Unraveling the mystery of stuttering: clinical and physiological insights into its manifestation (2026) -- Explanation of how fluency and stuttering occurs

This is my attempt to summarize this new research: "Unraveling the mystery of stuttering: clinical and physiological insights into its manifestation" (2026).

How does fluency and stuttering occur?

Fluency occurs:

1. Route 1: Error signals → no conscious error monitoring / no social evaluation → error signals processed within monitoring system.
2. Conscious attention of the SMS (self-monitoring system) is reassigned from speech error-monitoring, and directed toward the situation or task, allowing error detection and correction to proceed subconsciously. While the conscious monitoring system is temporarily overridden by the external demands and context. 
3. As a result, the speaker momentarily “forgets” themselves and stops focusing on errors. 
4. If conscious attention or social evaluation is absent, speech remains fluent. 
5.  in the absence of conscious attention or social evaluation, these signals are processed by the SMS as ordinary error signals. They are resolved either subconsciously or consciously but without the presence of social evaluative pressure.

Stuttering occurs:

1. Route 2: Error signals → social evaluation + conscious error monitoring → warning signals → recruitment of additional regions.
2. the rIFG (causal role) is excessively sensitive to warning signals from the SMS and the amygdala originating from the SMS, particularly the pars opercularis
3. Error signals: Emotional stress interacts with pre-existing dysfunction in speech production regions, which are interpreted by the SMS as error signals. 
4. Negative social experiences such as embarrassment and perceived social failure - condition the amygdala to interpret social situations as threats to personal value and social identity. This process, in turn, contributes to marked hyperactivity in the right insula, a region critically involved in self-awareness and the monitoring of bodily sensations.
5. The self-monitoring system (SMS) detects and corrects error signals - that continuously assess and regulate speech production/output. It identifies discrepancies between expected and actual speech outcomes by employing mechanisms such as conflict monitoring and forward models. It adjusts speech-plans in response to linguistic conflicts, motor planning issues, and the influence of emotional and social factors to optimize the accuracy of speech production. 
6. The SMS identifies the most important words in the upcoming utterance, as well as those perceived as most difficult (accompanied by a pronounced increase in amygdala activity and emotional arousal)
7. When PWS need to deliver an important message or convey something precisely, they pay much more attention to speech errors, and social evaluation is heightened due to the pressure to speak correctly and fluently
8. Once these initial blocks become consciously perceived, and especially when they elicit fear, embarrassment, or anticipatory worry, the SMS becomes increasingly hypervigilant. The resulting warning signals place additional load on the already atypical rIFG.
9. Social evaluation + conscious error monitoring: Once a socially evaluative context is established, such as saying one’s feared name, the SMS mediates the transition from subconscious, automatic speech error monitoring to conscious error detection. 
10. The SMS engages social evaluation which is determined by higher-order cognitive regions (ie. amygdala assesses threat-related significance and retrieves prior memories of similar socially evaluative events) and right-insula (contributing to monitoring self-awareness and reflecting on interoceptive bodily sensations associated with social stress).
11. when both factors are simultaneously present. Speech context transforms error signals from neutral markers of deviation into signals imbued with threat relevance. This involves a shift from subconscious to conscious control, mediated by higher-order neural regions. Warning signals are a reinterpretation of error signals broadcast by the SMS, indicating that these signals carry heightened contextual significance. Warning signals operate within a defensive framework, whereby the system attempts to recruit additional neural resources and allocate increased attentional focus in the service of caution, precision, and control, with the goal of producing fluent speech and achieving the intended communicative impression or goal of the speaker. 
12. Warning signals: This heightened significance emerges when the speech context is socially or personally salient, such as during social evaluation, perceived importance of the listener, performance-related expectations, fear of failure, and the desire to avoid negative attention. Within such contexts, these cognitive and affective factors imbue error signals with emotional weight, leading the SMS to reclassify them as warning signals. Warning signals: the involvement of cognitive, emotional, and logical processes can narrow signals to the specific words that seem most important within a sentence. The SMS then amplifies error-related signals as warning signals. 
13. There is a failure to properly process warning signals from the SMS. The inability to understand the signal can be viewed as a broad concept, encompassing not only the failure to process the signal but also the difficulty in interpreting it or the abnormal engagement with it. All of these factors contribute to an increase in tension and conflict within the region, making the signal appear as something dangerous that requires inhibition. 
14. Undergo an expansion in metacognitive capacity, social self-awareness, and emotional sophistication - could amplify the salience of communicative demands, sharpen sensitivity to listener evaluation, and heighten self-monitoring during speech
15. Recruitment of additional regions: This prompts the recruitment of additional neural resources to support speech production. Conscious attention to speech: an additional strategy employed by the system to further support speech production by recruiting perceptual regions and allocating explicit attentional resources to speech. Among the key regions involved in this compensatory process are control, inhibitory, and conflict-monitoring regions, particularly the pre-supplementary motor area (pre-SMA) and the right inferior frontal gyrus (rIFG). Some of these recruited regions, rather than facilitating fluent production in a normal manner, become maladaptively involved in the emergence of the stuttering behavior itself. 
16. However, despite this compensatory recruitment, the system ultimately fails to stabilize fluent speech, and stuttering emerges. In this framework, stuttering is the result of a context-dependent escalation of error signals into warning signals, driven by the convergence of conscious monitoring and social evaluative processing.
17. PWS frequently adopt alternative speaking strategies to compensate for or prevent anticipated difficulty, including employing easy onset to begin speaking, using fillers or sentence starters, and interrupting the communication partner. 
18. HDP supports two related control circuits. First, a stopping circuit, in which the rIFG (and potentially the pre-SMA) engages the STN via the HDP to implement rapid suppression of an initiated response. Second, a conflict circuit, in which dorsomedial frontal regions (pre-SMA/dmPFC) recruit the STN via the same HDP to impose a brief delay when competing response tendencies are raising the decision threshold before committing to an action. The HDP acts as a rapid means for stopping actions, such as when a person needs to cancel a planned movement or response due to changing environmental demands.
19. the rIFG (compensatory role) seems to initiate a direct inhibitory response to the speech production areas, leading to the mechanism of blocking/freezing of speech i.e., disrupting the continuity of articulatory programs / system-level inhibition of speech motor programs / transient inhibitory or delay interference with speech output / involuntary speech interruptions.
20. This sudden halting of the entire speech production system - lasts until a signal with minimal warnings can pass through, such as switching from the intended word to a less suitable one that does not trigger the attention of the SMS.