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

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), 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), 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), 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.