The reason I posted a research study on the autonomic nervous system is entirely connected to these particular studies: [this](https://www.jpccr.eu/Reaction-of-the-cardiovascular-system-during-anticipation-of-speech-and-while-speaking,71314,0,2.html) ([pdf](https://www.jpccr.eu/pdf-71314-8546?filename=Reaction%20of%20the.pdf)) I quote: >*"Persons who stutter often report their stuttering is influenced by emotional reactions, yet the nature of such relation is still unclear. Psychophysiological studies of stuttering have failed to find any major association between stuttering and the activity of the* [*sympathetic nervous system*](https://www.sciencedirect.com/topics/psychology/sympathetic-nervous-system)*. A review of published studies of heart rate in relation to stressful speech situations indicate that adults who stutter tend to show a paradoxical reduction of heart rate compared with nonstuttering persons. Reduction of heart rate has also been observed in humans and mammals during anticipation of an unpleasant stimulus, and is proposed to be an indication of* [*anticipatory anxiety*](https://www.sciencedirect.com/topics/psychology/anticipatory-anxiety) *resulting in a “freezing response” with parasympathetic inhibition of the heart rate. It is suggested that speech-related anticipatory anxiety in persons who stutter is likely to be a secondary, conditioned reaction based on previous experiences of stuttering.*" And [this ](https://jpedres.org/articles/evaluation-of-heart-rate-variability-in-children-with-stutter/doi/jpr.galenos.2024.50374)research study (2024), I quote: >*"The autonomic nervous system has a direct or indirect effect on motor speech and its development. The results of studies evaluating autonomic functions in stuttering individuals show that further research is needed in different age groups. In this study, the aim was to evaluate autonomic function by analysing heart rate variability (HRV) in children with stutter."* @ everyone: My question is as follows: Which research studies propose stuttering theories attributing its cause to the autonomic nervous system (specifically the parasympathetic nervous system of the ANS)?