2 leading hypotheses:
From Gene to Phenotype Genes Cells Systems Behaviour
Serial model of how genes impact brain development
Genes-multiple alleles each of small effect
Cells-subtle molecular bottlenecks
Systems-variable development/info processing
Bevr-complex functional interactions and emergent phenomena
Cognition
Family Environment
-Highly impactful for developmental stuttering
(interactionist theories)
-parental factors may favor devt of disorder (critical, greater senstivity to speech etc.)
Diagnosogenic Theory of Developmental Stuttering
Wendell Johnson (1942) Parents overreact to child's typical disfluencies, and child becomes stressed about it
The Tudor Study (1939)
Johnson
Tested hypothesis that labeling a child as a stutterer would create MORE hesitancies
-many orphaned children exhibited stuttering-like bevrs
Diagnosogentic Theory: Problems
Johnson misinterpreted data
Demands & Capacities Theory
disfluency = capacitiesm (inherited tendencies, strengths, weaknesses, perceptions) not equal to speech performance demands
Demands/Supports
Demands: parents w/ high expectations & standards
-increasing complex thoughts, parental interactions that cause stress
Supports: love, care, encouragement
D&C - Four Dimensions
Motoric
Motoric Demands
Speaking when someone is waiting, complex/long utterance, saying own name, telephone, repeating to clarify, speaking while rushed
Linguistic
Socio-Emotional
- increase child’s oral motor muscle activity and reduce fluency (children regulate emotion differently than adults)
Cognitive
-child’s ability to use metaling skills
-onset of stuttering, before meta skills developed
BUT communication is more natural w/ lessened cognitive effort
D&C Strengths
- accounts for individual variability
D&C Limitations
Utilization of D&C Theory for Tx of developmental stuttering
2 Categories of Stuttering brought out by significant life events:
Predisposition Positive
Etiology & Xtics
Etiology: Ability to learn speech & lang is subtly compromised
Xtics: Typical developmental stuttering
Psychogenic Stuttering
Etiology & Xtics
Etiology: traumatic life event leads to stuttering in a child or adult w/ no predisposition to disorder
Xtics: Atypical “atypical” disfluencies
Learning
Define, List 3 types
=change that takes place in person as result of their experiences in the environment
Classical Conditioning & Stuttering
Pavlovs dogs
Operant Conditioning & Stuttering
If bevr followed by REWARD it increases, and by an AVERSIVE consequence, it decreases
e.g., random struggle movements to escape stuttering rewarded with the removal/end of stuttering (negative reinforcement)
**Positive reinforcement as therapy tool (Lidcombe program)
**Mild punishment can be used (pointing out bumpy speech, asking child to practice using smooth speech)
-may increase escape bevrs
ENVIRONMENT IS KEY