Social signaling behaviors should be taught as part of language studies and it's a shame they aren't, honestly, because people who are going to pick up on it usually do so at, rough estimate, around 3-4 years old when they're gaining voluntary control of their fine and gross motor functions and typically developing toddlers will do a whole lot of imitating how their parents do things, right down to nasal "hhmphs" or ways of standing or pointing or looking. Toddlers attempting to use their parents "I am your parent and I need you to listen to me" Look can be absolutely hilarious (but laughing isn't helpful, we gotta save that for later, serious face means serious business!). That social cue learning does continue indefinitely, and starts before someone has the dexterity to mimic what they see, but before anyone gets the idea that "it's too late", this entire thing, from my perspective, is about what we can learn via comparison, and I am distinctly against "the developmental window for this CLOSES at this age/brain stops developing at 25" kinds of nonsense. For the most part, deliberate skill gain or re-training can be self-enacted at any age, the understanding of *how* people learn in a typical developmental path and *when* they do so might contain tools for how to develop such skills later in life if we choose, as well as how to help people who are still in those initial periods, but are for whatever reason having difficulties communicating with their age-mates.
For example, the fact that I preferred interacting with people much older or younger than me as a child over interacting with people my own age might have been a hint that I was experiencing social difficulties that people younger than me didn't notice and people older than me subconsciously compensated for on my behalf. Which, on further consideration, is something I remember my mom noticing, but she didn't have the extraordinarily specific knowledge to connect it to any sort of solution other than "give the kid social opportunities with a broad band of ages so there's always going to be someone they can bear having a conversation with" (props to my mom, memory loss ate those experiences for a long time but now that my brain is willing and able to index anything other than threat-avoidance topics, that bank of positive social experiences is in fact helping me immensely.)
Anyway! Because a typically developing person learns their culture's social cues so early, they don't remember that it was something they had to learn at all, and might never learn it's not innate unless they get really immersed in learning a second language/culture that's very different from their first.
This means that a typically developing person also directly benefits from actively being taught their own culture's nonverbal and/or subconscious social cues; much like socializing a dog or a horse, it makes for a more adaptable, more deliberate, less anxious and xenophobic person.
griping ahead, not especially serious but also not as structured and hopefully informative as previous content
Every time I'm reminded that subconscious social cues exist and that I can be using them without being aware of them, it feels a little bit like other people can read my mind. Which overlaps with the experience of genuinely *not* using social cues and then the lack of cue being also encoded as a communication, which just... feels so frustrating. It's my face, bud. It's doing whatever it's gonna do.
On good days I'm like "Wow I am so good at communicating I have successfully portrayed 'I am kind and comfortable and want to help" so well today, I'm getting a good grade in human!" and on bad days I'm like "it should be... rude. To look at someone. Feels invasive. Why must other people be able to know what I am looking at? That's not their business... I should be able to hide in the rafters like the Phantom of The Opera with no social consequences..."
And then I go home to my feline and I say "You, though, you get me. We are parkouring this language barrier so hard, mutual respect is present here. Please remove your feather-duster tail from my entire face. Thank you."