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Individual differences in attentional control predict working memory capacity in adults who stutter

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Purpose Prior research has suggested that people who stutter exhibit differences in some working memory tasks, particularly when more phonologically complex stimuli are used. This study aimed to further specify working memory differences in adults who stutter by not only accounting for linguistic demands of the stimuli but also individual differences in attentional control and experimental influences, such as concomitant processing requirements. Method This study included 40 adults who stutter and 42 adults who do not stutter who completed the Attention Network Test (ANT; Fan et al., 2002) and three complex span working memory tasks: the Operation Span (OSPAN), Rotation Span, and Symmetry Span (Draheim et al., 2018; Foster et al., 2015; Unsworth et al., 2005, 2009). All complex span tasks were dual-tasks and varied in linguistic content in task stimuli. Results Working memory capacities demonstrated by adults who stutter paralleled the hierarchy of linguistic content across the three complex span tasks, with statistically significant between-group differences in working memory capacity apparent in the task with the highest linguistic demand (i.e., OSPAN). Individual differences in attentional control in adults who stutter also significantly predicted working memory capacity on the OSPAN. Discussion Findings from this study extend existing working memory research in stuttering by showing that: (1) significant working memory differences are present between adults who stutter and adults who do not stutter even using relatively simple linguistic stimuli in dual-task working memory conditions; (2) adults who stutter with stronger executive control of attention demonstrate working memory capacity more comparable to adults who do not stutter on the OSPAN compared to adults who stutter with lower executive control of attention.

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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.
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Previous research employed silent phoneme monitoring tasks to examine differences in phonological encoding in adults who stutter (AWS) compared to adults who do not stutter (AWNS). The primary purpose of this study was to apply a modified version of the task – the delayed silent phoneme monitoring task – to examine the integrity of the phonological speech plan within working memory in AWS and AWNS before and after subvocal rehearsal. The secondary purpose of this study was to examine whether group differences were more apparent when greater phonological demand was placed upon phonological working memory. In Experiment 1, 20 adults (10 AWNS, 10 AWS) identified target phonemes within trochaic nonwords held in memory before the initiation of subvocal rehearsal (1 s) and after subvocal rehearsal (4 s). In Experiment 2, an additional 20 adults (10 AWNS, 10 AWS) monitored identical nonwords with low-frequency iambic stress. Speed and accuracy of manual response was measured, as well as post-trial verbal productions. Both groups identified the initial phoneme of trochaic stimuli fastest, irrespective of stress, and both groups monitored phonemes faster after the 4 s delay. However, AWS identified phonemes within iambic stimuli with less accuracy than AWNS. Group differences in monitoring errors were most evident for phonemes immediately following syllable boundary, and after subvocal rehearsal. Preliminary findings suggest AWS may exhibit distinct difficulties relative to AWNS when accessing segmental information after subvocal rehearsal is required, but only when target words are more phonologically demanding (i.e., low-frequency iambic stress).
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More than 40 years ago, Baddeley and Hitch (1974) published an article with a wealth of experimentation and theorization on working memory, the small amount of information held in mind and often used within cognitive processes such as language comprehension and production, reasoning, and problem solving. We honor this seminal accomplishment in the present special issue, and take this opportunity to provide an introduction to our perspectives on the origin of the theory of working memory, how it has affected our work, what may be coming in the near future, and how the research articles in the present issue contribute to several related themes within the clearly thriving field of working memory.
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The purpose of this study was to explore metrical aspects of phonological encoding (i.e., stress and syllable boundary assignment) in adults who do and do not stutter (AWS, AWNS). Participants monitored nonwords for target sounds during silent phoneme monitoring tasks across two distinct experiments. For Experiment 1, 22 participants (11 AWNS, 11 AWS) silently monitored target phonemes in nonwords with initial stress. For Experiment 2, an additional cohort of 22 participants (11 AWNS, 11 AWS) silently monitored phonemes in nonwords with non-initial stress. In Experiment 1, AWNS and AWS silently monitored target phonemes in initial stress stimuli with similar speed and accuracy. In Experiment 2, AWS demonstrated a within-group effect that was not present for the AWNS. They required additional time when monitoring phonemes immediately following syllable boundary assignment in stimuli with non-initial stress. There was also a between group effect with AWS exhibiting significantly greater errors identifying phonemes in nonwords with non-initial stress than AWNS. Findings suggest metrical properties may impact the time course of phonological encoding in AWS in a manner distinct from AWNS. Specifically, in the absence of initial stress, metrical encoding of the syllable boundary may delay speech planning in AWS and contribute to breakdowns in fluent speech production.
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This article presents a theoretical perspective on stuttering based on numerous findings regarding speech and nonspeech neuromotor control in individuals who stutter in combination with recent empirical data and theoretical models from the literature on the neuroscience of motor control. Specifically, this perspective on stuttering relies heavily on recent work regarding feedforward and feedback control schemes; the formation, consolidation, and updating of inverse and forward internal models of the motor systems; and cortical, subcortical, and cerebellar activation patterns during speech and nonspeech motor tasks. Against this background, we propose that stuttering may result when producing speech (a) with unstable or insufficiently activated internal models or (b) with a motor
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Unlabelled: This paper reviews Bloodstein's (1975) Anticipatory Struggle Hypothesis of stuttering, identifies its weaknesses, and proposes modifications to bring it into line with recent advances in psycholinguistic theory. The review concludes that the Anticipatory Struggle Hypothesis provides a plausible explanation for the variation in the severity of stuttered disfluencies across speaking situations and conversation partners. However, it fails to explain the forms that stuttered disfluencies characteristically take or the subjective experience of loss of control that accompanies them. The paper then describes how the forms and subjective experiences of persistent stuttering can be accounted for by a threshold-based regulatory mechanism of the kind described in Howell's (2003) revision of the EXPLAN hypothesis. It then proposes that shortcomings of both the Anticipatory Struggle and EXPLAN hypotheses can be addressed by combining them together to create a 'Variable Release Threshold' hypothesis whereby the anticipation of upcoming difficulty leads to the setting of an excessively high threshold for the release of speech plans for motor execution. The paper also reconsiders the possibility that two stuttering subtypes exist: one related to formulation difficulty and other to difficulty initiating motor execution. It concludes that research findings that relate to the one may not necessarily apply to the other. Learning outcomes: After reading this article, the reader will be able to: (1) summarize the key strengths and weaknesses of Bloodstein's Anticipatory Struggle Hypothesis; (2) describe two hypothesized mechanisms behind the production of stuttered disfluencies (tension and fragmentation & release threshold mechanisms); and (3) discuss why the notion of anticipation is relevant to current hypotheses of stuttering.
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Purpose Language abilities have long been thought to be weaker in adults who stutter (AWS) compared to adults who do not stutter (AWNS). However, it is unknown whether modality affects language performance by AWS in time pressure situations. This study aimed to examine lexical access and retrieval abilities of AWS in oral and typed modes. Method Fifteen AWS and 15 well-matched AWNS completed computer-administered letter fluency tasks. Adults were asked to orally produce words that began with one of two letter targets and type words that began with one of two alternate letters. Conditions were counterbalanced across participants. Results Generalized linear mixed-effects models were evaluated to determine the effects of group (AWS/AWNS), mode (oral/typed), and expressive vocabulary on letter fluency performance. Group predicted letter fluency such that AWS generated fewer items on both the oral and typed letter fluency tasks. Mode did not impact letter fluency results. Expressive Vocabulary Test scores predicted letter fluency similarly in both AWS and AWNS. Conclusions AWS were not penalized by oral task demands. AWS generated fewer items on the letter fluency tasks regardless of response mode, suggesting that they have weaker lexical access abilities. Furthermore, better expressive vocabulary skills were associated with better letter fluency performance in both groups.
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Purpose Recent studies have shown that many children who stutter may have elevated characteristics of attention-deficit/hyperactivity disorder (ADHD). Although childhood ADHD commonly persists into adulthood, it is unclear how many adults who stutter experience aspects of ADHD (e.g., inattention or hyperactivity/impulsivity). This study sought to increase understanding of how ADHD characteristics might affect individuals who stutter by evaluating (a) whether elevated ADHD characteristics are common in adults who stutter, (b) whether elevated ADHD characteristics in adults who stutter were significantly associated with greater adverse impact related to stuttering, and (c) whether individual differences in Repetitive Negative Thinking (RNT) and Effortful Control influenced this relationship. Method Two hundred fifty-four adults who stutter completed the Adult ADHD Self-Report Scale, the Perseverative Thinking Questionnaire, the Adult Temperament Questionnaire short form, and the Overall Assessment of the Speaker's Experience of Stuttering. Data were analyzed via multiple linear regression to determine whether the number of inattention or hyperactivity/impulsivity characteristics was significantly associated with RNT, Effortful Control, or Adverse Impact related to stuttering. Results Almost one quarter of participants (23.2%; 60/254) self-reported experiencing six or more inattention characteristics, while fewer participants (8.3%; 21/254) self-reported experiencing six or more hyperactivity/impulsivity characteristics. Participants with lower Effortful Control and higher levels of both RNT and Adverse Impact were significantly more likely to self-report experiencing more inattention characteristics. Discussion Many adults who stutter may exhibit previously unaccounted for characteristics of ADHD, especially inattention. Results highlight the value of continued research on the intersectionality of stuttering, ADHD, and attention, and the importance of individualizing therapy to the needs of each unique person who stutters.
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Purpose Phonological skills have been associated with developmental stuttering. The current study aimed to determine whether the neural processes underlying phonology, specifically for nonword rhyming, differentiated stuttering persistence and recovery. Method Twenty-six children who stutter (CWS) and 18 children who do not stutter, aged 5 years, completed an auditory nonword rhyming task. Event-related brain potentials were elicited by prime, rhyming, and nonrhyming targets. CWS were followed longitudinally to determine eventual persistence ( n = 14) or recovery ( n = 12). This is a retrospective analysis of data acquired when all CWS presented as stuttering. Results CWS who eventually recovered and children who do not stutter exhibited the expected rhyme effect, with larger event-related brain potential amplitudes elicited by nonrhyme targets compared to rhyme targets. In contrast, CWS who eventually persisted exhibited a reverse rhyme effect, with larger responses to rhyme than nonrhyme targets. Conclusions These findings suggest that CWS who eventually persisted are not receiving the same benefit of phonological priming as CWS who eventually recovered for complex nonword rhyming tasks. These results indicate divergent patterns of phonological processing in young CWS who eventually persisted, especially for difficult tasks with limited semantic context, and suggest that the age of 5 years may be an important developmental period for phonology in CWS. Supplemental Material https://doi.org/10.23641/asha.12682874
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Purpose Prior research has explored how repetitive negative thinking (RNT) contributes to both the increased persistence and severity of various disorders, such as depression, anxiety, and eating disorders. This study explored the potential role of RNT in the experience of stuttering, with a particular focus on the relationship between RNT, adverse impact, and certain temperament profiles. Method Three hundred thirteen adults who stutter completed a measurement of the frequency/severity of RNT (Perseverative Thinking Questionnaire; Ehring et al., 2011 ), 207 completed a temperament profile (Adult Temperament Questionnaire; Evans & Rothbart, 2007 ), and 205 completed a measurement of adverse stuttering impact (Overall Assessment of the Speaker's Experience of Stuttering; Yaruss & Quesal, 2016 ). Analyses were conducted within and across instruments to ascertain how RNT, temperament markers, and adverse impact interrelate within individuals. Results Results indicated that RNT significantly predicts Overall Assessment of the Speaker's Experience of Stuttering impact scores with great effect and that certain temperament markers (specifically, Effortful Control and Negative Affectivity) moderate this relationship for specific sections of the Overall Assessment of the Speaker's Experience of Stuttering. Conclusion By assessing RNT in people who stutter, clinicians can better understand individual differences in their clients, and this will allow them to make targeted diagnoses and develop more tailored intervention plans.
Article
Purpose This study explored group experiences and individual differences in the behaviors, thoughts, and feelings perceived by adults who stutter. Respondents' goals when speaking and prior participation in self-help/support groups were used to predict individual differences in reported behaviors, thoughts, and feelings. Method In this study, 502 adults who stutter completed a survey examining their behaviors, thoughts, and feelings in and around moments of stuttering. Data were analyzed to determine distributions of group and individual experiences. Results Speakers reported experiencing a wide range of both overt behaviors (e.g., repetitions) and covert behaviors (e.g., remaining silent, choosing not to speak). Having the goal of not stuttering when speaking was significantly associated with more covert behaviors and more negative cognitive and affective states, whereas a history of self-help/support group participation was significantly associated with a decreased probability of these behaviors and states. Conclusion Data from this survey suggest that participating in self-help/support groups and having a goal of communicating freely (as opposed to trying not to stutter) are associated with less negative life outcomes due to stuttering. Results further indicate that the behaviors, thoughts, and experiences most commonly reported by speakers may not be those that are most readily observed by listeners.
Article
Purpose: This study described the proportion of children who stutter who exhibit Attention Deficit Hyperactivity Disorder (ADHD) symptoms, manifesting in inattentive and hyperactive/impulsive behaviours. Children who stutter with these challenging behaviours may not respond as quickly and successfully to stuttering treatment. A preliminary exploration of differences in treatment responsiveness for children with and without ADHD symptoms was undertaken. Method: Participants were 185 preschool children who stutter who had completed stuttering therapy within 3 months prior to study commencement. Differences between groups of children who stutter with and without elevated ADHD symptoms were investigated, in terms of pre-treatment stuttering features (stuttering severity and typography), demographic variables (age at onset, time between onset and commencement of therapy, family history and sex) and treatment data (post-treatment stuttering severity and number of sessions to achieve discharge criteria). Results: One-half (50%) of participants exhibited elevated ADHD symptoms. These children required 25% more clinical intervention time to achieve successful fluency outcomes than children without elevated ADHD symptoms. Findings suggest that more ADHD symptoms, increased pre-treatment stuttering severity, and male sex were associated with poorer responsiveness to stuttering treatment. Conclusion: The large proportion of children exhibiting elevated ADHD symptoms, and the increase in clinical contact time required in this subgroup to achieve successful fluency outcomes, is suggestive of the need for clinicians to tailor stuttering intervention to address these concomitant behaviour challenges. Findings support the use of careful caseload management strategies to account for individual differences between children, and strengthen prognostic information available to parents and clinicians.
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Does producing a word slow performance of a concurrent, unrelated task? In 2 experiments, 108 participants named pictures and discriminated tones. In Experiment 1, pictures were named after cloze sentences; the durations of the word-production stages of lemma and phonological word-form selection were manipulated with high- and low-constraint cloze sentences and high- and low-frequency-name pictures, respectively. In Experiment 2, pictures were presented with simultaneous distractor words; the durations of lemma and phoneme selection were manipulated with conceptually and phonologically related distractors. All manipulations, except the phoneme-selection manipulation, delayed tone-discrimination responses as much as picture-naming responses. These results suggest that early word-production stages - lemma and phonological word-form selection - are subject to a central processing bottleneck, whereas the later stage - phoneme selection - is not.
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In this follow-up to my 2002 article on working memory capacity, fluid intelligence, and executive attention in Current Directions in Psychological Science, I review even more evidence supporting the idea that the ability to control one’s attention (i.e., executive attention) is important to working memory and fluid intelligence. I now argue that working memory tasks reflect primarily the maintenance of information, whereas fluid intelligence tests reflect primarily the ability to disengage from recently attended and no longer useful information. I also point out some conclusions in the 2002 article that now appear to be wrong.
Article
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.
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Working memory capacity is an important construct in psychology because of its relationship with many higher-order cognitive abilities and psychopathologies. Working memory capacity is often measured using a type of paradigm known as complex span. Some recent work has focused on shortening the administration time of the complex span tasks, resulting in different versions of these tasks being used (Foster et al., 2015; Oswald, McAbee, Redick, & Hambrick, 2015). Variations in the complex span tasks, such as the number of set sizes, can lead to varying power to discriminate individuals at different ability levels. Thus, research findings may be inconsistent across populations due to differing appropriateness for the ability levels. The present study uses a combination of item response theory and correlational analyses to better understand the psychometric properties of the operation span, symmetry span, and rotation span. The findings show that the typical administration of these tasks, particularly the operation span, is not suitable for above average ability samples (Study 1; n = 573). When larger set sizes are added to the tasks (Study 2; n = 351), predictive validity and discriminability is improved for all complex span tasks, however the operation span is still inferior to the spatial tasks. The authors make several conclusions about which tasks and set sizes should be used depending on the intended population, and further suggest avoiding the standard-length operation span for average or higher ability populations.
Article
This study investigated phonological memory in 5- and 6-year old children who stutter. Participants were 11 children who stutter matched on general language abilities, maternal education level, and sex to 11 typically fluent children. Participants completed norm-referenced nonword repetition and digit span tasks, as well as measures of expressive and receptive vocabulary and articulation. The nonword repetition task included stimuli that ranged from 1 to 7 syllables, while the digit naming task contained number strings containing 2 to 10 digits. Standardized tests of vocabulary and articulation abilities were tested as well. Groups were comparable on measures expressive vocabulary, receptive vocabulary, and articulation. Despite the fact that the majority of participants scored within typical limits, young children who stutter still performed significantly less well than children who do not stutter on the nonword repetition task. No between-group differences were revealed in the digit naming task. Typically fluent children demonstrated strong correlations between phonological memory tasks and language measures, while children who stutter did not. These findings indicate that young children who stutter may have sub-clinical differences in nonword repetition.
Chapter
Evidence indicates that speech movements are planned to follow auditory trajectories. This is followed by a description of the Directions Into Velocities of Articulators (DIVA) model, which provides a detailed account of the role of auditory feedback in speech motor development and control. A brief description of the higher-order brain areas involved in speech sequencing (including the pre-SMA and inferior frontal sulcus) is then provided, followed by a description of the Hierarchical State Feedback Control (HSFC) model, which posits internal error detection and correction processes that can detect and correct speech production errors prior to articulation. The chapter closes with a treatment of promising future directions of research into auditory-motor interactions in speech, including the use of intracranial recording techniques such as electrocorticography in humans, the investigation of the potential roles of various large-scale brain rhythms in speech perception and production, and the development of brain–computer interfaces that use auditory feedback to allow profoundly paralyzed users to learn to produce speech using a speech synthesizer.
Article
Purpose: Variability in frequency of stuttering has made the results of treatment outcome studies difficult to interpret. Many factors that affect variability have been investigated; yet the typical range of variability experienced by speakers remains unknown. This study examined the day-to-day variability in the percentage of syllables containing stuttered and nonstuttered disfluencies in the speech of six adult speakers in three spontaneous speaking situations and two reading tasks. Methods: The frequency of moments stuttering during the tasks were compared within and between speakers and days to document the degree of variability in stuttering frequency and explore whether there were any consistent patterns. The Stuttering Severity Instrument-Fourth Edition (SSI-4) and Overall Assessment of the Speaker's Experience of Stuttering for Adults (OASES-A) were also tested for day-to-day variability. Correlations between frequency, severity, and life impact were made. Results: The primary result of this study was the large range over which frequency of stuttering varied from day to day for the same individual. This variability did not correlate with any measures of stuttering severity but did correlate with life impact as measured by the OASES-A. No global pattern was detected in variability from day to day within or between participants. However, there were significantly more nonstuttered disfluencies present during the spontaneous speaking tasks than during the reading tasks. The day-to-day variability in the life impact of the disorder (OASES-A) was less than the day-to-day variability in observable stuttering behavior (percentage of syllables stuttered and SSI-4). Conclusion: Frequency of stuttering varies significantly from situation to situation and day to day, with observed variability exceeding the degree of change often reported in treatment outcomes studies from before to after treatment. This variability must be accounted for in future clinical and scientific work.
Article
Objective: We investigated whether language production is atypically resource-demanding in adults who stutter (AWS) versus typically-fluent adults (TFA). Methods: Fifteen TFA and 15 AWS named pictures overlaid with printed Semantic, Phonological or Unrelated Distractor words while monitoring frequent low tones versus rare high tones. Tones were pre- sented at a short or long Stimulus Onset Asynchrony (SOA) relative to picture onset. Group, Tone Type, Tone SOA and Distractor Type effects on P3 amplitudes were the main focus. P3 amplitude was also investigated separately in a simple tone oddball task. Results: P3 morphology was similar between groups in the simple task. In the dual task, a P3 effect was detected in TFA in all three distractor conditions at each Tone SOA. In AWS, a P3 effect was attenuated or undetectable at the Short Tone SOA depending on Distractor Type. Conclusions: In TFA, attentional resources were available for P3-indexed processes in tone perception and categorization in all distractor conditions at both Tone SOAs. For AWS, availability of attentional resources for secondary task processing was reduced as competition in word retrieval was resolved. Significance: Results suggest that language production can be atypically resource-demanding in AWS. Theoretical and clinical implications of the findings are discussed.
Article
This book is the magnum opus of one of the most influential cognitive psychologists of the past 50 years. This new volume on the model he created (with Graham Hitch) discusses the developments that have occurred in the past 20 years, and places it within a broader context. Working memory is a temporary storage system that underpins onex' capacity for coherent thought. Some 30 years ago, Baddeley and Hitch proposed a way of thinking about working memory that has proved to be both valuable and influential in its application to practical problems. This book updates the theory, discussing both the evidence in its favour, and alternative approaches. In addition, it discusses the implications of the model for understanding social and emotional behaviour, concluding with an attempt to place working memory in a broader biological and philosophical context. Inside are chapters on the phonological loop, the visuo-spatial sketchpad, the central executive and the episodic buffer. There are also chapters on the relevance to working memory of studies of the recency effect, of work based on individual differences, and of neuroimaging research. The broader implications of the concept of working memory are discussed in the chapters on social psychology, anxiety, depression, consciousness, and on the control of action. Finally, the author discusses the relevance of a concept of working memory to the classic problems of consciousness and free will.
Article
The purpose of the present study was to enhance our understanding of phonological working memory in adults who stutter through the comparison of nonvocal versus vocal nonword repetition and phoneme elision task performance differences. For the vocal nonword repetition condition, participants repeated sets of 4- and 7-syllable nonwords (n=12 per set). For the nonvocal nonword repetition condition, participants silently identified each target nonword from a subsequent set of three nonwords. For the vocal phoneme elision condition, participants repeated nonwords with a target phoneme eliminated. For the nonvocal phoneme elision condition, participants silently identified the nonword with the designated target phoneme eliminated from a subsequent set of three nonwords. Adults who stutter produced significantly fewer accurate initial productions of 7-syllable nonwords compared to adults who do not stutter. There were no talker group differences for the silent identification of nonwords, but both talker groups required significantly more mean number of attempts to accurately silently identify 7-syllable as compared to 4-syllable nonwords. For the vocal phoneme elision condition, adults who stutter were significantly less accurate than adults who do not stutter in their initial production and required a significantly higher mean number of attempts to accurately produce 7-syllable nonwords with a phoneme eliminated. This talker group difference was also significant for the nonvocal phoneme elision condition for both 4- and 7-syllable nonwords. Present findings suggest phonological working memory may contribute to the difficulties persons who stutter have establishing and/or maintaining fluent speech. Educational Objectives: (a) Readers can describe the role of phonological working memory in planning for and execution of speech; (b) readers can describe two experimental tasks for exploring the phonological working memory: nonword repetition and phoneme elision; (c) readers can describe how the nonword repetition and phoneme elision skills of adults who stutter differ from their typically fluent peers. Copyright © 2015 Elsevier Inc. All rights reserved.
Article
This study was a preliminary investigation of the relations between stuttering development and the maturation of speech motor processes. Electromyographic (EMG) activity was recorded from the orofacial muscles of children who stutter and their normally fluent peers during fluent and disfluent speech. Nine children who stutter (8 boys and 1 girl), ranging in age from 2:7 to 14:0, and 9 age- and sex-matched children who do.not stutter were subjects. Pairs of surface EMG electrodes were placed on children's faces overlying the anterior belly of the digastric (ABD), levator labii superior (ULIP), and orbicularis oris inferior (LLIP) muscles. Twenty segments of stuttered (for the children who stutter) and perceptually fluent speech were extracted from children's conversational speech samples. Spectra of the amplitude envelopes of the EMG activity were computed. The 3 oldest children who stutter showed evidence of tremorlike oscillations of EMG activity in the 5 to 15 Hz range during stuttering in either ULIP, LLIP, or ABD muscles. The younger children who stutter and the children who do not stutter demonstrated primary spectral peaks in the 1 to 4 Hz range during stuttered and/or perceptually fluent speech. It is hypothesized that the emergence of tremorlike instabilities in the speech motor processes of children who stutter may coincide with aspects of their general neural maturation and with the development of stuttering.
Article
Dysphoria is associated with persistence of attention on mood-congruent information. Longer time attending to mood-congruent information for dysphoric individuals (DIs) detracts from goal-relevant information processing and should reduce working memory (WM) capacity. Study 1 showed that DIs and non-DIs have similar WM capacities. Study 2 embedded depressive information into a WM task. Compared to non-DIs, DIs showed significantly reduced WM capacity for goal-relevant information in this task. Study 3 replicated results from Studies 1 and 2, and further showed that DIs had a significantly greater association between processing speed and recall on the depressively modified WM task compared to non-DIs. The presence of inter-task depressive information leads to DI-related decreased WM capacity. Results suggest dysphoria-related WM capacity deficits when depressive thoughts are present. WM capacity deficits in the presence of depressive thoughts are a plausible mechanism to explain day-to-day memory and concentration difficulties associated with depressed mood.
Article
Purpose In preschool children, we investigated whether expressive and receptive language, phonological, articulatory, and/or verbal working memory proficiencies aid in predicting eventual recovery or persistence of stuttering. Methods. Participants included 65 children, including 25 children who do not stutter (CWNS) and 40 who stutter (CWS) recruited at age 3;9-5;8. At initial testing, participants were administered the Test of Auditory Comprehension of Language, 3rd edition (TACL-3), Structured Photographic Expressive Language Test, 3rd edition (SPELT-3), Bankson-Bernthal Test of Phonology-Consonant Inventory subtest (BBTOP-CI), Nonword Repetition Test (NRT; Dollaghan & Campbell, 1998), and Test of Auditory Perceptual Skills-Revised (TAPS-R) auditory number memory and auditory word memory subtests. Stuttering behaviors of CWS were assessed in subsequent years, forming groups whose stuttering eventually persisted (CWS-Per; n = 19) or recovered (CWS-Rec; n = 21). Proficiency scores in morphosyntactic skills, consonant production, verbal working memory for known words, and phonological working memory and speech production for novel nonwords obtained at the initial testing were analyzed for each group. Results. CWS-Per were less proficient than CWNS and CWS-Rec in measures of consonant production (BBTOP-CI) and repetition of novel phonological sequences (NRT). In contrast, receptive language, expressive language, and verbal working memory abilities did not distinguish CWS-Rec from CWS-Per. Binary logistic regression analysis indicated that preschool BBTOP-CI scores and overall NRT proficiency significantly predicted future recovery status. Conclusion. Results suggest that phonological and speech articulation abilities in the preschool years should be considered with other predictive factors as part of a comprehensive risk assessment for the development of chronic stuttering.
Article
Purpose We investigated short-term practice and retention of nonwords in 10 adults who stutter (Mean age = 30.7 years, SD = 15.1) and age and sex-matched 10 control participants (Mean age = 30.8 years, SD = 14.9). Methods. Participants were required to repeat nonwords varying in length (3, 4, 6 syllables), phonotactic constraint (PC vs. NPC, on 3-syllable nonwords only), and complexity (simple, complex). They were tested twice with one hour gap between sessions. Results. Logistic mixed model of speech accuracy revealed that the AWS showed a significantly lower probability of correct responses with increasing length and complexity. Analysis of speech kinematics revealed practice effects within Session 1 in AWS seen as a reduction in movement variability for the 3-syllable nonwords; the control group was performing at ceiling at this length. For the 4-syllable nonwords, the control group showed a significant reduction in movement variability with practice, and retained this reduction in Session 2, while the AWS group did not show practice or retention. Group differences were not evident at the 6-syllable level. Conclusions. Group differences in speech accuracy suggest differences in phonemic encoding and/or speech motor processes. Group differences in changes in movement variability within and between sessions suggest reduced practice and retention in AWS. Relevance of the combined use of both behavioral and kinematic measures to interpret the nature of the skill acquisition deficit in persons who stutter is discussed.
Article
The complex span measure of working memory is a word/digit span measured while performing a secondary task. Two experiments investigated whether correlations between the complex span and reading comprehension depend on the nature of the secondary task and individual skill in that task. The secondary task did not have to be reading related for the span to predict reading comprehension. An arithmetic-related secondary task led to correlations with reading comprehension similar to those found when the secondary task was reading. The relationship remained significant when quantitative skills were factored out of the complex span/comprehension correlations. Simple digit and word spans (measured without a background task) did not correlate with reading comprehension and SAT scores. The second experiment showed that the complex span/comprehension correlations were a function of the difficulty of the background task. When the difficulty level of the reading-related or arithmetic-related background tasks was moderate, the span/comprehension correlations were higher in magnitude than when the background tasks were very simple, or, were very difficult.
Article
Purpose: In the present study a nonword repetition and a nonword reading task were used to investigate the behavioral (speech accuracy) and speech kinematic (movement variability measured as lip aperture variability index; speech duration) profiles of groups of young adults who do (AWS) and do not stutter (control). Method: Participants were 9 AWS (8 males, Mean age=32.2, SD=14.7) and 9 age- and sex-matched control participants (Mean age=31.8, SD=14.6). For the nonword repetition task, participants were administered the Nonword Repetition Test (Dollaghan & Campbell, 1998). For the reading task, participants were required to read out target nonwords varying in length (6 vs. 11 syllables). Repeated measures analyses of variance were conducted to compare the groups in percent speech accuracy for both tasks; only for the nonword reading task, the groups were compared in movement variability and speech duration. Results: The groups were comparable in percent accuracy in nonword repetition. Findings from nonword reading revealed a trend for the AWS to show a lower percent of accurate productions compared to the control group. AWS also showed significantly higher movement variability and longer speech durations compared to the control group in nonword reading. Some preliminary evidence for group differences in practice effect (seen as differences between the early vs. later 5 trials) was evident in speech duration. Conclusions: Findings suggest differences between AWS and control groups in phonemic encoding and/or speech motor planning and production. Findings from nonword repetition vs. reading highlight the need for careful consideration of nonword properties. Educational objectives: At the end of this activity the reader will be able to: (a) summarize the literature on nonword repetition skills in adults who stutter, (b) describe processes underlying nonword repetition and nonword reading, (c) summarize whether or not adults who stutter differ from those who do not in the behavioral and kinematic markers of nonword reading performance, (d) discuss future directions for research.
Article
This chapter describes the nature of working memory capacity (WMC), and addresses the nature of WMC limitations, their effects on higher order cognitive tasks, their relationship to attention control and general fluid intelligence, and their neurological substrates. Much of work explores these issues in the context of individual differences in WMC and the cause of those individual differences. Measures of WMC are highly reliable and highly valid indicators of some construct of clear relevance to feral cognition. Macroanalytic studies have demonstrated that the construct reflected by WMC tasks has a strong relationship with gF above and beyond what these tasks share with simple span tasks. The conflict might also arise from stimulus representations of competing strength. This two-factor model fits with current thinking about the role of two brain structures: the prefrontal cortex as important to the maintenance of information in an active and easily accessible state and the anterior cingulate as important to the detection and resolution of conflict.
Article
Performance on measures of working memory (WM) capacity predicts performance on a wide range of real-world cognitive tasks. I review the idea that WM capacity (a) is separable from short-term memory, (b) is an important component of general fluid intelligence, and (c) represents a domain-free limitation in ability to control attention. Studies show that individual differences in WM capacity are reflected in performance on antisaccade, Stroop, and dichotic-listening tasks. WM capacity, or executive attention, is most important under conditions in which interference leads to retrieval of response tendencies that conflict with the current task.
Chapter
Working memory is currently a 'hot' topic in cognitive psychology and neuroscience. Because of their radically different scopes and emphases, however, comparing different models and theories and understanding how they relate to one another has been a difficult task. This volume offers a much-needed forum for systematically comparing and contrasting existing models of working memory. It does so by asking each contributor to address the same comprehensive set of important theoretical questions on working memory. The answers to these questions provided in the volume elucidate the emerging general consensus on the nature of working memory among different theorists and crystallize incompatible theoretical claims that must be resolved in future research. As such, this volume serves not only as a milestone that documents the state-of-the-art in the field but also as a theoretical guidebook that will likely promote new lines of research and more precise and comprehensive models of working memory.
Article
Unlabelled: The present study investigated segmentation and rhyme abilities, skills critical for phonological encoding, of children who stutter (CWS) and those who do not (CNS). Participants were 9 CWS (8 males and 1 female, mean age=11.1, SD=2.31) in the age range of 7 and 13 years and 9 age and sex matched CNS (mean age=11.2, SD=2.19). Participants performed two verbal monitoring tasks, phoneme and rhyme monitoring, in silent naming. Performances in the verbal monitoring tasks were compared to a neutral, nonverbal tone monitoring task. Additionally, the complexity of the phoneme monitoring task was varied such that participants had to monitor for singletons vs. consonant clusters. Repeated measures analysis of the response time data did not reveal significant differences between the groups in the three monitoring tasks. Analysis of the complexity data revealed a trend for slower monitoring of the consonant clusters in the CWS group compared to the CNS. Present findings do not support a deficit in segmentation and rhyme abilities in CWS, although there was some preliminary evidence of segmentation difficulties with increasing phonological complexity of the stimuli. Educational objectives: At the end of this activity the reader will be able to: (a) discuss the literature on phonological encoding skills in children who stutter, (b) describe skills underlying the phonological encoding process, (c) summarize whether or not children who stutter differ from those who do not in segmentation and rhyme abilities, (d) suggest future areas of research in the investigation of segmentation and rhyme monitoring abilities in children who stutter.
Article
The DIVA model of speech production provides a computationally and neuroanatomically explicit account of the network of brain regions involved in speech acquisition and production. An overview of the model is provided along with descriptions of the computations performed in the different brain regions represented in the model. The latest version of the model, which contains a new right-lateralized feedback control map in ventral premotor cortex, will be described, and experimental results that motivated this new model component will be discussed. Application of the model to the study and treatment of communication disorders will also be briefly described.