Yes, this really happens. Writers do, occasionally and completely by accident, dismember their characters. There’s this quip about helicopters that is oddly relevant: “a helicopter is a large collection of parts all flying in formation.” Sometimes writers do that to their characters, with unfortunate results.

This happens when writers put a character’s parts in the forefront—feet, ears, eyes—instead of the character herself. It can happen with non-corporeal parts of a character too, particularly the senses. In paranormal and fantasy literature, it includes non-standard abilities as well, far-sight and the like. Here’s an example:

Susan’s worry rose, blocking out all other thought. Where’s Alex? He should be here by now. Her eyes scanned the theater lobby, the sidewalk outside, the parking lot, looking for him. But he was nowhere to be seen.

On the surface, it’s not literally true. Susan’s worry didn’t, itself, actually do anything. Susan is the one who did the worrying. Similarly, her eyes did not, in and of themselves, scan her surroundings. Susan scanned her surroundings, using her eyes.

This grammatical elevation of body parts to the subject position of a sentence may seem like a simple matter of style. After all, reasonable readers take the intended meaning just fine. They don’t automatically jump to the erroneous literal interpretation of those words. If that’s all it was, I wouldn’t be writing this post.

But under the surface, something much worse is going on. Every time you put one or more of a character’s composite parts in the subject position of the sentence, you rob the character of just a little bit of power. You take the whole character out of control, in favor of a mere portion of the character.

It may be a cliche that “the whole is greater than the sum of the parts” but in this case it’s absolutely true. A whole character, a whole person, creates much stronger resonance with the reader than the result of presenting the character’s parts one by one. Even if you include all the parts.

By putting a character’s parts to the fore, you make the overall character seem more passive, less action-oriented. Every time you do it, you send a subtle message that the character isn’t really in charge. That she, the whole person, is but a slave to her parts. When Susan’s senses reach out, when her parts act while, grammatically speaking, she sits idly by, it undermines the reader’s ability to believe in Susan as a strong agent of action in the story.

I suppose that this could work to great effect, if done well, in certain kinds of psychological dramas where a character suffers from some kind of dissociative mental problem. Or maybe in demonic possession stories. But for your ordinary sympathetic characters, it’s a problem.

There are some exceptions even for characters who aren’t mentally afflicted. Involuntary actions are chief among them. These are uncontrollable physiological responses to whatever’s happening in the story. When the heart quickens, it does so without our conscious bidding. When a sudden fright causes adrenaline to dump into our bloodstream, that’s automatic. Anything going on with a character’s body that is outside the character’s conscious control is fair game to put into the subject position of the sentence. In those circumstances, it’s really true that the character isn’t in control and therefore something else has to occupy the subject position.

The other notable exception is for the hands. Hands are so closely associated with the exercise of ordinary human will as to carve out their own exceptions. At least in English, it is almost idiomatic that hands stand in for our will. That is, this is perfectly fine:

John’s hand flew across the page as he penned the lines of a sonnet he was sure would win him the Frost Medal.

We all take John’s hand to be a tool in this usage.

Hands are so closely associated with the will that reversing this expectation creates a powerful effect. Horror fiction and movies, in fact, seem to delight in turning characters’ hands against them. It is a well-worn trope in horror to show demonic possession by making someone’s hands attack them. The character of Ash, from the Evil Dead movies, is the classic example: Ash had to resort to dismembering his own hand before it killed him.

Look at the reversal going on there, and how Ash’s response portrays him. Ash’s hand begins to attack him. It punches him. It tries to choke him. Ash is rightfully shocked. Ash is out of control of his own body. Part of him has become possessed. In order to reassert control and save himself, he fights back. He tries to pull the evil hand away from his neck using his unafflicted hand. But ultimately Ash must physically separate himself—willfully—from his own hand. It’s a powerful and dramatic action, and it utterly convinces the viewer that Ash is someone who will take action no matter how personally painful it might be.

Audiences root for him so strongly because even when his hand took the subject position, Ash remained the ultimate agent of action.

Obviously, that’s the exception. The rest of the time, in normal circumstances with normal characters, don’t dismember them by accident. Leave the whole person as the agent of action, and let the body parts remain tools of the will as they properly are.