Pascal van Lieshout

Speech Motor Skill and Stuttering

ABSTRACT The authors review converging lines of evidence from behavioral, kinematic, and neuroimaging data that point to limitations in speech motor skills in people who stutter (PWS). From their review, they conclude that PWS differ from those who do not in terms of their ability to improve with practice and retain practiced changes in the long term, and that they are less efficient and less flexible in their adaptation to lower (motor) and higher (cognitive–linguistic) order requirements that impact on speech motor functions. These findings in general provide empirical support for the position that PWS may occupy the low end of the speech motor skill continuum as argued in the Speech Motor Skills approach (Van Lieshout, Hulstijn, & Peters, 2004).

Stroop Effects in Persons with Traumatic Brain Injury: Selective Attention, Speed of Processing, or Color-Naming? A Meta-analysis

The color word Stroop test is the most common tool used to assess selective attention in persons with traumatic brain injury (TBI). A larger Stroop effect for TBI patients, as compared to controls, is generally interpreted as reflecting a decrease in selective attention. Alternatively, it has been suggested that this increase in Stroop effects is influenced by group differences in generalized speed of processing (SOP). The current study describes an overview and meta-analysis of 10 studies, where persons with TBI (N = 324) were compared to matched controls (N = 501) on the Stroop task. The findings confirmed that Stroop interference was significantly larger for TBI groups (p = .008). However, these differences may be strongly biased by TBI-related slowdown in generalized SOP (r² = .81 in a Brinley analysis). We also found that TBI-related changes in sensory processing may affect group differences. Mainly, a TBI-related increase in the latency difference between reading and naming the font color of a color-neutral word (r² = .96) was linked to Stroop effects. Our results suggest that, in using Stroop, it seems prudent to control for both sensory factors and SOP to differentiate potential changes in selective attention from other changes following TBI.

A resource of validated affective and neutral sentences to assess identification of emotion in spoken language after a brain injury

Primary objective: The ability to identify emotions in spoken language is an essential component of communication and could be disrupted in persons with brain injury. Current tools to assess this function show important shortcomings. The aim is to present a set of validated and linguistically equated lexical sentences that can be used to separate the impact of lexical content and prosody on the processing of emotion in speech in persons with brain injury. Methods and procedures: Using six-point Likert scales, a set of 125 sentences, carefully matched for linguistic variables, were rated by a group of young adults (n = 48) on their suitability to represent a particular emotion (anger, fear, happiness and sadness) in their lexical content. Main outcomes and results: The findings identified a set of 50 sentences that were reliably associated with one particular emotion only or no emotion at all (neutral). Using less stringent criteria, 94 sentences were also found to be good representatives for these affective categories. Conclusions: The findings generated a robust set of validated lexical stimuli necessary to reliably identify the specific contributions of verbal and prosodic information on difficulties in identifying emotions in speech with persons with brain injury.

Sensory feedback dependence hypothesis in persons who stutter.

The present study investigated the role of sensory feedback (auditory, proprioception, and tactile) at the intra- and inter-gestural levels of speech motor coordination in normal and fast speech rate conditions in two groups: (1) persons who stutter (PWS) and (2) those who do not (PNS). Feedback perturbations were carried out with the use of masking noise (auditory), tendon vibration (proprioception), and nonwords that differed in the amount of required tactile lip contact (/api/+tactile and /awi/-tactile). Comparisons were also made between jaw-free and jaw-immobilized (with a bite-block) task conditions. It was hypothesized that if PWS depend more strongly on sensory feedback control during speech production, they would show an increase in variability of movement coordination in the combined presence of fast speech rates and feedback perturbations, in particular, when jaw motions are blocked and adaptations in the other articulators are required to achieve the task goals. Significant feedback perturbation effects were found for both groups, but the only significant between-group effect was found at fast speech rates in the jaw-free condition, showing that control speakers were more perturbed at the intra-gestural level of coordination than PWS when simultaneous (auditory, proprioceptive, and tactile) perturbations were present. The findings do not provide support for either the feedback dependency or the sensory deficit hypotheses described in the literature to explain movement characteristics found in fluent speech production of PWS.

The stability of pen-joint and interjoint coordination in loop writing

This study is concerned with pen-joint and interjoint coordination in handwriting. In particular, it focuses on the stability of coordination as a means to find the locus of coordination control in the arm-pen effector system. Twelve subjects generated loop sequences of varying length at various positions on the baseline of writing. Joint excursions and pen-tip displacements were recorded by means of a 3D-motion tracking system. The coordination stability of 15 pairs of 6 mechanical degrees of freedom (d.f.s) of the arm-pen effector system was investigated by means of relative phase analyses. Pen-joint coordination between horizontal pen-tip displacements and wrist excursions was found to be most stable; that between vertical pen-tip displacements and finger excursions was considerably less stable. Interjoint coordination was generally less stable than pen-joint coordination, and most stable between the wrist and the elbow. Sequence length and its position on the line differentially affected the coordination stability of the d.f. combinations. The results are discussed in relation to assumptions about joint coordination in writing as expressed by computational handwriting models.

Treatment intensity and childhood apraxia of speech

BACKGROUND Intensive treatment has been repeatedly recommended for the treatment of speech deficits in childhood apraxia of speech (CAS). However, differences in treatment outcomes as a function of treatment intensity have not been systematically studied in this population. AIM To investigate the effects of treatment intensity on outcome measures related to articulation, functional communication and speech intelligibility for children with CAS undergoing individual motor speech intervention. METHODS & PROCEDURES A total of 37 children (32-54 months of age) with CAS received 1×/week (lower intensity) or 2×/week (higher intensity) individual motor speech treatment for 10 weeks. Assessments were carried out before and after a 10-week treatment block to study the effects of variations in treatment intensity on the outcome measures. OUTCOMES & RESULTS The results indicated that only higher intensity treatment (2×/week) led to significantly better outcomes for articulation and functional communication compared with 1×/week (lower intensity) intervention. Further, neither lower nor higher intensity treatment yielded a significant change for speech intelligibility at the word or sentence level. In general, effect sizes for the higher intensity treatment groups were larger for most variables compared with the lower intensity treatment group. CONCLUSIONS & IMPLICATIONS Overall, the results of the current study may allow for modification of service delivery and facilitate the development of an evidence-based care pathway for children with CAS.

Tongue control for swallowing in Parkinson's disease: Effects of age, rate, and stimulus consistency

Patients with Parkinsons disease often suffer from swallowing problems, especially at more advanced stages of the disease. Efficient swallows require well‐coordinated tongue movements during bolus flow, but little is known about such movements in Parkinsons disease.

Motor speech treatment protocol for developmental motor speech disorders

Abstract Objective: This study examines the effect of the Motor Speech Treatment Protocol (MSTP), a multi-sensory hybrid treatment approach on five children (mean: 3;3 years; S.D. 0;1) with severe to profound speech sound disorders with motor speech difficulties. Methods: A multiple probe design, replicated over five participants, was used to evaluate the effects of treatment on improving listeners’ auditory and visual judgements of speech accuracy. Results: All participants demonstrated significant change between baseline and maintenance conditions, with the exception of KM, who may have had underlying psychosocial, regulation and/or attention difficulties. The training- (practiced in treatment) and test-words (not practiced in treatment) both demonstrated positive change in all participants, indicating generalization of target features to untrained words. Conclusion: These results provide preliminary evidence that the MSTP, which integrates multi-sensory information and utilizes hierarchical goal selection, may positively impact speech sound production by improving speech motor control in this population.

Coupling Dynamics Interlip Coordination in Lower Lip Load Compensation

PURPOSE To study the effects of lower lip loading on lower and upper lip movements and their coordination to test predictions on coupling dynamics derived from studies in limb control. METHOD Movement data were acquired using electromagnetic midsagittal articulography under 4 conditions: (a) without restrictions, serving as a baseline; (b) with a small carrier device attached to the lower lip; (c) with a 50-g weight added to the device; and, at the end of the session (d) with the weight and device removed. For all conditions, 8 participants repeated nonwords at 2 speaking rates. Movement data were used to derive discrete kinematic measures, a cyclic index of spatiotemporal variability, phase deviations, and standard deviations of relative phase for interlip coupling. RESULTS Kinematic variables were not systematically affected by lower lip load. Phase deviations also showed no change, but in contrast, phase variability showed a significant increase for the lower lip load condition at fast rates. CONCLUSION Lower lip load effects are comparable to the reported impact of homologous limb loading, showing evidence for a tight coupling between both lips in line with predictions from coordination dynamics accounts in the literature.

The effect of phonetic context on speech movements in repetitive speech

This study examined how, in repetitive speech, articulatory movements differ in degree of variability and movement range depending on articulatory constraints manipulated by phonetic context and type of CVC-CVC word pair. These pairs consisted of words that either differed in onset consonants but shared rhymes, or were identical. Articulatory constraints were manipulated by employing different combinations of vowels and consonants. The word pairs were produced in a repetitive speech task at a normal and fast speaking rate. Articulatory movements were measured with 3D electro-magnetic articulography. As measures of variability, median movement ranges and the coefficient of variation of target and non-target articulators were determined. To assess possible biomechanical constraints, correlation values between target and simultaneous non-target articulators were calculated as well. The results revealed that word pairs with different onsets had larger movement ranges than word pairs with identical onsets. In identical word pairs, the coefficient of variation showed higher values in the second than in the first word. This difference was not present in the alternating onset word pairs. For both types of word pairs, higher speaking rates showed higher correlations between target and non-target articulators than lower speaking rates, suggesting stronger biomechanical constraints for the former condition.