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Some book characters really stick with you.

In fact, almost all readers say they hear the voices of characters as they read (in fiction and non-fiction) at least sometimes, according to a survey conducted by researchers from Durham University in the UK in partnership with the Edinburgh International Book Festival and The Guardian.

Perhaps more interestingly, almost a fifth of readers said they hear the voices or thoughts of characters in regular life even when they aren't reading the book, something the researchers call "experiential crossing."

Perhaps you've heard Gandalf or Dumbledore give a wise perspective on a real-life scenario; perhaps the voice of Ivan Karamazov saying "I most respectfully return him the ticket" has been your reaction to injustice in the world; perhaps — like Science of Us's Melissa Dahl— reading "The Catcher in the Rye" as a kid made you feel you could see the "phoniness" in everything.

"If the 'voice' of a good book gets into my head, it can seep into my own experience of the world and I find myself thinking in that voice, as that character, while carrying out normal activities," one survey respondent reported.

Another study participant described their reaction to reading Virginia Woolf:

"Last February and March, when I was reading "Mrs. Dalloway" and writing a paper on it, I was feeling enveloped by Clarissa Dalloway. I heard her voice or imagined what her reactions to different situations. I'd walk into a Starbucks and feel her reaction to it based on what I was writing in my essay on the different selves of this character."

So if you've ever found yourself perceiving a situation the way a character from a book would, you aren't alone.

This doesn't necessarily mean that most people hear voices as if they were spoken aloud. One in seven respondents reported that the voices they hear are so clear to them that it feels as if someone were in the room. But in the rest of cases, it's less vivid than that.

Film versions of a story also seem to influence the way readers imagine and hear characters. "Usually if I have watched the film version before reading, the voices will be those of the actors when I read the book," one respondent noted.

It's worth noting that survey participants may have been more interested in reading than the general population, since respondents were recruited from a project website, at a book festival, and via ads in the books and science sections of The Guardian. Survey respondents reported being 75% female, 24% male, 1% other; with a median age of 38.8; and came from a variety of English-speaking countries.

"The Neverending Story" kind of takes this idea to an extreme.
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In many ways, it's not surprising that readers "hear" characters. It makes sense that in an immersive narrative, the voices of all involved come to life — that's what "The Neverending Story" was all about, after all. When a good book is in your head and you are thinking about the "voices" involved, it seems logical that those voices would add new perspective to what you see around you.

But the study does add weight to the idea that in our brains, even fictional characters can seem real. In fact, the authors write that previous neuroscience research has found that the parts of the brain associated with hearing voices become active when people read dialogue.

This illustrates a power of literature that might be unique to the medium.

"It gives you the interiority of characters' minds," Novelist Edward Docx tells The Guardian. "The greatest film can't do that, and neither can a computer game. Only the novel can give you an intimate portrait of the complex cross-currents of human psychology, to the extent where you know another person's soul. And that's the most intimate thing in the world."