Key words about the research on this topic? Ambiguous, conflicting, sparse!
I’ve read two systematic reviews that aimed to pull together several studies on the topic & I picked key points from both to keep things simple.
First up is Choo & Smith’s (2020) review that looked at 50 studies about stuttering in bilingual children. Key findings from that review are:
- There’s no clear evidence that bilingual children are at an increased risk of stuttering.
- More bilingual boys stutter than girls.
- Bilingual boys are less likely to recover than bilingual girls.
- Onset of stuttering in bilingual girls is earlier than in bilingual boys.
- The majority of bilingual children who stutter have a positive family history of stuttering.
Bottom line according to Choo & Smith? The current research offers a fragmented, limited understanding of bilingualism & stuttering & more research is needed.
The second systematic review by Chaudhary and colleagues in 2021 examined 13 studies & mentioned 3 patterns of stuttering in bilingual people:
- Stuttering in one language only
- Stuttering of equal severity in both languages
- Less stuttering in (any) one language
They said that Pattern #3 is the most commonly observed.
What causes the differences? The research reports on things like:
- Language proficiency
- Language dominance
- Linguistic proximity between the languages
- Grammatical, phonetic, and syntactic differences between the languages
Dominance & Proficiency: these are not the same thing & they’re not straightforward!
Chaudhary & colleages define them like this:
Proficiency means knowledge of the languages in terms of syntax (grammar), vocabulary, and pronunciation of the languages.
Dominance means the relative strength of the proficiency of the languages along with the frequency and usage of the languages.
In their systematic review, Chaudhary & colleagues reported several studies that found more stuttering in the less dominant language, possibly indicating a less well-developed language system as a contributing factor to stuttering in people where one language is stronger than the other.
They reported conflicting results when it comes to the influence of proficiency on variations in stuttering. Some studies found more stuttering behaviours in L2 and others in L1 (where there was a clear L1 & L2).
The purpose of their systematic review was to identify linguistic factors that play a role in stuttering in bilingual people. The main conclusions that they came to are that:
- Proficiency and dominance are the major factors that influence the stuttering frequency in bilingual people who stutter but studies differ in terms of how they describe language proficiency and dominance so different studies find different things.
- When it comes to structural and functional features of the languages, although it’s common to attribute differences in stuttering behaviours to differences between the person’s languages, the evidence here is ‘whimsical ….. neither data-driven nor empirically proven’.
So while there are lots of gaps in the research, two things are clear:
- Speaking two or more languages does not cause stuttering.
- Dropping your home languages is not recommended.
Let’s get talking!
What I read so you don’t have to
Chaudhary, C., Maruthy, S. Guddattu, V., & Krishnan, G. (2021). A systematic review on the role of language-related factors in the manifestation of stuttering in bilinguals Journal of Fluency Disorders 68.
Choo AL, Smith S, Bilingual Children Who Stutter: Convergence, Gaps, and Directions for Research (2020) Journal of Fluency Disorders 63.