Wednesday, May 28, 2008

Christy Ludlow's talk at Paris

Christy Ludlow is heading a research team at NIH: see here. She is quite a dynamic multi-area scientist not only working on stuttering but also for example on swallow disorders. She has published an interesting article A Dynamic Motor Control Disorder where she and Loucks puts forward the idea that stuttering is a system disorder and that no single area is defect as such:
...the central control abnormalities in stuttering are not due to disturbance in one particular brain region but rather a system dysfunction that interferes with rapid and dynamic speech processing for production.
Admittedly, the article is very vague on details of an underlying mechanism, and does not provide proofs as such. They rather draw their conclusions on what makes most sense given all the observations on stuttering and related disorder. And, I completely share the system disorder idea and have written about similar ideas like the traffic-jam prone transport system of a city: see here. Actually, I have a hard time to see how stuttering could not be a system disorder given our current knowledge and the considerable variability of effects, and unfortunately also how you would actually prove this with the current data!

During her talk, she made a few interesting observations. First, 37% of people with acquired stuttering after brain injury reported that they stuttered as kids! Second, none seem to have lesions in speech and language areas but connecting areas. She also said that about 50% of the kids who stuttered after age 6 recover. (I have never come across this observation, but I do remember that my professor at Imperial College in London said that he stuttered as a teenager and then it went away...) And 50% of stuttering kids have concomitant (or in plain English "also other"!) disorders. She also spent time talking about possible models of a neural basis of stuttering and mentioned possible starting points like delayed or abnormal development of fiber tracts, genetic predisposition, and cell migration and neural pruning. A brain with such a starting deficit would then be modulated both neurologically and behaviourally by reaction to stuttering. But she did not commit to any specific direction. To be honest, I did not remember most, but I see her efforts as a clear attempt to put some meat on the bones of her system dysfunction idea from the above article.

Monday, May 26, 2008

TheStutteringBrain found a rare species

In my last post about Anne Foundas' talk, I mentioned that she hasn't come across a female left-handed stutterer. And I wondered whether this is a true effect or just statistical fluctuation. Well they do seem to exist, here is a reply to my last post:

..Long story longer, I read your post and saw that there is a dearth of left-handed female stutterers. Well, I just so happen to be one of those. Maybe I'll contact her!

New brain imaging on kids

I found this call for participants to a new brain imaging study. I haven't heard of the group before. Their study would be good to replicate the finding of Soo-Eun et al. and Watkins et al.

Columbia University Neuroimaging Study
Seeking Participants Who Stutter

Conducted by Dr. Bradley Peterson, this on-going research study is focused on learning more about the causes of several disorders that develop in childhood and adolescence. One of the conditions of interest is stuttering.

The study requires participants to agree to one or two visits, and includes an MRI scan which lasts about one and a half hours. This study requires a total of 6-7 hours to complete.

Participants must be between the ages of 6-14, can be taking medications, and also may have other diagnosed conditions in addition to stuttering.

No expense will be incurred by eligible subjects, and a modest payment for participation is being offered. Participants will receive $120, in the form of a gift certificate or a check depending upon age, as a "thank you" for being in the study.

Study location: Columbia University, NY State Psychiatric Institute, New York, NY

Contact person: Kristin Klahr - 1-212-543-6072 <>

Note: Those contacting the study coordinator to learn more about the project are under no obligation to agree to participate.

A new blog called StutteringMike

Here is a new blog called StutteringMike.

Saturday, May 24, 2008

Anne Foundas' talk at Paris

Anne Foundas, a professor of psychiatry and neurology at Tulane University, gave the first talk after the morning tea break (with free French patisserie) at Paris. I had never met her before, but she is well-known for her pioneering research on the anatomy of the stuttering brain. She was one of the first to report anatomical anomalies using MRI, though apparently the early MRI studies on brain anatomy were quite delicate to do. She is also quite interested in handedness. Check out her web page: here, and a recent article.

Her talk was different to the other talks in that she had a more systematic, top-down, and conceptual approach. She talked about the different types of possible models: anatomical, functional, and timing. She also mentioned a two-factor model of stuttering mentioned in (Buechel and Sommer 2004). This framework is a bit similar to what I had in mind when I wrote about stuttering being a two phase disorder: see here. She also made a distinction between local and global anomalies, and wondered which combination is leading to stuttering. Many people have abnormal brains but not automatically abnormal functionality, and many disorders show similar abnormalities. Interestingly, they are still looking for a left-handed female stutterer, and they just cannot find one. Is it a real effect (i.e. left-handed women are much less like to stutter?) or is it just statistics? Here is my calculation: of all stutterers, 20% are female (1 in 5), and 10% of the population is left-handed, so 2% of the stuttering population should be female and left-handed assuming no gender effect. Lets imagine they asked N stutterers, they should find 0.02*N. I guess they asked a few 100, so there should have been a couple of them. So if you are female and left-handed, post a comment! She also talked about their belief of possible sub-types with the main deficit in either 1) auditory processing-linguistic and sensory processing, 2) motor functions - speech motor planning & production, or 3) attention-arousal-emotion. She also talked about her latest brain imaging results, but again I got lost with too many brain regions. But she did say that the cerebellum in recovered stutterers is greater, (which would make sense if it helps with compensation), and she said that the typical female brains seem to be more variable.

At the end, Christian Kell made a very intriguing comment: Given some similarities in abnormalities across disorders, he was wondering whether stutterers should really be compared to controls as opposed to those with similar atypical brain anatomy? Do they have something in common? To me, this opens a fascinating possibility namely that all disorders have similar abnormalities because they share a common factor, namely abnormalities stand for the failure of brain plasticity: abnormal brains mean lower brain plasticity. Kids have deficiencies, and only the brains with low abnormalities can compensate well, and therefore the persistent ones (in all kinds of developmental disorders) are a biased sample.

Thursday, May 22, 2008

Soo-Eun Chang's talk at Paris

Sou-Eun Chang spoke second at the Paris conference. Soo-Eun is a post-doc and a trained speech and language pathologist. She was there together with her boss Christy Ludlow. They are based at Bethesda, close to Washington, at the National Institute of Health (NIH), a US government institution. I visited them at NIH in October at the same time as I visited a friend of mine who heads a brain imaging lab studying the visual cortex and with whom I often have discussions on neuroscience, genetics, consciousness, meaning of life (not very uplifting really :-), and politics. NIH is a bit of scary place: lots of security checks, the usual government big-brother-is-watching regulations with email and chat monitoring and the feel of a science factory with scientists as hens studying hens in their labs! But they have superb facilities, good scientists and the researchers are generally not dependent on outside money and hassled with writing millions of research proposals. It was Soo-Eun's first time in Paris, and she was probably a bit on a culture shock! Unfortunately, as NIH policy generally forbids their scientists to stay on after a conference, they had to go back the next day! What a shame! Check out their group's webpage for more references on their work: here.

Soo-Eun talked about her brain imaging work on older children, which we have already discussed on this blog. So let me first refer you to these posts: here, and here. She spent a rather long time on established stuff like the Ambrose and Yairi study on childhood stuttering and recovery (the group helped them with their study), on past brain imaging studies, and on how the latest brain imaging works (with very cool pictures and process diagrams), which was well presented but gave her less time to talk about her work and ideas. I always prefer to hear less in more depth from own work and repeated several times in different ways! This is especially true for all the brain imaging work, where people throw in all kinds of brain regions from different methods, one every 30 seconds, and I just get confused and have no time to digest. Too many details, especially because the terms are not second nature to me. But I cannot imagine that the speech therapists present actually understood what was said, and that the professional neuroscientists remember it all.

Soo-Eun's philosophy seem to be roughly: Stutterer's brains react to stuttering, and it therefore makes sense to look at younger brains to reduce the effect of brain plasticity. Not only compare with controls, but also compare the group of recovered and persistent early teens. Expect that even recovered teens show abnormalities, because strokes in recovered adult stutterers often make stuttering re-appear, and because the brain is well able to compensate for a deficiency to restore function if not normal structure. They choose 22 boys from the age of 8 to 12. Interestingly, she said that they choose to exclude nearly 50% due to other issues like ADHD. This is an important piece of information. I should have asked why they did not just scan them, and then analyse separatedly. As far as I followed, the two major results are: 1) Replication of white matter difference in a major fibre tract similar to what Watkins et al. and other studies found. Appararently, it is a major fiber tract supporting auditory and motor integration. 2) No replication of some gray matter differences from adult scanning results. (Remember: white matter are the neurons' tentacles connecting between neurons, and gray matter are the neurons themselves.) She also talked about the difference between recovered and persistent kids, but went too fast for me to digest or write down details. But recovered kids always seemed to be different to controls and persistent kids. So we should really be more precise when using the word recovery. We need to distinguish between functional recovery and structural recovery. Recovered kids generally seem to be fluent (functionally recovered) but still not normal (structurally).

After the talk, Peter Howell noted that some kids from the age group 8-12 are actually recovering from stuttering, and they might distort the grouping of recovered and persistent kids. He said nearly 50%, which sounds very high to me. But it might be true, and is good news for the Lidcombe treatment trialers to get more results out of nothing! :-) However, I guess they control this effect by monitoring these kids and if recovery is happening to do a further group analysis.

Tuesday, May 20, 2008

Ludo Max's talk in Paris

I am going to write short summaries of the conference talks so everyone gets an idea what was talked about. It would be shame if the non-attendants missed out on a good conference. Of course, I have to simplify and my notes are definitely not perfect. And I did not understand each statement, question or answer! But I am sure that this applies to all attendants! I will give my opinion at the end.

Ludo Max gave the first talk. He is a professor at the University of Connecticut, south of Boston. I visited him in October of last year. He is originally from Belgium. Check out his webpage with all relevant references to his work: here.

He didn't really say anything revolutionary new. His approach to stuttering is still the following:

1) Use the most plausible flow diagram of the processes that generate (speech) motor control.
2) Test the various components for people who stutter.

He argues that this is what real science should be about: namely testing theories. A key component of the model is the efference copy concept. In order to correct for imprecise muscle movement, the brain needs sensory feedback. For example, if I reach for the glass and I miss it by 1 cm, my finger and my visual cortex generate a "not touching by a bit" information. Then the brain can correct for this. However, this is quite slow as the brain needs to wait for the sensory feedback from my finger and my eyes, then combine and process the information, and then send the "not touching by a bit" information to my motor regions. This mechanism will fail if the brain has to do too many movements in a short period of time like in speech, and therefore it has invented the efference copy, which is effectively parallel processing. So once the motor command is sent to the muscles, a copy of the comman is sent to a region that predicts what the sensory feedback should be at the same time as the muscles are executing the command. So the expected sensory feedback is ready and waiting for the actual sensory feedback. Time is saved, because the actual feedback does not need to be analysed any more but only compared to the predicited sensory feedback.

Ludo showed results from his experiments. Actually, I participated in one of them. It is a nonspeech experiment that involved making reaching movements in the presence of a visuomotor rotation. You have to move your finger towards a target, which is easy enough. However after a while they manipulated the visual field by a rotation and you are actually missing the target by a bit. After a few minutes of irritation your motor control system gets used to this shift and automatically corrects for the rotation. The experiment tests how fast you can adapt, which depends on your inverse internal model (I think) which is part of the motor control framework. Ludo found a noticeable but not dramatic group difference between controls and people who stutter. He also talked about an experiment involving a formant shift, but I do not have anything written down on it. He also said that the visuomotor rotation experiment is currently being repeated with children, but the boring targets being replaced by basketball baskets. Ludo also talked about a new set of experiments he is conducting to find out whether differences in the control of orofacial movements lie in the sensory and/or the motor domain. The experimental setup involves being stuck into an apparatus that monitors your orofacial movements, which looks a bit like a chastity belts for your mouth!

Christy Ludlow asked a methological question. I did not really follow on what, but the gist of it is that the interpretation of the experiment is not completely clear-cut and other effects could distort results allowing for alternative interpretation. I asked Ludo whether he had tried to correlate the group difference in the visuomotor experiment with stuttering severity. I suggested he could divide the sample into three: controls, mild stutterers, and severe stutterers, and see whether the controls-to-mild difference was in between the controls-to-severe group. He replied that he hadn't done this but might do.

In my opinion, Ludo is a good scientist and in principle doing the absolutely scientifically correct thing, namely to start out with an established or candidate model and then test the different components. However, in the given circumstances his approach is probably not leading to significant results in the near term, because the setup, the result and the interpretation of the experiments is very sensitive to all kinds of experimental and theoretical issues. But he can prove me wrong! First, experiments like the visuo-rotation experiment seem to get only group difference results, i.e an average difference, because people who stutter do not have failures but only defficiencies. There is a high overlap between control's and pws's performance: some stutterers have in fact better skill than many fluent controls! Only their group average is lower. So deficiency is not a sufficient condition for stuttering. Second, there might well be sub-types distorting results. Third, the model is a functional model but processes of speech motor control might well be implemented differently in different people. So they might have the same functional ability but the brain actually uses different pathways. Fourth, in my opinion, most of the differences we see in stutterers across several areas are simply consequences or a side-effect in a stuttering brain, and not directly involved in causing stuttering. Fifth and probably most importantly, the experiments are quite hard work. You need to recruit the subjects, setup the experiments, be scared of all kinds of experimental artefacts. To me, his approach makes more sense from the perspective of a researcher interested in speech motor control with a focus on stuttering as opposed to a researcher only interested into stuttering.

Monday, May 19, 2008

Human language and brain plasticity at McGill

Maybe some of the researchers here are interested in this conference on language and brain plasticity:

International CRLMB symposium on human language and brain plasticity at McGill:
Mechanisms of Learning, Brain Plasticity and Critical Periods

The Centre for Research on Language, Mind & Brain (CRLMB) is pleased to invite you to join us for a two-day symposium on language, learning and brain plasticity, to be held on

20-21 June 2008 at McGill University (Moyse Hall) in Montreal

The symposium will examine recent advances in understanding mechanisms of language learning, and provide an overview of current developments in brain plasticity and critical periods. The goal of the symposium is to facilitate the interdisciplinary exchange of ideas among researchers whose complementary interests provide an important foundation for issues related to first and second
language learning and cognition development.

The meeting will feature presentations by eleven internationally renowned scientists whose work has contributed new and innovative perspectives on the neuro-cognitive basis of language learning and other cognitive processes. The topics to be addressed include: constraints on statistical language learning; the neurobiology of critical periods; and (psycho)linguistic perspectives on second language acquisition, among others.

Please help us to advertise this event by posting the enclosed Symposium poster
and give this email the widest possible distribution by forwarding it to your colleagues.

Karsten Steinhauer, PhD
(Organizing Committee & Chair in Neurocognition of Language at McGill)

Sunday, May 18, 2008

No speech but singing with TMS

Check out this cool demonstration on how TMS (transcranial magnetic stimulation) knocks out the speech regions. Watch how his speech stops when TMS is turned on, and how TMS has no impact when he is singing the ryhme! Does this effect sound familar? We who stutter can sing fluently and not speak fluenty!

Here is the Daily Telegraph article, and here is the direct link to the video.

(Thx to Dave Rowley for this tip!)

Saturday, May 17, 2008

Newsflash from Paris conference

I just made my way back to Luxembourg from the one-day conference in Paris. Have you ever been confused of the difference between "efficiency" and "efficacy"? Here is a good example: I took the TGV, the world's fastest train (the most efficient in terms of speed), but completely ineffective (i.e. in terms of actual output), because my return journey took 5 hours instead of the 3.5 hours with the old trains or the 2 hours in the morning!!! Some troubles on the rails which caused a late departure and reduced speed limits!

Here are my talking points:

1) We are currently seeing second generation brain imaging studies. I am very impressed with the latest very cool brain graphics, better scanners and the latest signal manipulation, interpretation (e.g. fiber tracking) and statistical software. The latest studies are now much more reliable than the first generation. I would even go as far as to say that we should forget about all studies older than 2-3 years, except maybe keep a summary in our minds with the meta-analysis by Brown et al.

2) All groups (Chang et al, Watkins et al, and Kell/Neumann et al.) have confirmed the presence of a white matter defficiency in the left frontal cortex, first found by Sommer et al. with more primitive and low resolution DTI scanning. What they disagree on is the exact location, however there are most likely differences in the sample and methods.

3) There was an interesting observation that stuttering and other disorders often show (similar) abnormalities, but that these abnormalities do not necessarily translate to dysfunction. A fascinating interpretation could be that a brain loaded with abnormalities actually shows a decreased (global) brain plasticity to compensate for a defficieny. And the people with disorders are just the biased sample of people who have failed to compensate adequately.

4) Riitta Salmelin talked about MEG and told us that she is going to take a second look at stuttering, after her first MEG study on stuttering where she showed some reversal in activation for people who stutter. MEG shows electrical activity down to a 1ms resolution, and she now has a working method to determine the time sequence of events. I am very keen to see what she will find as this tool has never been applied to stuttering!

5) No theoretical breakthroughs at all. The consensus seems to be to wait and get more empirical observations from the second generation brain imaging, especially in terms of correlating activities between different regions first.

OK. That's my first twist to a very interesting conference. I'll talk about each presenter over the next weeks. And pictures!!

Thursday, May 15, 2008

Off to the Paris conference

Sorry for not posting. I am very busy studying for an exam and playing an international chess tournament. Tomorrow, I am taking the train to Paris for a day to attend the workshop of neurology of stuttering. It should be very interesting. I will try to make notes and write posts.

Friday, May 09, 2008

Food allergy and stuttering

A reader wrote to me:
I’m 38 and started stuttering very late at about 8. I went to speech therapists etc and generally lost respect as the “techniques” never worked or helped me. After a conversation with a friend, I tried a different approach about 3 years ago. I got anti-anxiety meds that helped me greatly. I realized I had some “wires” crossed and started to dig deeper.

I saw various doctors and tried various homeopathic pathways. Which were hitting around the problem, but never got super close to answers. I was tested last fall for food allergies and the results were astounding; I was allergic to food and a diet change transformed my life. My speech improved very quickly and I also felt better. I was still having ups and downs but they were less severe. I went to see a couple gastroenterologists to explore the food allergy further. I would, at times, wake up with a headaches for seemingly no reason. My fluency would have ups and downs (however less severe) even when I would eat “safe” foods. My gastro said I might have an enzyme deficiency and prescribed some Creon (enzyme) for me. The Creon also changed my life.

I probably have never digested food well. When I eat, my body could not cope and it would ultimately engage my sympathetic nervous system instead of my parasympathetic nervous system. Thus, I would immediately go into fight or flight anytime I ate. This would increase my overall body tension and create an ever moving target with regard to my fluency. Good days, bad days, always unexplainable. My body became more and more averse to certain foods and I became more and more allergic to foods b/c of my difficulty in digesting them. This tension/anxiety would focus in my neck area and I would stutter. I cannot explain how much changing my diet and the digestive enzyme has helped me.

I would be really interested if anyone else out there has pursued this avenue

Tuesday, May 06, 2008

Are you close to or travel to Montreal/Toronto?

If you are close to or travel to Toronto or Montreal, you can help Sarah Smits-Bandstra in her research! Click on the picture to see the details...

Different types of researchers

In my experience, there are four types of researchers:

a) the full-time scientists that look at stuttering by opportunity and chance
b) the scientists that focus their academic career on stuttering but do not treat but teach.
c) the generalists that focus on all aspects of stuttering from research, teaching, and treatment.
d) the practitioners who focus on treatment and teaching but do research part-time.

Type a are mostly geneticists and neuroscientists. They are in my view the best scientists for experiments. They now relatively little about stuttering as a disorder, and live in their experimental paradigm. They just happen to fall on stuttering. Without bias, they just look at stuttering. They are mostly funded by general research councils, and publish mostly in non-stuttering focused journals. I trust them most in terms of experimental results.

Type b knows a lot about stuttering and are professional scientists, and direct their research according to what they perceive as an important experimental question. They say: I have a theory and I want to test it, whereas Type a says I have an experimental method and I want to use it. They publish in both stuttering and non-stuttering journals. They also get their funding from research councils but they might rely more on money pools with a focus on speech and language or communication sciences. Such research resources are often dominated by some professors. Especially junior type b are relatively sensitive as not to offend such an important person who might be editor of a stuttering-related journal or a powerful member of a research council. This is especially true in the UK, and also to some degree in the US and Australia. At least four have told me that they try not to provoke or openly criticise work by a big name, because they are scared of having a paper rejected or getting no funding. Actually, they like me because I say what they do not want to say out of political reasons! So view my blog also as the voices of some in the research community!

Type c is a bit of a generalist. They do teaching, treatment, and research. They are quite focused on stuttering journals, and are at all the conferences. They mostly publish in stuttering journals. In general, they are not full-time and not very good scientists, but are good all-rounders.

Type d are practitioners first. They treat patients, but are too energetic and intelligent to just do their job and go home at 5 o'clock. They are closely connected to the stuttering associations. They are very much focused on treatment, and do research in the area. It is often non-funded research, small pools of money or funded by private money.

In any research team there might a bit mixture of researchers.

I forgot Type e)

e) They stutter, generally have a good science background, and follow research in stuttering. They do not do any experimental work nor treatment nor teaching. They do meta-analysis of research and try to understand what stuttering is about. They do it all for free. Some even write blogs! :-)

Monday, May 05, 2008

Fall in different ways

Oren asked me:
I'm interested to know whether you have the same sensation for all types of stutters (repetitions, prolongations, pauses, etc.)? If not, how is the sensation different for each stutter type?
I think it feels the same before the event. There is some mental blockage, i.e. I know what to say, my brain gives the signal you can say it, but then I sense that I cannot. Whether this translates into repetition, prolongation or pause is secondary. Like if I fall, I can struggle not to hit the ground, I can fall on my knees, or use my hand to soften the fall. The share of different behaviour is either learned or based on where I am in the sentence I guess... So I would say that I do not know which symptom is going to happen. I often notice that if I try to suppress on symptoms like a block then I have a pause. Or if I stop hesitations and fillers, I have blocks.

Sunday, May 04, 2008

First donation!

Yesterday I received the first donation for TheStutteringBrain! It is good to know that someone thinks I am doing a good job and actually supports it with an action!

Friday, May 02, 2008

Natural dysfluency vs stuttering?

Another reader asks the following the question:
Do you -- as a person who stutters -- differentiate between disfluency and stuttering? Are they the same?
As a person who stutters, I can clearly sense a difference between natural disfluencies and stuttering. Natural disfluencies feel like a mental hesitation that is translated into disfluent speech. I do not know what to say or changed my mind, and I just say "ehhh" or "mmm" or do no continue or extend the syllable I have started. Or sometimes it feels like a glitch in my motor control in the same way as I sometimes make wrong hand or arm movements. It's more like "Funny.. why did I do this? I am clumsy today", and then I just do the correct one with ease.

Stuttered speech feels to me very differently. To start with, I know exactly what I want to say or at least I have the sense that my brain knows what it wants to say without me necessarily consciously knowing what it will be. :-) So I have this "your message is ready and we are ready to go live" feeling, but I can't get it out or I know it is going to be a struggle. It is also associated with other symptoms like tension, loss of control, and also some kind of blockage in the brain. It kind of feels like it involves more than just this local glitch. My whole mental space seems to become restricted to the moment of stuttering. And I know that it is not just a glitch, but will continue with the next sentences. I also feel that I have lost the control of my body posture.

Overtly when only listening to speech samples, it might well not be possible to distinguish clearly between natural disfluencies and stuttered speech, but internally it is most definitely very different. So I think a person who stutters has also natural disfluent speech like a fluent speaker and in addition he or she stutters.

What is your experience? I would like to hear from people who stutter, but also from others who listen a lot to stutterers. Can they detect the difference between natural disfluencies and stuttering?

The last provacative question

And here is the last question I was asked by the reader:
Do you think non-stuttering researchers do better research in stuttering, they seem to get more funding and on "the cutting edge" of modern stuttering research.
Let's start with therapists. For the typical adult cases, I am convinced that people who stutter or stuttered can well compensate most if not all of their lack in an appropriate qualification or training, as long as they are qualified or trained in something that requires some kind of self-control, moderate intelligence, and learning ability. For difficult cases with psychological issues, a professional is needed.I have also seen so many "therapists" who are just not very good: BEING A NICE SMILING CARING PERSON DOES NOT MAKE YOU A GOOD THERAPIST! :-). For children you need a professional to diagnose children and deal with the parents. So you need to know all the kinds of developmental disorders that can happen and exclude them. But some part of the therapy itself again could well be done by any people who stutter or parents who are not completely out of their mind. So I could well see myself organising a therapy for adults, but if I had a stuttering child, I would take him or her to a generalist speech and language therapist first to exclude other disorders and then discuss with a specialist one on what to do. But I would probably most of the training with the child myself, because as a parent I have more "access" unless the child wants someone else.

For researchers, my answer is a clear yes, but out of statistical reasons. A good researcher has to have an above-average intelligence. So from a pool of 100 researchers, there is on average one that stutters. So if I impose an equal ratio, I would decrease the quality of researchers because I have to hire some less qualified stuttering researchers than qualified non-stuttering researchers. But I guess I am not answering the question, because he most likely means: Does the fact that you stutter makes you an even better researcher, assuming you are a good researcher? Is there an added-value? There are three reasons in favour. First, the researcher is probably truly interested in the research, and does not mind to work on the topic above his calls of duty. Second, he or she understands some issues much better. I have often seen researchers misinterpreting certain behaviours of people who stutter or being unaware of certain issues. Third, the stuttering researcher might have a better connection to the consumer associations, and finds it easier to recruit for experiments or get invited to conferences. He or she is also not open to suspicion that they are only nice to stutterers because they need subjects. On the other hand, a stutterer might hold biased views, and might be reluctant to accept "hurting" experimental results. Let's say he finds strong evidence for Freud's anal displacement theory, he might ignore it, not publish it, or minimize the results. A neutral researcher just reports what he or she finds.

So it is a mixed bag in my view. Both kinds of researchers are needed really. And I have also not seen any evidence that research councils favor researchers who do not stutter. I would guess that the opposite might be more likely.