Stuttering Etiology

six groups of stuttering theories

neurogenic, psychogenic, language, learning, motor, and genetic

neurogenic

brain structure and function

psychogenic

emotional and environmental factors

language

semantic, syntactic, phonological and phonetic factors

learning

operant conditioning

motor

motor control factors

genetics

hereditary factors

cerebral dominance theory (Orton and Travis)

neurogenic theory, one cerebral hemisphere must be dominant, and a lack of hemisphere dominance results in stuttering, based on the assumption that stuttering and handedness are linked. research does not support this theory.

what does the cerebral dominance theory suggest

1. theory predicted that there is a higher proportion of left handedness/ambidexterity in people who stutter

2. shifting handedness against natural dominance causes stuttering

3. strengthening natural dominance reduces stuttering

Diagnosogenic theory (Johnson et al)

psychogenic disorder that states that stuttering begins with its diagnosis. research does not support diagnosogenic theory

what does the diagnosogenic theory suggest

parents mislabel nonfluencies as stuttering which causes a negative reaction, children become self conscious and try to avoid nonfluencies. their typical nonfluencies become stuttering dysfluencies

covert repair hypothesis

language theory that says there are difficulties at the level of the formulator which causes stuttering. research is ongoing to confirm or reject

what does the cover repair hypothesis state

• slower phonological encoding in people who stutter

• phonetic plans cannot be completed as quickly as in fluent speakers

• This is detected as an error and is repaired by postponing or restarting until the phonetic plan is available

stuttering as operant behavior

learning theory, behaviors are modified by their consequences, secondary behaviors learned through operant conditioning

stuttering as motor speech disorder

motor theory, people who stutter have longer reaction times for speech and nonspeech tasks, slower fluent speech, ongoing research

stuttering and genetics

genetic theory, family studies and twin studies

family studies

genetic predisposition for stuttering, higher familial incidence of stuttering for people who stutter

twin studies

higher concordance of stuttering in identical than fraternal twins, concordance in identical twins less than 100%, evidence suggests that both genetic and environmental factors have an effect on stuttering occurrence