FLUENCY LESSON 2

Constitutional Factors

• Basic physiological tendency that is believed to contribute to personality, temperament, and etiology of specific mental and physical disorders

  • e.g. hereditary predispositions and physiological characteristics

• At birth

Biological Background, Sensory & Sensory-Motor Functions, Language Factors, Emotional Factors

Discussion of Constitutional Factors (4)

Hereditary Factors, Congenital & Early Childhood Factors, Brain Structure & Function

Biological Factors (3)

Hereditary Factors

• There are 2 individuals that contributed to understanding heredity

  • Gregor Mendel & Charles Darwin

• Stuttering often runs in families long in families (Andrews et al., 1983; Bloodstein & Ratner, 2008)

• Some debated that the appearance of stuttering is caused by an inherited neurological difference or whether it stems from family attitudes towards speech

  • e.g. earlier theories suggested that if parents are overly critical of child’s normal disfluencies, child may be fearful and begin hesitating more = presence of stuttering and spiral into more stuttering later on in life

  • broad agreement: heredity plays a significant role in the presence of stuttering

    • For most PWS, 1 or 2 parent/s may have had a genetic predisposition that was passed on from the previous generation

• For some researchers, the appearance of stuttering is caused by an inherited neurological difference called an anomaly

  • anomaly - a difference from the normal structure or function

• Some researches argued that stuttering develops in response to a critical attitude toward normal disfluency that has been handed down from one generation to the next (Johnson & Associates, 1959)

• A child whose parents were critical of their normal disfluencies would grow afraid and would "hesitate to hesitate" spiraling to more hesitations and greater fear and so on.

Gregor Mendel, Charles Darwin

1. established the principle that each parent in a breeding pair has equal contribution to the genetic makeup of the offspring

   • children will inherit some of the traits their parents have

   • concept of dominant and recessive traits

2. widely famous for theory of evolution

   • thought to have inherited stuttering from his grandfather, Erasmus (Thomson, 2009);

   • while specific characteristics could be generated across generations, variations in how these characteristics expressed themselves produced

   • the most favorable traits for the current environment of the species would be increased because individuals possessing them would

     • theory highlights how traits are passed down across generations but also have variations in expression 

     • some traits become more common because it helps in survival and reproduction

     • His framework gives an idea how stuttering may be passed on genetically but expressed differently in each person.

Heredity and Environment

• Research has shown, for a number of inherited disorders, that genes do not work alone.

• Stuttering, asthma, migraine, headaches, and certain other disorders are seen as the result of _ and _ acting together with the element of chance thrown in (Kidd, 1984)

• We can say that our parents have specific traits or disorders that are within their genes, but we are unsure that the offspring would get them as well 

Example:

• a child in one family may inherit genes predisposing him to stutter, but his home environment does not trigger the presence of stuttering making the stuttering to never develop.

• a similar child, inheriting the same genes, may grow up in a demanding, hectic, fast-talking home and begin to stutter at age 3.

Family Studies, Twin Studies, Adoption Studies

• 3 Approaches to the Study of Heredity

• different ways of gathering evidences suggest that for many individuals, stuttering is partly attributable to heredity

• vital in counseling individuals and families about the nature of stuttering

• The approaches when together, give us a full picture of how genetics contribute to the presence of stuttering

Family Studies

• looks at whether stuttering occurs across relatives and whether there is a pattern of inheritance

• examination of family trees of individuals to determine the frequency and pattern of the occurrence of stuttering in relatives of PWS

• these studies can answer questions such as:

  • whether males or females are more likely to have children who stutter 

  • whether persistent stuttering as (opposed to natural recovery) is a trait that is inherited

Persistent Stuttering

• stuttering that lasts years after the onset or beyond age of natural recovery occurs

• some evidence also suggest that there may be more than one genetic mechanism involved in persistent stuttering

• process: interview individuals who stutter and who don't stutter and compare the results on whether which among the two have more relatives who stutter than don't stutter

  • compares family tree of PWS and people who don’t stutter and frequency of presence of stuttering in respective family trees

• geneticists know that certain inherited traits occur in specific patterns in families, and they ask whether stuttering follows a known pattern of inheritance

• despite the small number of studies and their limitations, family studies provided strong evidence for a genetic predisposition in many individuals who stutter

• one or more genes may carry the predisposition for the speech breakdown for children who begin to stutter, while an additional genetic predisposition may prevent or facilitate natural recovery

Males, Females

• Family Studies

  1. _ tend to be at more risk to develop persistent stuttering

  2. _ tend to recover from stuttering more easily

Genetic Predisposition

• means that there is an increased chance or likelihood that a person will develop a disease based on the genetic makeup

Twin Studies

• compares identical and fraternal twins to see how much genes versus environment matter when it comes to the presence of stuttering

• research on the co-occurrence of both members of a twin pair if one twin stutters

• questions such as whether identical twins show more concordance than fraternal twins can be answered, shedding light on the extent of the genetic basis of stuttering

Concordance

• if one twin has a condition, such as stuttering, the other twin also has the condition

• Identical twins (monozygotic twins) have completely identical genes

• Fraternal twins (dizygotic twins) only 25% of their genes are identical, like any other two siblings.

• Revealed 2 major findings:

  • Compared to fraternal, same-sex twins, identical twins show more concordance

Discordance

• Even though there is much concordance among identical twins, there are still many identical twin pairs where one twin stutters and the other doesn't

• These findings suggest that genes don’t work alone;

• The environment must interact with the genes to produce behavior in question, and even in twins, their environments (both before they are born and after) may not be as similar as they superficially seem

Adoption Studies

• examines whether stuttering is more common among biological relatives compared to adoptive families

• Investigation on adopted siblings who were adopted soon after birth and placed with different families 

  • Example: Magkapatid one of the siblings were adopted and then they were observed whether their stuttering behavior would appear 

• A higher stuttering among biological relatives than adoptive family members also provide evidence of a genetic basis of stuttering rather than an environment basis

  • It means that in a family that if there is an adopted relative and that adopted relative stutter more frequently than their biological relative it just means that its not a matter of environment anymore but it’s more of the genetic disposition 

• Few studies that have been done produce mixed results but one study found that although both heredity and environment play a role in the occurrence of stuttering, heredity plays a slightly stronger role (Felsenfeld,1977)

Genes

• Humans have between 25,000 and 35,000 genes

• _ are segments of DNA that determine various individual traits 

• Almost every cell in the body contains 23 pairs of chromosome (one of each pair from the mother and father)

• Genes associated with stuttering have been found on chromosomes 1,7,9,12,13,15,16, and 18

• One of these chromosomes has been shown to carry 3 genetic mutations, one of which is not associated with motor control and emotional regulation (Kang, Riazuddin, Mundorff, Krasnewich, Friedman et al., 2010.)

• According to genetic studies both persisted and recovered stuttering are associated with chromosome 9, but persistent stuttering by itself is associated with chromosome 15

• Studies in very different cultural groups have identified chromosome 12 as a significantly related to stuttering

  • Mutations of three different genes in these chromosomes have been identified as being associated with stuttering 

• Genetic influences of stuttering are very complex and involves multiples sites  and mutations when it comes to genetics

Chromosomes 1, 7, 8, 12, 13, 15, 16, 18

• Genes associated with stuttering have been found on chromosomes ..? (8)

• One of these chromosomes has been shown to carry 3 genetic mutations, one of which is not associated with motor control and emotional regulation

Chromosome 9

• According to genetic studies both persisted and recovered stuttering are associated with chromosome _

Chromosome 15

• persistent stuttering by itself is associated with chromosome _

Chromosome 12

• Studies in very different cultural groups have identified chromosome _ as a significantly related to stuttering

  • Mutations of three different genes in these chromosomes have been identified as being associated with stuttering 

DNA

• contains the “instruction book” that tells the body how to make various chemicals that determine characteristics  (e.g. eye color, height, weight, athletic ability, etc)

• Wrapped into worm-like structures called chromosomes

Congenital and Early Childhood Factors

• A physical or psychological trauma that occurs at or near birth that may be predispose an individual to develop stuttering

• According to studies it has been estimated that 30-40% of individuals who stutter have family histories of stuttering (Yari, Ambrose, Cox,1996)

  • For the remaining 40-70 percent these people may have been predisposed to congenital factors or also form events that may have occurred during early childhood 

  • There are relatively little research studies

  • In summary, studies revealed history of infectious diseases, anoxia at birth, childhood surgery, head injury, mild cerebral palsy , mild retardation and intense fear prior to the onset of stuttering 

  • Studies of young adults who had brain injuries had greater incidence of stuttering 

Infectious diseases, Anoxia at birth, Childhood surgery, Head injury, Mild cerebral palsy, Mild retardation and Intense fear prior to the onset of stuttering 

• Examples of Congenital and Early Childhood factors

Brain structure & function

• Whether an individual's stuttering results from an inherited predisposition or congenital factors, it seems likely that structures and functions in the central nervous systems would be different or “anomalous” for those who stutter

• We could say that _ _ and _ of individual is the bridge between the etiology of the disorder and the behavior of stuttering

Brain Structure Differences in people who Stutter

•  The areas of the left and right side of the brain of a person that may be involved in speech and language processing which includes:

  • Motor Cortex

  • Broca’s Area

  • Left auditory association area 

  • Wernicke’s area

  • Right frontal Operculum

  • Right insula

• Scientists tried to study what are the differences on the structures in patients who stutter vs those who not so studies between 2000 and 2007 measured shape, size, and density of speech and language areas studies revealed that sensory, planning, and motor areas developed differently as opposed to non-stuttering individuals

• Cykowski, Fox, Ingham, and Robin (2010) suggested that the most robust difference between Pws and non-stutterers is in left hemisphere fiber tracts that communicate between the inferior parietal cortex (sensory integration) with the ventral frontal cortex (motor planning). 

• authors found that in individuals who Broca's area stutter, certain nerve fibers aren't structured as effectively to conduct impulses along the directional flow of the nerve bundle; thus, conduction is not as fast as it might be

• For people who stutter they often show decrease white matter integrity in the left superior  longitudinal fasciculus (SLF) which is a critical pathway connecting auditory and motor areas for speech or the area responsible for providing sensory-motor integration for speech 

• both old and new studies show that

• PWS have a greater activity in their RH than in their LH, during both fluent and stuttered speech

• Neuroimaging studies showed a great deal of underactivation of LH structures typically active for speech, such as white matter tracts 

Less dense

• White matter tracts, which convey information from sensory centers of the brain and may store phonological representation of sounds to motor execution areas of the Left hemisphere is shown to be _ _ than normal speakers

• It is also found that for people their white matter tracts in the RH are denser 

Reduced volumes of gray matter around Broca’s area, Bilateral Temporal lobe

• both recovered and persistent stutterers had _ volumes of _ matter around the _ area

• As well as in the bilateral _ _ areas that may be related to auditory perception of speech (Chang, Erickson, Ambrose, Hasegawa-Johnson, & Ludlow, 2008)

Less dense white matter tracts

• The subgroup that persisted in stuttering showed _ dense _ matter tracts connecting phonological representations of sounds to speech motor execution areas, the same deficit as discovered in adult stutterers.

Left hemisphere fiber tracts

• Cykowski, Fox, Ingham, and Robin (2010) suggested that the most robust difference between Pws and non-stutterers is in _ _ _ _ that communicate between the inferior parietal cortex (sensory integration) with the ventral frontal cortex (motor planning). 

Underactivation of Left Hemishphere

• Neuroimaging studies showed a great deal of _ of _ structures typically active for speech, such as white matter tracts 

• These images show us a positron emission tomography or PET scan of brains of people who do not stutter (Left picture) and person who stutters (Right picture) while reading aloud 

• Statistical parametric mapping which is a quantitative neuroimaging method for analysing functional and structural brain data to identify differences in brain activity or tissue 

  • You can see that non stuttering speakers placed more activity on the left side of the brain whenever they read a loud 

  • For stuttering speaker there is a greater activity on the right side of the brain whenever they read aloud 

EEG studies

• PWS differ from non-stutterers in showing more activity on the right side of the brain in structures similar to those on left side active in non-stutterers

  • However after therapy or fluency inducing conditions causes imbalance shifts

  • PWS show more left-hemisphere activity during speech after treatment these suggests do not only change behavior but also change brain function fo people who stutter  

MRI and PET scans

• Neuroimaging methods like _ and _ scans reveal structural and functional brain differences.

  • Ex. Anomalous symmetry in planum temporal (part of Wernicke’s area) in PWS, less dense fibers in white matter tracts of left operculum

    • The left operculum is a key motor area for integrating planning and speech execution.

  • For PWS, there are usually anomalies observed in the areas involved in motor planning and speech execution.

• Overactivation of RH during speaking, especially during stuttering

• Deactivation of left auditory cortex during stuttering

• After either long-term or transitory fluency is induced, for example through therapy or speaking conditions, RH overactivity is reduced and left-hemisphere speech, language, and auditory areas are activated in these brain imaging studies.

  • This reinforces the idea that the brain is plastic and can be reorganized with intervention.

Sensory Processing

•  refers to the activity of the brain as it interprets information coming from the senses, such as sounds arriving via the ears and the auditory nerves.

Sensory-Motor Control

• is the way all movement is carried out with sensory information used before, during, and after to improve the precision of movement.

• It has something to do with sensory integration and being able to produce the necessary coordination and voluntary action of the muscles whenever our senses perceive sensory information.

Lack/absence or delayed feedback

• PWS abnormal speech as the result of the disturbance of feedback - normal speech depends on proprioceptive (position & movement) and tactile (touch) feedback.

  • Can either be caused by:

    • _/_ of feedback

    • _ feedback

  • The feedback provided by your sensory system is enough for you to be able to identify that the movement and the positioning of your articulators are correct and the tactile feedback provided your body is also telling you that how you’re speaking is correct.

Altered sensory processing

• _ _ _ as cause of stuttering

• Studies, which have _ _ processing (e.g. delayed auditory feedback), have created repetitions, prolongations, and blocks in normal speakers.

  • Ex. When you try to speak in a microphone with delayed auditory feedback, the voice that you will hear from the speakers is a little bit delayed which will somehow affect the way you speak.

Central Auditory Processing Studies

• These are studies conducted on how accurately and quickly PWS can identify and judge the duration of auditory signals as compared to non-stutterers.

• They have found out that PWS:

  • Have poorer central auditory processing, especially with regard to temporal information or timing

  • Are less accurate at identifying under noisy conditions.

  • Are poorer at judging duration of tones

Brain Electrical Potentials Reflecting Auditory Processing

• Brainwaves of PWS may have longer latencies (longer delays between stimuli and brain wave responses) and lower amplitudes (smaller brain waves) when listening to linguistically complex stimuli.

Dichotic Listening Studies

• Based on the Dichotic Listening Test by Kimura (1961).

  • This test simultaneously presented 2 different syllables (like “ba” and “da”) dichotically - a different syllable to each ear.

    • The sounds are presented on both ears and a different syllable is heard by the person on each ear.

• In the 1960s, this procedure was developed to assess hemispheric dominance for speech and language by testing which ear was more accurate in hearing speech sounds.

  • When we say hemispheric dominance, we would want to know which hemisphere of the brain is more active whenever we hear the speech sounds presented.

• Found out that auditory nerves connecting the ears to the cerebral hemispheres carry more information to the hemisphere on the opposite side than on the same side.

  • Normal Speakers: syllables presented to the right ear were most frequently reported as heard.

    • Left-hemispheric dominance

  • PWS: have less right-ear/left-hemisphere advantage.

    • We would assume that they would hear more sounds in the left ear.

    • More evident in severe stutterers, and more likely when stimuli are linguistically complex.

• This procedure is used to assess laterality between PWS and non-stuttering groups.

• However, these studies had conflicting findings, but most dichotic studies that used linguistic stimuli such as words and sentences, reported that PWS have reversed hemispheric dominance for the perception of speech.

  • Instead of being more left hemispheric dominant, PWS have right hemispheric dominance when it comes to speech perception.

Auditory feedback studies

• Demosthenes is an ancient Greek who stuttered and improved his speech by orating above the roar of the Mediterranean Sea.

• Masking noise, delayed auditory feedback, frequency shifts, and alteration in the other properties of the auditory signal can create temporary fluency in PWS (Van Riper, 1982).

  • In the case of Demosthenes, auditory feedback is affected because of the masking noise of the Mediterranean Sea which made his speech more fluent.

• Delayed feedback can create an artificial stutter for a normal speaker (Black, 1951; Lee, 1951).

  • When auditory feedback is delayed, it will seem as though you are more predisposed to stuttering.

• Explanations on the effect of altered feedback on the PWS (Bloodstein, 1995; Garber & Martin, 1977):

  • A distraction

  • Causes them to change how they talk

    • Prompts the stutterer to speak louder

  • Compensates for a defect in the auditory monitoring of their speech

Sensory-motor control

• Fluent speech depends on the _-_ _ of the muscles that move speech structures to produce airflow, voicing, and articulation in a coordinated fashion so that speech sounds are produced smoothly, in a specific sequence, and at a reasonable rate.

  • allows the body to move in coordination.

• Stuttered speech is caused by a disruption in the smooth, sequenced muscle contractions necessary for coordinated structural movements.

• Stuttering is a temporal disruption of the simultaneous and successive programming of muscular movements (Van Riper, 1971).

• Control of smooth movements of speech depends in part on sensory input and motor output.

  • Some brain studies would say that there would be differences in terms of brain structure that are responsible for the sensory inputs and motor outputs and that there would be problems in terms of sensory-motor control.

• In the principle of _-_ _, part of the control of any complex movement uses sensory information:

  • Where the structure is now

    • Are my articulators placed properly? Are they in the proper position?

  • Where it is going in order to produce just the right amount of contraction of all the muscles involved

• When the brain plans the movements needed to produce sounds:

  • It uses stored memories of past movements and their consequences in planning what must be moved;

    • When you speak, you don’t really plan where to position your articulators; you talk based on stored memories of past movements or what we call muscle memory.

  • When and how to produce the desired acoustic and perceptual result.

    • In terms of planning and movement, we need to be able to identify when and how to produce the desired perceptual and acoustic result, like if we want to make our voice louder, or to make it softer, there are specific movements and plans that our brain needs to send to our articulators.

Reaction Time Studies

• is the time between the appearance of the object on the screen and the first sound or movement made by the participant.

  • It involves the processing stages in a reaction time task:

    • Sensory Analysis - subject hears signal, sees image on screen, senses the position of speech structures and tension of muscles.

    • Response Planning - subject chooses word to say, selects phonemes and muscles to use.

    • Response Execution - subject activates muscles in proper sequence to say “bicycle”.

  • In the _ _ experiment, the participant is asked to watch the computer screen for a picture of an object and to say its name the moment it appears.

• Beginning in 1976, experimenters have shown that PWS (including children) of ten have slower response times than individuals who don’t

  • Both auditory and visual stimuli

    • Not just about picture scenes but also sounds heard

  • Responses involving initiating and terminating a vowel sound, pressing lips together, and making respiratory movements

• Differences were more significantly present when using linguistically meaningful stimuli

• Reflect the brain imaging evidence on anomalies in parts of the brain involving sensory-motor integration

Sensory analysis, Response planning, Response execution

Processing stages in reaction time task

1. subject hears signal, sees image on screen, senses the position of speech structures and tension of muscles.

2. subject chooses word to say, selects phonemes and muscles to use.

3. subject activates muscles in proper sequence to say “bicycle”

Fluent Speech

• Findings generally show that PWS have slower speech movements and sometimes have abnormal sequencing in the movement of their articulators

• Interpretation: 

  1. PWS have sensory-motor delays caused by abnormalities in the brain pathways

  2. These findings only reflect strategies that PWS use to be fluent

     • You would see that they would tend to have slower speech movements since they would use strategies to be more fluent

  3. PWS are slower in their speech production because, even in apparently fluent speech, they abnormally tense speech muscles

     • Some people who stutter, there would be tensing of muscles between the words that they say so this also affects their rate of speech production

• Researchers found more direct assessments of speech processing by examining the speed coordination of PWS’ speech movements when they are talking fluently and by analyzing the sound waves of their fluent speech

Non-Speech Motor Control

• Researchers began to examine complex motor coordination of nonspeech muscles and structures

• Apart from observing people who stutter speak whenever they communicate or use words, they were also observed whenever they use nonspeech movements

• Advantages:

1. It eliminates the effect of stuttering itself that may contaminate measures of speech movement

2. Complex motor coordination, such as sequential finger movements, appears to be planned and organized by areas of the brain, such as the supplementary motor area (SMA), which is also involved in the sequential articulatory movements of speech (Goldberg, 1985)

   • This way, they are able to eliminate the speech factor, but still they can assess the supplementary area of the brain

   • A number of studies shown that in various non- speech tasks such as tapping with fingers in a prescribed sequence, PWS are slower than non-stutters

   • Even in non-speech motor tasks, they tend to be slower as compared to non stutterers

     • May be significantly slower in the initiation of the sequence of taps

     • More severe stutters ay be notably slower than mild stutters or non-stutters

     • Also suggested that RH activity may interfere with stutter’s dominant (right)-hand sequential finger tapping, which requires input from the LH

       • If they use their right hand (especially if they are right-hand dominant), it would require input from their LH

   • Another study suggested that PWS optimal tapping rate was slower than that of non-stutterers

   • However, when instructed to tap at a fast rate, PWS could tap very fast but became highly unstable (high degree of variability) when doing so (Subramanian & Yairi, 2006)

   Study of children’s hand clapping - group of children who stuttered was highly variable compared to children who didn’t when clapping their hand at a specified rate (Olander, Smith, & Seleznik, 2010

Language development, language delays, language complexity

• Language Factors

• The influence of language on stuttering is threefold:

Language Development

• The rapid language acquisition that occurs in all children between the ages 2 and 5 places high demands on brain resources

• Stuttering usually begins at the very time when language growth is greatest (Bloodstein & Ratner, 2008)

• Yairi & Ambrose (2005) reported that in more than 50% of their sample in stuttering children, parents reported the onset of stuttering during a sudden increase in a language development

  • Most parents reported that when they see their children are starting to talk or develop language skills, they then notice disfluencies and stuttering behaviors

Language delays or disorders

• May precipitate or worsen the stuttering because they deal with two deficits:

  • Speech motor control

  • Language problem

• This may cause children who stutter to divert resources or attention away from compensating for the speech motor control to deal with the language problem

  • In effect, there is some way of compensation that is happpening so instead of focusing on correction for the speech motor control, their brain resources are more focused on the language deficit

• Meta-analysis of 22 students that compared language ability in samples of stuttering and non-stuttering children (Ntourou, Conture, & Lipsey, 2011)

  • 4 language measures differed in these two groups: overall language, receptive vocabulary, expressive vocabulary, and mean length of utterance

  • Production of speech disfluencies - revisions, hesitations caused by difficulties in encoding & retrieving lexical items

Language Complexity

• More stuttering occurs in more complex sentences;

• Stuttering is influenced by linguistic factors such as lexical class of word, length, and location in a sentence

  • Certain grammatical word types (e.g. nouns and verbs), longer words, and words at the beginning of an utterance are more likely to be stuttered

• More linguistically complex stimuli result in poorer performances by stuttering on many performance tasks

Emotional Factors

• Relationship between emotion and stuttering varies among individuals

• For some, emotions may be an important etiological factor that triggers the onset of stuttering

  • The relationship between emotion and stuttering varies between individuals

• The experience of stuttering generate motions such as frustration, fear, and anger in everyone who stutters

• Emotional arousal may cause stuttering, but some may also cause emotional arousal

Anxiety and Autonomic Arousal

• Research about anxiety and stuttering have been ongoing for more than 50 years

• Many studies find that PWS are not more anxious than non-stutterers, but a few indicate they are more anxious

• There is evidence that changes in speech-related physiology occur in PWS but non-stutterers under conditions of anxiety

• Studies showing physiological measures of anxiety also showed PWS and non-stutterers to be equally anxious, but only PWS showed effects in speech in terms of disfluencies

Anxiety

• Generally describes a state of alert, concern about a future event

• If you watch the movie Inside Out, Anxiety usually shows alertness whenever he thinks ahead of a possible event that might happen

Autonomic arousal

• Denotes activation of the sympathetic nervous system, which prepares the body for action such as fight-or-flight response

Temperament

• Aspects of individual’s personality, such as sensitive versus thick-skinned, that are thought to be innate, rather than learned

• There is some evidence that PWS tend to have a more sensitive or inhibited temperament

• There is speculation that this may be related to RH activity associated with stuttering

  • Their RH is more active and in charge of our emotions and affect

• Sensitivity may influence physical tension

  • Which influences stuttering

Persistent stuttering

• If the child still stutters beyond 6 years old.

Developmental Factors

• It has something to do with the development of everything.

  • Physical and Motor Skills development 

  • Speech and Language Development

  • Cognitive Development

  • Social and Emotional Development

• Our view of how developmental factors affect children’s fluency assumes that there is in the growing child a competition for neural resources.

  • It is a concept that the brain has a limited amount of resources that can be applied to tasks such as learning to speak and learning to walk.

    • The brain is not yet well developed, thus the capacity to allot resources to different demands is limited.

  • If some tasks require a great deal of attention or neural activity, other tasks would have fewer resources and may thus be less well performed.

    • It is how you would distribute the cognitive demands.

    • It is how the brain would allot resources for different demands.

    • The problem of shared resources is more acute in children because their immature nervous systems have less processing capacity to share.

    • Some children are especially at risk for straining their developing resources.

      • Their speech and language skills may be delayed, yet they have to compete in a highly verbal environment.

Physical and Motor Skill Development

• Between ages 1 and 6, children grow, their bodies get bigger and their nervous systems form new pathways and new connections.

  • Their perceptual and motor skills improve with maturation and practice.

  • Their brain has not yet matured.

• Neurological maturation may provide more functional cerebral space that supports fluency, but it also spurs development of other motor behaviors that may compete with fluency for available neuronal resources.

  • There are other skills that the brain allots its resources, not only fluency.

  • Examples:

    • Children learn to walk or talk first but not at the same time.

      • Children learn how to talk first.

• The practice of walking or talking seems sufficient to tie up all the available sensorimotor circuitry because the toddler seldom, if ever, undertakes both activities at once (Netsell, 1981).

  • You do not see a child who talks and walks at the same time.

• When infants forge ahead in spoken language, they seem to temporarily postpone mastery of new motor skills or vice versa (Berk, 1991).

  • There is a delay in terms of motor skills.

• The learning of motor control of speech by itself, even without acquisition of other motor skills at the same time, puts enormous demands on the child’s brain.

• Speech development in children draws on a number of anatomical, motor, sensory, and cognitive resources.

  • Ultimately, these various factors need to be integrated to account for a child’s progress toward the faculty of speech (Kent & Verperian, 2007).

• Another problem for children who stutter may be delays in motor development.

  • Bloodstein and Ratner (2008) cited several studies that have found children who stutter to be somewhat delayed as a group compared to nonstuttering children.

  • In terms of case history, particularly in the child’s developmental history, they would notice that children have delayed skills in terms of development.

Onset of Stuttering

• Speech and Language Development

• Most stuttering begins between the ages 2 and 4, a time when children acquire new sounds and learn new words almost by the hour (Bloodstein and Ratner).

  • Stuttering usually dissolves at age 6.

Recent findings with children who stutter suggest that areas of the brain used for integration of articulator planning, sensory feedback, and motor execution are compromised (e.g., Chang, Erickson, Ambrose, Hasegawa-Johnson, & Ludlow, 2008).

• Motor planning is usually affected since the child’s articulators do not have proper contact.

• Thus, planning and production of speech and language may use atypical neural pathways that may be slow or inefficient.

  • The flow of impulses are slower.

• As a child produces longer, faster, and more complex sentences = greater demands.

• Tasks using different neural networks for segment selection, grammatical formulation, and prosodic planning must be orchestrated precisely so that each element is in place at the proper time as utterances are produced

  • For them, it is an extra additional task and their brain is not capable of holding it all together.

• If some components are ready but others are delayed, initial sounds or syllables may be repeated, prolonged, or even blocked, waiting for the whole sentence to be put together in the brain.

• Speech traffic jam → development of maladaptive learning, or development of compensatory strategies paving way to normal speech.

  • This is the reason why there would be kids that would pronounce speech sounds in a different manner, although it is still considered as normal speech.

Delayed and Deviant Speech & Language Development

• It is important to understand how delays in speech and language development might be related to the appearance of stuttering or disfluency.

• In general, research has found that speech and language delays or difficulties are more common among children who stutter than those who do not.

  • However, this doesn’t mean that every child who has a language delay, they are already stuttering.

  • Findings are not clear cut or conclusive, and implications are unclear.

• Delays in language development may be related to stuttering because children with delayed language may become frustrated at their difficulty speaking, develop fears related to speaking, and thus learn to stutter as an anticipatory avoidance response (Bloodstein & Ratner, 2008).

  • They would feel frustrated and would not talk since they would stutter.

  • They develop anticipatory behaviors while stuttering.

• Example: A child with a gap between vocabulary development and growth of syntactic syntax skills.

  • Syntactic skills = sentence formulation

    • The child isn’t able to form sentences despite enough vocabulary → they would not want to speak.

Cognitive Development

• It refers to the growth of perception, attention, working memory, and executive functions that play roles in spoken language but are separate from it.

  • The cognition of children is already starting to be developed and they are now undergoing cognitive growth.

• There are 2 ways on how it affects stuttering:

  • Spurts in cognitive development may accompany the onset of stuttering as well as sudden increases in stuttering

    • A child's cognition improves → they develop greater self-awareness of their disfluencies → they would stutter more.

  • As a child who stutters develops more advanced cognitive abilities, he is more likely to  become aware and even self-conscious of that stutter specifically at the age of cognitive development.

Cognitive Development and the Onset and Fluctuation of Stuttering

• Parents would report onset of stuttering of their child’s stuttering occurred under most normal of circumstances—no extra stresses in the household and no apparent increase in child’s anxiety.

• We have to consider the child’s cognitive development.

• Learning to think may make great demands on cognitive-linguistic abilities, leaving fewer resources available for rapid production of fluently spoken language

Cognitive Development and Reactions to Stuttering

• The role of cognitive development is important in explaining how and when a child begins to form negative attitudes and beliefs about him/herself about his/her speech.

• Between ages 3 and 4, children’s cognitions mature enough so that they internalize the standards and behaviors of those around them, including peers (Fagan, 2000).

  • They tend to compare themselves to other kids.

• It is at this point that all children can evaluate how they are performing in comparison to others and will experience the "self-conscious" emotions of embarrassment, pride, shame, and guilt.

  • They think that if they are stuttering, it is something wrong.

• Once children who stutter compare their speech with others, they are likely to conclude that they are doing something wrong.

• Studies:

  • Awareness in stuttering in puppets at age 3 for some, most are not aware until age 5.

    • They used puppets then they studied them, they made the puppets stutter on purpose to see how the child would react.

    • It has something to do with the children’s reactions to stuttering.

  • Most children at 4 showed a preference for fluent speech, suggesting a negative evaluation of disfluent speech.

    • They already have a concept of stuttering and they can already distinguish it from fluent speech.

Interference with Speech by Emotion

• Social and Emotional Development

• The same sort of interference by emotion may be even more prevalent in early childhood, because a child’s speech and language neural networks and structures are immature, not fully myelinated, and may not be buffered from “cross talk, ” or interference by the limbic (emotional) system structures and pathways involved in the regulation and expression of emotion.

  • Cross Talk - someone is talking at the same time as the child.

  • Their neural structures are not yet developed.

• Lower maturing speech and language functions may not be optimally localized or adequately insulated from interference and may be closer to centers of emotion in the right hemisphere.

  • Thus, when children are emotionally aroused, fluency may suffer because neural signals for properly timed and sequenced muscle contractions may be interrupted in some way.

  • When the child feels extreme emotions, it would result in stuttering.

• Excitement is commonly mentioned in the literature as a  that elicits disfluency.

  • All children speak more disfluently when they are excited (Starkweather, 1987).

    • Children tend to repeat words when they are excited.

  • Dorothy Davis (1904), reported that of the 10 situations in which children showed  repetitions in their speech, excitement over own activity was when they most frequently repeated sounds and words.

  • In a study by Joshnson & associates (1959), the parents most often reported that the first appearance of stuttering occurred when the child was in a hurry to tell something or was in an excited state.

• Both stuttering and normal disfluency seem to occur most often or noticeably during states of transitory emotional arousal

  • There is a change of one emotion to another.

Stages of Social and Emotional Development

• Some stages of development may provide more social and emotional stress than others.

  • Examples:

• Processes of separation and individuation

• Transition from a dependent infant to an independent preschooler

  • The child will be left alone to do things on their own.

• Emotional ambivalence and conflict affect motor control of speech (Lidz, 1968).

Emotional security

• A child’s resentment at having to share his mother’s attention may elicit feelings of anger, aggression, and guilt.

  • Example: Feeling resentment because of the birth of a sibling 

• Many threats to feelings of security can create emotional stress that may disrupt speech of children who are predisposed to stutter.

  • Children are more likely to develop stuttering due to this.

Self-Consciousness and Sensitivity

• It reflects the child’s growing awareness of how he is performing relative to adult expectations.

  • Their awareness also develops and it goes hand in hand with their cognitive development.

• The self-corrections a child makes in his speech are evidence of this self-awareness.

• Increasing self awareness in a child who is excessively disfluent might lead to self-corrections and stoppages that only worsen the problem.

  • This is related to the diagnosogenic theory.

• People who stutter as a group may have unusually sensitive temperaments.

• Social-emotional traits of fearfulness and withdrawal that accompany more sensitive temperaments can change over the course of a child’s preschool years (Kagan & Snidman, 1991; Calkin & Fox, 1994).

• Some children become better able to modulate their temperamental tendencies, but others do not.

Parents

• Environmental Factors

• Some studies produced mixed results.

  • Some indicate that parents of stutterers are more anxious or more rejecting, while others find no differences.

    • Such as in a fast-paced household where a child should not make any mistakes, this might worsen their stutter.

• On balance, it seems likely that some children who stutter grew up with parents who were a little more demanding or anxious than average.

• In some cases a child’s hypersensitivity to parents’ concern and their increased tension as a response to their disfluencies is a component of an overall vulnerable temperament found in some children who stutter (Anderson, Pellowski, Conture, & Kelly, 2003; Karrass et al., 2006; Oyler & Ramig, 1995).

  • Their environment is not safe anymore, which may lead to disfluencies.

• Some parents may have an ameliorating effect on a child’s temperament, making it possible for a child who begins to stutter and who is emotionally reactive to recover from stuttering.

  • When some parents become caring, their child’s confidence will increase, thus they will have a better outlook on life and it will be less likely that they will persist stuttering.

Speech and Language Environment

• The communication style that characterizes people in a child’s environment—usually his home.

  • The child’s communication at home is a part of their speech and language environment.

    • Examples: Some parents, siblings, and other relatives of a child may speak very rapidly, use advanced forms or language, or interrupt the child frequently; some family members may be forgiving and supportive of the child’s speech and language development.

• These aspects of the speech and language environment are thought to stress the child.

Stressful Adult Speech Models

Rapid speech rate	Complex syntax
Polysyllabic vocabulary	Use of two languages in home

Stressful Speaking Situations for Children

Competition for speaking	Hurried when speaking
Frequent interruptions	Frequent questions
Demand for display speech	Excited when speaking

Life events

• There are happenings in a child’s life that may stress them.

  • Examples: 

    • Parents’ divorce

    • Being hospitalized

    • Death of someone close or a loved one

      • These can trigger the start of stuttering.

• Kagan (1994a) noted that some children who begin life with relaxed temperaments may even become shy and fearful under the onslaught of stressful events.

• There is little research on the rs between stressful life events and stuttering, but many authors have observed the connection.

  • Psychogenic stuttering is a condition where the cause of stuttering is a traumatic event.

• All children speak more disfluently during periods of tension–—when moving or changing schools, when their parents divorce, or after the death of a family member (Starkweather, 1987).

• Johnson and associates (1959) noted that the following events were among the 16 situations in which parents first noticed their child’s stuttering: 

  • Child’s physical environment changed (e.g., moving to new house) 

  • Child became ill

  • Child realized his mother was pregnant

  • A new baby arrived

Other Examples of Life Events that may Precipitate Stuttering

1. The child’s family moves to a new house, a new neighborhood, or a new city.

2. The child’s parents separate or divorce.

3. A family member dies.

4. A family member is hospitalized.

5. The child is hospitalized.

6. A parent loses his or her job.

7. A baby is born, or a child is adopted.

8. An additional person comes to live in the house.

9. One or both parents go away frequently or for a long period of time.

10. Holidays or visits occur, which cause a change in routine, excitement, or anxiety.

11. A discipline problem involving the child.

Classical conditioning

• Learning factors

• This is exemplified by the famous dog-bell experiment by Pavlov in 1897.

• It is the repeated pairing of a neutral stimulus (such as a person) with a stimulus (a humiliating long stutter) that elicits a response (such as fear), so that the neutral stimulus eventually elicits the response.

• For classical conditioning to take place, several things must occur:

  • A stimulus that reliably elicits a response must be present.

    • This stimulus is called the unconditioned stimulus (UCS), and the response it elicits—often a reflexive or hardwired response—is called an unconditioned response (UCR).

      • Example: You have associated a specific experience with a specific person; you get anxious every prax because you have already associated it with the previous prax.

  • Then a neutral stimulus that doesn’t elicit any particular response must be paired with the UCS.

• The neutral stimulus is called the conditioned stimulus (CS) because it will be conditioned to elicit a response.

• After repeated pairing of the CS with the UCS (which reliably elicits the UCR), the CS is then presented without the UCS, and voila! The CS elicits the UCR.

• This process explains the spread of stuttering to more and more situations and words.

• Stuttering treatment can break this link with procedures like desensitization, which pairs the old behavior that elicited fear (e.g., a long stutter) with a different response (e.g., the clinician’s positive interest in the client’s long stutter).

Operant conditioning

• It is following a behavior with a reward or punishment so that the behavior becomes more frequent (if rewarded) or less frequent (if punished).

  • Example: Every time a child stutters → they receive a punishment → their stutter worsens.

    • More stutter → more escape and avoidance behaviors.

• This explains why stuttering behaviors become more and more abnormal as the child stutters more.

  • Although this can be a powerful treatment as well.

Avoidance conditioning

• This type of learning occurs when a person uses a behavior to try to prevent an unpleasant occurrence by doing something.

  • Children who stutter use interjections when they feel like they will stutter because it is effective.

• It is perpetuated by the successful prevention of the unpleasant experience, at least some of the time.

• In stuttering, avoidance conditioning may begin when a person first escapes from a stutter by saying an extra sound or word (like “uh”). Then he may make that sound even before saying the feared word, like “uh, can I have some pizza?”