The Science of Fluency

By Anna Margolina
Anna’s Blog:

During one of my first coaching sessions with John Harrison, he asked me, “Why do you laugh so often?” Frankly, I wasn’t even aware that I had this habit. But since then I started paying attention and soon realized that he was right. It seemed that this small nervous laugh was coming out every time the content of my speech became too emotional. I had no idea how to express my emotions, so I masked them with laugh.

At the time I encountered (and promptly devoured) John Harrison’s book Redefining Stuttering, I was a mess. I had poor control over my speech – my voice would easily become high pitched (something I also wasn’t aware of, until John commented on this) and my speech rate was often too fast. This speeded up speech was frequently punctuated with painful struggles – blocking episodes that could last up to seven seconds (according to the official evaluation).

From time to time I would enter the speech block from which there was no escape, and then my struggle could last for a really long time. To make it even worse, it was accompanied by strong facial contractions, eye squeezing, cheek puffing and other involuntary movements. Even one such episode could ruin any pleasant memory, such as having a party with my friends. Instead of remembering all the happy moments, I would ruminate over the time when I couldn’t deliver a punch line, thus, turning an attempt to tell a joke into an embarrassing experience. I imagined of course that everybody at the table remembered my blocks as long as I did.

For someone who stuttered for almost 40 years I was blissfully ignorant – my knowledge about science of stuttering could be easily summed with just one phrase, “It is incurable”. This phrase has been repeated over and over by many therapists and it became imbedded in my mind. But as soon as this belief was shattered by many real-life examples of successful recovery from stuttering, there was nothing left that would prevent me from absorbing new ideas.

As we progressed with our investigation of my speaking habits, I accumulated more and more evidence of my tendency to hold back, to block something within me, while I spoke. To allow emotions to emerge, John advised me to slow down my speech and pause often. Soon I noticed that slowing down my speech and coloring it with emotions had the added benefit of more fluency, since it allowed me to stay in touch with myself. I still had plenty of stuttering episodes in my speech, but it became easier to manage my hard blocking.

In addition to having sessions with John Harrison, I also started sessions with NLP practitioner Bob Bodenhamer – an author of the book Mastering Blocking and Stuttering. I had a suspicion that my tendency to block my emotions was rooted in my childhood memories, which were not all pleasant. After one of the sessions, something clicked, and I suddenly started speaking with amazing fluency.

For about four weeks, I spoke with a freedom and flow that I had never imagined was possible. However, one day I had a minor block. Then I had a dream in which I stuttered just as badly as I did before. When I woke up, I felt tension in my throat, and that day I had some minor blocking. It was at this point that I remembered John’s advice to slow down and try to express my emotions as freely as possible in order to regain fluency. Even though my stuttering remained very mild and occurred only in some situations, I yearned for the state of effortless fluency I had tasted and couldn’t forget.

As I kept practicing my art of slow and expressive speech, first with John then in Toastmasters and finally in my clown and acting class in which I enrolled with the goal of exploring my silly and expressive side, I kept trying to find the key to the state of free flowing fluency. It seemed that this state had distinct characteristics. Words gently rolled from my tongue. I didn’t plan what to say. The moment I knew what word I was saying was the moment I said it. I wasn’t listening to my speech or monitoring it.  I was going with the flow.

Stuttering was different. It was easy for me to see how different the stuttering state was, because it occurred so rarely now. When stuttering, I’d suddenly become self-conscious. I’d become aware of the word I was going to say, and I was sure that on this word I would block. Sometimes I did, and sometimes I was able to avoid it by slowing down and trying to speak with more expression.

This was something I had no explanation for. How could it be that I would become fluent, then get some of my stuttering back, and then again become more fluent? And what was it about slow and expressive speech that made even my stuttering state more fluent.

All this occurred in 2010 around that time when the media created a big fuss about a discovery of “stuttering genes”. Many journalists hailed this research as the one that finally solved “the mystery of stuttering” and made all other theories obsolete!

To my dismay, this ignited fierce discussions on whether John Harrison, Bob Bodenhamer and others who help people who stutter to regain more fluency could really do them any good, or whether they just fostered unrealistic dreams, from which a devastating fall to the harsh and sobering reality would inevitably follow.

To me all this talk about stuttering being genetic and therefore incurable held little interest, because the fluency I enjoyed by this time was something that no other method of therapy had ever given me. But since I had a medical and biological education and a PhD in biology, I became curious how the existence of genetic anomalies associated with stuttering might fit into John Harrison’s hexagon theory of stuttering. There was certainly a place for it in the hexagon. For example, physiological responses could be influenced by genetics, but I wanted more understanding.

So far, as it seemed from genetic studies, there were some families in which stuttering occurred more frequently (although this wasn’t the case with me.). Also, analysis of a large family from Pakistan showed that many stuttering individuals of this family had mutation in the gene GNPTAB. Still, three stuttering persons from this family didn’t have this mutation and apparently stuttered for a different reason. Even more intriguing was the fact that 11 subjects from the same family had one or two copies of this mutation, but “currently didn’t stutter” (it was not clear from the article whether or not they stuttered before). This mutation was also found in two unrelated stuttering subjects from Pakistan as well as in one who didn’t stutter. Among 270 unrelated stuttering subjects from North America (all with family history of stuttering), only one person (of Indian-Asian origin) had this mutation.

Two other mutations were in genes GNPTG and NAGPA; however, none of those mutations were found in all the studied Pakistani PWS. Among 270 unrelated North American-British PWS only a few had this mutation – four persons had mutation in GNPTG gene and six persons (all of the European descent) had mutations in NAGPA gene. The researchers didn’t find mutations in these genes in the control subjects, which affirmed their belief that the mutations they found were the cause of stuttering. However, this seemed like a bit too big jump to the conclusion.

First of all, the researchers selected only those PWS, who had distinct family history of stuttering, therefore, it remained unknown how frequently those mutations occur in the rest of the PWS population. Secondly, what about those individuals who stuttered as children, but later recovered? What about those who gained fluency as adults?

Probably the most intriguing finding in this study was that all of the above-mentioned mutations affected certain enzymes found in lysosomes – waste disposal stations of the cells. However, it remained unclear how exactly those mutations interfere with fluent speech – what specifically do they change in the brain. Because of the lack of available genetic mapping of the human brain, researchers used maps for the mouse brain and discovered that genes GNPTG and NAGPA were expressed predominantly in the areas responsible for emotional processing and motor coordination. As the authors pointed out “a person’s emotional state can exert a strong effect on the severity of stuttering”.[1] I can’t agree more.

Yet another genetic study featured an individual from Brazil with complex speech/language problems including stuttering who had a mutation in a completely different gene – CNTNAP2, which was a gene associated with various speech/language pathology and autism.[2] Also a different mutation, this time in gene DRD2, was found in some Han Chinese PWS.[3]

All in all those genetic studies indicated that in a very limited number of cases, people who stutter had a genetic condition that in some obscure way affected their speech production. It is still unclear what aspects of speech production are affected by genetics, but since most people who stutter can speak fluently under some circumstances, and since there are many who stuttered, but were able to gain significant degree of fluency, it is unlikely that any of those mutations cause direct interruption of speech flow.

No more clarity came from brain imaging studies. Although there were various differences observed in the brain of people who stutter compared to fluent people, it was unclear whether these differences were the cause of stuttering or the consequences of it. From my own experience I conclude that speaking with severe blocking and stuttering from an early age is very demanding and leads to the emerging of different coping strategies. There should be some consequences for the brain, considering that modern science shows that brain, even in adults is plastic and undergoes structural changes. For example, a famous study of London taxi drivers’ brains showed enlargement of the brain area responsible for navigation[4]. Surely if driving a taxi for a few years can change your brain, speaking with stuttering for several decades could do this too.

There is substantial evidence that various interventions can elicit structural changes in the brain. For example, it was found that assisted recovery from stuttering (with a help of a professional) caused different changes in the structure of the brain compared to the unassisted (spontaneous) recovery in adults. It is worth mentioning that unassisted recovery was associated with more prominent healing compared to recovery following medical treatment. For example, those who recovered on their own as adults didn’t have the white matter anomaly typical for people who stutter, although they retained some differences in grey matter. Nevertheless, those differences, whatever their cause, apparently did not prevent those people from speaking fluently[5].

Still, all this science couldn’t explain the changes I observed in my own speech. If my stuttering was caused by genes or a brain anomaly, what happened to all those factors when I started speaking fluently? Did they go on vacation? Did they take a really long nap and then wake up to nag me some more?

In 2011, I came across a fascinating article, which finally shed light on this issue. The article titled “Simulation of feedback and feedforward control in stuttering” discussed the possibility that stuttering was caused by a different method of quality control in fluent people than in those who stuttered.

The authors focused on two primary methods of speech control in the human brain – feedback and feedforward control.

Feedback requires constant auditory monitoring of produced speech. Such monitoring is crucial for language development. An infant first listens to the sounds of speech, all the while building a sound database in the brain.  Then the infant starts babbling and producing a wide range of sounds that are matched to stored sounds in the brain. Every time an error is detected, the position of articulators is corrected and new sound is matched to the “correct answer”. Such error-based monitoring allows an infant to adjust movements of the tongue, jaws and lips to the point when they can produce the correct sound.

The same probably happens with grammatical structures.  As a child speaks, his or her brain detects mismatch errors in the sentences structure and adjusts signals accordingly.

But fluent speech due to its high rate and complexity requires a different method of control, called feedforward. This type of control is the prerequisite for fluency and it is not error-based. The brain monitors signals (commands) as they are sent to the articulators with only a minimal control of the result. The commands are so well learned, that they can be trusted to produce the result without constant checking for errors.

According to the authors, the sequence in this model is as follows:

  1. Tune feedback control system during babbling (self generated speech sounds),
  2. Learn an auditory target, when a new sound sample is present,
  3. Learn a feedforward command for the sound by practicing its production.

The authors hypothesize that in people who stutter feedforward control is weak; therefore, feedback remains the dominant form of speech control. They note that stuttering usually starts around the time that children start switching from feedback to feedforward mode. However, in my opinion the authors missed a good opportunity to discuss what factors other than genetics or brain abnormalities could prevent or delay a normal transition to the feedforward mode of control.

Furthermore, using a computerized model of speech production, the authors showed that extensive errors detected by the feedback mechanism may cause the system to reset and repeat the sound. They also demonstrated that white noise, which makes auditory feedback impossible, encourages a reliance on feedforward control leading to fluent speech.

This by the way is a phenomenon used in some fluency enhancing devices, which produce loud noise, preventing those who stutter from listening to their own voice. In most cases it magically extinguishes stuttering. Their theory also explains why stuttering more often occurs in the beginning of the speech or word – feedback control is pretty useless while the speech has not even started yet and attempts to monitor something that isn’t there may result in a perceived “block”.[6]

To me this idea seemed very interesting, since it confirmed to my own observation that fluent speech feels different from stuttered speech, and because it seemed to agree with John Harrison’s article “Zen in the Art of Fluency”, in which he compared fluent speech with the effortless but precise performance of Zen archers, who could hit the target without consciously aiming.

This also agreed with what I learned in my acting class – namely that a performer must be able to abandon self-consciousness and be fully immersed in the flow of the moment to prevent “choking” on stage.

When we start watching for errors, we are more likely to trip.

But I failed to see why the authors believed that such overreliance on feedback could only be a result of some brain anomaly. For example, it is known that feedforward control is crucial in sports, since athletes often must be able to act automatically, without delay. Such automatic action requires first that many hours are put into practice. When enough trust in the ability to perform the skill is built, the athlete can let it go and switch to the automatic mode. However, if a traumatic accident or a brutal failure occurs before such transition is made, it may never happen.

With regard to this, it seems very probable that when parents or teachers draw a child’s attention to his or her stutter, adding new sinister meaning to any minor hesitations or repetitions in the speech, the transition to the feedforward mode of speech control may be halted for the lack of trust in own abilities. This idea was first expressed by Wendell Johnson, but later fell out of favor. However, many PWSs can attest that fear of stuttering plays a huge role in their life and in many ways governs their behavior and life choices. If you do not trust yourself to pick up the phone, how could you expect to let go of excessive control?

In a movie “The King’s Speech”, there is a scene in which Lionel (the therapist) keeps annoying his patient, the king, until he explodes. In his angry outburst the king starts speaking with increased fluency. In my experience, the onset of strong emotions has been usually accompanied by an increase of blocking. However, if I blew the roof, my speech would become perfectly fluent. Since voice is a vehicle for emotions, a perceived need to control one’s emotions, may also lead to overreliance on feedback control in speech. Many PWSs report that strong emotions make them uncomfortable and they tend to suppress them rather than express.

Another possible reason for not trusting yourself is fear of the negative reaction. For example, if a husband returns home late and his wife asks him “Where have you been?” – a question, for which he hasn’t a good answer – he will tend to speak very carefully. No sane person will let go of control in the situation they perceive as dangerous. The same way a child who was frequently unsure whether or not his or her words or actions will bring the hammer down, may exhibit a heightened degree of control in speech.

As we see there could be many factors that prevent a child from making a timely transition to feedforward control. Initially, because of robust adaptive mechanisms of young children such transition may still occur spontaneously.  High rates (80%) of recovery from stuttering in childhood indicate a rather wide window of opportunity when natural switching to feedforward mode is still possible. As soon as habit grows deep and strong roots, however, this becomes very difficult to accomplish.

Therefore, even though I don’t dismiss the possibility that in some cases there could be an organic cause for the inability to develop feedfroward control, it doesn’t seem like a requirement.  In most cases, especially for individuals who can speak fluently under some circumstances, there seemed to be plenty of other explanations.

In my opinion, when we get rid of “organic causes” of inability to maintain feedforward control, it is much easier to explain the effect of many fluency evoking conditions. For example, choral reading and speaking to animals remove “the judge” from the equation and therefore, turn off the need to monitor one’s speech. On the other hand, many people stutter even when they are alone, because even in the privacy of their solitude they continue listening to their speech watching for blocking. Fear of certain “difficult” sounds also encourages feedback control, because you never let go of control as long as you have red flags all over the alphabet.

Since I spoke fluently after NLP sessions, I knew that I didn’t have anything that physically prevented me from using feedforward control in my speech, except of my reluctance to let it go and except for the lack of practice of doing so in everyday situations. I supposed that what happened after this memorable session with Bob Bodenhamer, when I started speaking fluently, was my sudden realization that I did not have to monitor my speech anymore and that I could trust my ability to speak.

This happened because the profound healing of childhood hurts allowed me to reframe the experiences that had triggered distrust in my ability to speak without constantly holding myself in check. Similarly it removed the need to constantly monitor my speech for errors.

I suddenly realized that my belief that I never would be able to speak normally wasn’t based on anything but empty words heard in childhood. I realized that my fear of stuttering was irrelevant to my current adult life and that some negative experiences that I had with my speech in childhood could have been caused by problems in my speech for reasons other than stuttering.

Did I speak too fast? Did I swallow word endings? Did my thoughts follow a rambled and wild pattern that no one could follow? I do not know, and I am not going to search for answers.  But I had a strong feeling that whatever it was, as an adult, I did not have to fear something that haunted me in my childhood.

This positive reframing removed an invisible barrier that was preventing my feedforward mechanism (the system for automatic control of speech) from taking over.  And when that happened, fluent speech followed.

Then one day I had an unanticipated block, which opened a gate for an old distrust to creep in. More distrust followed the dream in which I had a vivid image of myself resuming my heavy blocking. The result was the return of some blocking due to resumed feedback control of my speech. However, since I didn’t have the same reaction to blocking that I had before the NLP sessions, and since I deliberately slowed down my speech rate, thus reducing the possibility for errors, I had only mild disfluency and none of my previous heavy blocking.

When I look in the future, I see somewhere far ahead a comprehensive theory of stuttering developed in collaboration between neuro-scientists, behavioral specialists, psychologists and people who stutter. This theory would include the influence of individual history, consequences of growing up with stuttering, individual emotional makeup, as well as some neurophysiology and genetics. This theory will pretty much resemble John Harrison’s hexagon and will present stuttering as a system with many interacting and interdependent components. But as this hasn’t happened yet, I would like to make my small contribution and put in the center of John Harrison’s hexagon two additional components (See Figure 1):

1)    An ability to activate and maintain feedforward speech control
2)    A level of an individual’s reactivity to some imperfections (real or perceived) in his or her speech.

Figure 1
John Harrison’s Stuttering Hexagon

Stuttering in a form of repetition and minor hesitations is more likely to occur when an individual speaks with a high degree of self-consciousness, constantly scanning his or her speech for errors. Such “stuttering” often appears in the speech of fluent speakers in the moments of self-doubt and anxiety. However, people who stutter have also a high intolerance to any disturbances in their speech. And they have learned to counteract this by holding the breath, tensing vocal cords and other muscles involved in articulation. Such behavior results in more prominent and struggled blocks. An extensive “library” of difficult words and situations stored in the memory of most adult PWS’ makes it even more difficult to let go of control.

The fluent state achieved by a majority of the population without any effort resembles that of an athlete who is able to entrust his or her success to automatic, well-learned movements and paying little attention to minor flaws. If an athlete starts thinking “Oh, I fell down at this spot during the last game, what if I fall again today”, it will be a disaster. Therefore, they don’t do this.

Building this kind of trust, after keeping yourself in check for decades, is not easy. However it can be done. And even though for some PWS’ it may initially be necessary to increase control over their speech in order to learn new speaking patterns (such as speaking more slow, using more efficient type of breathing etc), it is a natural fluency, a state of full immersion into the flow of conversation and letting go of control, that should be an ultimate goal.

At the moment this article is written, most of my speech is fluent, and by fluent I mean effortless carefree speech with very little control, which feels very enjoyable (in contrast to my past turmoil and anguish). However, I still experience some situations (although they are rare now) when I feel blocked. In those situations I slow down my tempo and try to re-capture the fluent state. Typically with very rare exceptions, I am able to jump back on the fluent tract and let go of the control.

To me fluency feels like a strong current that sweeps me and carries forward through the conversation with words rolling effortlessly wave by wave.  It feels very good. I know that I might have had some issues with speech production when I was a small child – problems that could make my surrounding too harsh on me and convince me that I shouldn’t trust my ability to speak.  That fear could have made it impossibly difficult to switch to unconscious control at the usual time.

But at present there is nothing that prevents me from speaking fluently.



  1. Kang C, Riazuddin S, Mundorff J, Krasnewich D, Friedman P, Mullikin JC, Drayna D. Mutations in the lysosomal enzyme-targeting pathway and persistent stuttering. N Engl J Med. 2010 Feb 25;362(8):677-85.
  2. Petrin AL, Giacheti CM, Maximino LP, Abramides DV, Zanchetta S, Rossi NF, Richieri-Costa A, Murray JC Identification of a microdeletion at the 7q33-q35 disrupting the CNTNAP2 gene in a Brazilian stuttering case. Am J Med Genet A. 2010;152A(12):3164-72.
  3. Lan J, Song M, Pan C, Zhuang G, Wang Y, Ma W, Chu Q, Lai Q, Xu F, Li Y, Liu L, Wang W. Association between dopaminergic genes (SLC6A3 and DRD2) and stuttering among Han Chinese. J Hum Genet. 2009 ;54(8):457-60.
  4. Maguire EA, Gadian DG, Johnsrude IS, Good CD, Ashburner J, Frackowiak RS, Frith CD. Navigation-related structural change in the hippocampi of taxi drivers. Proc Natl Acad Sci U S A. 2000; 11;97(8):4398-403.
  5. Kell CA, Neumann K, von Kriegstein K, Posenenske C, von Gudenberg AW, Euler H, Giraud AL.How the brain repairs stuttering. Brain. 2009;132(Pt 10):2747-60.
  6. Civier O., Tasko S.M., Guenther F.H. Overreliance on auditory feedback may lead to sound/syllable repetitions: simulations of stuttering and fluency-inducing conditions with a neural model of speech production. J. Fluency Disord. 2010;35(3):246-79.

Anna Margolina