If it is indeed the case that everyone knows for certain what the signals mean, then they can be very specific communications of intent and consent: there is not actually any guessing going on!
It's possible to send signal A and the other person not understanding what the signal means and doing nothing.
But it's also possible that they don't understand the signal but the signal causes them to feel a certain emotion and that emotion lets them engage in an action without them having any idea of the casual chain.
The more I learn about how humans work the more I get those practical ethical dilemmas. Even worse, to really know what I'm doing I have to experiment and I'm curious ;)
If it's worth saying, but not worth its own post (even in Discussion), then it goes here.
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