YOUR FACE · 6:25pm May 16th, 2018
Here's this weird, obscure little thing in prose that took me a long time to figure out.
I noticed something that felt like lazy writing. This is probably something that doesn't bother anyone else, but it bugs me.
YOUR FACE 
no no stop that Fluttershy, we're done with that joke.
The alleged bad writing goes something like this short and simple sentence:
Rarity smiled.
Before you jokers ask, it's not because it's Rarity.
It feels off to me. Sometimes.
But I couldn't figure out why, or how to fix it. Does it need fancier descriptive prose? A thesaurus-provided synonym of "smiled"? Glitter?
But sometimes it didn't bother me at all, and it felt perfect. Some authors could make it work just fine. Maybe it was some weird bias.
I didn't copy down any examples, because my reaction seemed so vague and I couldn't explain it. I just see it sometimes in fanfics. And published books too. It was just a few words. Facial expressions, even body language, but I had no idea why it felt off to me.
One emerging – and increasingly supported – theory is that facial expressions don’t reflect our feelings. Instead of reliable readouts of our emotional states, they show our intentions and social goals.
Then I thought outside the box. Outside the quotebox. At the surrounding context in the writing.
I'm still a little skeptical of those research results (the photographs seem flawed to me), but I think the article does a good job deconstructing a lot of common sense stuff about how facial expressions actually work.
1. It's pretty rare that an expression directly reflects our emotional states.
I think this may be where most of that "Rarity smiled" thing came from. Writers are always told to show, don't tell. Don't tell us that Rarity is happy, show it to us. How do you show it? A smile. Done. It's a mental shortcut, and it's still basically telling.
You can put any face behind a mask. But be careful. Because someone else might be pretending.
Telling, but can also be misunderstood. Characters can lie with words and expressions. If you just want to show that Rarity is happy, a smile is about as vague as writing that she wore a blue hat. And fancying it up with purple prose doesn't make it any clearer either.
2. An expression can indicate what direction we want interaction to go, rather than how we currently feel.
Remember that they're usually making an expression toward another character, not just for the sake of the audience. Write a scene with this in mind, and the audience will want to see how the other character responds.
3. Others can interpret an expression very differently from intended.
Even when you're not from a totally different culture, people can be bad at reading faces, and project their own ideas into what they see. Character interpretation is a possibility here for communication.
Alternatively, maybe a character takes every smile at face value (heh), even if it's someone shifty trying to sell them something.
4. Some of the indigenous groups in the study automatically associated faces with an action, not a feeling.
If you can write the action well, do you really need to specify the facial expression? If amazing things are happening for Rarity, the audience can imagine her face. Same as if terrible things are happening in her life.
But if terrible things are happening to her, and she smiles.... now that's something important to make note of.
5. If it's true that we're evolutionary created to conceal our inner states, then maybe you'll have to find other ways to communicate an emotion in writing.
Expressions and body language should be deliberately chosen, not a constant status update on how a character is feeling. Use them sparingly.
I guess that sums up that question I had in the beginning. Sometimes, "Rarity smiles" is all you really need to say, when it's moving the story along. It's communicating to another character, offering a choice in where the story might go next. That line only bugs me when it's used as a boring mood ring for the audience. About as vague as a mood ring too, because there's a lot of social nuance involved in interpreting these, and we need the context of what's happening around it.
I've linked it before, but analysis of facial expressions teaches a lot. That blog shows how even visual artists can often get it wrong, just from a few crucial details that we're trained to notice. The people tested couldn't agree on a lot of vague faces... and they're not even from Mozambique!
It's easier in prose, you merely have to write a word like "smile", but keep in mind how much of the meaning in such words is subjective for the audience.
Maybe I'm the only one who gets bothered when it's done badly, but I think everyone subconsciously appreciates when it's done effectively.
Wait a minute there's an entire song about smiling, I could've used that as the pony reference at the beginning instead. 
YOUR FACE
Great post. I've added it to my blog index. (Which might not get updated on my home page for several months, since knighty wrecked text formatting again.)