Autonomic arousal in adults who stutter prior to various reading tasks intended to elicit changes in stuttering frequency

Reduced duration of stuttering-like disfluencies and consistent anticipatory slowing during an adaptation task

PURPOSE

The adaptation effect in stuttering, traditionally described as the reduction of stuttering moments over repeated readings, provides a context to investigate fluency facilitation as well as a relatively controlled means of comparing fluent speech in the immediate vicinity of words that were stuttered versus fluently produced. Acoustic studies have documented decreased duration of fluent speech during adaptation but rarely address changes in disfluencies or the speech preceding or following the disfluencies. This study addresses this gap in the research by documenting frequency and duration changes in both fluent and stuttered syllables.

METHOD

Fifteen people who stutter read passages aloud five times in succession. Frequency and duration of fluent syllables, pauses, stuttering-like disfluencies (SLDs) and other disfluencies (ODs) were compared across the five readings. In addition, durations for syllables before and after pauses and SLDs were compared to determine if there were anticipation or carryover effects of SLDs on surrounding syllables.

RESULTS

Durations measured for more than 22 000 fluent syllables, 1531 pauses, 128 ODs and 1752 SLDs. For most of the 15 participants, significant decreases in both frequency and duration of SLDs over the five readings were observed. In addition, lengthening of fluent syllables immediately preceding the disfluent syllables was observed: this pre-SLD lengthening did not change over the five readings.

CONCLUSIONS

Decreased duration of SLDs across readings supports the motor practice hypothesis, which assumes that successive reading of the same text increases the efficiency of the speech motor plans resulting in less stuttering and decreased durations of the stuttering that persists. Pre-SLD lengthening merits further study, because it informs our knowledge of the time course of stuttered events and may be associated with conscious or unconscious anticipation of upcoming SLDs that does not decrease with motor practice.

WHAT THIS PAPER ADDS

What is already known on this subject The frequency of stuttering-like disfluencies (SLDs) can be reduced using a variety of fluency-enhancing strategies. For example, the adaptation effect, in which a reduction of stuttered events occurs over repeated readings of the same material, has been widely studied. Previous studies have shown that durations of fluent syllables decrease during adaptation, supporting the hypothesis that repeated practice of the motor plan leads to increased fluency. However, temporal changes in disfluent syllables and syllables preceding and following SLDs have rarely been studied, so our understanding of the effect of motor practice on stuttering reduction is incomplete. What this study adds This study has two significant findings. First, stuttered disfluencies that persisted after the initial reading of the adaptation task tended to become shorter in duration. Fluently produced syllables and those that were stuttered, both of which are speech events related to motor control of articulators, were affected in a similar manner by the motor practice associated with adaptation. Second, lengthening of fluent syllables immediately preceding stuttered syllables was observed. This pre-stuttering lengthening, however, did not decrease in duration over the five readings: the mechanism that drives this anticipatory behaviour is not affected by repeated practice. What are the clinical implications of this work? People who stutter have neural differences that lead to speech motor planning and/or execution that is less efficient than that of typical speakers. The finding that stuttering is reduced and that persisting SLDs become shorter in duration over repeated readings provides evidence that motor practice can influence the manifestation of stuttering by temporarily making those specific motor plans more efficient. This may inform treatments for stuttering. The observation that fluent syllables immediately before SLDs were lengthened, and that this lengthening was not influenced by repeated practice, extends our understanding of the time course of stuttering events and may be useful in understanding anticipation and listener reactions to stuttering.

A novel non-word speech preparation task to increase stuttering frequency in experimental settings for longitudinal research

PURPOSE

The variable and intermittent nature of stuttering makes it difficult to consistently elicit a sufficient number of stuttered trials for longitudinal experimental research. This study tests the efficacy of using non-word pairs that phonetically mimic English words with no associated meaning, to reliably elicit balanced numbers of stuttering and fluent trials over multiple sessions. The study also evaluated the effect of non-word length on stuttering frequency, the consistency of stuttering frequency across sessions, and potential carry-over effects of increased stuttering frequency in the experimental task to conversational and reading speech after the task.

METHODS

Twelve adults who stutter completed multiple sessions (mean of 4.8 sessions) where they were video-recorded during pre-task reading and conversation, followed by an experimental task where they read 400 non-word pairs randomized for each session, and then a post-task reading and conversation sample.

RESULTS

On average, across sessions and participants, non-word pairs consistently yielded a balanced distribution of fluent (60.7%) and stuttered (39.3%) trials over five sessions. Non-word length had a positive effect on stuttering frequency. No carryover effects from experimental to post-task conversation and reading were found.

CONCLUSIONS

Non-word pairs effectively and consistently elicited balanced proportions of stuttered and fluent trials. This approach can be used to gather longitudinal data to better understand the neurophysiological and behavioral correlates of stuttering.

Eliciting Stuttering in School-Age and Adolescent Stutterers in Experimental Settings

PURPOSE

Most neural and physiological research on stuttering focuses on the fluent speech of speakers who stutter due to the difficulty associated with eliciting stuttering reliably in the laboratory. We previously introduced an approach to elicit stuttered speech in the laboratory in adults who stutter. The purpose of this study was to determine whether that approach reliably elicits stuttering in school-age children and teenagers who stutter (CWS/TWS).

METHOD

Twenty-three CWS/TWS participated. A clinical interview was used to identify participant-specific anticipated and unanticipated words in CWS and TWS. Two tasks were administered: (a) a delayed word reading task in which participants read words and produced them after a 5-s delay and (b) a delayed response question task in which participants responded to examiner questions after a 5-s delay. Two CWS and eight TWS completed the reading task; six CWS and seven TWS completed the question task. Trials were coded as unambiguously fluent, ambiguous, and unambiguously stuttered.

RESULTS

The method yielded, at a group level, a near-equal distribution of unambiguously stuttered and fluent utterances: 42.5% and 45.1%, respectively, in the reading task and 40.5% and 51.4%, respectively, in the question task.

CONCLUSIONS

The method presented in this article elicited a comparable amount of unambiguously stuttered and fluent trials in CWS and TWS, at a group level, during two different word production tasks. The inclusion of different tasks supports the generalizability of our approach, which can be used to elicit stuttering in studies that aim to unravel the neural and physiological bases that underlie stuttered speech.

Virtual reality exposure therapy for reducing social anxiety in stuttering: A randomized controlled pilot trial

We report on findings from the first randomized controlled pilot trial of virtual reality exposure therapy (VRET) developed specifically for reducing social anxiety associated with stuttering. People who stutter with heightened social anxiety were recruited from online adverts and randomly allocated to receive VRET (n = 13) or be put on a waitlist (n = 12). Treatment was delivered remotely using a smartphone-based VR headset. It consisted of three weekly sessions, each comprising both performative and interactive exposure exercises, and was guided by a virtual therapist. Multilevel model analyses failed to demonstrate the effectiveness of VRET at reducing social anxiety between pre- and post-treatment. We found similar results for fear of negative evaluation, negative thoughts associated with stuttering, and stuttering characteristics. However, VRET was associated with reduced social anxiety between post-treatment and one-month follow-up. These pilot findings suggest that our current VRET protocol may not be effective at reducing social anxiety amongst people who stutter, though might be capable of supporting longer-term change. Future VRET protocols targeting stuttering-related social anxiety should be explored with larger samples. The results from this pilot trial provide a solid basis for further design improvements and for future research to explore appropriate techniques for widening access to social anxiety treatments in stuttering.

Activation in Right Dorsolateral Prefrontal Cortex Underlies Stuttering Anticipation

People who stutter learn to anticipate many of their overt stuttering events. Despite the critical role of anticipation, particularly how responses to anticipation shape stuttering behaviors, the neural bases associated with anticipation are unknown. We used a novel approach to identify anticipated and unanticipated words, which were produced by 22 adult stutterers in a delayed-response task while hemodynamic activity was measured using functional near infrared spectroscopy (fNIRS). Twenty-two control participants were included such that each individualized set of anticipated and unanticipated words was produced by one stutterer and one control participant. We conducted an analysis on the right dorsolateral prefrontal cortex (R-DLPFC) based on converging lines of evidence from the stuttering and cognitive control literatures. We also assessed connectivity between the R-DLPFC and right supramarginal gyrus (R-SMG), two key nodes of the frontoparietal network (FPN), to assess the role of cognitive control, and particularly error-likelihood monitoring, in stuttering anticipation. All analyses focused on the five-second anticipation phase preceding the go signal to produce speech. The results indicate that anticipated words are associated with elevated activation in the R-DLPFC, and that compared to non-stutterers, stutterers exhibit greater activity in the R-DLPFC, irrespective of anticipation. Further, anticipated words are associated with reduced connectivity between the R-DLPFC and R-SMG. These findings highlight the potential roles of the R-DLPFC and the greater FPN as a neural substrate of stuttering anticipation. The results also support previous accounts of error-likelihood monitoring and action-stopping in stuttering anticipation. Overall, this work offers numerous directions for future research with clinical implications for targeted neuromodulation.

Speech Related Anxiety in Adults Who Stutter

Abstract. The relationship between anxiety and stuttering has always been a topic of debate with a great emphasis on research focused on examining whether speech-related anxiety can exacerbate stuttering. This investigation compares some speech-related anticipatory anxiety indices in fluent and dysfluent utterances in adults who stutter (AWS). We scored the level of cognitive speech-related anxiety (anticipatory anxiety) using a self-reporting method and also evaluated the autonomic aspects of anxiety (state anxiety) through recording changes in Galvanic Skin Response (GSR) signals. Explaining the link between stuttering and anxiety is expected to assist practitioners in stuttering assessment and subsequent treatment strategies. Phasic GSR values of six events related to answering the verbal stimuli through fluent and dysfluent responses were registered to measure sympathetic arousal as an index of state anxiety in 20 AWS ( Mage = 35 ± 4 years, range: 21–42). To quantitatively examine the cognitive aspects of speech-related anticipatory anxiety, two questionnaires were rated by participants addressing the stuttering anticipation and semantic difficulty of verbal stimuli. GSR measures of fluent events were significantly higher than dysfluent counterparts within time windows before and during answering aloud the verbal stimuli ( p < .001). Later in the experiment, GSR values of dysfluent events were found to be higher than their fluent counterparts ( p < .001). Stuttering anticipation yielded a weak negative meaningful correlation with the scores of fluency ( r = −0.283, p = .046) and a positive yet nonsignificant correlation with the stuttering scores. The semantic difficulty had a moderately significant correlation with stuttering anticipation ( r = 0.354, p = .012) but not a meaningful correlation with fluency state. Autonomic and cognitive indices of speech-related anticipatory anxiety are not robust predictors of fluency. Anxiety seems to be more of a consequence of stuttering than a cause.

Comparison of Stuttering Severity and Anxiety During Standard and Challenge Phone Calls

PURPOSE

This study was designed to answer three questions. (a) Does percentage of syllables stuttered (%SS) differ between standard and challenge phone calls. (b) Does anxiety differ between standard and challenge phone calls. (c) Is there a relationship between %SS and anxiety during standard and challenge phone calls?

METHOD

Participants were 230 adults diagnosed with stuttering, who were participants from five clinical trials. Each participant received two 10-min phone calls at pretreatment and a further two phone calls 6 months or 20 weeks postrandomization. One phone call was standard, and the other presented challenge: occasionally disagreeing with, interrupting, and talking over participants, or asking for clarification of their views.

RESULTS

Statistically significant, but clinically minor, increases of %SS and anxiety occurred during the challenge phone calls. There was a statistically significant association between %SS and anxiety.

CONCLUSIONS

Variable phone call procedures to assess stuttering severity in clinical trials are not likely to spuriously inflate or deflate treatment outcomes to a clinically important extent. Regardless, the present results suggest that there is statistical merit in controlling the nature of phone calls during clinical trials with the simple and replicable method developed in this report. Additionally, there is procedural merit in the challenge phone call procedure; it is a more valid representation of the challenges of everyday speech than the standard procedure. However, a disadvantage of the challenge phone call procedure is the practical issues associated with its use. The clinical and theoretical applications of the results are discussed.

Attentional Biases in Adults Who Stutter before and following Social Threat Induction

<b><i>Purpose:</i></b> We know that adults who stutter report higher levels of social anxiety [Craig and Tran: J Fluency Disord 2014;40:35–43; Iverach et al.: J Anxiety Disord 2009;23(7):928–34]. What is not clear is whether adults who stutter develop maladaptive attentional shifts, similar to what is observed in socially anxious individuals, in response to social anxiety. The purpose of this study was to investigate the attentional biases in adults who stutter compared to adults who do not stutter before and after social evaluative threat induction and determine whether responses are associated with objective and subjective measures of anxiety. <b><i>Method:</i></b> Twelve adults who stutter and 14 matched adults who do not stutter performed a modified response time paradigm, the dot-probe task, where they responded to a probe appearing behind one of two faces, one emotional (positive or negative) and one neutral. Participant’s reaction times were measured before and after a social threat induction task. Skin conductance levels were used as an index of induced stress. Self-reports of trait and social anxiety were used as subjective measures of anxiety. <b><i>Results:</i></b> Adults who stutter compared to controls exhibited an attentional bias towards negative facial expressions following a social evaluative threat induction. This effect remained when covarying for levels of trait and social anxiety. Before social evaluative threat induction, visual inspection of the data showed that adults who stutter compared to adults who do not stutter avoided positive facial expressions as they attended more to the negative facial expressions; however, these differences were not significant. <b><i>Discussion:</i></b> This study provides evidence for a maladaptive attentional behavior in adults who stutter when undergoing feelings of social evaluative threat. Results provide rationale for research aimed at assessing the use of attention restructuring in highly anxious adults who stutter.

Resting autonomic activity in adults who stutter and its association with self-reports of social anxiety

PURPOSE

The purpose of this study was to investigate resting autonomic activity in adults who stutter (AWS) compared to adults who do not stutter (ANS) and the relationship this has on self-reports of social anxiety.

METHODS

Thirteen AWS and 15 ANS completed the Social Interaction Anxiety Scale (SIAS; Mattick & Clark, 1998) and Brief Fear of Negative Evaluation (BFNE; Leary, 1983). Following this, measures of skin conductance levels (i.e. index of sympathetic activity) and respiratory sinus arrhythmia (i.e. index of parasympathetic activity) were taken during a 5-minute resting, baseline period. Independent sample t tests were used to assess differences between groups on self-reports of anxiety (SIAS, BFNE) and resting autonomic levels (SCL, RSA). Separate multiple regression analyses were performed in order to assess the relationship between self-reports of anxiety and autonomic measures.

RESULTS

Results showed significantly higher mean SCL and lower mean RSA levels in the AWS compared to the ANS at resting, baseline. Regression analysis showed that self-reports from the SIAS had a significant effect on RSA levels for the AWS but not the ANS. No significant effects were found for BFNE on RSA. Nor was there a significant effect from SIAS or BFNE on SCL levels for either group.

CONCLUSION

Findings suggest that resting RSA levels may be a physiological marker for social anxiety levels in adults who stutter.

Temperament is Linked to Avoidant Responses to Stuttering Anticipation

PURPOSE

The purpose of the present study was to examine the degree to which certain temperament constructs predict individual differences in three types of behavioral responses to anticipation among children and adults who stutter (CWS and AWS, respectively): avoidance, physical change, and approach.

METHODS

Participants included 64 CWS (9- to 17-years-old) and 54 AWS (18- to 50-years-old) who completed an online survey package including a temperament questionnaire (Early Adolescent Temperament Questionnaire-Revised for the CWS; Adult Temperament Questionnaire for the AWS) and the Stuttering Anticipation Scale. The data were analyzed separately for CWS and AWS using multivariate multiple regressions to assess how each temperament construct predicted avoidance, physical change, and approach responses to anticipation.

RESULTS

CWS who reported higher levels of shyness were more likely to engage in avoidant behavioral responses when they anticipate an upcoming moment of stuttering. AWS who reported higher levels of orienting sensitivity were more likely to engage in avoidant behavioral responses when they anticipate an upcoming moment of stuttering. No temperament constructs predicted physical change or approach responses to anticipation among either age group.

CONCLUSION

Specific aspects of temperament appear to be linked to the degree that CWS and AWS engage in avoidant behavioral responses to stuttering anticipation. These findings support the continued study of how individual differences impact the internal experience and outward manifestation of stuttering behaviors.

The impact of self-reported levels of anxiety on respiratory sinus arrhythmia levels in adults who stutter

PURPOSE

This study investigated whether subjective levels of anxiety predict respiratory sinus arrythmia (RSA) levels in adults who stutter (AWS) compared to (ANS) during baseline and social stress situations.

METHODS

Participants were eight AWS and 10 ANS who performed a modified version of the Trier Social Stress Test (TSST-M). For this, participants were required to prepare and deliver a 5-minute speech and perform a nonword reading task in front of what was perceived as a group of professionals trained in public speaking. Measures of respiratory sinus arrhythmia (RSA) were calculated for baseline and TSST-M conditions. Participants also completed the State-Trait Anxiety Inventory (STAI), both the trait (STAI-T) and state (STAI-S) portion, which served as subjective anxiety ratings. Univariate analyses of variances (UNIANOVA) were used to assess the effects of the STAI-T and STAI-S anxiety on respiratory sinus arrhythmia (RSA) levels at pre-stress and TSST-M conditions. RSA, an index of parasympathetic nervous system activity, is considered to be a measure of emotional regulation. The strength of the effects of STAI-T and STAI-S on RSA levels was evaluated with the unstandardized coefficients for each group separately.

RESULTS

Results showed a significant difference between groups for the effects of STAI-T on RSA values for the pre-stress nonword reading task. No other significant differences were found between groups for the pre-stress or TSST-M conditions. Slope estimates showed that STAI-T was a significant predictor of RSA values for pre-stress speaking conditions for the AWS but not ANS. No significant fixed effects or interaction effects were found for the STAI-S and RSA levels in the AWS or ANS. Nor were there significant effects of STAI-T on RSA levels in the AWS or ANS for TSST-M conditions. Descriptive analysis revealed the effects found in the AWS during pre-stress conditions were attributed to a subgroup of AWS who reported low self-reports of anxiety (i.e. STAI-T) and high levels of emotional regulation (i.e. RSA) across social stress conditions.

DISCUSSION

Low self-reported STAI-T scores simultaneous with high RSA levels in some AWS may reflect a self-regulatory strategy adapted in response to chronic, daily stress associated with stuttering.

Effect of word phonetic properties on stuttering anticipation and speech production in adults who stutter

PURPOSE

Stuttering anticipation is a significant factor in an individual's stuttering experience. People who stutter have reported words and sounds that they anticipate stuttering on. Attempts at understanding the association between stuttering anticipation and stuttering outcomes and the impact of phonetic properties on stuttering anticipation and overt stuttering have been insufficiently examined. This study aims to address these important issues.

METHODS

Data were collected as part of a larger brain imaging study. Twenty adults who stutter rated a 414 word-list on stuttering anticipation. Participant-specific 'high' and 'low' anticipated words were selected. Twelve of the 20 participants returned for a second session 2-11 weeks later, during which they read the selected words again and stuttering occurrence was recorded.

RESULTS

Among the 20 participants, three sub-groups with "high" (N = 6), "moderate" (N = 5) and "low" (N = 9) stuttering anticipation were identified. Significant "high stuttering" anticipation was found on consonants, plosives, bilabials and alveolars, as well as labials and coronals. In 5 of the 8 participants who stuttered during session 2, more than 80 % of words stuttered were previously rated with high anticipation. Consonants, plosives, bilabials and alveolars, and labials and coronals were the most frequently stuttered (>27 %).

CONCLUSION

While not all adults who stutter demonstrate high word-specific stuttering anticipation, we found that more than half anticipated this to a high degree. Furthermore, both word-specific phonetic properties and stuttering anticipation impact stuttering occurrence. The inclusion of word-specific stuttering anticipation ratings may increase the likelihood of stuttering in experimental studies and improve treatment outcomes through individualized intervention.

Eliciting Stuttering in Laboratory Contexts

Purpose The contextual variability of stuttering events makes it difficult to reliably elicit stuttered speech in laboratory settings. As a result, studies that compare stuttered versus fluent speech are difficult to conduct and, thus, are limited in the literature. The purpose of the current study is to describe a novel approach to elicit stuttering during laboratory testing. Method A semistructured clinical interview leveraging the phenomenon of stuttering anticipation was administered to 22 adults who stutter (1st visit). The interview was used to generate participant-specific anticipated and unanticipated word lists, which were used as stimuli during a 2nd visit so that the validity of the method could be tested. Results The method yielded a near-equal distribution of unambiguously stuttered and fluent utterances (43.6% and 43.5%, respectively). Moreover, 12.9% of the utterances were judged to be ambiguous, that is, not unambiguously stuttered or fluent. Conclusion This approach outperformed previous attempts to elicit stuttering during laboratory testing. It could be implemented in future studies that compare neural, physiological, or behavioral correlates of fluent versus stuttered speech.

Effects of Social Stress on Autonomic, Behavioral, and Acoustic Parameters in Adults Who Stutter

Purpose The purpose of this study was to assess changes in autonomic, behavioral, and acoustic measures in response to social stress in adults who stutter (AWS) compared to adults who do not stutter (ANS). Method Participants completed the State-Trait Anxiety Inventory ( Speilberger, Gorsuch, Luschene, Vagg, & Jacobs, 1983 ). In order to provoke social stress, participants were required to complete a modified version of the Trier Social Stress Test (TSST-M, Kirschbaum, Pirke, & Hellhammer, 1993 ), which included completing a nonword reading task and then preparing and delivering a speech to what was perceived as a group of professionals trained in public speaking. Autonomic nervous system changes were assessed by measuring skin conductance levels, heart rate, and respiratory sinus arrhythmia (RSA). Behavioral changes during speech production were measured in errors, percentage of syllable stuttered, percentage of other disfluencies, and speaking rate. Acoustic changes were measured using 2nd formant frequency fluctuations. In order to make comparisons of speech with and without social-cognitive stress, measurements were collected while participants completed a speaking task before and during TSST-M conditions. Results AWS showed significantly higher levels of self-reported state and trait anxiety compared to ANS. Autonomic nervous system changes revealed similar skin conductance level and heart rate across pre-TSST-M and TSST-M conditions; however, RSA levels were significantly higher in AWS compared to ANS across conditions. There were no differences found between groups for speaking rate, fundamental frequency, and percentage of other disfluencies when speaking with or without social stress. However, acoustic analysis revealed higher levels of 2nd formant frequency fluctuations in the AWS compared to the controls under pre-TSST-M conditions, followed by a decline to a level that resembled controls when speaking under the TSST-M condition. Discussion Results suggest that AWS, compared to ANS, engage higher levels of parasympathetic control (i.e., RSA) during speaking, regardless of stress level. Higher levels of self-reported state and trait anxiety support this view point and suggest that anxiety may have an indirect role on articulatory variability in AWS.

An exploratory factor analysis of action responses to stuttering anticipation

PURPOSE

We previously introduced theStuttering Anticipation Scale (SAS; Jackson, E. S., Gerlach, H., Rodgers, N. H., & Zebrowski, P. M. (2018). My Client Knows That He's About to Stutter: How Can We Address Stuttering Anticipation during Therapy with Young People Who Stutter? Seminars in Speech and Language, 39, 356-370) - a non-standardized self-report measure for children, teens, and adults who stutter (CWS, TWS, AWS) that quantifies how often they engage in 25 commonly reported action responses to anticipation. The purpose of this study was to leverage the SAS to explore the factor structure of action responses to stuttering anticipation.

METHODS

A total of 121 people who stutter completed the SAS online (27 CWS, 40 TWS, 54 AWS). We used exploratory factor analysis (EFA) to determine the underlying latent variables within the 25 SAS items that characterize how people who stutter respond to anticipation.

RESULTS

A three-factor model was most appropriate for the data with regard to factor loadings and other model fit indices. The three factors were named: avoidance (17 items), physical change (4 items), and approach (4 items).

CONCLUSION

Understanding these three types of action responses to anticipation can help guide clinical decision-making by providing a novel framework for clinicians and their clients who stutter to discuss how the client tends to respond to anticipation, and explore ways to facilitate productive responses to anticipation.

Speech Disfluency-dependent Amygdala Activity in Adults Who Stutter: Neuroimaging of Interpersonal Communication in MRI Scanner Environment

Affective states, such as anticipatory anxiety, critically influence speech communication behavior in adults who stutter. However, there is currently little evidence regarding the involvement of the limbic system in speech disfluency during interpersonal communication. We designed this neuroimaging study and experimental procedure to sample neural activity during interpersonal communication between human participants, and to investigate the relationship between the amygdala activity and speech disfluency. Participants were required to engage in live communication with a stranger of the opposite sex in the MRI scanner environment. In the gaze condition, the stranger gazed at the participant without speaking, while in the live conversation condition, the stranger asked questions that the participant was required to answer. The stranger continued to gaze silently at the participant while the participant answered. Adults who stutter reported significantly higher discomfort than fluent controls during the experiment. Activity in the right amygdala, a key anatomical region in the limbic system involved in emotion, was significantly correlated with stuttering occurrences in adults who stutter. Right amygdala activity from pooled data of all participants also showed a significant correlation with discomfort level during the experiment. Activity in the prefrontal cortex, which forms emotion regulation neural circuitry with the amygdala, was decreased in adults who stutter than in fluent controls. This is the first study to demonstrate that amygdala activity during interpersonal communication is involved in disfluent speech in adults who stutter.

How Stuttering Develops: The Multifactorial Dynamic Pathways Theory

Purpose

We advanced a multifactorial, dynamic account of the complex, nonlinear interactions of motor, linguistic, and emotional factors contributing to the development of stuttering. Our purpose here is to update our account as the multifactorial dynamic pathways theory.

Method

We review evidence related to how stuttering develops, including genetic/epigenetic factors; motor, linguistic, and emotional features; and advances in neuroimaging studies. We update evidence for our earlier claim: Although stuttering ultimately reflects impairment in speech sensorimotor processes, its course over the life span is strongly conditioned by linguistic and emotional factors.

Results

Our current account places primary emphasis on the dynamic developmental context in which stuttering emerges and follows its course during the preschool years. Rapid changes in many neurobehavioral systems are ongoing, and critical interactions among these systems likely play a major role in determining persistence of or recovery from stuttering.

Conclusion

Stuttering, or childhood onset fluency disorder (Diagnostic and Statistical Manual of Mental Disorders, 5th edition; American Psychiatric Association [APA], 2013), is a neurodevelopmental disorder that begins when neural networks supporting speech, language, and emotional functions are rapidly developing. The multifactorial dynamic pathways theory motivates experimental and clinical work to determine the specific factors that contribute to each child's pathway to the diagnosis of stuttering and those most likely to promote recovery.

Executive Functions Impact the Relation Between Respiratory Sinus Arrhythmia and Frequency of Stuttering in Young Children Who Do and Do Not Stutter

Purpose

This study sought to determine whether respiratory sinus arrhythmia (RSA) and executive functions are associated with stuttered speech disfluencies of young children who do (CWS) and do not stutter (CWNS).

Method

Thirty-six young CWS and 36 CWNS were exposed to neutral, negative, and positive emotion-inducing video clips, followed by their participation in speaking tasks. During the neutral video, we measured baseline RSA, a physiological index of emotion regulation, and during video viewing and speaking, we measured RSA change from baseline, a physiological index of regulatory responses during challenge. Participants' caregivers completed the Children's Behavior Questionnaire from which a composite score of the inhibitory control and attentional focusing subscales served to index executive functioning.

Results

For both CWS and CWNS, greater decrease of RSA during both video viewing and speaking was associated with more stuttering. During speaking, CWS with lower executive functioning exhibited a negative association between RSA change and stuttering; conversely, CWNS with higher executive functioning exhibited a negative association between RSA change and stuttering.

Conclusion

Findings suggest that decreased RSA during video viewing and speaking is associated with increased stuttering and young CWS differ from CWNS in terms of how their executive functions moderate the relation between RSA change and stuttered disfluencies.

Utility of virtual reality environments to examine physiological reactivity and subjective distress in adults who stutter

PURPOSE

Virtual reality environments (VREs) allow for immersion in speaking environments that mimic real-life interactions while maintaining researcher control. VREs have been used successfully to engender arousal in other disorders. The purpose of this study was to investigate the utility of virtual reality environments to examine physiological reactivity and subjective ratings of distress in persons who stutter (PWS).

METHOD

Subjective and objective measures of arousal were collected from 10PWS during four-minute speeches to a virtual audience and to a virtual empty room.

RESULTS

Stuttering frequency and physiological measures (skin conductance level and heart rate) did not differ across speaking conditions, but subjective ratings of distress were significantly higher in the virtual audience condition compared to the virtual empty room.

CONCLUSION

VREs have utility in elevating subjective ratings of distress in PWS. VREs have the potential to be useful tools for practicing treatment targets in a safe, controlled, and systematic manner.

Sensorimotor Oscillations Prior to Speech Onset Reflect Altered Motor Networks in Adults Who Stutter

Adults who stutter (AWS) have demonstrated atypical coordination of motor and sensory regions during speech production. Yet little is known of the speech-motor network in AWS in the brief time window preceding audible speech onset. The purpose of the current study was to characterize neural oscillations in the speech-motor network during preparation for and execution of overt speech production in AWS using magnetoencephalography (MEG). Twelve AWS and 12 age-matched controls were presented with 220 words, each word embedded in a carrier phrase. Controls were presented with the same word list as their matched AWS participant. Neural oscillatory activity was localized using minimum-variance beamforming during two time periods of interest: speech preparation (prior to speech onset) and speech execution (following speech onset). Compared to controls, AWS showed stronger beta (15–25 Hz) suppression in the speech preparation stage, followed by stronger beta synchronization in the bilateral mouth motor cortex. AWS also recruited the right mouth motor cortex significantly earlier in the speech preparation stage compared to controls. Exaggerated motor preparation is discussed in the context of reduced coordination in the speech-motor network of AWS. It is further proposed that exaggerated beta synchronization may reflect a more strongly inhibited motor system that requires a stronger beta suppression to disengage prior to speech initiation. These novel findings highlight critical differences in the speech-motor network of AWS that occur prior to speech onset and emphasize the need to investigate further the speech-motor assembly in the stuttering population.

Linguistic and emotional-valence characteristics of reading passages for clinical use and research

PURPOSE

Fluency assessment in people who stutter (PWS) includes reading aloud passages. There is little information on properties of these passages that may affect reading performance: emotional valance, arousal, word familiarity and frequency and passage-readability. Our first goal was to present an extensive examination of these factors in three commonly used (“traditional”) passages. The second goal was to compare a traditional passage to a new passage, designed to minimize the impact of these properties.

METHODS

Content words were rated (129 participants) on arousal, valence and familiarity. Other linguistic features were analyzed based on available datasets. This information was used to assess traditional passages, and to construct a new well-balanced passage, made of neutral, low-arousal and highly-familiar words. Readability for all passages was tested using formula-based and CLOZE tests (31 participants). Finally, 26 PWS were evaluated on fluency comparing the commonly used “Rainbow” passage with the novel one.

RESULTS

The three traditional passages contain a share of emotionally valenced (22-34%), high arousal (15-18%), lower familiarity (6-8%) and polysyllabic (5-9%) content words. Readability was highest for the novel passage (on formula-based scales). Average disfluencies percent for the Rainbow and our novel passage were not significantly different. Yet half of the individuals in this sample showed a large difference between the two passages.

CONCLUSION

We provide detailed information on potential sources of variance using the traditional passages. Knowledge about these characteristics can inform clinical practice (and research). We suggest a combined procedure, using more than one passage to assess stuttering in individual cases.

Premonitory Awareness in Stuttering Scale (PAiS)

Anticipation of stuttering events in persistent developmental stuttering is a frequent but inadequately measured phenomenon that is of both theoretical and clinical importance. Here, we describe the development and preliminary testing of a German version of the Premonitory Awareness in Stuttering Scale (PAiS): a 12-item questionnaire assessing immediate and prospective anticipation of stuttering that was translated and adapted from the Premonitory Urge for Tics Scale (PUTS) (Woods, Piacentini, Himle, & Chang, 2005). After refining the preliminary PAiS scale in a pilot study, we administered a revised version to 21 adults who stutter (AWS) and 21 age, gender and education-matched control participants. Results demonstrated that the PAiS had good internal consistency and discriminated the two speaker groups very effectively, with AWS reporting anticipation of speech disruptions significantly more often than adults with typical speech. Correlations between the PAiS total score and both the objective and subjective measures of stuttering severity revealed that AWS with high PAiS scores produced fewer stuttered syllables. This is possibly because these individuals are better able to adaptively use these anticipatory sensations to modulate their speech. These results suggest that, with continued refinement, the PAiS has the potential to provide clinicians and researchers with a practical and psychometrically sound tool that can quantify how a given AWS anticipates upcoming stuttering events.

Yoga: Potential Benefits for Persons Who Stutter

Yoga has been demonstrated to modulate autonomic nervous system activity, decreasing anxiety and stress, and improving quality of life. This preliminary study sought to examine the use of yogic techniques on persons who stutter given the interaction between physiological arousal/anxiety and stuttering that current multifactorial models of stuttering propose. Four participants (M = 52 yr, SD = 10; 2 female, 2 male), recruited from local stuttering support groups in the greater Philadelphia community volunteered to participate. Stuttering severity, anxiety, and experiences regarding stuttering and communication were measured at baseline, post intervention, and at 4 months follow-up. The participants attended group yoga sessions and engaged in home practice. Descriptive results revealed that participants showed improvements across outcome measures, with the most improvement related to anxiety. Participants also reported improvements in their perceptions about communication as per qualitative analysis of responses to the open-ended questionnaires. The results suggest the potential benefits of yoga for persons who stutter and warrants further study using an experimental design.

Responses of adults who stutter to the anticipation of stuttering

PURPOSE

Many people who stutter experience the phenomenon of anticipation-the sense that stuttering will occur before it is physically and overtly realized. A systematic investigation of how people who stutter respond to anticipation has not been previously reported. The purposes of this study were to provide self-report evidence of what people do in response to anticipation of stuttering and to determine the extent to which this anticipation occurs.

METHODS

Thirty adults who stutter indicated on a Likert rating scale the extent to which they anticipate stuttering and answered three open-ended (written) questions regarding how they respond to anticipation.

RESULTS

All participants reported experiencing anticipation at least "sometimes," and 77% of the participants reported experiencing anticipation "often" or "always." The extent to which participants reported experiencing anticipation was not related to stuttering severity, impact, or treatment history. Analysis of written responses revealed 24 major categories, which were heuristically divided into action or non-action responses. Categories representing avoidance and self-management strategies were further divided into 14 and 19 subcategories, respectively. Participants were just as likely to view anticipation as helpful as they were to view it as harmful.

CONCLUSION

Findings demonstrate that most, if not all, adults who stutter experience anticipation, and the majority of adults who stutter report doing so at least often. Adults who stutter respond to this anticipation by altering the speech production process in various ways. Results highlight the importance of the role that anticipation plays in how stuttering behaviors manifest themselves.

EDUCATIONAL OBJECTIVES

The reader will be able to: (a) summarize existing literature on the anticipation of stuttering; (b) describe the role and extent of anticipation of stuttering in adults; (c) describe the various ways that adults who stutter respond to anticipation; (d) describe the importance of measuring anticipation in clinical and research domains.

Anticipation in stuttering: A theoretical model of the nature of stutter prediction

The fact that some people who stutter have the ability to anticipate a stuttering moment is essential for several theories of stuttering and important for maximum effectiveness of many currently used treatment techniques. The "anticipation effect," however, is poorly understood despite much investigation into this phenomenon. In the present paper, we combine (1) behavioral evidence from the stuttering-anticipation literature, (2) speech production models, and (3) models of error detection to propose a theoretical model of anticipation. Integrating evidence from theories such as Damasio's Somatic Marker Hypothesis, Levelt's Perceptual Monitoring Theory, Guenther's The Directions Into Velocities of Articulators (DIVA) model, Postma's Covert Repair Hypothesis, among others, our central thesis is that the anticipation of a stuttering moment occurs as an outcome of the interactions between previous learning experiences (i.e., learnt associations between stuttered utterances and any self-experienced or environmental consequence) and error monitoring. Possible neurological mechanisms involved in generating conscious anticipation are also discussed, along with directions for future research.

EDUCATIONAL OBJECTIVES

The reader will be able to: (a) describe historical theories that explain how PWS may learn to anticipate stuttering; (b) state some traditional sources of evidence of anticipation in stuttering; (c) describe how PWS may be sensitive to the detection of a stuttering; (d) state some of the neural correlates that may underlie anticipation in stuttering; and (e) describe some of the possible utilities of incorporating anticipation into stuttering interventions.

The impact of threat and cognitive stress on speech motor control in people who stutter

PURPOSE

In the present study, an Emotional Stroop and Classical Stroop task were used to separate the effect of threat content and cognitive stress from the phonetic features of words on motor preparation and execution processes.

METHOD

A group of 10 people who stutter (PWS) and 10 matched people who do not stutter (PNS) repeated colour names for threat content words and neutral words, as well as for traditional Stroop stimuli. Data collection included speech acoustics and movement data from upper lip and lower lip using 3D EMA.

RESULTS

PWS in both tasks were slower to respond and showed smaller upper lip movement ranges than PNS. For the Emotional Stroop task only, PWS were found to show larger inter-lip phase differences compared to PNS. General threat words were executed with faster lower lip movements (larger range and shorter duration) in both groups, but only PWS showed a change in upper lip movements. For stutter specific threat words, both groups showed a more variable lip coordination pattern, but only PWS showed a delay in reaction time compared to neutral words. Individual stuttered words showed no effects. Both groups showed a classical Stroop interference effect in reaction time but no changes in motor variables.

CONCLUSION

This study shows differential motor responses in PWS compared to controls for specific threat words. Cognitive stress was not found to affect stuttering individuals differently than controls or that its impact spreads to motor execution processes.

EDUCATIONAL OBJECTIVES

After reading this article, the reader will be able to: (1) discuss the importance of understanding how threat content influences speech motor control in people who stutter and non-stuttering speakers; (2) discuss the need to use tasks like the Emotional Stroop and Regular Stroop to separate phonetic (word-bound) based impact on fluency from other factors in people who stutter; and (3) describe the role of anxiety and cognitive stress on speech motor processes.