Hello. I believe I can be of help to you with this issue.
Screams are automatic, unlearned reactions emitted by birds and mammals (mostly) when they are in extreme danger. They represent either intense fear or distress. Fear screams appear to function as a signal to others (cry for help). Screams are also known to startle a predator into momentarily ceasing its assault, allowing an opening for the victim to escape. Ironically, screams may alert other predators, who seek to take advantage of prey already in distress; this can result in predators initiating a fight for the prey, allowing it to escape. These are the reasons we seem biologically programmed to scream. So why NOT scream?
Not screaming tends to occur when the person is startled, but not in dire life/death danger. Screaming is momentarily incompatible with what we want to do when merely 'seriously startled' and sense imminent life/death danger, which is do a "double-take" on what is happening. I suspect that when the man followed you into the bathroom and took down his pants, in your intoxicated state you where initially, more shocked and surprised, that fearful for your life in that moment. If your recall your experience, you will probably realize that an initial reaction was an internal thought , "What the the heck is he doing? Is he for real". So we don't scream if we are very quickly and instantaneously pausing to assess what is going on. You also didn't scream because once you figured it out, you then gave him firm commands that you would scream if he did
not behave himself. You literally gave him a gracious way out of this situation, which was very kind of you, though perhaps not deserved. Not screaming suggests you had a fair sense of control over this fear situation.
I hope this answers your question. Please let me know if I have overlooked anything in providing this response.
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