Individualism and communalism aren’t the only aspects of culture so pervasive, we can barely even see them. Like fish taking for granted the water they swim in, we make plenty of other assumptions on a regular basis, never even noticing that we’re doing so until we run abruptly into someone who doesn’t.
Take, for example, the communication styles often glossed as “ask culture” vs. “guess culture.” Most specifically, this refers to how requests get made: are they asked directly, or are they indirectly implied, with the requestee expected to figure out from context what the requester wants?
You don’t even need to cross national or ethnic boundaries to find two people from opposite sides of this divide — it can vary on a family-by-family basis — and all kinds of trouble can result from the mismatch. The ask-culture person thinks the guess-culture person is being passive-aggressive, never coming out and saying clearly what they want, yet also feeling hurt when that unspoken desire isn’t fulfilled. The guess-culture person thinks the ask-culture person is straight-up aggressive, constantly inconveniencing other people with their needs. The asker might think the guesser is free to turn them down or defer until later, but to the guesser, a direct request is a demand for action this instant; refusing or delaying puts them in the position of having to be rude. Indirect requests leave the recipient more free to deal with the matter in their own way, on their own time — or not at all. Assuming, of course, that the recipient knows what they’re supposed to do!
Other aspects of personal interaction are equally open to misinterpretation, one person’s normal behavior coming across as overbearing or standoffish to another. Proxemics is the term for our spatial relationships; on the level of interpersonal distance, academics divide it into intimate space, personal space, social space, and public space. Have you ever had somebody stand way closer to you than you’re comfortable with? They’re crossing an unseen boundary, an acquaintance you’re not very (socially) close with getting as (physically) close as a good friend would — or even closer. Such an invasion can be good for both flirtation and intimidation, depending on how it’s used . . . and how it’s read. If you’re in the habit of maintaining greater distance between yourself and others than your conversational partner is, what they see as perfectly reasonable positioning might register on you as an invitation or a threat.
Closely coupled with this (because it requires a high degree of closeness to happen!) is haptic communication, aka touch. What kinds of touch do you consider normal, and with what kinds of people in what circumstances? Bowing, shaking hands, and kissing cheeks are all culturally acceptable ways to greet somebody, but ohhhhh the awkwardness that results when the cultures being referenced differ. Is touching somebody’s shoulder a come-on, or merely a nice gesture of friendliness and support? Haptic communication can often be asymmetric: an individual in a position of authority (whether that’s a boss or a parent) will touch their subordinate in casual ways, but the subordinate is not equally welcome to touch back. In modern western society, it’s also moderately gendered, with the stigma against homosexuality constraining when and how men can touch other men, while women can engage in it more freely.
Body language in general is partially universal, partially culture-specific (and therefore vulnerable to being misinterpreted). Somewhat famously, Indians and other South Asians have a particular gesture sometimes called a “wobble,” which is neither a nod nor a shake of the head. Does it mean “yes” or “no”? Its meaning is flexible, depending on context, and it can be mystifying to people for whom that’s not part of their gestural lexicon. The “OK sign,” forming a circle with the thumb and index finger, means approval or assent in some places, a variety of insulting messages or even a curse in others. Even a smile has a certain amount of ambiguity: for many animals, baring their teeth is a sign of aggression rather than friendliness. Especially when different sentient species come into play, as they might do in fantasy or science fiction, how universal can you assume any gesture to be?
There’s also wide variation simply in how much people deploy body language. Italians are stereotyped as “talking with their hands,” making frequent and emphatic gestures as they speak; in another culture, that amount of animation might seem bizarre, even half-frenzied. Conversely, someone from a society where you’re expected to remain fairly still as you talk, especially if your facial expressions are also relatively muted, might seem anything from passive to frightened to bored to inscrutable — that last being the old stereotype attached to East Asians. Precisely because we take our own style of communication so much for granted, anyone who diverges from it will seem odd, and a whole society of divergence will seem alien.
Or just, y’know, rude. Does your interlocutor speak (what you consider to be) too loudly or too softly? I’ve seen an American resident in France caution a visiting American to bring their voice down in a restaurant, because the average volume of conversation there is notably lower. Hello, the stereotype of the Loud American! Again, though, the boundaries can lie along lines other than those of nationality or ethnicity: going back to proxemics, we’ve coined the term “manspreading” for the portion of the male population that reflexively claims a larger share of space than other people do, women in particular. Rich people will behave differently from poor ones, with the poor thinking the rich are affected in their mannerisms, the rich thinking the poor are vulgar.
Because so much of this has to do with aspects of behavior that don’t often show up on the page, it tends to be neglected in fiction. We only know someone is speaking very loudly or softly, or gesturing too much or too little, or standing too close or too far away, if the writer makes an active effort to call it out. Which means that, much as in real life, we mostly only see these kinds of things when a disconnect happens: the viewpoint character notices a difference and reacts to it. The rest of the time, the reader likely assumes — to the extent that they think about it at all — that the characters’ behavior is in line with what they consider normal. Only when it comes to something more visible, like the ask vs. guess distinction, might they notice without the writer making an effort to call it out . . . and even then, the noticing probably happens when the writer’s assumption of normality differs from that of the reader.
And most of the time, that’s fine. Not every story needs attention to things like interpersonal distance or the dynamics of touch. But especially when culture contact features in the story, noting the little differences as well as the big, obvious ones can really help sell the effect.