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Transcript
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 “selfimitate” 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 3 - 4 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 = 24.15 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
Valence (happy - unhappy)
5
Fluent speech
Stuttered speech
4
3
2
1
Baseline
Sample 1
Conditions
Sample 2
Results: Arousal scale
Fluent speech
Arousal (excited - calm)
5
Stuttered speech
4
3
2
1
Baseline
Sample 1
Conditions
Sample 2
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
Model of the possible effects of emotional
arousal during stuttered conversation
Model of the possible effects of emotional
arousal during stuttered conversation