With all the emphasis now on showing rather than telling, it's no surprise that so many writers employ physicality to express the emotional states of their characters. One of the earliest lessons we learn is not to say "she looked angry," but instead "her eyes narrowed" or "her jaw clenched" or whatever other mini-action seems appropriate. They can also replace basic adverbs: Her eyes narrowed. "That's none of your business." rather than "That's none of your business," she said angrily. Physicalities can even denote a physical state, like being hungry, cold, or in pain.
I am entirely in favor. It's much more interesting to get a specific visual than it is to read, "he looked nervous." But most writers know that. As I said before, this is showing versus telling at its most basic, and one of the situations in which most everyone prefers the former to the latter. What some writers don't know is that there are a few pitfalls to this popular technique.
This is rarely a problem, since some of the most commonly-used physicalities - smiling, crying, and blushing, for example - are realistic and easily understood. Some, like smiling and frowning, don't annoy the reader if they occur with moderate frequency. Still, it pays to sometimes vary the actual descriptions. This might mean using "grinned" or "beamed" rather than smiled some of the time, or it might mean playing with metaphors and similes:
"[Uncle Vernon's] face went from red to green faster than a set of traffic lights. And it didn't stop there. Within seconds it was the grayish white of old porridge . . ." - Harry Potter and the Sorcerer's Stone
David L. Robbins, who taught my Advanced Fiction class at William & Mary, would contend that practically any physicality is too much. He cut it with a vengeance, encouraging his students to express characters' emotions through dialogue and action alone.
I tend not to be quite that sparse. If the action or dialogue really does stand alone, that's great, but sometimes a facial expression - or a growl, a fist through the wall, what have you - adds to the scene. Besides, it can be a great tool for expressing unexpected or hidden emotions. A character might wince at hearing what should be good news, or smile at a private joke.
There is still such a thing as too much.
As a visual person, I sympathize with writers who want to share every twitch and blink that they see in their minds with the readers. That doesn't mean it's a good idea. If every line of dialogue is accompanied by a physicality, the pace slows, attention is distracted from the spoken lines, and the scene runs the risk of feeling silly. Also, a character who is saddled with a dozen mini-actions in one page can come off as kind of a spaz.
Aside from the overuse of physicality in general, writers should be aware of how frequently they use specific expressions, especially the less-common ones. It's just like vocabulary: Your characters can "smile" almost as often as they like, but they should try to avoid more than one "pout" or "flinch" per chapter or so. And please, please, if your characters must have eyes that "smolder," don't let them do it more than once per book. "Smolder" is not only a distinctive action, it's also a distinctive word, so repeating it breaks both the expression rule and the vocabulary rule. But even expressions that aren't so distinctive can be overused: The protagonist of a book I recently read bit her lip so many times that I ended up picturing her as just sort of munching on it through the whole story, and was surprised that she had any lips left by the end.
This is the one that actually prompted me to blog about this topic. Many physicalities, especially facial expressions, have familiar causes that everyone knows. We've all smiled, laughed, and winced. We know when it's appropriate for a character to do these things. Some of the less-common ones - blushing, shivering, fainting - can be accidentally abused by writers looking to be vivid or dramatic. It's worth a bit of research, or just a second thought, to do these things right.
Some writers overuse strong physical reactions. When was the last time you actually shivered from fear? I don't think I ever have. I catch fictional characters doing it all the time. There's also a lot of screaming, sobbing, and turning white with anger. These are all things real people do, of course, but not all the time - and, worth remembering, not all people.
I find the biggest problem with these reactions is not inaccuracy, but frequency. A writer may develop a standard way to convey certain emotions - say, fear with shivering, embarrassment with blushing. In reality, however, these reactions differ by person. Even something as simple as blushing may be common in one person but rare occur in another. My mom says that, when she was younger, she would turn "so red!" when embarrassed, and still does when she exercises. I went to school with a girl who did the same thing. My face, on the other hand, seems to change color only with sunburn or medical issues - see recent post on fainting. :P It makes more sense to have a separate standard response for each character, so that embarrassment causes Sally to blush but Billy to shuffle his feet or avoid people's eyes. Then, too, there are degrees. Maybe Sally goes pink around the ears, while Rex does a full-on tomato impersonation. (What? People named Rex can blush!)
Fainting is a similar, if more extreme, example. Some people are prone to it and others simply not. No amount of surprise, prolonged standing, or watching surgery will cause fainting in some people, whereas others get woozy at one or all of the above, or a number of other causes. While you may never write a fainting scene, it's worth remembering: Under the right circumstances, almost anyone will blush/faint/scream/tremble/etc., but some people are blushers, fainters . . . you get the idea. Making one such reaction your go-to for a certain emotion can not only be unrealistic, but diminish the oomph that you get from something like a real shiver. You also lose an opportunity to distinguish your characters from one another.
Physical expressions can be tremendous fun. As a fantasy writer, I love creating expressions for characters who aren't human. Two of the characters in The Dogwatchers have magical reactions to certain emotional states. Then, too, I've always liked characters who come from a different culture and revert to old mannerisms when startled or upset - like my Latin teacher from Alabama, who ordinarily had no noticeable Southern accent, but once exclaimed, "Oh mah Lawd!" at the sight of a gory illustration in a graphic novel.
So yes. If Lesson One in writing emotions is to show, not tell, then Lesson Two is that there are a zillion creative, effective ways to show. Use them!