The Topography of Disfluency in Spoken Language: A Scoping Review.
Yangfan Xu, Yunyi Hu, Michael C-F Tong and 1 others
PMID 42348483WHAT IT FOUND
Across 69 studies, the same disfluency terms (repetition, prolongation, block, filler) carry 368 different definitions.
The same label in two papers may mean different things, so check each paper's definition before comparing its results to your own assessment.
Key findings
01Across 69 included studies, 155 disfluency subcategories and 368 distinct definitions were identified and grouped into seven broad categories: repetition, prolongation, revision, pause, filler, incomplete production, and nonverbal behaviors.
02The same term carries contradictory definitions across studies. For example, 'block' is defined by some authors as a silent interval between sounds, while most researchers define it as an involuntary, uncontrolled pause in airflow or voicing during or before producing a vowel or consonant. 'Prolongation' is described by one source as either silent or audible, while another restricts it to audible lengthening of sounds.
03SLP studies contributed the largest proportion of disfluency definitions across all seven categories, and most SLP classification frameworks trace their roots to Johnson's 1961 eight-category system, with subsequent adaptations subdividing these into overlapping groupings such as 'stalls and repairs' or 'stalls and revisions.'
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The review is restricted to English-language publications, so disfluency types and definitions described only in non-English literature are not captured, even though 12 non-English languages were represented among the included studies. Studies that cited existing classification frameworks without modifying terms or definitions were excluded, but the authors acknowledge that distinguishing these from studies with minor or hybrid modifications was difficult, which may have affected which studies were included. Only one included study examined disfluency classification in populations with cognitive decline, leaving a large gap for clinicians working with dementia or mild cognitive impairment. Task-dependent variations in disfluency (for example, conversational speech versus picture-description tasks) were not systematically analysed, despite evidence that task complexity changes both the frequency and type of disfluencies.
Declared interests
No conflicts of interest declared. The study was supported by the Guangdong Provincial Clinical Research Center for Rehabilitation Medicine (grant 2023B110003).
The easy way to misread this
Do not assume that a paper's definition of 'repetition,' 'prolongation,' or 'block' matches the one you use in your clinic. This review found 113 different definitions of repetition alone and contradictory definitions of block (silent interval versus involuntary airflow pause) within the same body of literature. Before comparing a study's outcome to your own assessment or to another paper, read that paper's operational definition of each disfluency type it reports.