Effects of Emotional Processes on Speech Motor Control in Early Childhood Stuttering.

The Influence of Contextual and Constitutional Emotional Processes on Speech Motor Control and Speech Motor Learning in Early Childhood Stuttering

This study will compare speech variability between preschool-age children who stutter and typically fluent, age-matched peers. Differences in emotional reactivity, regulation and speech motor control have been implicated in stuttering development in children. This study seeks to understand further how these processes interact. Children will repeat a simple phrase after viewing age-appropriate images of either negative or neutral valence to assess speech motor control.

Stuttering is a developmental disorder that emerges in the preschool years as children are undergoing rapid development of their speech, language, and emotional regulation processes. This study aims to understand how speech motor control and emotional processes interact in young children who do and do not stutter. In Aim 1, the investigators will be observing how speech motor control and learning are affected by emotional (physiological) arousal. High arousal (e.g., stress) has been shown to disrupt highly skilled performances such as in sports and music performance (Yoshie et al., 2009). Parents of children who stutter often report that that exciting or stressful situations lead to increased stuttering in their children. There is little research, however, on how excitement or stress affects fluency in children. In Aim 2, the investigators will observe how behavioral inhibition plays a role in speech motor control and motor learning in the context of emotional processes. Behavioral inhibition is one aspect of a child's temperament. Temperament refers to self-regulation as well as emotional, motor, and attentional reactivity that differs among individuals. Children with high behavioral inhibition (BI) are hyper-vigilant and more sensitive to new stimuli and negative emotional states. Therefore, the purpose of Aim 2 is to see if children with high BI are more susceptible to contextual emotional processes, therefore affecting speech motor control and learning. Outcomes will be measured by calculating the variability in speech motor movements (STI). The two groups, children who stutter and age-matched peers who do not stutter, will be compared to see how speech motor control varies between groups and conditions.

Speaking Condition 1: 10 age-appropriate pictures from the International Affective Picture System (IAPS; Lang, Bradley & Cuthbert, 2005) will be shown to participants. These pictures are classified as high arousal, negative valence stimuli. Participants will be asked to repeat a simple phrase between picture presentations. Speaking Condition 2: A blank screen will be shown to participants in place of pictures. This condition is classified as low arousal, neutral valence. Participants will be asked to repeat a simple phrase between blank screen picture presentations.

The spatiotemporal index (STI) of lip aperture during a negative valence condition on Day 1 (pretest).

The spatiotemporal index (STI), a measure of speech coordination developed by Smith and colleagues (e.g., Smith, Goffman, Zelaznik, Ying & McGillem, 1995). It will be employed to quantify speech motor control ability and speech motor learning effects. The STI reflects the degree to which repeated performance of a task produces movement trajectories that converge on a single pattern. Children produce less stable movement trajectories, as reflected in higher values of the STI (e.g. Smith & Goffman, 1998), while adults produce more stable movement trajectories as reflected in lower STI values. The STI of lip aperture (a relative distance between upper and lower lips) will be calculated.

The spatiotemporal index (STI) of lip aperture during a neutral valence condition on Day 1 (pretest).

The spatiotemporal index (STI), a measure of speech coordination developed by Smith and colleagues (e.g., Smith, Goffman, Zelaznik, Ying & McGillem, 1995). It will be employed to quantify speech motor control ability and speech motor learning effects. The STI reflects the degree to which repeated performance of a task produces movement trajectories that converge on a single pattern. Children produce less stable movement trajectories, as reflected in higher values of the STI (e.g. Smith & Goffman, 1998), while adults produce more stable movement trajectories as reflected in lower STI values. The STI of lip aperture (a relative distance between upper and lower lips) will be calculated.

The spatiotemporal index (STI) of lip aperture during a negative valence condition on Day 2 (retention).

The spatiotemporal index (STI), a measure of speech coordination developed by Smith and colleagues (e.g., Smith, Goffman, Zelaznik, Ying & McGillem, 1995). It will be employed to quantify speech motor control ability and speech motor learning effects. The STI reflects the degree to which repeated performance of a task produces movement trajectories that converge on a single pattern. Children produce less stable movement trajectories, as reflected in higher values of the STI (e.g. Smith & Goffman, 1998), while adults produce more stable movement trajectories as reflected in lower STI values. The STI of lip aperture (a relative distance between upper and lower lips) will be calculated.

The spatiotemporal index (STI) of lip aperture during a neutral valence condition on Day 2 (retention).

The spatiotemporal index (STI), a measure of speech coordination developed by Smith and colleagues (e.g., Smith, Goffman, Zelaznik, Ying & McGillem, 1995). It will be employed to quantify speech motor control ability and speech motor learning effects. The STI reflects the degree to which repeated performance of a task produces movement trajectories that converge on a single pattern. Children produce less stable movement trajectories, as reflected in higher values of the STI (e.g. Smith & Goffman, 1998), while adults produce more stable movement trajectories as reflected in lower STI values. The STI of lip aperture (a relative distance between upper and lower lips) will be calculated.

Skin conductance level (SCL) measures the activity of the sympathetic branch of the autonomic nervous system. Higher SCL during experimental conditions as compared to the baseline is associated with higher sympathetic nervous system activity and provides physiologic validation of the emotional reactivity differences between the experimental conditions.

Phasic skin conductance responses (SCR) measures the activity of the sympathetic branch of the autonomic nervous system. It is elicited by specific stimuli (in this study, by the pictures presented in the two experimental conditions).Greater number of SCRs elicited by picture presentations during experimental conditions is associated with higher sympathetic nervous system activity and provides physiologic validation of the emotional reactivity differences between the experimental conditions.

Respiratory sinus arrhythmia (RSA) (rhythmic fluctuations in heart rate associated with the respiratory cycle) measures the activity of the parasympathetic branch of the autonomic nervous system. Decreased RSA during the experimental conditions as compared to the baseline provides physiologic validation of the emotional reactivity differences between the experimental conditions.

Executive function skills will be assessed through behavioral tasks using the NIH Toolbox Early Childhood Cognition Battery (Gershon et al., 2013; Zelazo et al., 2013). The tasks include the Flanker Inhibitory Control and Attention Test to examine inhibitory control, Picture Sequence Memory Test to examine episodic memory, and Dimensional Change Card Sort Test to examine mental flexibility and attention.

Inclusion Criteria: English as the primary language of communication. No history of neurological diseases or diagnosed speech-language disorders apart from stuttering. Parent report or direct observation of oral-facial structural abnormalities (such as cleft lip and/or cleft palate). Free of any medications that may affect neural functions (e.g., medications of seizures). Normal hearing acuity (must pass a hearing screening). Normal vision per parent report. Exclusion Criteria: Failure to meet the inclusionary criteria listed above Parental report of neurodevelopmental disorders (such as autism spectrum disorders) Parental report of vision problems that are not corrected or corrected with glasses.