A double-edged sword: producing repetitions and prolongations inhibits stuttering and propagates emotional arousal via the mirror system Joseph Kalinowski, Jianliang Zhang, Daniel Hudock East Carolina University Tim Saltuklaroglu University of Tennessee Vijaya Guntupalli East Tennessee State University

What is stuttering?

Part 1: The ‘inhibition’ of stuttering Conditions in which stuttering is dramatically reduced: –Sensory conditions: Choral Speech - speaking in unison with another person Shadow speech - direct repetition Visual choral speech – chorals speech with no auditory signal Altered auditory feedback - delayed and frequency altered Other ‘second speech signals’ - vowel trains, fluent speech, stuttered speech, expanded speech, sine-wave speech In comparison: non speech signals (e.g., pure tones) have been relatively much less effective

The ‘inhibition’ of stuttering Conditions in which stuttering is dramatically reduced: –Motor conditions: Prolonged speech Singing Using a foreign accent Pseudostuttering - artificial stuttering

Implications from these data A perception / production link appears to exist in the inhibition of stuttering. –Sensory and motoric forms of stuttering inhibition may be related. Inhibition is related directly to speech and appears to have a ‘gestural basis’. –Not just an auditory phenomenon. –Speech inputs are most effective sensory inhibitors May be explained by the engagement of mirror neurons.

Mirror Neuron Systems Originally discovered in monkeys F5 area (considered an analog of Broca’s area). –In humans circuitry has been found to include: Inferior frontal gyrus Inferior parietal lobe Superior temporal sulcus Emotional centers including amygdala and insula Fire when goal-directed gestures are both perceived and produced. Are thought to be involved in development of: –Action and emotion recognition / empathy –Imitation –Language (Rizzolatti & Arbib, 1998) Motor theorists may see a role for mirror neurons in providing the neural substrate for linking speech perception and production (Liberman & Whalen, 2000).

Mirror neurons and stuttering inhibition Choral speech / shadow speech are forms of direct imitation. –Mirror systems have been found to show highest levels of engagement during imitative tasks (e.g., Nishitani & Hari, 2002). Thus, it is likely that mirror neurons are engaged in the process of inhibiting stuttering. –It has been suggested that imitation is an act that humans perform fluently. Broca’s area has been found to be relatively deactivated during stuttering and normalized under choral speech. –Broca’s area is one of the primary mirror areas in mirror system. –One of the main roles of Broca’s areas is in producing fluent combinations of gestural sequences (Cooper, 2006)

Mirror neurons and stuttering inhibition When perceiving other ‘second’ speech signals, the common goal is still speech. Therefore, the exogenous gestural sequence does not need to exactly match for stuttering to inhibited. However, the closer the linguistic match, the more stuttering is inhibited.

Repetitions and prolongations as inhibitors Primary overt behaviors: –Repetitions and prolongations of sounds. –~80% recovery in children. Are these the problem or the solution to stuttering? –Interestingly, these behaviors are similar to motoric methods of inhibiting stuttering. Maybe they are ways to endogenously “self- imitate” to engage the mirror system and release the central block.

A recent study We examined how altered auditory feedback differentially inhibits stuttering on during speech initiation and after speech has been initiated during 10s trials. Stuttering frequencies were examined in the first syllable and compared to stuttering frequencies on the next four syllables and 5 more syllables produced after the 5 second mark,

Stuttering during speech initiation Stuttering was times more frequent on first syllable than all other syllables in NAF and AAF conditions.

Implications Stuttering on the first syllable may be helping to inhibit further stuttering. Speech for people who stutter is difficult from a ‘cold start’ as no endogenous or exogenous speech feedback is present. AAF cannot aid directly in initiation but is powerful after speech is initiated. Choral speech, because it is exogenous can help inhibit stuttering during speech initiation.

Part 2: Reactions to stuttering Hypothesis: –Stuttering causes emotional responses in naïve listeners that may be detected by physiological changes. –galvanic skin response. –Heart rate. –Ocular responses (responses of the eye).

Method Participants Twenty fluent adults. 10 females and 10 males. Mean age = yrs., SD = 3.4 yrs. 17 students, 2 managers, 1 from armed forces.

Method Stimuli Two fluent and two stuttered speech samples of 30 s. Stuttered speech samples were rated as ‘severe’ (SSI-3; Riley, 1994).

Method Experimental setup

Valence scale (1-5) Arousal scale (1-5)

Response measurement Self-report measures Nine bipolar adjectives on a nine-point Likert scale (1 -9).

Procedure Baseline rating task (hypothetical individual) SAM valence and arousal dimensions and a nine bipolar adjectives. Preparation for the physiological measures.

Procedure 5-min adaptation period. Baseline autonomic responses (30 s). Event markers were placed to indicate the onset of stimulus presentation. After each stimulus, participants rated SAM scale and nine bi-polar adjectives.

Procedure A two-minute recovery period was provided between stimulus tokens. The fluent and stuttered speech tokens were arranged using digram-balanced Latin square method and participants were randomly assigned to one order.

Results: Valence scale

Results: Arousal scale

Results: SCR and HR

Changes in eye behaviors Emotional responses can also be inferred from changes in eye behaviors. Preliminary data shows that witnessing stuttering may induce: –Increased pupil dilation. –Increased gaze aversion - breaking eye contact.

Model of the possible effects of emotional arousal during stuttered conversation