Stop. What are you thinking at this very moment? Engage the thought, the conversation going on in your mind. Write down the actual words that you hear. Whose voice is speaking? Is there language in the thought? Are there full sentences, or compressed fragments, a coded language tailored only to your mind?

These are some of the questions that may be asked during a Descriptive Experience Sampling (DES) debriefing. DES is an experimental method utilized by psychologist and author Charles Fernyhough and his colleagues in Berlin to help understand how inner voice works. (In other words, to understand how we talk to ourselves.) Now, the next thought going through your head is probably: Why does it matter? That’s exactly the question Charles Fernyhough’s new book, The Voices Within: The History and Science of Why We Talk to Ourselves, aims to answer, and what he reveals is often as enlightening as it is surprising.

Fernyhough, who received his Ph.D in psychology, has been studying inner voice since the early 1990s. For many people, inner voice is a significant part of daily life; yet the subject is vastly underexplored and often misunderstood. In fact, it’s frequently lumped together with “voice hearing” or neurological disorders such as schizophrenia (itself a misunderstood phenomenon). With The Voices Within, Fernyhough is hoping to not only illustrate the distinct difference between voice hearing and inner voice, but alter the common narrative around inner voice completely.

“There’s a lot to be done by changing the climate in which people think about inner voice experiences and start to recognize them as part of the incredible richness of the human experience,” he argues. “Inner voice is something that’s been around for a long time and crossed cultures. These experiences can carry all sorts of different meanings.”

One key factor to achieving this change, Fernyhough proffers, is to reimagine how inner voice is studied. “We have amazing scientific methods now, but we’re not doing a good enough job of paying attention to what’s inside, to what’s in someone’s experience,” he explains. “If you’re upset by hearing voices, you don’t go to a psychiatrist and say, ‘I’m experiencing functional disconnectivity between my temporal and frontal lobes.’ You go to the psychiatrist and say, ‘I’m hearing a voice.’ It’s about experience.”

Relaying these complex findings and results could have been a confounding reading experience, but that’s not the case. By entwining inner voice theories,  research, and data into easy-to-digest literary, pop culture, and personal anecdotes, Fernyhough has (quite intentionally) crafted a book that reads like a novel but never strays from its carefully examined scientific foundation. “I wanted to write about science differently,” Fernyhough says. “I haven’t just been treating these experiences [of inner speech and voice-hearing] as scientific puzzles to be understood; that was really important to me. When you’re writing about human experience, the humanity has to be right at the center.”

Despite years of research, though, Fernyhough admits science is just at the forefront of understanding inner voice. Which bends back to the initial question: Why does it matter, especially for those who are wary of their inner voice to begin with? “Inner voice or inner speech is seen as a bad thing. I don’t think that’s true. Some people say we might get rid of our inner voices because they might be trouble,” he says. “If you silenced the inner dialogue, you’d lose a lot of other things as well, such as the ability to think creatively and a lot of things that make our minds what they are.”

Alex Layman is a writer living in Austin.