Can you detect past stuttering?

Let's assume I give you speech samples of 100 stutterers, 100 "recovered stutterers", 100 people who stuttered as children, and 100 "normal" people, but I wont tell you who is who. Can you accurately put them in the right category?

I would guess that the distinction becomes clearer the more demanding the speaking situation: from reading to talking while doing other tasks.

I believe that you can distinguish the "recovered stutterers" vs "normal" people quite accurately. I often hear "recovered stutterers" who are fluent and communicate well, but still you can sense they struggle more and speak more controlled, less spontaneous and ironically too fluent without natural disfluencies!! :-)

The interesting question is whether you can distinguish between people who stuttered as children and those you didn't stutter as children. Is it possible to detect a difference? I guess that it might be possible but only by severely stressing their brains... If it is not possible, either stuttering is just a learned behaviour or the brain completely compensates for a weakness.

1000+ visitors!!

OK. I admit that I am a bit of a Web counter junkie. I regularly check the hits and from where the people are. So I am happy to see that more than 1000 visitors read my blog in January, though these are not unique visitors. I have around 40 visitors per day with a mix of daily and weekly regulars and people stranded on my shores in cyberspace thinking what the hell is he talking about. I dont expect the number to go up much, as I am really catering for a minority of a minority, for the more research-oriented from the stuttering community. I guess I could get more reader with more emotional topics and more personal stories. But I am not too turned on with such matters!! I am a scientist at heart and obsessively curious at what is going on with people having PDS. But I try to make it sexy! ;-)

On cost-benefit & devils

In economic theory, you have the concept of benefit versus cost. Everyone wants to maximise this ratio, the most benefit at the lowest cost.

So let me ask the people with PDS the following question. Contrary to what I have been saying there is a cure (but just for this paragraph and then there is no cure. OK? :-)

The cure is quite simple: you need to do a daily exercise and then you are completely fluent for the rest of the day.

If the exercise takes 5 minutes, would you do it?
If the exercise takes 15 minutes, would you do it?
If the exercise takes 30 minutes, would you do it?
If the exercise takes 1 hour, would you do it?
If the exercise takes 2 hours, would you do it?

What is your tolerance? I think mine is at 30 minutes. And 1 hour if I can skip days and only use it if I really need it.

So now there is no cure. OK? But now I am the devil, but just for this paragraph, OK? :-)

So I am Devil Tom, and I have real superpowers. Do you want to make a deal with the devil?

Would you like to exchange your stuttering for your little finger? for a leg? for being blind on one eye? for being deaf? for being less intelligent (assuming you are intelligent)? for being ugly and oversized (assuming you are not)? for the house that you own? for your wife? (be honest with yourself! but dont tell her)

But unfortunately, I am not a devil.... at least not with superpowers. ;-)

Bad theory good outcome

I dont have a lot of time today, so a quick thought of the day: A therapy based on a bad theory might well produce positive outcomes. You might well be wrong of what causes stammering, but if you work on breathing, non-avoidance, and general control of symptoms, you become more fluent!!!

So often people say I am cured because I did A and B which followed from my theory of stuttering, but this is a logical fallacy. Other theories might also get to A and B!!!

Someone is not happy

Oh oh... someone is not happy with Andrew Bell's claim for a cure: see here. I have the impression we have another candidate for the Crackpot Award, though I am not yet convinced that he doesnt know better or is just out to make money.

Top 10 Outings

If you absolutely have to reveal your darkest secret, here are TheStutteringBrain's choices.

1) I am a stutterer. What do you do?
2) I stutter, but I am not the only one.
3) I live with a stutter but not with my parents anymore!
4) I st--- you know what I mean...
5) I am not quite as fluent as you, my dear.
6) You are so beautiful you make me stutter.
7) I was part of the Monster study.
8) I was a method actor for a Hollywood movie on stuttering but they took Tom and I kept stuttering.
9) My mother gave me gene Xi-362 - bitch.
10) I am the re-incarnation of a recovering stutterer's soul from the psychodelic 60s when he still stuttered!

Let me know if you have more.

What's the name?

On the STUTT-L mailing list was a long discussion on how to call us. The choice was between "People who stutter" and "stutterer".

These expressions might be OK for superficial use, but are quite sloppy and inaccurate expressions, because

1) non-pws stutter occasionally,
2) pws are sometimes not stuttering,
3) some pws rarely stutter but avoid,
4) most children who stutter do not become pws,
5) and people having had a stroke stutter but differently!


The term "stuttering" is also quite ambiguous as it refers both to

1) the main symptom of the disorder i.e. "dysfluent speech" and
2) the disorder itself,

leading to endless confusions.

I think "stuttering" is best left to mean the main symptom of the disorder i.e. "dysfluent speech" plus possibly secondary symptoms, and the disorder should be called "persistent developmental stuttering" (PDS), which makes the distinction between two related but different disorders non-persistent stuttering (childhood stuttering) and non-developmental stuttering (due to a neurological incident like a stroke). And then the "pws" are people with PDS, or possibly having or suffering from PDS. More on this post on my blog.

Per Alm mentioned two other expressions to me: dsyphemia, and gluency:

"I think the old concepts of "dysphemia" and Van Riper's "gluency" are relevant here – see my thesis page 22. However, I have no clear opinion about what terminology to use. For example, I do not think dysphemia is a good word but I think we would need a word for that concept".

And he betrays me by saying that

"For example, I'm not using the concept PDS very often because I think there is no sharp division between PDS and "acquired stuttering", with onset after for example head injury. I think the number of neurological lesions in "developmental" stuttering has been underestimated. "

Two types of habits

There are two types of habits than influence our stuttering: automatic and cognitive habits.

An automatic habit is a process that runs independently of an executive order by the person. You might be choking when swallowing a pill, getting nervous when the phone rings, looking down when you have a block, word substitution when you cannot say a word. This process is more or less automatised, and cannot be controlled at all or only with outmost focus, attentation and energy. You can force yourself to look into someone's eyes while blocking, but it is very hard if you have always looked down. Such habits are really programmed in your brain, most likely in the amygdala that says in "Situation X -> do Y without asking for permission by the cortex". Without such functionality, our life would be a nightmare.

A cognitive habit is an habitual way of thinking about the same situation without really thinking. Examples: I need to do a phone call I will ask my partner to do it, They want me to speak I will say no, When I call someone I will stutter, I will never be more fluent, Without my stuttering I would have achieved more. All these habitual thoughts are done without any pressure from a situation, i.e. there are no 50 people looking at you or the person on the phone is waiting or you are feeling a block coming. No, you are under no pressure, but you have pre-prepared lines of thoughts for certain situations.

Cognitive habits are easier to tackle by re-thinking one's constructs. Automatic habits are much more difficult to change.

In defense of Johnson

Instead of commenting on the study, let me take on the role of Professor Johnson's lawyer defending my client.

"Professor Johnson is shocked by the vicious smear campaign againt him from
former colleagues who now suddenly question his professionality. Throughout his
professional life as a hard working and well-respected university professor,
Professor Johnson has sought to advance our scientific understanding of
stuttering, and provide people, and especially children, who stutter with the
best care possible. His insightful research project has been a turning point in
improving treatment for stuttering and widely applied even 50 years later.
Moreover, it is important to note that this project has only come after years of
fruitless search for a neurophysiological cause for stuttering. Unlike many of
his colleagues, Professor Johnson had the courage to realise that the hopes for
a neurophysiological cause were unfortunately unfounded, and had the courage to
develop a new theory, namely that stuttering is of psychological origin, which
is supported by facts. Therefore, together with other experts including
statisticians they developed a carefully designed and monitored experiment to
test the theory. When Yairi and Ambrose attacked Professor Johnson's project in
The Journal of Fluency disorders, they not only had to base their arguments on
second-hand information, but were inconsistent in their criticism. They claim
great danger for the children, but at the same time claim that no children were
harmed and none became adult stutterers! This in fact shows how carefully
Professor Johnson's team has been! In fact, probably due to a lack of proper
research of the topic, they have missed a crucial element, namely that Professor
Johnson has made sure that the children immediately received special care after
the end of the trial. Moreover, he has even stayed in contact with some of them,
being a mentor and friend for years to come. As a parent of two kids himself,
Professor Johnson has always sought the best possible for his patients and
points out that his scientific work has been able to bring improvements in the
life of people who stutter. He finds it unfortunate that certain quarters of
academia and therapists are still clinching to a neuro-physiological cause,
which is unfounded by facts!" (Disclaimer: This text is a work of fiction, and does not represent anyone's view not even the author's!!)

Go ahead what would you say to Johnson's lawyer's statement?

The Monster study

Have you read about the Monster study? Check out the wikipedia entry:

In 1939, a controversial study on the possibility of "creating a stutterer" was conducted by University of Iowa speech pathologist Wendell Johnson and his graduate student Mary Tudor. The study tried to create stutterers over the course of 4 months, using 22 unwitting orphans from the Soldiers and Sailors Orphans’ Home in Davenport, Iowa. Ethically acceptable at the time, it was designed to induce stuttering in normally fluent children and to test out Johnson's "diagnosogenic theory"—a theory suggesting that negative reactions to normal speech disfluencies cause stuttering in children. The study divided the orphans into 3 groups: 6 normally fluent orphans would be given negative evaluations and criticisms regarding their speech, another group of 5 orphans who allegedly already stuttered would also receive that treatment, and the remaining 11 would be treated neutrally. The study concluded that the children given negative evaluative labeling went on to develop persistent, permanent stutters. The study was influential at the time, with many speech pathologists and child-health and educational professionals accepting Johnson's theory. In 1988, Silverman first reported the results of this study in the Journal of Fluency Disorders and labeled it "The Monster Study." While the information was well known to professionals in the area of stuttering, it was not until 2001 when the information was distributed to the public in a newspaper article. In June 2001, the San Jose Mercury News revealed this study to the public for the first time, leading to widespread controversy and debate about scientific ethics. Soon after, University of Illinois professors Nicoline Ambrose and Ehud Yairi wrote a paper discrediting the 1939 study, revealing flaws in data collection and method, as well as pointing out that none of the orphans actually did develop a permanent stutter. While criticism of a developing child's speech can certainly make a present stutter worse, it does not create a stutter.

My comments in my next post!

Mail from a stuttering poet

Today, I got an email from a stuttering poet! He was inspired by my discussion with Andreas Starke (see here) on a German discussion forum

His poem "complains" that during our discussion we treated people as a number and not as people! So I wrote him a poem back! Here it is. Dont be too critical with me. It is my first poem! Sorry it is in German...

Der Klippel auch wenn er's nicht gerne mag
lebt auch als Sammlung von Atomen Tag fuer Tag

Er verspuert sich wohl als stotternde Einheit,
Ist berueht von deren Geistes und Seelesfeinheit.

Doch, bitte schoen, soll er nicht vergessen,
Wer der Krankheiten weiss sich zu messen.

Es ist die Wissenschaft, die stets rational
Sich erweist des Unerklaerten Todespfahl.

Drum soll er uns streiten lassen,
Und vor unserer Aufopferungsgabe erblassen!

Le poete Tom

Why did the window break?

I read an interesting paragraph on causes, which really makes me question whether anyone who talks about causes of PDS actually knows what s/he means by "cause".

The author asks "Why did the window break?", and offered the following answers

A) "Because the brick hit the window.",
B) "Because Tom threw the brick.",
C) "Because the window glass was brittle."

He also gave the following definition: The English ‘cause’ suggests efficient causation, some factor present in a situation that actually brings about a change

This makes me think that causes can be classified

1) Into EVENTS or STATES. Event: Brick hit the window or Tom threw the brick. States: Glass was brittle.

2) Into HOW CLOSE TO "breaking the window". For example, The brick hitting the glass is a more direct cause than Tom throwing the brick.

3) Into WHETHER THEY ARE SUFFICIENT to "breaking the window". Some causes are a necessary but not sufficient conditions for the change "window breaks". For example, the glass needs to be brittle for it to break, but you need some extra i.e. the brick hitting the glass.

So "Why do people stutter?"

Getting rid of a habit

We all know that therapy also involves unlearning bad and unnecessary habits. Not being able to say a word is one thing, but avoiding eye contact, speaking faster, body grimaces and being tense in order to somehow avoid stuttering is not only unnecessary and doesnt look cool, but is contra-productive and actually makes a block worse. I think all people with PDS can agree that these habits are unnecessary, but then again once in a block we just cant prevent the habits from being executed by this vicious part of our brain that overrides our executive orders. I want to tell you the following story illustrating how difficult it is to get rid of a habit.

As a kid I was good at sports. But, I was terrible when it came to swimming. I couldnt swim well, not because I was unfit, but because I was not able to apply the breathing techniques well to do crawl. Why? I somehow developed this habit of choking when I tried to breathe into the water. So after a few strokes, I couldnt continue and gasped for air. Four years ago, I started swimming regularly. It took me nearly four years to get rid of this choking habit. Now I can swim crawl without problems. Parodoxically, even when I try to choke, I cant anymore... The unlearning of this habit came very slow.. Stage One, I tried to change and the choking was worse. I hated swimming crawl. Stage Two, I was able to swim longer without choking, but still experiencing a feeling of being uncomfortable and of having to choke any second. Stage Three, once a while I started choking again, and I was pissed off and switch to breast stroke. Stage Four, I was able to swim without choking, but still felt a bit nervous. Stage Five, I just swam without thinking about it. Stage Six, I realised that I conquered it and saying to myself "I got you. Come on. I challenge you. Make me choke!" I can now confirm that I am a recovered choker, but I am not sure whether I am cured! :-)

I hate to think that unlearning stuttering habits is probably even harder...

Are you a crackpot?

I am not sure whether you know what a crackpot is. According to wikipedia, Crackpots are: "Pejoratively, the term Crackpot is used against a person, who writes or speaks in an authoritative fashion about a particular subject, often in science, but is alleged to have false or even ludicrous beliefs." They are especially common in my home field of theoretical physics. Either they claim to have disproven Einstein, or have found the laws of physics that unify all fundamental theories from quantum mechanics to general relativity. A negative response from the physics community often leads to claims of conspiracies. Examples are here, here, and here. When I was a visiting researcher at DAMTP (the institute where Prof Stephen Hawking works) at the University of Cambridge, the news went around that a Japanese person called up Hawking in the middle of the night: "asking to talk to the prof to tell him that he had solved all mysteries in physics". I also had my share of crackpots. It is virtually impossible to convince them why their theory is not correct. Here is a test for physics.

So how about in the field of PDS? Here is Tom's ...

Are you a crackpot? test

1) Do you have a cure for stuttering?

2) Have you cured yourself from stuttering?

3) Did you have an inspirational moment, where suddenly you instinctively you knew what stuttering is really about?

4) Do you often refer to big names to agree or disagree with them like "I agree with Freud that..." or "I disagree with van Ripper that..."

5) Do you dismiss brain imaging and genetics studies as irrelevant without having read the research articles?

6) Do you think that people ignore your ideas to protect their own interests? Or that there is a secret conspiracy against you and your ideas?

7) Do you firmly believe that PDS is purely psychological?

8) Do you write a blog making comments about PDS research even though you only have a PhD in theoretical physics? (quote from a university professor)

9) Do you talk, talk, talk, talk, talk, talk, talk, talk, talk about your experience instead of asking others about theirs?

10) Do you over-use words like holistic, in-touch-with-oneself, and so on?


If you have answered more than three questions with YES: Congratulations!, you are a crackpot! :-) Please note that a university degree or a professorship does not neutralise the results, as experience shows in physics.


Here are the solutions:

1) There is no cure that works for everyone.

2) You might well have become fluent through hard work or / and an X event, but you are not cured in the sense that you have the same speech system as normal people.

3) You might well have had such a moment, and as a consequence became more fluent, but that does not mean that you understand PDS. You can very well become fluent by using a wrong theory of PDS. Like someone who thinks the treatment is a cure will be more successful that Tom who knows about relapse and so on.

4) Science is about strength of arguments and not about who made an argument. Personally, I couldnt care less about who said what. For example, in my field of physics, I have never heard any of the world leading people say "Einstein said that...". All the so-called authorities in PDS are just human beings who also make mistakes. And then again, why does someone become an authority??

5) Dismissing this kind of research without trying to understand it is just insane.

6) They might well protect their interest, but that doesnt make your theory right! Because if your theory is wrong, they would have behaved in the same way!

7) There is now so much research on brain and genes that this position has become untenable.

8) :-)

9) If you start talking to other people, you will realise that your stuttering is very different to others, and that generalising your situation or building a theory only on your experience is not possible.

10) These terms are very vague and not useful for a scientific discussion.

More fluent at ovulation!

Here is another interesting observation of the strange aspects of PDS. Per Alm pointed me to a study of the menstrual cycle, showing more stuttering during the premenstrual phase! This clearly points to neurotransmitter (brain chemicals) levels in the brain affecting fluency. So PDS cannot really just be psychological, because the menstrual cycle is related to changing hormone levels?

Silverman, E. M. (1975). Speech fluency fluctuations during the menstrual cycle. Journal of Speech and Hearing Research, 18, 202-206.

Abstract: This study sought to determine whether changes in disfluency characteristics accompany biological and emotional changes during the menstrual cycle. Four extemporaneous speech samples were collected from each of 12 women, one at ovulation (when the average woman experiences her greatest feelings of self-esteem and self-confidence) and one at premenstruation (when she experiences a significant increase in anxiety level) for two consecutive cycles. The mean total frequency of the women's speech disfluencies produced at premenstruation was significantly greater than the mean total of their speech disfluencies produced at ovulation. The disfluency type that accounted for much of the difference in total frequency of disfluency between the two cycle points was revision-incomplete phrase. The tendency for these nonstutterers to produce more speech disfluencies at premenstruation than at ovulation is similar to a tendency we have observed in stutterers

Silverman, E. M., Zimmer, C. H., & Silverman, F. H. (1974). Variability of stutterers' speech disfluency: the menstrual cycle. Perceptual and Motor Skills, 38, 1037-1038.

Abstract: Studied whether women who stutter produce more speech disfluencies at premenstruation (when anxiety level has been reported highest) than at ovulation (when anxiety level has been reported lowest). 4 speech samples were collected from each of 4 Ss, one at ovulation and one at premenstruation for 2 consecutive cycles. Results show that Ss produced more disfluencies premenstrually.

Time line of discoveries

In my last post, I talked about the maximum understanding and treatment that is possible in the future.

Here is Tom's oracle for major research events in 2006 and what they will find:

1. Brain imaging studies of teenagers, children who stutter, and adults who have stuttered as children: They will probably show that structural abnormalities already exist from very early onwards, and that children and adults who recover also have structural abnormalities.

2. More detailed genetics studies: Past studies have localised the responsible chromosomes for specific cases. They will localise the genes on these chromosomes. The function of the gene(s) will probably be building a protein that is (partially) needed to direct the development of language and speech areas in the brain.

3. The pagoclone study: The results will be very mixed. Some experiencing great improvement, but other none at all. Side effects will exist but relatively small. Leaving everyone do wonder why the hell it works for some and not for others? The company will probably go on with the next phase of trials, but instead of a cure they will focus their message on "Pagoclone works for some very well and for others not at all. You need to try it out with your doctor to see whether it works for you."


Within the next five years, 2010:

1. Medication (possibly Pagoclone or others) will become available. It will prove not be a perfect cure, but alliviate severity for most and considerably for some. There will be more clues as to why medication works for some more than for others. Possibly subtypes are identified by other means, or effect of medication will be used to define subtypes.

2. Brain and genetics research is now 15 years old, and the field will have come to a consensus on the broad features of PDS within the brain and the genes.

3. Meta-analysis is finally becoming more important in fitting everything together, because by now experimental evidence is detailed and plenty enough to be able to construct good theories.

4. Most early baby-boomer professors / therapists with old (anti-brain and so on) ideas will finally be in retirement leaving the way open for new people. (I do not mean all professors, just some! :-)

5. Other brain disorders will have been sorted out giving clear directions on within which framework to think about PDS.

Understanding and treatment in 9999

Pablo from Spain asked me some time ago: "Do you believe that in our life time (I am 36) there will be a truly scientific understanding of stuttering and a truly scientific therapy for curing it?"

Let me first say what I believe is the maximum understanding and treatment we can achieve: (I will talk about timeline in my next post)

1) PDS is very likely not a local problem but a more distributed problem. I give an example: it is not like computer hardware breaking down due to a faulty cable or a software with a bug in the code, but it is more like a very inefficient transport system or a high crime rate in a city. You will never be able to answer the question: Where exactly is the problem? You see the effects, but many factors play a role like the underground trains are very old, only one underground line, and the unions block any change. Currently, we don't even know what the various factors are. It's like, the city is still very foggy, and we slowly need to get rid of the fog (also due to genetics and brain imaging tools) and explore the different factors. The maximum understanding will come when there is no fog anymore, and all factors and how they interact are known.

2) There will not be a cure in the sense as having the same speech system as normal speakers, but more like the children who have recovered. Much greater fluency will be achieved faster with fewer relapse. Thus, it will not be like the computer doesn't work due to a cable failure so lets replace the cable or the computer bug is here lets replace this line of code. It is more like lets improve the inefficient transport system. God knows where you should start. So build a new underground line or lets get new trains. BUT the problem is that you cannot shut down a city (or a human being) for a few months and re-build everything. You can only do slow step-wise improvements. In therapies you always need to work on a change in behaviour, but with no fog around the city anymore, we will know much better where to attack the problem (which might be slightly different for different people). Medication is probably the most straightforward way to help people, as you just take a pill and nothing else. You don't need to follow some therapy which is much harder. Taking a pill will change neurotransmitter level in the brain and is like ensuring that there is never bad weather in the city or the people using the transport system are not stressed. And the transport system improves tremendously (without solving underlying issues), but is not really a cure as such.

Actually, to be completely honest with you, I think that in 9999 there will be no human beings anymore as we know now. So there will also be no stuttering anymore!! We will have morphed with computers into one big system. We will be sub-entities like cells in our body. And communication between sub-entities (direct descendants of us) will not involve speech anymore. This process has just started with the Internet. For example, take my blog, I am currently putting ideas into your mind, and you can influence my mind by posting comments. These comments are just like my own thoughts: I might take them on or ignore them. Wikipedia and google have also dramatically increased our common shared memory and so on. This process will continue... :-)

Is PDS research as exciting??

Here is another interesting talk on preliminary brain imaging results by Kell, Neumann, and Giraud: I know Katrin Neumann and I have spoken to Anne-Lise Giraud once. I googled Christian Kell, and he is most web-famous for scanning the cortex representation on the penis! See here. Apparently, the region is very small! (contrary to the commonly presented picture! See above) Dispelling the terribly dangerous myth created by sexist females that men are controlled by their... I am wondering whether Kell finds his research of PDS as exciting?! :-)

The researchers from Frankfurt claim that prosodic production tasks during fMRI reveal functional deficits in stutterers. Prosody can be defined as the patterns of stress, intonation and timing in a language. They say that both groups with or without PDS show similar performances, but have different brain activation. I am not sure what to think. From my personal experience, I seem to be far more fluent when I actively control the prosody of my speech. It feels a bit like singing, or chorus reading. So even if abnormal, the prosody neural network seems to help me to be more fluent. But of course, this might only be the case when I actively control my prosody and on automatic mode it becomes unstable? How does this fit with the dual premotor systems hypothesis Per Alm has been advocating: see here? Not sure how their results would fit in. I don't think they have published the findings yet. I guess they are in the review process.

Here is the abstract:

Persistent developmental stuttering can be interpreted as the result of impaired linguistic motor executive function. Previous studies revealed pathologies in somatomotor as well as language-related cortices of stutterers. Frontal opercular regions (Broca and its right-hemispheric homologue) appear differentially activated in stutterers when compared with healthy controls. Stutterers seem to compensate their defect spontaneously via an activation of the right frontal operculum, while after fluency-shaping therapy a more left-lateralized frontal activation can be observed. Based on these findings, we sought to preferentially activate either the left or the right frontal lobe. Prosody perception usually involves lateralized cortical networks depending on whether it emphasises linguistic or emotional features. We therefore hypothesized that a similar functional lateralization should be observed in frontal regions during speech production emphasizing different prosodic features. While production of linguistic prosody should predominantly activate left-hemispheric regions, emotional prosody should reveal a more right-hemispheric network. The production of linguistic prosody should therefore reveal in a very selective manner relative left-hemispheric deactivations in stutterers, while production of emotional prosody should tell us more about the functional meaning of right frontal overactivations in stutterers relative to controls. After confirming functional lateralization of spoken prosody in normal subjects we compared activations in stutterers and controls. Despite similar behavioural performances, we found a very circumscribed left frontal deactivation in stutterers in the linguistic prosodic task in BrocaÂ’s area. The emotional prosodic task activated larger fronto-temporal networks in stutterers, but no significant differences were found in the group analysis. Our results delineate a focal functional lesion in the stutterersÂ’ left language executive network, which may require compensation by BrocaÂ’s right homologue.

Blog of the week

Check out the Genetics & Health blog by Hsien Hsien Lei. The Stuttering Brain is the blog of the week. :-)

Tom vs RCT: 2nd round.

Some time ago, I discussed the Lidcombe random control trial (RCT) and why I believe they need to revise their statistical measures: see here, and here.

Mark Jones et al. have responded to the rapid responses, but they have not directly responded to the arguments put forward in my rapid response. For example, they say that

"... spontaneous recovery has been a recurring theme in the rapid responses to our article... The rate of natural recovery from stuttering in young children in the general population has been estimated at 74%(1), but in clinical populations with this condition this estimate is expected to be much lower...Evidence from a previous study(2) suggests that approximately 40% of children identified as stuttering had the condition for less than 6 months."

However, they do not directly relate this or other statements to my arguments to disprove my case, so it is difficult for me to respond in a constructive way. My guess is that they imply that any effect due to the spontaneous recovery rate on the statistics is very small because the rate in the clinical setting is only about 40% and not about 75%. But this argument is not correct. The great irony is that the closer the recovery rate is to 50%, the greater the impact on the statistics!! :-) So by claiming a 40% rate instead of a 74%, they have actually strengthened my argument that they need to revise the statistical significance and effect size of their study to take into account the natural recovery rate!

I have sent a response, where I explain in more details. The response should be on-line in one or two days. Check here.