Some writers have always claimed they can hear their characters speaking, with Enid Blyton suggesting she could “watch and hear everything” and Alice Walker describing how her characters would “come for a visit ... and talk”. But a new study has shown this uncanny experience is very widespread, with almost two-thirds of authors reporting that they hear their characters’ voices while they work.

Researchers at Durham University teamed up with the Guardian and the Edinburgh international book festival to survey 181 authors appearing at the 2014 and 2018 festivals. Sixty-three per cent said they heard their characters speak while writing, with 61% reporting characters were capable of acting independently.

“I hear them in my mind. They have distinct voice patterns and tones, and I can make them carry on conversations with each other in which I can always tell who is ‘talking’,” said one anonymous writer. “They sometimes tell me that what I have in mind for them isn’t right – that they would never behave or speak that way. I don’t usually answer back,” said another.

The study, which appeared last month in the journal Consciousness and Cognition, also found that 56% of the writers surveyed reported visual or other sensory experiences of their characters when they were writing, while a fifth had the sense that their character was occupying the same physical space. Fifteen per cent of writers said they could even enter a dialogue with their creations.

“When I’m trying to ‘put words in their mouth’ instead of listening they often talk back. And then we discuss things until I find what they would say,” reported one anonymous respondent. Another revealed that their characters’ voices were distinct from their own inner speech: “When my characters are running dialogue in my head I feel like a spectator, but with my own inner speech I feel like the one speaking.”

According to Durham University’s Dr John Foxwell, the lead researcher on the project, the authors in the study reported a wide variety of experiences.

“The writers we surveyed definitely weren’t all describing the same experience,” Foxwell said, “and one way we might make sense of that is to think about how writing relates to inner speech.” Internal dialogue, or inner speech, is a phenomenon that people experience in many different ways, he continued, with some people including the voices of people they know as part of their verbal thinking. “Whether or not we’re always aware of it, most of us are trying to anticipate what other people are going to say and do in everyday interactions. For some of these writers, it might be the case that after a while their characters start to feel independent because the writers developed the same kinds of personality ‘models’ as they’d develop for real people, and these were generating the same kinds of predictions.”

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Even though some authors reported that their characters had a life of their own, the researchers were keen to stress that there was no question of writers confusing fiction with reality. When the academics rated the writers on how prone they were to hallucinations, they did not score differently to other samples of the population. “Hearing voices and other unusual experiences are not in themselves a symptom of a mental health problem,” they wrote. “This shows that vivid imaginative states – including losing control of one’s own imagination – [are] a healthy and safe thing which is important for how some people create fiction.”

One Day novelist David Nicholls said he could hear his characters, “and I think I could pick them out of a line-up too. They certainly have a physicality and a vocal rhythm, though often for me that comes from actors rather than real-life friends.”

The bestselling crime novelist Val McDermid recognised the phenomenon, but explained that she is able to exert a measure of control. “They don’t just pop up out of nowhere,” she said. “But when I’m working on a novel, I have conversations in my head with them. When I’m out for a walk, there are all sorts of interrogations going on in my head and sometimes out loud. But if I’m not working with a character, silence.”

As a writer who has worked in parallel on independent series of novels, this ability to quiet the voices in her head is crucial. If she’s working on a Karen Pirie novel, for example, McDermid will never hear the voices of other series characters Carol Jordan or Kate Brannigan. And there’s never any question of who is in charge.

“I do not think they act independently,” McDermid said. “They have the life I give them and no more. Sometimes when I set myself a problem or a question before I go to sleep, my subconscious provides the answer in the morning, and that answer is sometimes surprising or unexpected. But I don’t think I’m possessed by the characters; I just think my subconscious is good at processing data.”

Her mind may be working hard in the background, she added, but there are limits. “I don’t feel their physical presence. Nor do I smell them...”