MS. DIANE REHMThanks for joining us. I'm Diane Rehm. As children, we all talk to ourselves out loud for all to hear. As adults, a similar conversation occurs, but it's private, existing solely within our own minds. A new book explores these inner monologues and dialogues. It's called "The Voices Within: The History and Science of How We Talk To Ourselves." The author, Charles Fernyhough, joins me from a BBC studio in London.

MS. DIANE REHMIf you'd like to talk with us, you can call us on 800-433-8850. Send us an email to drshow@wamu.org. Follow us on Facebook or send us a tweet. And Charles Fernyhough, it's good to have you on the program.

MR. CHARLES FERNYHOUGHIt's great to be here. Thank you for having me.

REHMIndeed. And, you know, you start your book with an example of your own when you were riding on a train and, all of a sudden, you start laughing out loud because of something you've heard in your own mind. What was the phrase you heard and did you surprise yourself and those around you when you started laughing?

FERNYHOUGHYes. I was having a thought about a story I was writing and this phrase just popped into my head about funny slices of cheese. And I started laughing. No, everybody around me was kind of looking at me and wondering why I'd suddenly burst out laughing. But after a while, after thinking about this for a moment or two, I thought, actually, these guys aren't that surprised because they've realized that I've just done something pretty ordinary. I've entertained myself with my stream of consciousness.

FERNYHOUGHI've entertained myself with a thought. And that's the kind of most ordinary experience a person can have in a way. So this is about human experience. It's about the stuff that goes on in our heads and it's something that I think is experienced by everybody listening to this show.

REHMWhat I'm fascinated by is that you were working on a story. So did you use the phrase that popped into your head in your story?

FERNYHOUGHI don't know if the story ever got finished, actually, but it got me -- certainly got me thinking about this, you know, this topic and I guess the result maybe is the book that's in front of you.

REHMYou know, I have written several books and things do pop into my mind that are of relevance to what I'm trying to write. So what I'll do is write them down. I would imagine you do the same thing.

FERNYHOUGHSure. I think one of the things that inner speech, which is the topic of my book, this conversation that we have with ourselves, usually silently in our head, one of the things it does is help us to prepare for what we write. You know, I think it's an important thing for writers to have to be able to work what you're going to say before you say it. But it's only one of many, many different functions.

FERNYHOUGHA kind of related function is when people use in a speech, when they're learning a second language, and they sort of prepare in an unfamiliar language what they're going to say in their head before they blurt it out to their audience.

REHMBut until I saw your book, I never knew that there was a science of how we talk to our self. Tell me about that science, how it got started and how you are studying it.

FERNYHOUGHWell, when I started out researching this topic, I guess, a couple of decades ago, I did indeed get some funny looks 'cause people seem to suggest that there wasn't really a science of this thing. You know, how on Earth do you study what's going on in our deepest heads.

REHMInner thought, yeah.

FERNYHOUGHExactly. We're not mind readers. We don’t have the capacity to see inside each other's heads. But there is a real substantial history to the idea that we talk to ourselves. You know, Plato was talking about it 2,000 years ago. Some very important work was done in the Soviet Union in the '20s and '30s by a psychologist called Lev Vygotsky and I think he came up with the theory that is still the most useful theory, a theory that I've spent a lot of my career trying to develop and enhance and test and refine and so on.

FERNYHOUGHSo there's a lot to say about why we should talk to ourselves and what sort of form inner speech should take. But increasingly, there's an awful lot of science out there. So we published an article last year and there were hundreds and hundreds of references on this topic so it was a real change from when I started out.

REHMSo what you're saying is that scientists are looking at this in both positive and negative ways, that perhaps, up to now, we've only thought about it in negative ways, in sort of medical ways and expressing concerns about people who either talk to themselves out loud or within their own minds.

FERNYHOUGHThis is where the story, for me, got particularly interesting. So I started out as a developmental psychologist, so someone who studies those kids that you mentioned in the intro, those kids who will be talking to themselves quite happily. Often when there's other kids around, they'll be chatting away to themselves. I was studying it from within that context, from within the Vygotsky theory. Vygotsky's ideas are really nice and simple. He argues that we start off in life engaged in social dialogues. We're talking to the people around us. They might be parents and caregivers or they might be other kids.

FERNYHOUGHThat -- we then go through the stage of what we now call private speech, the children talking to themselves out loud and then that turns into inner speech. And that's the stuff that's hard to study because that's going on silently inside. So I was thinking about this from Vygotsky and from a developmental point of view. But over there, I could see people talking about this other phenomenon, this unusual phenomenon, this often very distressing phenomenon of hearing voices. And then, I saw that they were using the same idea.

FERNYHOUGHThey were using the idea of inner speech to explain hearing voices. And I thought are they talking about the same thing as I'm talking about? Let's go and have a look.

REHMSo what was your conclusion?

FERNYHOUGHOh, I haven't concluded yet, but I certainly have had a lot of interesting thoughts, which I've tried to set out in the book and as I say this, some really fascinating research, why should inner speech, this ordinary conversation that we have with ourselves as we're walking to work or chopping vegetables or lying in the bath, why should that have anything to do with what we -- what most people see as a sign of a very severe mental illness? The theory is actually, again, thankfully, pretty simple.

FERNYHOUGHThe idea is that when somebody hears a voice when there's nobody else around, what's going on is that they, themselves, have actually -- they have talked to themselves. They've produced some inner speech. But for some reason, they haven't recognized it as their own work. It's like they've done the thing, but they haven't owned it. They haven't realized that it's them who's done it. And as a result, that bit of language gets perceived as an external voice. That’s quite a nice, neat theory.

FERNYHOUGHIt allows us to test different aspects of it, the psychology, the neuroscience of it. And it's a theory that has done pretty well. We've got quite a lot of support for it. At the same time, there are many, many problems with it. There's also some other stuff going on in the phenomenon of hearing voices. And what I wanted to do with this book was just put those two things in a speech, hearing voices, side by side and show them in some of the richness and complexity.

REHMSo you're talking certainly about the creative voice that comes from within and, frankly, I must say I talk to myself a lot out loud when I am at home, reminding myself to do this or that or I may get an idea, which, as I've said, I put down on paper. But on the other hand, I've not had an external voice in my head. The voice that I hear is my own. Is there a line that is crossed when that voice is an external voice in your head?

FERNYHOUGHThis is where things get really complicated and very interesting. When we talk about hearing voices, as I say, it's usually associated with severe mental illness, like schizophrenia -- around 70 percent of people with schizophrenia will hear voices, but so do they in a whole range of other psychiatric disorders, everything from eating disorders to post traumatic stress disorder. It goes with a lot of different psychiatric diagnosis. Further than that, there is a significant minority of people, maybe around about one percent of the population who hear voices quite regularly and are not mentally ill.

FERNYHOUGHThere's no point giving them a psychiatric diagnosis because they don't meet the criteria for it. They are not ill. They are living perfectly comfortably with this experience. Beyond that, there's an even bigger chunk of people, maybe 5 to 15 percent of people will have some -- perhaps one-off, perhaps fleeting experience of hearing voices. And when you turn it round to ask about the kind of experience you have on the fringes of sleep, so what we call they hypnologic state, in other words, when you're falling asleep or when you're just waking up, it's incredibly common to have hallucinations of different kinds.

FERNYHOUGHSo what I want to say is that hearing voices is a part of human experience. It's often a very distressing part of human experience, but it can be a fairly neutral one or it can be an uplifting one. And that's some of the complexity that I wanted to portray. In terms of your question about voices versus thoughts, it seems like it should be really simple. And many people, in fact, who hear voices do actually -- are able to make a clear distinction between the voice they hear and their internal thought. That includes, by the way, people who hear the voice of God, people who hear voices in a religious context. But for others, it's much more complicated and people will say, my voice is kind of mixture between thoughts and voice.

REHMCharles Fernyhough, his new book is titled "The Voices Within: The History and Science of How We Talk To Ourselves." What a fascinating topic. We'll take a short break here. We'll be right back.

REHMWelcome back. If you've just joined us, psychologist Charles Fernyhough is professor of psychology at Durham University in England, author of works of both non-fiction and novels, including "Pieces of Light." His newest book is titled "The Voices Within: The History and Science of How We Talk to Ourselves."

REHMCharles, I'd like to read to you a very powerful email from Chris in Illinois, who says, you do the mentally ill no good service by blurring the distinction between normal talking to oneself and the phenomenon of voices that schizophrenics hear. My wife was a member of the latter category. It was debilitating, the opposite of the effect talking to oneself produces in planning the day. They should not be discussed as two sides of a common coin. They are not.

FERNYHOUGHThat's an extremely good point. And I hope I've made it clear that these experiences are highly distressing for many people. But we are starting to understand that the experience can come in different shapes and sizes, it has different forms. For some people who hear voices, the voices can be quite neutral, they can even be positive and guiding. And in particular, what's happened in the last 25 years or so has been the growth of an international movement, the Hearing Voices Movement, which has rejected the standard biomedical view of hearing voices as a fault in the brain that needs to be fixed and, instead, has started to understand it as a rich, varied experience that has personal meaning to a lot of people.

FERNYHOUGHSo there is this opposition between traditional biomedical psychiatry and a new view of hearing voices from people who say, don't you tell me. Don't you, doctor, tell me what this experience means. We're making sense of this experience ourselves. And I'm very, very sympathetic to the view. I talk to people who hear voices from both camps. I talk to people who are seeing it as a meaningful part of their experience, something that's related to things they've been through in the past, something that has an emotional message to them. But I also talk to people who just want it to go away.

FERNYHOUGHThe only way to make progress, to do better science, and to find better ways of managing the experience is to find out more. And it wasn't my idea to put inner speech and hearing voices together. This was a theory that was out there before I came along. And I've wanted to explore it and make it a better theory and test it out.

REHMHere's a tweet saying, can you discuss the role of inner speech in the learning process? How can teachers incorporate it in the classroom?

FERNYHOUGHThere's a very interesting kind of social pressure that happens when children are growing up. So we talked about these kids earlier, who are happily babbling away to themselves as they're playing, as they're -- there are often other kids around. It seems like the presence of other kids kind of stimulates this speech. It makes kids more willing to do it, even though they're not actually talking to the other kids, they're just talking to themselves.

FERNYHOUGHSo how do you cope with the fact that at a certain age, kids go to school? I mean, any elementary school teacher will tell you how utterly exhausting it is to be in charge of a bunch of kids who are mostly being quiet? You know, how would you cope with the fact that they were talking to themselves out loud? So that's a really tricky question. There's a growing recognition among elementary school teachers I think that this kind of self talk, if it's out loud or internal, is very valuable. But, of course, in a classroom, you've got to keep things pretty quiet for a lot of the time. So it's finding ways to enhance children's use of language to regulate their behavior in a way that they can use it constructively in educational processes.

REHMCharles, going back to that question from our caller in Illinois, when did hearing voices -- when was that determined to be part of a pathology?

FERNYHOUGHThe idea of schizophrenia has only really been around for a hundred years or so. And it's very interesting to take a look further back in time. I mean, I've already mentioned the Greek philosopher, Plato. In our project at Durham, which is called Hearing the Voice and is funded by the Wellcome Trust, we've tried to take a broad, interdisciplinary approach to the topic. So we're looking at it from the perspectives of psychology and neuroscience. But we're also looking at it from a literary, from a historical, from a theological, from a philosophical perspective.

FERNYHOUGHAnd that is fascinating, because it means we can look back at the writings of people like Margery Kempe and Julian of Norwich, two incredibly important, early 15th century English mystics -- who should be much, much better known -- and looking at how they described their voice-hearing experiences, looking at how those experiences had meaning made of them at that time, in that particular thought world of the late Middle Ages and seeing whether that can give us any clues to how we should make sense of the experience now, to how people are making sense of the experience now.

FERNYHOUGHAnd there are a lot of really interesting connections to be made. If anyone gets a chance to go to England in the next few months, we have an exhibition just opening in Durham where we're able to show -- thanks to a generous loan from the British Library -- we're able to show Julian of Norwich's unique early 15th century manuscript of her revelations of divine life. It's the only manuscript in existence and it's the first time it's every been loaned.

REHMAnd what about Plato and his speaking to himself, either within or out loud?

FERNYHOUGHFor Plato, talking to oneself -- the conversation the soul has with itself is, in his words, was a fundamental part of how we can think through problems. It's a part of our rationality. And of course, Plato didn't explore the psychology and neuroscience of it. But he left us a clue to how people have been thinking about this through the centuries. And it keeps popping up in philosophy, in particular. And as I say, in the last, I guess, hundred years or so, there's been a growing body of scientific research that's tried to understand how that works.

FERNYHOUGHBut actually, this idea of inner speech being a conversation is right there in Vygotsky's theory. Because if this comes about through the conversations we have with others, then it stands to reason that whatever is ultimately internalized, whatever ultimately goes inside to become this silent inner speech, should have something of the social about it. It should still be a conversation. And there are different bits of evidence that point to the fact that our inner speech does have this strongly dialogic quality -- a conversation between different points of view.

REHMBut doesn't that, if you will, speak to the idea that you should think before you speak or think before you act and hear what your inner voice is telling you?

FERNYHOUGHThat's often a very good idea, to think before you act. If you mean -- if, by thinking, you mean inner speaking. I think thinking is one of these words that we -- that gets us into all sorts of pickles, because we're not very clear about what exactly we mean by it. But certainly, as I say, inner speech can be very valuable in planning all sorts of behaviors, including what you say out loud.

REHMYou know, it was interesting -- I don't mean to bring the U.S. election into this in any broad way -- but the other day Donald Trump was saying, out loud, stick to the script, stick to the script. And he was talking to himself. He was saying it out loud to the applause of his audience, trying to remind himself not to go off script.

FERNYHOUGHOh, that is brilliant. I didn't see that.

REHMYes.

FERNYHOUGHI think it's a lovely example of how -- I mean, whatever we think about these candidates, they have a hell of a difficult thing to do, to stand up in front of the whole world and come up with stuff and answer questions and so on. And I'm sure I would be talking to myself a lot in that situation as well. But you see it a lot in athletes. For example, Andy Murray, when he won the U.S. Open in that historic win in 2012. He says he took himself off to the changing rooms. He gave himself a pep talk out loud, in front of the mirror. And he credits that with his victory. Somebody posted recently the gymnast Laurie Hernandez talking to herself just before she did a move.

FERNYHOUGHSo it's a bit of a myth that private speech, this out loud conversation with the self, only happens in childhood. I think we're doing it throughout life.

REHMAll right. Let's go to the phones, your questions, comments for Charles Fernyhough about his book "The Voices Within." Let's go first to Patricia in Dallas, Texas. Hi, you're on the air.

PATRICIAGood morning. I love your show. First time to call in.

REHMThanks.

PATRICIAAnd I love the speaker and I love this topic. I'm a child neurologist who specializes in taking care of autistic folks through the lifespan. And one of the things that's commonly worried about by their caregivers is that -- of course, we're in a epidemic, one of 50 boys now will earn a diagnosis under the autistic spectrum and one in 88 children and they're becoming adults. And what I have often seen is these folks, the ones who are very verbal, talk a lot. And if they're not talking out loud, you can tell that they're ruminating. And I've had a few of these folks, but very few, actually be diagnosed as having a psychotic break.

PATRICIAMy question for your guest lecturer is, would he talk about the content of this, it -- the term I was taught was testing reality -- as being the marker for whether or not it's pathologic versus simply the talking to one's self. My own thinking is that autistic folks do lots of self talk in an effort to reassure themselves that what they're doing is right in a world that they don't otherwise really understand well. Thanks.

FERNYHOUGHThat is a really brilliant question. And the puzzle of autism and what happens in the autism spectrum is something we don't know nearly enough about, particularly as it relates to private speech and inner speech. There are some little bits of research suggesting that, yes, private speech can be very common on the autism spectrum. But that maybe people on the spectrum use it in a slightly different way. This would certainly follow from Vygotsky's theory about how it develops within social interactions. You might expect things to pan out differently in autism.

FERNYHOUGHSo, for example, there's a little bit of research that suggests that young people with autism will use inner speech for rehearsal, for kind of keeping an idea in mind, as a sort of memory aid, but not so much for planning out what they're going to do. As I say, it's very early days for this research. I think it could be really key to understanding the spectrum much better.

FERNYHOUGHIn terms of your question about the content being pathological, I don't think that's the right way to go. When we look at the difference between people who hear voices, who are either distressed by them or not distressed, there aren't a great number of differences in what the voices say, how the voices are structured and so on. What tends to be -- what tends to discriminate those two groups is that for people who are distressed by hearing voices -- the voices, tend to be more negative. People who are not distressed, the voices are a kind of neutral or positive. And they also are probably more frequent in those who are distressed by the experience. So again...

REHMSo it's the content of those voices.

FERNYHOUGHIt's the negative quality of the voices. But that, in itself, is a really tricky thing to pin down. Because somebody can say to you, you're a bitch, for example. And that can be incredibly damaging and hurtful. But in another context, if that's the thing you're expecting to hear and you know where that thing is coming from...

REHMHmm.

FERNYHOUGH...maybe it's a bit kind of neutral, I can deal with that. And so just putting it down to the meaning of the words, it doesn't quite do it. And this is something we're trying to understand at the moment. Why is it that some voices are distressing?

REHMAnd you're listening to "The Diane Rehm Show." And let's go to Paul in Pittsburgh, Pa. You're on the air.

PAULHi, Diane. I just wanted to say how much I love your show.

REHMThank you.

PAULMy question is the following. So if an adult talks out loud a lot, is that something that serves a different kind of neurological function from just thinking those thoughts? I mean, for example, when I'm alone, I have a tendency to kind of narrate what I'm doing. Does that serve any kind of function? Thanks.

FERNYHOUGHYeah. So why do we, as adults, sometimes talk out loud, sometimes we do it silently? I think there are a couple of things going on there. I think one reason why we do it out loud -- and I think is one reason why kids do it -- is that putting your words out there gives them a kind of material form that makes them easier to grab hold of. I mean they stay in memory. They're kind of out there resonating in the air for a little bit longer. Inner speech is a bit more ephemeral. So I think that's one thing that's going on.

FERNYHOUGHThe other thing I've already alluded to, which is this idea of social pressures. I talk to myself all the time. And I do it when people are around, but I mostly do it when I'm alone, because I can. And it's interesting to think about some of the possibly evolutionary reasons why private speech turned into inner speech. One of the reasons, surely, is if we say everything out loud, we're not going to last very long. We're going to give our positions away...

REHMYeah.

FERNYHOUGH...to predators.

REHMOf course.

FERNYHOUGHWe're going to give our plans away to rivals, and so on.

REHMBut there are simple things that speaking out loud helps us do, helps me do. For example, my late husband used to say, as we were walking out the door, is there anything you need to bring with you? Now, having that in my head, I now ask myself, is there anything you need to bring with you? And repeating that as a way to remind myself is really very helpful. Sometimes I ignore that question to my detriment. So I think that that inner voice or the outer expression of that question is really helpful to me.

FERNYHOUGHI think, for me, the equivalent is when I'm driving and I come up to a roundabout and I have to -- I know I have to give way to the right. If I'd been driving in the states, for example, I -- it's a different thing. We're driving on the other side of the road.

REHMYeah.

FERNYHOUGHAnd I say to myself, you know, give way to the right, give way to the right. I mean, I've been driving for 30 years. I shouldn't need to. But I do. And I don't have any problem with talking to myself out loud, possibly because I know something about the science behind it.

REHMAnd...

FERNYHOUGHBut another thing that...

REHMI was just going to ask you, would you do that if someone were also in the car with you?

FERNYHOUGHI think so. Yeah. It's likely that it would be my wife or my kids, so -- and they're well used to it.

REHMAll right. And short break here. We'll be back to take more of your calls, your email, and hear about your voices, whether they're within or expressed. Stay with us.

REHMWelcome back to our conversation with Charles Fernyhough, and by the way the spelling on that is F like Frank, E-R-N like Nancy, Y-H-O-U-G-H, pronounced Fernyhough. His new book is titled "The Voices Within: The History and Science of How We Talk to Ourselves." Who would've thunk it, I mean the idea of a book on the science of how we talk to ourselves? He is professor of psychology at Durham University in England. We have so many fascinating emails and phone calls. I'm not sure we'll get to all of them.

REHMBut a Facebook comment from Rob. Could you address your finding on pervasive inner speech? As someone with severe anxiety and OCD, it can be crippling when these conversations become all-consuming in your head.

FERNYHOUGHWe focused on the experience of hearing voices, which is one of the potentially distressing aspects of -- possibly of this internal conversation. But another area of concern are disorders like anxiety and depression, which are characterized by negative thoughts about the self, about the future and so on. We actually know very little about how much these so-called negative thoughts are expressed in language, but if they are, then it's what I would count as inner speech. It's the downside of inner speech.

FERNYHOUGHThe same goes for rumination, the kind of pervasive dwelling on negative emotions. We need to know more. We need to start asking that question. How much of this is happening in language? Because if we can find that out, we can start to connect it to what we already know about inner speech. So it's a really important topic to address.

REHMAnd then a comment from Chris in Pittsburgh, something I know you've addressed in your book. He wonders if people who are born deaf have inner speech.

FERNYHOUGHYes, it seems they do. So so far I've been talking about language, and when we think about the thing we're communicating in now, but of course there are lots of different kinds of language. Deaf people use sign language. There's evidence that deaf people communicate with themselves in sign language. There's evidence that deaf people hear voices, even people who have never heard anything before. They have an experience which is as close to hearing voices as we can discern, and that's a real puzzle for all sorts of reasons.

FERNYHOUGHBut everything I say about inner speech in no way ties that necessarily to a regular language like English. It certainly incorporates sign languages. And so there is some research to be done on this topic. To what extent -- what exactly is inner sign or inner speech like for deaf people? We're just starting a research project as part of our Hearing the Voice Project to address just that question.

REHMInteresting. And an email from Bonnie (PH) in Loveland, Ohio. Are there any gender or racial differences in hearing voices?

FERNYHOUGHNot that we have good evidence for. In the field of private speech, where we look at out-loud self-talk in children, there's been some tentative evidence suggesting -- well actually it seems to go two different ways, depending on which study you read. I'm very interested in cultural differences in a speech. I think different languages potentially afford different kinds of talking to oneself. I've got an example in the book of a Pakistani writer who speaks very interestingly on the difference between Urdu and English as a mode for thinking, the different affordances, the different things that those languages allow. But we know very little about it scientifically, and I'd love to see more research done on that.

REHMAnd someone in, let's see, I don't know where he is, Ed says my all-American, 24-year-old son raised in Florida tells me his inner voice speaks to him in a British accent. He is serious, and this baffles me and scares me a bit. I have an inner voice, but it's merely thoughts. I never imagined an actual voice and never hear it verbally talking to me. Do I have reason to be concerned for him?

FERNYHOUGHI don't think so on the basis of that description. The key thing for everybody listening is that if your experiences are causing you distress, there is lots of help out there, and we've put some useful links on the program website. But from the description you've just given, it doesn't sound to me like that is a cause for concern. One reason that we've been -- that this topic has taken off as a research area is that there has been so many kind of presuppositions about inner speech.

FERNYHOUGHPeople have assumed that your inner speech is just this single voice intoning the whole day long, and, okay, sometimes it is like that. But there's other stuff going on, as well, and inner speech takes different forms. And one of the things that our research has shown is that other people can appear in your inner speech. You can have conversations with other people in your inner speech. People report this to me a lot, and our scientific studies have supported it.

FERNYHOUGHSo to hear another accent in your inner speech doesn't to me sound worrying.

REHMLet's take that one step further, to Mark in Cleveland, Ohio, you're on the air.

MARKHi, good morning.

REHMHi.

MARKI'm an artist and an admirer of (unintelligible) so this is right in my wheelhouse. My comment is about pets and our relationship with pets because we have these long conversations with them, and they do understand some things, and they're communicating certain things but certainly not the level that we attribute to them. And I wondered how this plays in to what the subject is today.

FERNYHOUGHThat's fascinating. Maybe talking to animals gives us a way of sort of something for our private speech to latch onto. So we are kind of talking to ourselves, but it is kind of getting directed at the dog. That's something like what goes on in childhood. As I mentioned, put a bunch of four-year-olds in a room together, and they will start yapping away. They're not talking to each other. They're talking to themselves. But something about the other person being there stimulates the speech in a very positive way because it helps those kids to get their thoughts out in the air.

REHMYou know, I have to wonder exactly how you go about your studies. I mean, it would seem to me that the inner voices of people, unless they relate them to you outwardly, would be something rather difficult to study.

FERNYHOUGHAbsolutely, and that's why I got those frowns when I set out on this course of research all those years ago. But things have changed. We've got better at asking questions, we got -- we're asking better questions of people in questionnaires. We're also using methods such as experience sampling. There's a particular version of experience sampling called descriptive experience sampling that I talk about in the book.

FERNYHOUGHAnd the idea here is that you wear this little beeper attached to your clothing. Every so often it delivers a beep into your ear, and you gain skill over a period of time, you gain skill in making careful descriptions of what was going on in your mind just before the beep. That's a very powerful method of getting at people's experience. But you can do other things as well. So in a psychology lab, for example you can make somebody do -- or ask somebody to do a task, give them another thing to do whilst they're doing that and specifically give them something to do that will knock out their language.

FERNYHOUGHIf they're doing something like repeating a word over and over again, they can't be doing inner speech. And then you can look to see what effect that has on the main thing that you're asking them to do.

REHMWhat about brain scans while somebody is thinking or not thinking?

FERNYHOUGHAnd of course you're quite right. The big thing that's changed in the last 20 years or so is this extraordinarily powerful technology that we have for seeing what individual groups of neurons are doing whilst we're -- whilst we're thinking. And this kind of cuts to ways. We've been very good at developing the technologies and seeing what the brain is doing, but we haven't been nearly so good at asking what the experience is actually like for the person who's lying there in the scanner.

FERNYHOUGHAnd an intriguing scanner we just published tried to tease this question open. We asked people to do the usual thing that these studies do, in other words go into the scanner and say some stuff to yourself, do some inner speech because we're telling you to do it, and we're telling you what to say, and we looked at the brain patterns associated with that.

FERNYHOUGHBut then using this method, description experience sampling, we were able to capture inner speech as it naturally happened, okay, not because we were telling people to do inner speech but just because they were doing it. We looked to the brain patterns for those two different kinds of -- those two different conditions, and we found they looked very, very different. And that makes us question whether if you want to study inner speech, just putting someone in the scanner and saying do some inner speech right now is actually the right way to do it.

REHMThe wrong way to do it or the right way to do it?

FERNYHOUGHYeah, the question is that the right way? It could well be the wrong way. We need to find better ways of capturing inner speech as it happens naturally, rather than imposing it on our subjects.

REHMThe other thing I was wondering about is meditation. So many people these days meditate to quiet that inner voice, and I wonder whether inner voices can truly be quieted. I mean, it's got to be difficult, and I know people study for years to learn how to truly quiet the brain. What are your thoughts on that?

FERNYHOUGHI do think it's very difficult. I have spoken to some people, who say they can do it. In many ways, everything I'm saying about inner speech suggests that it has all these different roles and functions in our minds, so turning it off might not necessarily be a good thing. But certainly when we're talking about those more negative aspects of inner speech we just mentioned, then yeah, bring it on, turn them off, let's have some inner silence, and that could be a good thing.

FERNYHOUGHI would say the couple of situations in which my inner speech stops includes two of the most relaxing things I do. When I go for a run, it stops. I don't talk to myself. And when I play music, I'm fiddling around on the guitar, it stops. And I find both of those things incredibly relaxing. So like most things in life, we need a bit of a balance, and making them stop sometimes can be good thing.

REHMSo you're saying that learning somehow or finding some activity that quiets the brain can actually help us to be more balanced or healthier?

FERNYHOUGHI think all I'm saying is rest is good. I'm not saying there's any scientific evidence to prove this either way, and I think the -- we're getting a bit too far off the topic of what we know about in terms of inner speech. Very little research -- there's lot of research on meditation, but not very much of it has focused particularly on inner language, and I'd love to see that research being done.

REHMAnd you're listening to "The Diane Rehm Show." And let's go to Stefan in Cary, North Carolina, you're on the air.

STEFANOh fantastic. This is fascinating to me. A question I've always wanted to ask, and I apologize if this has come up, I did hear a caller asking about accents in speech. My father grew up in one country, and about -- in his early 20s moved to another. So I would imagine his inner speech started out in Dutch, and having been now in the States for 40 years and speaking primarily English now, his inner speech has switched to English. So is there a time when our spoken speech changes that it's sort of mirrored with our inner speech language changing? And by extension, you know, do our -- does the language in our dreams change when we change from one language to another?

FERNYHOUGHOne of my favorite questions when I'm giving talks on this topic is I ask people to put their hands up if they're bilingual, and then I pick out a volunteer, and I ask what languages do you speak, and what language do you think in. And you get the most fascinating answers. I mean, people have all sorts of interesting things to do with the fact that, you know, they might think in one language if it's more emotionally resonant or if they've been in that country for a certain time.

FERNYHOUGHAnd at that point, I stop them, and I say, that's really great, but in a way, the thing I'm most interested in is the fact that the question even makes sense. If thinking didn't have something linguistic about it, then it wouldn't make any sense to ask what language do you think in. So we need to do much more research on this. There's some interesting work on memory in migration and how people have an experience in a country where they speak one language, and then they find it easier to access that memory in the same language once they've moved to another.

FERNYHOUGHSo I'd love to see more similar work being done on this, but what you describe makes -- rings true to me.

REHMAnd a tweet from Sweeny, who says I'm an engineer, and I'm also ADHD and find myself speaking out loud as I work through problems as a means of keeping myself on track. That sounds like the same sort of thing both you and I were talking about earlier, you driving in the car and me walking out the door remembering what I'd forgotten.

FERNYHOUGHIt seems to make perfect sense to me. I mean, why not talk to yourself out loud? It's good company if nothing else. And it makes sense to me scientifically, as well. I can't understand where this proverb, you know, talking to yourself is the first sign of madness comes from. It doesn't make any sense to me at all scientifically.

REHMBut you're up against a scientific community that may disagree to a certain extent.

FERNYHOUGHI think the people who study inner speech and private speech would probably see that the evidence supports that point of view, that it's useful to talk to yourself, it's useful to talk to yourself out loud.

REHMAnd there's no concern about that either being a condition of or leading to mental illness?

FERNYHOUGHWell I think that's a different question. The person who emailed earlier on was very concerned that we keep a line between the regular thoughts and the very often very distressing experience of hearing voices. And we do need to keep that line because when you hear -- you, for example, Diane, has given an example of hearing your thoughts. You recognize those thoughts as your own. It feels like you. For people who are troubled by distressing voices, it doesn't feel like them, and we need to try and understand that.

REHMWell leave it at that, Charles Fernyhough, "The Voices Within." Thank you so much for joining us.

FERNYHOUGHThank you.

REHMAnd thanks for listening, all. I'm Diane Rehm.