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

Neuroregulatory Effects of Microcone Patch Stimulation on the Auricular Branch of the Vagus Nerve and the Prefrontal Cortex: A Feasibility Study

Background: The primary purpose of this study was to preliminarily examine the effects of autonomic nervous system activity on the dorsolateral prefrontal cortex. Recent studies have examined approaches to modulating autonomic activity using invasive and non-invasive methods, but the effects of changes in autonomic activity during cognitive tasks on the dorsolateral prefrontal cortex have not been fully investigated. The purpose of this preliminary investigation was to examine changes in autonomic activity and blood oxygen saturation in the dorsolateral prefrontal cortex during reading tasks induced by vagus nerve stimulation using a microcone patch. Methods: A cohort of 40 typically developing adults was enrolled in this study. We carefully examined changes in autonomic nervous system activity and blood oxygen saturation in the dorsolateral prefrontal cortex during a reading task in two conditions: with and without microcone patch stimulation. Results: Significant changes in brain activation in the dorsolateral prefrontal cortext due to microcone patch stimulation were confirmed. In addition, hierarchical multiple regression analysis revealed specific changes in reading task-related blood oxygen saturation in the dorsolateral prefrontal region during microcone patch stimulation. Conclusions: It should be recognized that this study is a preliminary investigation and does not have immediate clinical applications. However, our results suggest that changes in autonomic nervous system activity induced by external vagal stimulation may affect activity in specific reading-related regions of the dorsolateral prefrontal cortex. Further research and evaluation are needed to fully understand the implications and potential applications of these findings.

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.

The effects of attentional focus on speech motor control in adults who stutter with and without social evaluative threat

PURPOSE

We sought to investigate the effects of cued attentional shifts on speechmotor control in adults who stutter (AWS) and adults who do not stutter (ANS) when speaking under low and high social stress conditions.

METHOD

Thirteen AWS' and 10 ANS' lip aperture (LA) and posterior tongue (PT) movements were assessed under a Cued-Internal and Cued-External attentional focus condition with and without social stress induction (i.e. speaking to an audience). Skin conductance levels were used to measure a stress response. Speech motor control was assessed by measuring movement duration and variability of movement for LA and PT using the spatial temporal index (STI).

RESULTS

A significant Group x Condition interaction was found for LA STI. Post-hoc comparisons indicated AWS' LA STI significantly decreased under Cued External Focus conditions during both low and high social stress. No significant Group x Condition interaction was found for PT STI. AWS showed significantly slower tongue movements (PT) across all low and high social stress conditions; however, there was no significant Group x Condition interaction for PT or LA.

DISCUSSION

Findings yield preliminary insights into the role of attentional focus on speech motor control when speaking during high social stress. Theoretical and clinical implications are discussed.

Covert and overt stuttering: Concepts and comparative findings

PURPOSE

One way of conceptualizing stuttering is on a continuum from primarily covert to primarily overt. Assertions have been made as to how those with covert stuttering might be impacted differently to those with overt stuttering, but findings from well-controlled studies remain scarce. The principal aim of the present study was to compare the impact of stuttering and emotional distress related to two subgroups of persons who stutter: people with primarily overt stuttering and people with primarily covert stuttering. In exploring this, we also offer some preliminary thoughts on challenges with the terminology surrounding the concepts of 'overtness' and 'covertness'.

METHODS

Twenty-one adults already enrolled in a multiple, single-case treatment study (Sønsterud et al., 2019, 2020) took part in the present study, and underwent a battery of tests that assessed anxiety, depression, fear of negative evaluation, and quality of life. The sub-groups were identified on the basis of self-categorization using the Tomaiuoli, Del Gado, Spinetti, Capparelli, and Venuti (2015) classification, as well as the evaluation of speech samples from two independent SLPs (Sønsterud et al., 2020). The classifications were further explored by five independent 'lay' assessors who reviewed pre-therapy video and rated participants' speech on a 4-point Likert Stuttering Probability Scale (1 = 'fluent with no doubt', 2 = 'fluent with some doubt', 3 = 'stuttering with some doubt' and 4 = 'stuttering with no doubt').

RESULTS

No significant differences were found between the primarily overt and primarily covert groups in relation to self-reported symptoms of anxiety, depression, and fear of negative evaluation. However, investigation at item level identified a significant difference in linguistic avoidance between the two groups.

CONCLUSION

There may be fewer differences between people with primarily overt and primarily covert stuttering than previously thought with regards to emotional impact, as well as most aspects of avoidance behavior.

Selective effects of psychosocial stress on plan based movement selection

Efficient movement selection is crucial in everyday activities. Whether this function is governed by our stress system is so far unknown. In the current study, data from thirty-six young male adults were analyzed. They performed rule- and plan-based movement selection tasks before (session 1) and after (session 2) a psychosocial stressor, or after a control condition without additional social stressor. Results showed that the rule-based efficiency advantage which was observed prior to the psychosocial stressor was significantly reduced afterwards in the whole sample, as well as in the stress group. Regression analyses revealed that this effect was due to a modulation of the plan-based approach. Especially variations-both increase and decrease-in the parasympathetic activity (reflected by the heart rate variability measure RMSSD) appeared to be disadvantageous for plan-based movement selection improvement. In contrast, performance in the rule-based movement selection tasks appeared to be rather invariant to external influences. The current results suggest that autonomic nervous system activity might modulate motor-cognitive performance. This modulatory capability might be selective for plan-based approaches, hence the applied strategy to movement selection could be decisive when it comes to the vulnerability of motor-cognitive processes towards psychosocial stress.

Contemporary Theories of Stuttering Development

The article presents a theoretical analysis of contemporary models of persistent stuttering development in children and adults at the current period of development of science. The accumulated amount of scientific knowledge suggests that stuttering has a neurological basis: it is associated with disorders in the structure and function of the brain. On this basis, there have been emerged models of stuttering that link the cause of a speech disorder with an unstable speech motor system. Theories and models of stuttering based on cognitive and language processing are likely to be useful in that they have explanatory power in relation to the mechanisms that play an important role in the production of key symptoms of stuttering. Considering that stuttering is a complex disorder, the logical result of this was the proposal of multifactorial models of impaired speech fluency. The presented overview may be useful to psychiatrists, clinical psychologists, speech therapists, teachers, and practitioners interacting with children and adults with stuttering and other speech fluency disorders.

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.

Verbal Response Inhibition in Adults Who Stutter

Purpose Adults who stutter (AWS) often attempt, with varying degrees of success, to suppress their stuttered speech. The ability to effectively suppress motoric behavior after initiation relies on executive functions such as nonselective inhibition. Although previous studies found that AWS were slower to inhibit manual, button-press response than adults who do not stutter (AWNS), research has yet to confirm a consistent relationship between manual and verbal inhibition. No study has examined verbal inhibition ability in AWS. The purpose of this study, therefore, is to compare verbal response inhibition between AWS and AWNS, and compare verbal response inhibition to both the overt stuttering and the lived experience of stuttering. Method Thirty-four adults (17 AWNS, 17 AWS) completed one manual and three verbal stop-signal tasks. AWS were assessed for stuttering severity (Stuttering Severity Instrument-Fourth Edition: SSI-4) and experience with stuttering (Overall Assessment of the Speaker's Experience With Stuttering [OASES]). Results Results indicate no correlation between manual and verbal inhibition for either group. Generalized linear mixed-model analyses suggested no significant group differences in manual or verbal inhibition. Manual and verbal inhibition did not predict SSI-4 in AWS. However, verbal inhibition was uniquely associated with OASES scores. Conclusion Although underlying manual and verbal inhibition was comparable between AWS and AWNS, verbal inhibition may be linked to the adverse experience of stuttering rather than the overt symptoms of stuttering severity. Supplemental Material https://doi.org/10.23641/asha.15145185.

Speech Movement Variability in People Who Stutter: A Vocal Tract Magnetic Resonance Imaging Study

Purpose People who stutter (PWS) have more unstable speech motor systems than people who are typically fluent (PWTF). Here, we used real-time magnetic resonance imaging (MRI) of the vocal tract to assess variability and duration of movements of different articulators in PWS and PWTF during fluent speech production. Method The vocal tracts of 28 adults with moderate to severe stuttering and 20 PWTF were scanned using MRI while repeating simple and complex pseudowords. Midsagittal images of the vocal tract from lips to larynx were reconstructed at 33.3 frames per second. For each participant, we measured the variability and duration of movements across multiple repetitions of the pseudowords in three selected articulators: the lips, tongue body, and velum. Results PWS showed significantly greater speech movement variability than PWTF during fluent repetitions of pseudowords. The group difference was most evident for measurements of lip aperture using these stimuli, as reported previously, but here, we report that movements of the tongue body and velum were also affected during the same utterances. Variability was not affected by phonological complexity. Speech movement variability was unrelated to stuttering severity within the PWS group. PWS also showed longer speech movement durations relative to PWTF for fluent repetitions of multisyllabic pseudowords, and this group difference was even more evident as complexity increased. Conclusions Using real-time MRI of the vocal tract, we found that PWS produced more variable movements than PWTF even during fluent productions of simple pseudowords. PWS also took longer to produce multisyllabic words relative to PWTF, particularly when words were more complex. This indicates general, trait-level differences in the control of the articulators between PWS and PWTF. Supplemental Material https://doi.org/10.23641/asha.14782092.

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.

Evaluating three stuttering assessments through network analysis, random forests and cluster analysis

PURPOSE

In stuttering, cognitive and behavioural variables interact in nonlinear fashion. These variables can be assessed by instruments which evaluate perceived impact of stuttering and stuttering severity. We applied three statistical methods in combination to the analysis of three assessment protocols to discover relationships within and between the tests to better understand variations in behavioural and social aspects of stuttering.

METHODS

Scores from Stuttering Severity Index (SSI-IV), Overall Assessment of the Speaker's Experience of Stuttering scale (OASES), and Unhelpful Thoughts and Beliefs About Stuttering scale (UTBAS), collected from 26 participants were compared using three statistical methods: network analysis, random forests, and cluster analysis.

RESULTS

Network analysis demonstrated that SSI-IV only weakly interacts with a quality of life index (OASES) and a self-perception and belief systems index (UTBAS). Random forest analyses revealed the last two measures relate strongly to each other. The results from cluster analysis suggest a) a possible regrouping of OASES items and b) a possible use of one UTBAS scale instead of the three.

CONCLUSION

A combination of three statistical methods allowed us to evaluate the three assessments in more depth. The lack of interaction between the SSI-IV on the one hand, and OASES and UTBAS on the other, suggests that the network of the three commonly used stuttering assessments may be fractured in a non-productive way. A potential gap may exist for an assessment tool that would link behavioural and social aspects of stuttering.

Manual response inhibition and quality of life in adults who stutter

BACKGROUND

A considerable amount of research has identified inhibition differences, including slower inhibition of manual responses, in people who stutter. Recent investigations have failed to link slowed motor inhibition with overt stuttering severity. This study investigated the potential relationship between slowed manual response inhibition and the negative impact of stuttering upon individual lives of adults who stutter (AWS).

METHODS

Thirty-four adults (AWS, n = 17; AWNS, n = 17) matched by nonverbal IQ completed a manual stop-signal task and provided a conversational speech sample. Motor inhibition latency for AWS and AWNS were compared. For AWS, motor inhibition latency was compared to the four subsections of the Overall Assessment of the Speaker's Experience with Stuttering (OASES; Yaruss & Quesal, 2006; General Information, Reactions to Stuttering, Communication in Daily Situations, Quality of Life).

RESULTS

Similar to previous studies, AWS were significantly slower to inhibit inaccurate manual responses than AWNS. Quality of Life subtest of the OASES was found to significantly predict inhibition latency.

CONCLUSION

These data replicate findings that indicate that AWS exhibit slower manual inhibition latency, and suggest that these inhibition differences may be associated with an individual's negative experience with stuttering rather than stuttering severity.

Effects of Physiological Arousal on Speech Motor Control and Speech Motor Practice in Preschool-Age Children Who Do and Do Not Stutter

Purpose We examined the effects of physiological arousal on speech motor control and speech motor practice effects in preschool-age children who do (CWS) and do not stutter (CWNS). Method Participants included 18 CWS (M _age = 4 years 5 months) and 18 age- and gender-matched CWNS. The participants repeated a phrase "buy bobby a puppy" interspersed with viewing pictures from the International Affective Picture System under two experimental conditions speaking after viewing pictures with (a) negative and (b) neutral valence. Participants' lip movements were tracked using Optotrak system. The spatiotemporal index and mean utterance duration were calculated to examine speech motor control and speech motor practice effects. Skin conductance level was measured during the experimental conditions to assess participants' physiological level of arousal. Results Preschool-age CWS demonstrated greater speech movement variability across all conditions and trials than CWNS. Furthermore, the younger participants produced more variable articulatory movements than the older participants. Participants' speech movement variability did not significantly differ between the negative and neutral experimental conditions, and the level of physiological arousal did not have a significant effect on it. There was a nonsignificant trend of decrease in speech movement variability across the repeated trials in both groups. Last, CWS and CWNS did not differ in their mean utterance duration, suggesting that their articulation rate was similar across all conditions and trials. Conclusions Our findings indicate that, compared to preschool-age CWNS, CWS demonstrate less mature speech motor control. However, present findings do not support the hypothesis that CWS benefit less from motor practice relative to CWNS. Given that our conditions elicited similar levels of arousal in the participants, future research is needed to examine whether physiological arousal disrupts speech motor control in preschool-age children potentially contributing to disruptions of speech fluency and the development of stuttering.

Attentional Bias Among Adolescents Who Stutter: Evidence for a Vigilance-Avoidance Effect

Purpose The purpose of this study was to examine group and individual differences in attentional bias toward and away from socially threatening facial stimuli among adolescents who stutter and age- and sex-matched typically fluent controls. Method Participants included 86 adolescents (43 stuttering, 43 controls) ranging in age from 13 to 19 years. They completed a computerized dot-probe task, which was modified to allow for separate measurement of attentional engagement with and attentional disengagement from facial stimuli (angry, fearful, neutral expressions). Their response time on this task was the dependent variable. Participants also completed the Social Anxiety Scale for Adolescents (SAS-A) and provided a speech sample for analysis of stuttering-like behaviors. Results The adolescents who stutter were more likely to engage quickly with threatening faces than to maintain attention on neutral faces, and they were also more likely to disengage quickly from threatening faces than to maintain attention on those faces. The typically fluent controls did not show any attentional preference for the threatening faces over the neutral faces in either the engagement or disengagement conditions. The two groups demonstrated equivalent levels of social anxiety that were both, on average, very close to the clinical cutoff score for high social anxiety, although degree of social anxiety did not influence performance in either condition. Stuttering severity did not influence performance among the adolescents who stutter. Conclusion This study provides preliminary evidence for a vigilance-avoidance pattern of attentional allocation to threatening social stimuli among adolescents who stutter.

Adult stuttering and attentional ability: A meta-analytic review

Purpose: The study presents the first review in which the link between attentional ability and developmental stuttering is explored. The review aimed to summarise the published research literature and provide a more conclusive understanding as to the relationship between stuttering and attention.Method: To be included in this review, the studies had to compare the attentional performance of adult people who stutter (PWS) and people who do not stutter (PWNS) over the age of 18 years with a validated psychometric instrument for measuring attentional ability. Articles were searched in four electronic databases where each of the following search terms (attention, vigilance, inhibitory, inhibition, interference, executive and processing) was cross-referenced with each of the following terms (stutter, stammer, speech disfluency and speech dysfluency). A total of 21 studies met the inclusion criteria to be submitted into a meta-analysis.Result: The results of the main meta-analysis, which included all selected studies, demonstrated that PWS had a significantly worse attentional performance as compared to PWNS. Two further meta-analyses on selective attention and dual tasking performance confirmed the latter finding. Importantly, however, the effect was not present in all studies.Conclusion: Our findings should be taken as an indication that stuttering sometimes (but not always) manifests together with poorer attentional ability, such that the identified link does not affect all PWS. These results provide support for the notion that there is a close association between stuttering and attentional ability in a subgroup of PWS, highlighting potential practical implications for stuttering treatment.

What do people search for in stuttering therapy: Personal goal-setting as a gold standard?

PURPOSE

Stuttering affects people in individual ways, and there are multiple factors which may influence a person's goals when seeking therapy. Even though there is a common consensus that speech-language pathologists should discuss the individual's goals and expectations for stuttering therapy and outcomes, few studies have systematically investigated this issue. The aims of the present study were to investigate individual motivations and goal-setting related factors in stuttering therapy. The associations between self-reported impact of stuttering and the participants' perceptions of stuttering interference in communication, speaking abilities, and relationships with other people were also investigated.

METHOD

This study is part of a wider-ranging treatment study of individualized stuttering management tailored to the participants' personal goals and preferences. A mixed method, multiple single-case design was used to address the research questions. Twenty-one adults, age 21-61 years, took part in a pretherapy interview, which also included two quantitative measures: the Client Preferences for Stuttering Therapy-Extended version (CPST-E) and the Overall Assessment of Speakers' Experience of Stuttering-Adult version (OASES-A). Findings from the study sample was compared with a Norwegian reference group, in order to check for the representativeness of the study sample.

RESULTS

Quantitative data showed that most participants wanted to focus on both physical and psychological aspects of therapy, and that 95% considered 'to gain a sense of control over the stuttering' as important. Participants' perspectives on their speaking ability and stuttering interference in communication were identified as central factors, particularly in social and professional settings. These outcomes aligned well with the finding of avoidance behaviors, such as avoiding words and speaking situations. Qualitative data identified four main areas that the participants wanted to improve: speech fluency, emotional functioning, activity and participation, and understanding of their stuttering.

CONCLUSION

The study confirms that multiple and individual factors may influence the person's goals for therapy. Goals were mainly anchored in participants' wish of better coping in real world settings. A high degree of avoidance behavior was reported, suggesting that anxiety, and in particular linguistic-related anxiety needs to be taken into account when addressing social anxiety in fluency disorders.

A parent-report scale of behavioral inhibition: Validation and application to preschool-age children who do and do not stutter

PURPOSE

This two-part (i.e., Study 1, Study 2) study investigated behavioral inhibition (BI) in preschool-age children who do (CWS) and do not (CWNS) stutter. The purpose of Study 1 was to develop the Short Behavioral Inhibition Scale (SBIS), a parent-report scale of BI. The purpose of Study 2 was to determine, based on the SBIS, differences in BI between CWS and CWNS, and associations between BI and CWS's stuttering frequency, stuttering severity, speech-associated attitudes, and stuttering-related consequences/reactions.

METHOD

Participants in Study 1 were 225 CWS and 243 CWNS with the majority of them being included in Study 2. In Study 2, a speech sample was obtained for the calculation of stuttering frequency and severity, and the parents of a subset of CWS completed the Communication Attitude Test for Preschool and Kindergarten Children Who Stutter (Vanryckeghem & Brutten, 2007), and the Test of Childhood Stuttering Disfluency-Related Consequences Rating Scale (Gillam, Logan, & Pearson, 2009).

RESULTS

Study 1 analyses indicated that SBIS is a valid and reliable tool whose items assess a single, relatively homogeneous construct. In Study 2, CWS exhibited greater mean and extreme BI tendencies than CWNS. Also CWS with higher, compared to CWS with lower, BI presented with greater stuttering frequency, more severe stuttering, greater stuttering-related consequences, and more negative communication attitudes (for CWS older than 4 years of age).

CONCLUSION

Findings were taken to suggest that BI is associated with early childhood stuttering and that the SBIS could be included as part of a comprehensive evaluation of stuttering.

Negative emotional state slows down movement speed: behavioral and neural evidence

BACKGROUND

Athletic performance is affected by emotional state. Athletes may underperform in competition due to poor emotion regulation. Movement speed plays an important role in many competition events. Flexible control of movement speed is critical for effective athletic performance. Although behavioral evidence showed that negative emotion can influence movement speed, the nature of the relationship remains controversial. Thus, the present study investigated how negative emotion affects movement speed and the neural mechanism underlying the interaction between emotion processing and movement control.

METHODS

The present study combined electroencephalography (EEG) technology with a cued-action task to investigate the effect of negative emotion on movement speed. In total, 21 undergraduate students were recruited for this study. Participants were asked to perform six consecutive action tasks after viewing an emotional picture. Pictures were presented in two blocks (one negative and one neutral). After the participants completed a set of tasks (neutral of negative), they were subjected to complete a 9-point self-assessment manikin scale. Participants underwent EEG while performing the tasks.

RESULTS

At the behavior level, there was a significant main effect of emotional valence on movement speed, with participants exhibiting significantly slower movements in the negative emotional condition than in the neutral condition. EEG data showed increased theta oscillation and larger P1 amplitude in response to negative than to neural images suggesting that more cognitive resources were required to process negative than neutral images. EEG data also showed a larger late CNV area in the neutral condition than in the negative condition, which suggested that there was a significant decrease in brain activation during action tasks in negative emotional condition than in the neural. While the early CNV did not reveal a significant main effect of emotional valence.

CONCLUSION

The present results indicate that a negative emotion can slow movement, which is largely due to negative emotional processing consuming more resources than non-emotional processing and this interference effect mainly occurred in the late movement preparation phase.

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.

Cognitive Load Affects Speech Motor Performance Differently in Older and Younger Adults

Purpose The aim of this study was to determine the impact of cognitive load imposed by a speech production task on the speech motor performance of healthy older and younger adults. Response inhibition, selective attention, and working memory were the primary cognitive processes of interest. Method Twelve healthy older and 12 healthy younger adults produced multiple repetitions of 4 sentences containing an embedded Stroop task in 2 cognitive load conditions: congruent and incongruent. The incongruent condition, which required participants to suppress orthographic information to say the font colors in which color words were written, represented an increase in cognitive load relative to the congruent condition in which word text and font color matched. Kinematic measures of articulatory coordination variability and movement duration as well as a behavioral measure of sentence production accuracy were compared between groups and conditions and across 3 sentence segments (pre-, during-, and post-Stroop). Results Increased cognitive load in the incongruent condition was associated with increased articulatory coordination variability and movement duration, compared to the congruent Stroop condition, for both age groups. Overall, the effect of increased cognitive load was greater for older adults than younger adults and was greatest in the portion of the sentence in which cognitive load was manipulated (during-Stroop), followed by the pre-Stroop segment. Sentence production accuracy was reduced for older adults in the incongruent condition. Conclusions Increased cognitive load involving response inhibition, selective attention, and working memory processes within a speech production task disrupted both the stability and timing with which speech was produced by both age groups. Older adults' speech motor performance may have been more affected due to age-related changes in cognitive and motoric functions that result in altered motor cognition.

Phonological working memory in developmental stuttering: Potential insights from the neurobiology of language and cognition

The current review examines how neurobiological models of language and cognition could shed light on the role of phonological working memory (PWM) in developmental stuttering (DS). Toward that aim, we review Baddeley's influential multicomponent model of PWM and evidence for load-dependent differences between children and adults who stutter and typically fluent speakers in nonword repetition and dual-task paradigms. We suggest that, while nonword repetition and dual-task findings implicate processes related to PWM, it is unclear from behavioral studies alone what mechanisms are involved. To address how PWM could be related to speech output in DS, a third section reviews neurobiological models of language proposing that PWM is an emergent property of cyclic sensory and motor buffers in the dorsal stream critical for speech production. We propose that anomalous sensorimotor timing could potentially interrupt both fluent speech in DS and the emergent properties of PWM. To further address the role of attention and executive function in PWM and DS, we also review neurobiological models proposing that prefrontal cortex (PFC) and basal ganglia (BG) function to facilitate working memory under distracting conditions and neuroimaging evidence implicating the PFC and BG in stuttering. Finally, we argue that cognitive-behavioral differences in nonword repetition and dual-tasks are consistent with the involvement of neurocognitive networks related to executive function and sensorimotor integration in PWM. We suggest progress in understanding the relationship between stuttering and PWM may be accomplished using high-temporal resolution electromagnetic experimental approaches.

The effect of emotion on articulation rate in persistence and recovery of childhood stuttering

PURPOSE

This study investigated the possible association of emotional processes and articulation rate in pre-school age children who stutter and persist (persisting), children who stutter and recover (recovered) and children who do not stutter (nonstuttering).

METHODS

The participants were ten persisting, ten recovered, and ten nonstuttering children between the ages of 3-5 years; who were classified as persisting, recovered, or nonstuttering approximately 2-2.5 years after the experimental testing took place. The children were exposed to three emotionally-arousing video clips (baseline, positive and negative) and produced a narrative based on a text-free storybook following each video clip. From the audio-recordings of these narratives, individual utterances were transcribed and articulation rates were calculated.

RESULTS

Results indicated that persisting children exhibited significantly slower articulation rates following the negative emotion condition, unlike recovered and nonstuttering children whose articulation rates were not affected by either of the two emotion-inducing conditions. Moreover, all stuttering children displayed faster rates during fluent compared to stuttered speech; however, the recovered children were significantly faster than the persisting children during fluent speech.

CONCLUSION

Negative emotion plays a detrimental role on the speech-motor control processes of children who persist, whereas children who eventually recover seem to exhibit a relatively more stable and mature speech-motor system. This suggests that complex interactions between speech-motor and emotional processes are at play in stuttering recovery and persistency; and articulation rates following negative emotion or during stuttered versus fluent speech might be considered as potential factors to prospectively predict persistence and recovery from stuttering.

The Effect of Practice and Visual Feedback on Oral-Diadochokinetic Rates for Younger and Older Adults

Assessments of oral-diadochokinetic rates are commonly performed to evaluate oral-motor skills. However, the appropriate administration protocol is not defined, and varies across therapists, clinics and laboratories. In three experiments and an auxiliary one, this study analyzes the effects of brief (motor) practice and visual feedback on the performance of 98 younger (20-40 years old) and 78 older adults (over 65) with the sequential motion rate (SMR) version. Overall rates were significantly faster for younger over older adults. Irrespective of age-group, averaged performance was significantly better on the second round, but the third round was found to be superfluous, across experiments and age-groups. Visual feedback (using a mirror) was found to be detrimental for younger adults, eliminating the advantage reaped from a practice round. For older adults, visual feedback did not alter the effect of a practice round. Sensory (visual) degradation is presented as a possible source for this age-related difference. We discuss these findings and suggest an administration protocol for younger and older adults with the SMR version, including a total of two rounds and no visual feedback.

Spectral Coefficient Analyses of Word-Initial Stop Consonant Productions Suggest Similar Anticipatory Coarticulation for Stuttering and Nonstuttering Adults

A longstanding hypothesis about the sensorimotor mechanisms underlying stuttering suggests that stuttered speech dysfluencies result from a lack of coarticulation. Formant-based measures of either the stuttered or fluent speech of children and adults who stutter have generally failed to obtain compelling evidence in support of the hypothesis that these individuals differ in the timing or degree of coarticulation. Here, we used a sensitive acoustic technique-spectral coefficient analyses-that allowed us to compare stuttering and nonstuttering speakers with regard to vowel-dependent anticipatory influences as early as the onset burst of a preceding voiceless stop consonant. Eight adults who stutter and eight matched adults who do not stutter produced C1VC2 words, and the first four spectral coefficients were calculated for one analysis window centered on the burst of C1 and two subsequent windows covering the beginning of the aspiration phase. Findings confirmed that the combined use of four spectral coefficients is an effective method for detecting the anticipatory influence of a vowel on the initial burst of a preceding voiceless stop consonant. However, the observed patterns of anticipatory coarticulation showed no statistically significant differences, or trends toward such differences, between the stuttering and nonstuttering groups. Combining the present results for fluent speech in one given phonetic context with prior findings from both stuttered and fluent speech in a variety of other contexts, we conclude that there is currently no support for the hypothesis that the fluent speech of individuals who stutter is characterized by limited coarticulation.

A preliminary study on the neural oscillatory characteristics of motor preparation prior to dysfluent and fluent utterances in adults who stutter

PURPOSE

Recent literature on speech production in adults who stutter (AWS) has begun to investigate the neural mechanisms characterizing speech-motor preparation prior to speech onset. Compelling evidence has suggested that stuttering is associated with atypical processing within cortical and sub-cortical motor networks, particularly in the beta frequency range, that is effective before speech production even begins. Due to low stuttering frequency in experimental settings, however, the literature has so far predominantly reported on fluent speech production in AWS. Consequently, we have limited understanding of the way in which fluent speech processing in AWS is disturbed leading to a dysfluency. This preliminary study aims to characterize neural motor preparation prior to stuttered utterances in AWS.

METHODS

Eight AWS participated in the study. A total of 336 stuttered utterances were compared to the participants' own fluent utterance productions. Beta oscillatory activity was analyzed with magnetoencephalography (MEG) and localized using minimum-variance beamforming.

RESULTS

Preparation for speech production induced beta suppression in the bilateral premotor and motor cortex prior to speech onset. Although the data revealed some interesting trends, no significant differences between fluent and stuttered utterances were present. This may be due to a relatively low and variable number of stuttered trials analyzed in individual subjects.

CONCLUSION

While the lack of significant differences may have resulted from the relatively low numbers of stuttered utterances across subjects, the observed trends demonstrated that the proposed methodology and experimental paradigm is a promising approach for future studies aiming to characterize differences between stuttered and fluent speech.

Cognitive bias modification for social anxiety in adults who stutter: a feasibility study of a randomised controlled trial

OBJECTIVE

To determine the feasibility and acceptability of a computerised treatment for social anxiety disorder for adults who stutter including identification of recruitment, retention and completion rates, large cost drivers and selection of most appropriate outcome measure(s) to inform the design of a future definitive trial.

DESIGN

Two-group parallel design (treatment vs placebo), double-blinded feasibility study.

PARTICIPANTS

31 adults who stutter.

INTERVENTION

Attention training via an online probe detection task in which the stimuli were images of faces displaying neutral and disgusted expressions.

MAIN OUTCOME MEASURES

Psychological measures: Structured Clinical Interview Global Assessment of Functioning score; Liebowitz Social Anxiety Scale; Social Phobia and Anxiety Inventory; State-Trait Anxiety Inventory; Unhelpful Thoughts and Beliefs about Stuttering. Speech fluency: percent syllables stuttered. Economic evaluation: resource use questionnaire; EuroQol three-dimension questionnaire.Acceptability: Likert Scale questionnaire of experience of trial, acceptability of the intervention and randomisation procedure.

RESULTS

Feasibility of recruitment strategy was demonstrated. Participant feedback indicated that the intervention and definitive trial, including randomisation, would be acceptable to adults who stutter. Of the 31 participants who were randomised, 25 provided data at all three data collection points.

CONCLUSIONS

The feasibility study informed components of the intervention. Modifications to the design are needed before a definitive trial can be undertaken.

TRIAL REGISTRATION NUMBER

I SRCTN55065978; Post-results.

Sibilant production in Hebrew-speaking adults: Apical versus laminal

The Hebrew IPA charts describe the sibilants /s, z/ as 'alveolar fricatives', where the place of articulation on the palate is the alveolar ridge. The point of constriction on the tongue is not defined - apical (tip) or laminal (blade). Usually, speech and language pathologists (SLPs) use the apical placement in Hebrew articulation therapy. Some researchers and SLPs suggested that acceptable /s, z/ could be also produced with the laminal placement (i.e. the tip of the tongue approximating the lower incisors). The present study focused at the clinical level, attempting to determine the prevalence of these alternative points of constriction on the tongue for /s/ and /z/ in three different samples of Hebrew-speaking young adults (total n = 242), with typical articulation. Around 60% of the participants reported using the laminal position, regardless of several speaker-related variables (e.g. tongue-thrust swallowing, gender). Laminal production was more common in /s/ (than /z/), coda (than onset) position of the sibilant, mono- (than di-) syllabic words, and with non-alveolar (than alveolar) adjacent consonants. Experiment 3 revealed no acoustical differences between apical and laminal productions of /s/ and of /z/. From a clinical perspective, we wish to raise the awareness of SLPs to the prevalence of the two placements when treating Hebrew speakers, noting that tongue placements were highly correlated across sibilants. Finally, we recommend adopting a client-centred practice, where tongue placement is matched to the client. We further recommend selecting targets for intervention based on our findings, and separating between different prosodic positions in treatment.

The Impact of Social-Cognitive Stress on Speech Variability, Determinism, and Stability in Adults Who Do and Do Not Stutter

Purpose

This study examined the impact of social-cognitive stress on sentence-level speech variability, determinism, and stability in adults who stutter (AWS) and adults who do not stutter (AWNS). We demonstrated that complementing the spatiotemporal index (STI) with recurrence quantification analysis (RQA) provides a novel approach to both assessing and interpreting speech variability in stuttering.

Method

Twenty AWS and 21 AWNS repeated sentences in audience and nonaudience conditions while their lip movements were tracked. Across-sentence variability was assessed via the STI; within-sentence determinism and stability were assessed via RQA.

Results

Compared with the AWNS, the AWS produced speech that was more variable across sentences and more deterministic and stable within sentences. Audience presence contributed to greater within-sentence determinism and stability in the AWS. A subset of AWS who were more susceptible to experiencing anxiety exhibited reduced across-sentence variability in the audience condition compared with the nonaudience condition.

Conclusions

This study extends the assessment of speech variability in AWS and AWNS into the social-cognitive domain and demonstrates that the characterization of speech within sentences using RQA is complementary to the across-sentence STI measure. AWS seem to adopt a more restrictive, less flexible speaking approach in response to social-cognitive stress, which is presumably a strategy for maintaining observably fluent speech.

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.

Assessing attentional biases with stuttering

BACKGROUND

Many adults who stutter presenting for speech treatment experience social anxiety disorder. The presence of mental health disorders in adults who stutter has been implicated in a failure to maintain speech treatment benefits. Contemporary theories of social anxiety disorder propose that the condition is maintained by negative cognitions and information processing biases. Consistent with cognitive theories, the probe detection task has shown that social anxiety is associated with an attentional bias to avoid social information. This information processing bias is suggested to be involved in maintaining anxiety. Evidence is emerging for information processing biases being involved with stuttering.

AIMS

This study investigated information processing in adults who stutter using the probe detection task. Information processing biases have been implicated in anxiety maintenance in social anxiety disorder and therefore may have implications for the assessment and treatment of stuttering. It was hypothesized that stuttering participants compared with control participants would display an attentional bias to avoid attending to social information.

METHODS & PROCEDURES

Twenty-three adults who stutter and 23 controls completed a probe detection task in which they were presented with pairs of photographs: a face displaying an emotional expression-positive, negative or neutral-and an everyday household object. All participants were subjected to a mild social threat induction being told they would speak to a small group of people on completion of the task.

OUTCOMES & RESULTS

The stuttering group scored significantly higher than controls for trait anxiety, but did not differ from controls on measures of social anxiety. Non-socially anxious adults who stutter did not display an attentional bias to avoid looking at photographs of faces relative to everyday objects. Higher scores on trait anxiety were positively correlated with attention towards photographs of negative faces.

CONCLUSION & IMPLICATIONS

Attentional biases as assessed by the probe detection task may not be a characteristic of non-socially anxious adults who stutter. A vigilance to attend to threat information with high trait anxiety is consistent with findings of studies using the emotional Stroop task in stuttering and social anxiety disorder. Future research should investigate attentional processing in people who stutter who are socially anxious. It will also be useful for future studies to employ research paradigms that involve speaking. Continued research is warranted to explore information processing and potential biases that could be involved in the maintenance of anxiety and failure to maintain the benefits of speech treatment outcomes.

Sympathetic arousal of young children who stutter during a stressful picture naming task

PURPOSE

The purpose of the current study was to investigate sympathetic arousal of young children who do and do not stutter during a stressful picture-naming task under instructions to name pictures as rapidly as possible.

METHOD

Thirty-seven young children who stutter (CWS) and 39 young children who do not stutter (CWNS) served as participants. Dependent measures consisted of tonic skin conductance during a pretask baseline, a stress-inducing rapid picture-naming task, and post-picture-naming task condition.

RESULTS

Findings indicated that, when chronological age was not taken into account, there was no between-group difference in tonic skin conductance level. When age was taken into account, however, there was a significant talker group×age group interaction, with follow-up analyses indicating that 3-year-old CWS exhibited significantly higher sympathetic arousal than their CWNS peers, and their 4-year-old CWNS peers.

CONCLUSIONS

Findings were taken to be consistent with non-physiological results indicating an association between emotional processes and childhood stuttering. This association, at least for this cross-sectional study of tonic skin conductance level (SCL) during a picture-naming task, was moderated by children's chronological age. Such developmental differences may be associated with various processes, for example, attention, cognition, or physiology, or some combination of two or more of these processes. Future empirical study of these processes in young CWS and CWNS may profit from longitudinal measurement of converging lines of evidence from behavioral, parent and psychophysiological indexes of emotional reactivity and regulation.

EDUCATIONAL OBJECTIVES

After reading this article, the reader will be able to: (a) discuss salient findings in the literature regarding the association between emotional processes and childhood stuttering; (b) discuss sympathetic arousal, and how skin conductance is used to measure it; and (c) discuss the role of chronological age in the association between emotion and stuttering in young children.

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.

Effects of aging and distractors on detection of redundant visual targets and capacity: do older adults integrate visual targets differently than younger adults?

In the redundant target effect, participants respond faster with two (redundant) targets. We compared the magnitude of this effect in younger and older adults, with and without distractors, in a simple visual-detection task. We employed additional measures that allow non-parametric assessment of performance (Townsend's capacity coefficient) and parametric estimates (Linear Ballistic Accumulator model). Older participants' latencies were slower, especially in the presence of distractors, and their calculated capacity indicators increased with distractors. Parametric estimates indicated that these increases were generated by the older adults' increased difficulty in inhibiting the distractors, and not the results of either improved detection of redundant-targets, or of a generalized slowing of processing.