Note that my answers, at least in part, are derived from the theory presented on this website; therefore, be skeptical!
What causes stuttering?
Stuttering is caused by a misallocation of attention, i.e., of perceptual- and processing capacity during speech. The causal chain is: Symptoms are a brain response to invalid error signals in the monitoring system. The invalid error signals result from a mismatch between expectation and feedback. The mismatch is caused by feedback disruptions due to insufficient capacity for feedback processing because of the misallocation of attention (Sections 2.1–2.3).
What are risk factors for stuttering?
Deficits in attention regulation, particularly of auditory attention, and a subtle anomaly in central auditory processing (a less effective auditory gating) may contribute to a predisposition for stuttering, whereas hyperactivity and impulsivity seem to play a role in the chronification of the disorder (Section 3.3).
Is stuttering genetically caused?
I would not say stuttering is genetically caused, but only the predisposition is genetically caused. That means there may be people who have a “stutter gene” in their genome, but their speech is completely fluent. However, a stronger inherent predisposition for stuttering might imply a higher risk of the disorder to become persistent.
Is stuttering caused by a deficit in the brain?
I think it isn’t. Most deviations in gray and white matter, as well as in brain activation patterns seem to be consequences or concomitants either of the stuttering itself or of the person’s attempt to cope with the disorder. (Section 3.2). However, a predisposition for stuttering may also be associated with deviations in brain structure or -function.
Is stuttering psychologically caused?
Usually not. But in some cases, particularly of late-onset stuttering, a psychic trauma or the memory of an experienced trauma seems to have triggered the outbreak of the disorder. That’s plausible if, as assumed in the present theory, stuttering is caused by a misallocation of attention: The memory of a trauma might occupy much of the person’s attention or may make attention shift to things not supporting fluent speech.
Is stuttering a learned behavior?
The core behavior is not learned, but is the person’s spontaneous response to an internal blockage of speech flow. However, many of the secondary behaviors are learned – as attempts to overcome or to avoid the core symptoms. Further, in the theory proposed on this website, stuttering is assumed to be caused by feedback disruptions due to a misallocation of attention during speech. A tendency to allocate attention in a manner inappropriate for speech production may possibly be acquired in early childhood as a response to acoustic hypersensitivity (see Section 3.3)
Is stuttering caused by anxiety?
No, it isn’t. Social anxiety as well as fear of speaking are consequences of persistent stuttering. However, angst-burdened communication situations may contribute to the maintenance of the disorder (see this report)
How do the core symptoms come about?
In all these cases, a motor program controlling the articulation of a speech unit (mostly a word) is blocked. Now, either the motor program tries to start repeatedly, but gets blocked again and again at the same point, or the program gets caught at the point of blockage. The latter case either results in a prolongation (if phonation is not interrupted), or speaking is completely blocked. Which symptom occurs is depending on several factors: the sound affected (for instance, k, p, b, t, d can be repeated but not prolonged), the degree of muscular tension (the more tension the greater the tendency to tonic symptoms), and the inclusion of breathing or phonation in the underlying motor blockage (Section 2.1).
Is stuttering a multifactorial disorder?
Yes, it is. But a theory should tell us which of the factors are necessary, and which are sufficient. After the theory proposed on this website, the causal chain consisting of: misallocation of attention → disruption of sensory feedback → invalid error signal → blockage of a speech motor program is necessary as well as sufficient for stuttering. A predisposition for stuttering seems to be necessary, but is possibly not sufficient – that may depend on the degree of the predisposition. Learning to speak in sentences seems to be the necessary linguistic factor. Environmental factors may be necessary for the outbreak of stuttering if the predisposition is not heavy, but they alone might hardly be sufficient.
Why does stuttering mostly onset when children start forming sentences?
First, the misallocation of attention causing stuttering (after the present theory) is, in most cases, triggered by the unfamiliar requirements of sentence forming (syntax, grammar). Second, stuttering is a phenomenon of connected speech, because the stutter at the onset of a word is mostly the brain response to a feedback disruption at the end of the word before (Chapter 2).
Why do many of the affected children spontaneously recover from stuttering?
They learn to incrementally plan their sentences, and by doing so, they learn to allocate their attention in a way so that sufficient capacity is left for feedback processing. Some factors, however, seem to hamper the development of an appropriate allocation of attention during speech, namely a subtle central auditory processing disorder associated with a deficit in the control of auditory attention and, particularly in boys, a tendency towards hyperactivity and impulsivity. These factors seem to cause persistent stuttering.
Why do much more girls than boys spontaneously recover?
The male:female ratio in persistent developmental stuttering is very similar to that in attention deficit hyperactivity disorder (ADHD). If stuttering is caused by a misallocation of attention, as assumed in the present theory, then a relationship is probable and plausible. Especially hyperactivity seems to be a problem with some stuttering boys (see here), including a tendency to overreact to stuttering symptoms, some way or other, which again increases and maintains the misallocation of attention during speech and the likelihood of stuttering.
Why is stuttering so much influenced by situations, e.g., by the number and the kind of listeners?
Whether a speaker is talking to himself, to a baby, or a pet, or is talking to a teacher, to a superior, or to a large audience – these different situations and not least the speaker’s attitude towards the situation – influence the allocation of the speaker's attention. Especially stress can result in a misallocation of attention (focusing on the stressor, e.g., expected stuttering and the listeners’ response) And a misallocation of attention during speech is assumed to be the cause of stuttering in the present theory.
Why is a sort of speech sounds (plosives, vowels...) more frequently stuttered by one individual, another sort by another individual?
The anticipation of stuttering on certain speech sounds or sound combinations is fed by the person’s experience (Garcia-Barrera & Davidow, 2015) and by the mind’s desire for reducing the fear of stuttering: Better to fear only a few sounds than to fear all sounds. In other words: The mind unconsciously searches for what is at fault for the stuttering, and finds some sounds. The consequence is that trouble is anticipated with just these sounds if they occur in word- (or syllable-) initial position. Now, attention prematurely focuses on these sounds in order to cope with them anyway. As a result, the speaker’s attention (perceptive- and processing capacity) is misallocated: Too little attention remains for feedback processing at the end of the word or syllable prior to the feared sound, thus feedback is timely disrupted at this moment And exactly this – a feedback disruption at the end of a word or syllable – is assumed to be the cause of a stutter at the onset of the next word or syllable in the theory proposed on this website (Section 2.1–2.3).
Why does stuttering often occur at positions at which it is anticipated?
The speaker’s attention prematurely focuses on the position where stuttering is anticipated, e.g., the onset of a certain word. As a result, attention (perceptive- and processing capacity) is misallocated: Too little attention remains for feedback processing at the end of the word prior to the word on which stuttering is anticipated, thus feedback is temporarily disrupted there; an invalid error signal is elicited, and the brain reacts by blocking the subsequent motor program – just the motor program of the word on which stuttering has been anticipated. See also the last question.
Why does stuttering mostly occur at the onset of words and always in the initial part of syllables?
The reason is that invalid error signals resulting from a feedback disruption because of a misallocation of attention during speech (which are assumed to be cause of stuttering in the present theory) are always elicited either at the end of a word or syllable or at the end of an inhalation phase (Section 2.1–2.2). In both cases, the response of the control system to these error signals affects the execution of the subsequent motor program of a word or a syllable, respectively.
Why are stressed syllables, long words, and words with high information load more frequently stuttered?
Such words or syllables attract the speaker’s attention, thus attention prematurely focuses on them with the effect that too little attention is directed to the end of the preceding ‘nimportant’ word or the preceding unstressed syllable. It is the same mechanism as with word onsets on which stuttering is anticipated (see above): Stuttering occurs just at the position on which the speaker’s attention is prematurely focused because perceptive- and processing capacity is insufficient at the end of the word or syllable before, thus auditory feedback is temporarily disrupted there.
Why is stuttering so influenceable by alterations of auditory feedback?
When one’s own speech is heard in an unfamiliar manner, e.g., delayed (like an echo), frequency-shifted (in a higher or lower pitch), very low (whispering, blocked ears), in an unfamiliar dialect, etc., then attention is drawn to the auditory channel, that is, to the perception of one’s own speech, because it sounds odd. In this way, the processing of auditory feedback (which is depending on attention to the auditory channel) becomes stabilized, thus no or less feedback disruptions occurs, and for that reason, stuttering disappears or becomes markedly reduced (Section 3.1).
Why does stuttering mostly disappear when one’s own speech cannot be heard?
When one’s own speech is not to hear, e.g., with auditory masking by loud noise (through headphones), in cases of hearing loss, during ‘mouthing’ (silent speech movements), or during inner speech (verbal thinking) attention automatically shifts to the internal auditory feedback loop (see here). In this condition, no feedback disruption can occur, and stuttering usually disappears (Section 3.1). Cases, in which stuttering occurs despite complete masking, may have to do with disruptions of the feedback of breathing (see Section 2.2) and/or with secondary behaviors not influenceable by auditory masking.
Why is stuttering reduced if a text is read repeatedly?
This so called ‘adaptation effect’ results from the fact that less attention for word recognition is needed when a text is read for the second or third time; thus more attention (perceptive- and processing capacity) remains for other things, e.g., for auditory feedback. A further factor might be that the more familiar the text, the fewer speech motor programs of words are fragmented, and the more words are bundled to phrases produced by only one motor program (see Section 1.2). Since stuttering, after the present theory, is immediately caused by the blockage of a speech motor program, fewer program starts result in fewer stuttering.
Why does stuttering disappears during speaking in chorus or to the beat of a metronome?
It has often been assumed that the speaker gets external cues for syllable starts, but that’s wrong. If the speaker, at each time, waits until he hears the metronome beat or the co-speakers starting a syllable, he will always be too late. Instead, he must capture the given pace so that he can predict and anticipate it. Then, he must adjust his own pace to the given pace and continuously monitor whether both are still in sync. Therefore, he must attentively listen to both, the given pace and his own speech, in order to adjust his own pace if necessary. The need of listening to his own speech stabilizes auditory feedback, which results in fluency.
Why does stuttering not occur in singing?
Not the rhythm is the crucial factor – you can sing very well without a rhythm. The crucial factor is that you are listening to your voice while singing, in order to monitor the melody. That is, a sufficient portion of attention is directed to the auditory channel, by which auditory feedback is stabilized. A supporting factor is that lyrics are usually learned and memorized as one speaking program (Section 1.2). After the proposed theory, stuttering can only occur when a speaking program starts, but not within a running program (Section 2.1).
Why are some people able to work as an actor despite they stutter?
The lines of an actor’s part are spoken from memory, thus the actor is usually not required to formulate sentences by himself, and his attention is mainly directed to expression and prosody, which is monitored by hearing; thus, a portion of attention is directed to the auditory channel, which stabilizes auditory feedback. Additionally, every unbroken passage of the lines is recommitted to memory as one speaking program (Section 1.2). After the proposed theory, stuttering can only occur when a speaking program starts, but not within a running program (Section 2.1). For the same reasons, some people who stutter can recite poems from memory without difficulty: A poem is learned and automatized as only one speaking program, and the speaker’s attention is mainly directed to expression, voice, and prosody that are monitored via auditory feedback. So attention is well allocated for fluent speech.
What is the best way to treat stuttering?
After the theory presented on this website, developmental stuttering is caused by a misallocation of attention during speech. Therefore, the chief aim of treatment should be a change in attentional behavior during speech: A sufficient portion of the speaker’s attention should be directed to auditory feedback and, if stuttering frequently occurs after inhalation, some attention should be directed to the perception of breath. Attention should not too much be directed to speech planning, i.e., speech should be as spontaneous as possible. No attention should be directed to a deliberate avoidance of stuttering in any way, including the control of articulation or breathing by the will (Section 3.4).
Can persistent developmental stuttering be cured?
It cannot be cured because it is not a disease. It is a disorder of a learned behavior, namely speaking. The cause, after the proposed theory, is a misallocation of attention during speech – and attention allocation is a behavior, that means, the stuttering person behaves wrong albeit unconsciously and without blame. And since the allocation of attention is, at least in part, influenceable by the will, we can change our behavior after having realized what goes wrong. However, what a progress in fluency we ever make – we never get free of the predisposition for stuttering and the risk of relapse.