion is momentarily halted) as the reticular formation - the tissue mass at the center of the brain stem - augments our alertness as we attempt to sort through our thoughts.
Yes, all that in well under a second. That’s how quickly someone is going to judge our communications.