Language and stuttering

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Language and stuttering
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Overview

• Language factors in models of stuttering
• Linguistic factors that affect the frequency and
  loci of stutter events
• Language factors in the development of stuttering
• Language factors that affect fluency treatment in
  children
• Language disorders and disfluency

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• Ways to think about Fluency and Language

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Extant models of stuttering

• Most of the available models of stuttering assume
  a mature linguistic and motor system (i.e., The
  Covert Repair Hypothesis Postma Kolk, 1993
  the Neuropsycholinguistic Theory Perkins, Kent
  Curlee, 1991).
• The major developmental theory (Capacities
  Demands Adams, 1990 Starkweather Gottwald,
  1990) proposes limits in the childs ability to
  integrate linguistic and motor functions, but
  lacks evidence of the specific limitations that
  predispose to stuttering.

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A Multifactorial Model of Stuttering in adults
(Smith, 1999)
Cognitive proc.
Language
Cognitive
Language proc.
Language
Motor
Cognitive
NOT
Pre-motor plan
Patterned output emerges from the interaction of
multiple systems
Motor output is the result of various stages
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Linguistic effects on motor function Use of the
spatial-temporal index (STI) to assess
interactions among systems
Is there evidence of an underlying template of
movement, despite trial to trial differences in
duration and amplitude? Smith Weber-Fox, ASHA
1999
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The STI decreases with age. Adults are
highly reliable pattern generators from trial to
trial. Thus we can use the STI as an index of the
depth of the attractor. Adults have a very stable
attractor for this utterance. Children are less
stable than adults even at age 12.
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Childrens (five-year olds) speech motor
output is negatively affected by increasing the
length and complexity of the utterance. The STI
increases when the phrase buy bobby a puppy is
embedded in a complex sentence.
Maner, K., Smith, A., Grayson, L. (2000).
Influences of length and syntactic complexity on
speech motor performance of children and adults.
Journal of Speech, Language, and Hearing
Research. See also J. Kleinow A. Smith (2000)
same issue.
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The speech motor output of adults was not
adversely affected by embedding the phrase in a
longer, complex sentence.

Maner, K., Smith, A., Grayson, L. (2000).
Influences of length and syntactic complexity on
speech motor performance of children and adults.
Journal of Speech, Language, and Hearing
Research.
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But, adults who stutter show motor stability
effects when linguistic complexity is increased
(Kleinow Smith, 2000 -- example of AWS.)
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From adults to children Problems in modeling
stuttering onset

• Although stuttering is widely viewed as a
  disorder of speech motor control, abnormalities
  in speech motor function are not seen in early
  stages of the disorder, and become apparent only
  later (Kelly, Smith Goffman, 1995).
• Stuttering is not present at the onset of
  language acquisition, but has its onset after
  children develop rudimentary syntax (Bernstein
  Ratner, 1997).

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Additional concerns for models of stuttering onset

• Psycholinguistic models of stuttering and normal
  disfluency predict moments of fluency breakdown,
  but NOT THE TYPES witnessed in early stuttering,
  which are characterized by struggle and awareness
  of speech difficulty.
• Stuttering is thus distinct from other childhood
  communicative disorders, in which childrens
  abilities are impaired from onset, and children
  show little awareness and reactivity to their
  impaired output.

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Some data Linguistic factors at stuttering onset

• Language screening scores predict chronicity
  (Yairi, et al., 1996)
• Onset during rapid period of language growth
  (lexical spurt, morphological acquisitions)
• Stuttering gravitates toward grammatically
  incorrect productions, utterances with higher
  TTR, MLU.

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• Other language findings at stuttering onset

• Stuttered utterances have higher MLU, TTR and
  show developmental formulation errors (Bernstein
  Ratner, 1998)
• CWS have lowered expressive lexicon, and shorter
  utterances (Bernstein Ratner Silverman, 1998)
  in general, evidence of sub-clinical linguistic
  weaknesses is emerging (Conture colleagues)
• CWS show atypically heightened self-monitoring of
  speech, as measured by response to DAF (Razzak
  Bernstein Ratner, 1999)

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Linguistic properties of stuttered events across
the lifespan

• Phonetics
• Syntax
• Lexicon
• Metalinguistics
• Trade-offs among domains and fluency

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• Phonetic factors in stuttering

• Phonetic factors
• impossible to separate from word frequency
  factors
• may differ across languages in bilingual
  stuttering, suggesting higher-order determinants
  (Bernstein Ratner Benitez, 1985)
• Phonological factors
• word-initial loci consistent with phonological
  distinction between onset and rhyme in encoding
  of word forms
• Stress
• recent evidence suggests that relationship of
  lexical stress to stuttering is conflated with
  word frequency patterns in English
• Possible interactions with syntax at onset (i.e.,
  Wh-words), with subsequent motor learning effects

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• Other considerations - phonology

• At onset, no evidence of phonological disorder
  (Yairi, et al, 1996), though persistent cases may
  show phonological delay (Louko).
• Stuttering does not appear to gravitate toward
  late-acquired ("difficult") or errored phonology
  (Throneburg, et al., 1995), possibly because
  other factors are more important
• No evidence of motor abnormalities in young
  children (Kelly, Smith Goffman), suggesting
  non-motor based origin for early stutter moments

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How syntax affects fluency
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• Does Length or Syntax determine the frequency of
  stuttering?

• Syntactic complexity more highly correlated with
  utterances stuttered (r .954) than is length (r
  .701) (Bernstein Ratner Sih, 1987)
• MLU a better predictor of stuttering than
  syllable length of utterance (Brundage
  Bernstein Ratner (1989)
• DSS less well correlated with stuttering than
  utterance length, but both are strongly
  associated with frequency of stuttering (Logan
  Conture, 1995)

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• A sample syntactic hierarchy

Sentence type Sample Sentence and order 1.
Simple active declarative The boy found the
lady. 2. Negative The boy didn't find the
lady. 3. Question Did the boy find the
lady? 4. Passive The boy was found by the
lady. 5. Dative The boy found the lady a
chair. 6. Prepositional phrase The boy found
the lady with the red hair. 7.
Coordinate w. forward The boy is finding a
lady or a man. reduction 8. Right-embedded
relative clause We had thought that the boy
found the lady. 9. Left-embedded
relative That the boy found the lady was a
lie. 10. Center-embedded
relative The chair that the boy found the lady
was broken.
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• Stuttering loci in children

• Stuttering most likely to be utterance- and
  clause-initial
• Stuttering loci primarily at syntactic
  constituent boundaries (i.e., before NP, VP, PP,
  etc.) (Bernstein, 1981 Bloodstein Gantwerk,
  1967 Bloodstein Grossman, 1981 Wall, et al.,
  1981)
• Syntactic loci remain constant across languages
  in bilingual adults, while phonetic loci vary
  (Bernstein Ratner Benitez, 1985 Newman, 1990)
• Syntactic effects on fluency appear to decline in
  adolescence (Silverman Bernstein Ratner, 1997)

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Lexical access and fluency
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Formulation difficulty and stuttering

• There are strong interactions between fluency and
  grammaticality (stuttering children) in
  spontaneous speech (Bernstein Ratner, 2000)

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Implications for stuttering therapy

• If language demand affects fluency in children,
  what does this imply for diagnosis and
  therapeutic planning?

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Self-monitoring and early stuttering - DAF
responses Children who stutter - responses are
slightly heightened
Difference between conditions significant at t
-2.32 p .05
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DAF responses Children who do not stutter
(Razzak Ratner, ASHA, 1999)
Difference between conditions non-significant
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A developmental model of early stuttering
(Bernstein Ratner, 2000 and in prep.)
Hyperfunctional self-monitoring
Linguistic fragility
Awareness struggle
Disfluency
Learning/development of secondaries
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Language disorder and fluency

• A growing literature suggests that children with
  SLI differ from typically developing children in
  fluency of verbal output (Hall, et al., 1993
  Hall,1996 Boscolo, Ratner Rescorla, 2002
  Miller et al., ASHA,2001). Because of growing
  concern that a standard set of linguistic
  features may not suffice to identify SLI
  cross-linguistically (Leonard, 1998), the
  potential of extra-linguistic factors in
  diagnosis of SLI is of practical research and
  clinical value.

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Data from a longitudinal study of SLI children

• The following data derive from 34 pairs of
  children followed longitudinally by Rescorla
  (1989) and her colleagues (e.g., Rescorla
  Schwartz, 1990 Rescorla Ratner, 1996
  Rescorla Fechnay, 1996) from ages 2 to 13.
• In each group, half of the children had been
  identified as late talkers/SLI-E, while the
  others were identified as typically-developing.
• For these analyses, there were 14 pairs of
  children at age 3, 12 pairs of children at age 5,
  and 22 TD/30 LT children at age 9.

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Method

• At ages 3 and 5, children were engaged in
  15-minute play sessions with their mothers at
  age 9, they produced a narrative in response to
  Frog, where are you?
• Data were transcribed in CHAT, with fluency codes
  to indicate place and nature of fluency
  breakdown.
• The following types of disfluencies were
  considered normal filled and unfilled pauses,
  phrase revisions and repetitions
• The following types of disfluencies were
  considered stutterlike disfluencies (Yairi et
  al., 1996) blocks, broken words, part and whole
  word repetitions, prolongations of consonants.

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Disfluency rates - age 3
Note distribution of Stutter-like Dysfluencies
(SLDs) statistically different between groups by
Kolmogorov-Smirnov Test For Different
Distributions
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Results Age 5
No statistical differences between groups.
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Results age 9

• As reported in Boscolo, et al. (2002), by age
  nine, frequency of SLDs was significantly
  different (p lt.02) for children who had started
  as late talkers. These children had nearly twice
  the rate of SLDs per 100 words as their typically
  developing peers.

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Summary group fluency effects

• Collapsed across the age range, SLDs were
  significantly more likely to be found in the
  speech output of children with a history of late
  expressive language development (p lt.019,
  Mann-Whitney-Wilcoxon), whereas overall
  disfluency rates and normal disfluency types were
  only slightly more frequent in the speech of
  these children than their typically-developing
  peers. SLD rates were statistically elevated in
  LTs at ages 3 and 9.

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• There was also a large range of disfluency rates
  unique to the late-talking groups, suggesting the
  potential for individuals in these groups to be
  misdiagnosed as having a clinical fluency
  problem.
• At ages 3 and 5, a total of four different
  late-talking children had SLD scores in excess of
  the typical 3 diagnostic cut-off for stuttering
  (Yairi, et al., 1996), while at age 9, one
  additional child approached this level of SLD
  frequency in spoken output.

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Discussion

• Our findings confirm that children with SLI-E
  demonstrate substantially more disfluency in
  spontaneous conversation, including some types of
  disfluency more typical of stuttering, rather
  than typically fluent, children, although no
  child in the study demonstrated clinical
  stuttering, as defined by the presence of
  struggle, accessory behaviors or self-image as a
  child who stutters.
• Similar data have been reported by Hall (1996)
  and Hall, Yamashita Aram (1993).
• What are the ramifications for clinical practice?

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• Specifically in regard to the distinct patterns
  of fluency breakdown observed in our sample of
  children with SLI-E, results concur with those of
  Miller et al. (2001) that fluency profiles may be
  useful in compiling profiles of SLI, when
  combined with other assessment measures. These
  data add to ongoing work that suggests a high
  degree of overlap in the linguistic, fluency and
  phonological abilities of very young children
  having primary language and fluency disorders
  (Ratner, in press).