Sources and Credentials

Evidence vs. Experience

My credentials are that I’ve read almost all the scientific literature in the field of stuttering, which is called evidence-based practice (EBP). I’ve tried every stuttering therapy I write about in this e-book, except the pre-school therapies, tDCS, and CBM. I also built the only website for stutterers to write reviews of therapies they’ve done. I call this experience-based practice. Evidence-based practice and experience-based practice are different. They’re complementary but one is not part of the other. The former is “book learning” and the latter is “street smarts.”

According to the American Speech-Language Hearing Association (ASHA) Position Statement on Evidence-Based Practice in Communication Disorders

The term evidence-based practice refers to an approach in which current, high-quality research evidence is integrated with practitioner expertise and client preferences and values into the process of making clinical decisions.

Expertise should be at best questioned and at worst avoided. Psychologists began studying expert decision making in 1977 after the Tenerife airport disaster, in which two 747s collided on a foggy runway in the Canary Islands, killing 583 people. The disaster was the fault of one of KLM’s most experienced pilots, who was also featured in ads for the airline. The co-pilot didn’t question the pilot’s decision to take off. The third, lowest-ranking crew member in the cockpit was the flight engineer. He understood a garbled radio message from the control tower and told the pilot that a Pan Am 747 was still on the runway. The pilot ignored the flight engineer’s objections and took off, slamming into the Pan Am at 160 mph.

Since 1977, the airline industry has extensively studied expert decision making. Low-ranking crew members are taught how to talk to pilots when they see a pilot make a mistake. Pilots are taught to listen. Air travel is now much safer than it was in the 1970s.

In this e-book I’ve included experts’ views on each stuttering therapy. In most cases my views are the opposite of the experts.

As for “client preferences and values,” of course treatment providers have to listen to stutterers. If a stutterer doesn’t want to do something they’ll go somewhere else, or do nothing. 

The problem with ASHA’s position on evidence-based practice is that it doesn’t recommend pairing EBP with experience-based practice.

Another problem with EBP is that, in my view, if a treatment is cheap, fast, and has no dangers or side effects then my standards for inclusion (and for me trying the treatment) are lower than for treatments that are expensive, time-consuming, or have dangerous side effects. For example, you can buy thiamin at the drug store for $5, the effects are usually seen in a few days, and there are no side effects. Two studies (one for children, one for adults) were enough for me to try it.


I used the following literature reviews and meta-analyses to write this e-book.

  • A 1995 literature review of 13 studies of indirect therapy with pre-school stutterers, published in the Journal of Speech and Hearing Research (JSHR).[ref]Nippold, M., & Rudzinski, M. Parents’ Speech and Children’s Stuttering: A Critique of the Literature. Journal of Speech and Hearing Research, 38, 978-989, October 1995.[/ref]
  • A 2006 systematic review of 162 studies of “behavioral, cognitive, and related approaches,” published in the American Journal of Speech-Language Pathology (AJSLP).[ref]Bothe, A., Davidow, J., Bramlett, R., & Ingham, R. (2006). Stuttering treatment research 1970–2005: I. Systematic review incorporating trial quality assessment of behavioral, cognitive, and related approaches. American Journal of SpeechLanguage Pathology, 15, 321-341; 1058-0360/06/1504-0321.[/ref]
  • A 2006 literature review of 17 studies of altered auditory feedback (AAF) devices, published in the Journal of Fluency Disorders (JFD).[ref]Lincoln, M., Packman, A., & Onslow, M. (2006) Altered auditory feedback and the treatment of stuttering: A review. Journal of Fluency Disorders, 31, 71-89.[/ref]
  • A 2006 systematic review and meta-analysis that examined 224 studies, published in Contemporary Issues in Communication Science and Disorders (CICSD).[ref]Herder, C., Howard, C., Nye, C., Vanryckeghem, M. (2006). Effectiveness of behavioral stuttering treatment: A systematic review and meta-analysis. Contemporary Issues in Communication Sciences and Disorders, 33, 61-73.[/ref]
  • A 2008 tutorial about evaluating clinical trials for stuttering treatments found 21 studies that met the definition of a clinical trial, published in the American Journal of Speech-Language Pathology.[ref]Mark Onslow, Mark Jones, Sue O’Brian, Ross Menzies, and Ann Packman. (2008). Defining, Identifying, and Evaluating Clinical Trials of Stuttering Treatments: A Tutorial for Clinicians. Am J Speech Lang Pathol 2008 17: 401-415. doi:10.1044/1058-0360(2008/07-0047)[/ref]
  • A 2010 systematic review by ASHA’s National Center for Evidence-Based Practice in Communication Disorders.[ref]Frymark, T., Venediktov, R., Wang, B. (2010) Effectiveness of Interventions for Preschool Children with Fluency Disorders: A Comparison of Direct Versus Indirect Treatments. National Center for Evidence-Based Practice in Communication Disorders, American Speech-Language-Hearing Association, Rockville, MD. March, 2010.[/ref]
  • A 2013 systematic review and meta-analysis of 9 childhood stuttering treatment studies, published in the Journal of Speech, Language, and Hearing Research.[ref]Nye, C., Vanryckeghem, M., Schwartz, J., Herder, C., Turner, H., & Howard, C. (2013) Behavioral Stuttering Interventions for Children and Adolescents: A Systematic Review and Meta-Analysis. Journal of Speech, Language, and Hearing Research.[/ref]
  • The chapter “Treatment” in the book A Handbook on Stuttering: Sixth Edition, by Oliver Bloodstein and Nan Bernstein Ratner (2008) reviewed 218 studies.[ref]Bloodstein, O., & Bernstein Ratner, N. (2007). A Handbook on Stuttering, Sixth Edition. Clifton Park, NY: Thomson. ISBN 978-1-4180-4203-5, pages 337-421.[/ref]
  • In 2016 the United Kingdom’s National Health Service wrote a 330-page review of stuttering treatments. The good news is that it’s a free download. The bad news is the review concluded that “It was not possible to recommend any particular programmes that are more effective versus those that are less effective.”[ref]Susan Baxter, Maxine Johnson, Lindsay Blank, Anna Cantrell,
    Shelagh Brumfitt, Pamela Enderby and Elizabeth Goyder. Non-pharmacological treatments for stuttering in children and adults: a systematic review and
    evaluation of clinical effectiveness, and exploration of barriers to successful outcomes. HEALTH TECHNOLOGY ASSESSMENT, VOLUME 20 ISSUE 2 JANUARY 2016, ISSN 1366-5278[/ref]
  • A 2020 systematic review of all five–count ’em five–stuttering treatment research articles published from 2005 to 2020.[ref]Amanda Brignell, Michelle Krahe, Martin Downes, Elaina Kefalianos, Sheena Reilly, Angela T Morgan. A systematic review of interventions for adults who stutter. Journal of Fluency Disorders 64 (2020) 105766.[/ref]
  • A 2020 review of medications for stuttering. [ref]Gerald A. Maguire, Diem L. Nguyen, Kevin C. Simonson, and Troy L. Kurz. The Pharmacologic Treatment of Stuttering and Its Neuropharmacologic Basis. Front Neurosci. 2020; 14: 158. doi: 10.3389/fnins.2020.00158[/ref]

I also used the National Center for Biotechnology Information (NCBI) at the U.S. National Library of Medicine (NLM) to search for studies published after 2006 or otherwise missed by the above reviews.

I did hand-searches of the Journal of Speech, Language, and Hearing Research, the American Journal of Speech-Language Pathology, and the Journal of Fluency Disorders since 2006.

I receive a weekly email from the NCBI for new research articles with “stuttering” or “stammering” in their titles.

If a study is recommended in a literature review or meta-analysis I read the original article. I found two mistakes in the NHS review’s reports of studies of my devices.

In one case an article in a major speech and hearing journal looked sketchy so I asked the researchers for their data. The data revealed results opposite of what the authors reported in their article. I wrote to the journal asking them to look at the data; the editor responded that they don’t do that (they only look at the article). I wrote to the National Institutes of Health (NIH), which funded the research. The NIH examined the data and wrote back that the study was so poorly done that no conclusions could be reached.

Why Is There So Little Research on Stuttering Treatments?

From the 1980s to the early 2000s there were many stuttering treatment research articles in the peer-reviewed scientific journals. Now there’s one every few years. Several factors work against stuttering treatment research.

Stuttering treatment research can take years. For example, the 2015 Modifying Phonated Intervals study[ref]Ingham, R., Ingham, J., Bothe, A., Wang, Y., & Kilgo, M. (2015) Efficacy of the Modifying Phonation Intervals (MPI) Stuttering Treatment Program with Adults Who Stutter. American Journal of Speech-Language Pathology, January 28, 2015. doi:10.1044/2015_AJSLP-14-0076[/ref] averaged three years for each participant. The study had 27 participants. Applying for the grants for the millions of dollars it takes to run a clinical trial takes typically five years. Publishing the study takes another two or three years. The 2015 MPI therapy study followed a 2001 MPI therapy pilot study. The 2015 study took fourteen years to complete.

Most research is done by graduate students trying to get their Ph.D. in five years. They want to graduate and get a job. Then when they have a job teaching at a university they want to get tenure within seven years. The tenure committees want to see many published studies.

Etiology (the nature of stuttering, or, more typically, borrowing some new scanner or questionnaire from another department and trying it out on stutterers), electronic devices, and social issues such as bullying are topics that can be done relatively quickly and cheaply. Pharmaceuticals and traditional face-to-face therapies are long and expensive.

After a professor gets tenure in addition to teaching and university administration duties they’ll want to start a private practice, which pays better than teaching. Research pays nothing.

This is why my devices have more than twenty studies. DAF studies are fast and cheap and graduate students love them.

For medications a clinical trial costs hundreds of millions of dollars. Pharmaceutical companies will spend this for a drug they’ve patented but for an older drug whose patent has expired or for a vitamin that can’t be patented there’s no profit incentive.

Another issue is review boards. The Schwartz thiamin study was rejected for publication because Dr. Schwartz hadn’t asked an Institutional Review Board (IRB) to approve the study. He had a private speech clinic and asked his adult clients to try a harmless vitamin. He collected the data and wrote up the results. The journals rejected the study not on scientific grounds but on legal grounds. Back in the 1980s and 1990s, when there were many stuttering treatment research studies, there weren’t IRBs.

(Continuing on this rant against IRBs, one study of a hearing aid-style device that was spec’ed to have a maximum volume of 115 dB, which can cause permanent hearing damage in minutes, the IRB approved a study that tested hearing before using the device but not after using the device. I wrote to the IRB saying that the participants’ hearing should be tested to see if anyone suffered hearing loss as a result of the study. The IRB responded that they didn’t see this as necessary.)