Examining the Role of Processing Limitations in SLI

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Examining the Role of Processing Limitations in
SLI

• Susan Ellis Weismer
• University of Wisconsin-Madison

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Funding Acknowledgment

• NIDCD P50 DC02746 (J. Bruce Tomblin, Director
  Ellis Weismer, Subcontract PI)
• NIDCD T32 DC05359 (Ellis Weismer Kent, PIs)
• NICHD, Grant P30 HD03352 (Waisman Center Core
  Grant)
• University of Wisconsin Graduate School Research
  Committee Award (Project 020856)

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UW-Madison Project Staff

• Chris Hollar, Research Specialist
• Heather Lohmeier, Research Specialist
• Bryn Borgh, Associate Research Specialist
• Susan Bunton, Associate Research Specialist
• Maura (Jones) Moyle, Project Assistant (PhD)
• Beth Roos, Project Assistant (PhD)
• Student hourly assistants Laurie Eisenband,
  Molly OShea,
• Erin Green, Jordan Scheid, Nicole Schad
• UW-Madison Statistical Consultants
• Associate Professor Daniel Bolt
• Professor Mary Lindstrom

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Theoretical Accounts of SLIProcessing Limitation
Deficit

• Temporal Processing
• Generalized Slowing hypothesis
• Phonological Storage
• Limited Processing Capacity in Working Memory
• Executive Function deficit

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Processing Limitations in SLI Claimed to Account
for Deficits in .

• Speech perception (Tallal and colleagues)
• Vocabulary development (Adams Gathercole, 2000
  Gathercole Baddeley, 1990)
• Nonword repetition (Gathercole et al., 2005)
• Novel word learning (Ellis Weismer Hesketh,
  1996)
• Grammatical comprehension (Bishop, Adams,
  Rosen, 2006 Deevy Leonard, 2004 Montgomery,
  2000)
• Morphological/syntactic production (Riches,
  Faragher, Conti-Ramsden, 2006)

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Processing Limitations in SLI Claimed to Account
for Deficits in .

• Mathematical abilities (Cowan et al., 2005
  Fazio, 1994, 1999)
• Performance on nonverbal tasks (Miller, Kail,
  Leonard, Tomblin, 2001 Bavin et al., 2005)

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Cognitive Processes Investigated Relative to
Processing Limitations

• Auditory temporal processing
• Speed of processing
• Phonological storage
• Working memory verbal/visuospatial
• Executive function dual processing, attentional
  control mechanisms, response inhibition/suppressio
  n, generativity

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Theoretical Models of Information Processing and
Memory

• Generalized speed of processing (Kail, Salthouse)
• Multiple-component model of WM (Baddeley,
  Gathercole)
• Embedded-processes model of WM (Cowan)
• Capacity theory of comprehension (Just,
  Carpenter)
• Alternate view of verbal WM (MacDonald,Christianse
  n)
• Propose that processing capacity is not
  distinct from long-term linguistic knowledge

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Broad Research Aim

• Determine the role of processing limitations in
  specific language impairment, with a primary
  focus on working memory
• Cognitive Processes phonological storage,
  verbal and spatial complex WM, executive function
  (dual processing and allocation of attentional
  resources)

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Prior Findings for School-age Children with SLI

• Reduced WM on a listening span measure
• Problems with dual processing, such that their
  competing listening scores were
  disproportionately poorer than their
  non-competing scores compared to NL controls
• Deficits in nonword repetition interpreted as
  reflecting limitations in phonological WM
• (Ellis Weismer, Evans, Hesketh, 1999 Ellis
  Weismer Thordardottir, 2002 Ellis Weismer et
  al., 2000)

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Functional MRI Investigation of Verbal WM in SLI

• Combined use of neuroimaging and behavioral
  techniques
• Do children with SLI exhibit atypical patterns of
  neural activity during a verbal working memory
  task compared to NL controls?
• Ellis Weismer, Plante, Jones, Tomblin (2005)

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fMRI Investigation Findings

• Behavioral data
• Large group difference in word recognition
  accuracy
• SLI group exhibited longer RTs than NL group
  during encoding of high syntactic complexity
  items
• Ellis Weismer et al. (2005)

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fMRI Investigation Findings

• Imaging data
• SLI group displayed hypoactivation in regions
  implicated in attentional control mechanisms
  (PAR) and memory (PRCS), as well in an area
  implicated in language processing (IFG)
• Atypical patterns of co-activation among brain
  regions
• Support claim of constraints in nonlinguistic
  systems
• Ellis Weismer et al. (2005)

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Processing Capacity Limitations in SLI Part II
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Midwest Collaboration on Specific Language
ImpairmentNIH P50 DC02746J. Bruce Tomblin,
Director

• Project 2
• Limitations in Processing Capacity

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Epidemiologic Longitudinal Study of SLI

• Population-based sample of children with SLI
  identified at kindergarten (5 years old)
• Language, cognitive and social assessments
  conducted at 2nd, 4th, 8th, and 10th grades

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Sample(N527) 8th grade diagnosis

• SLI - normal cognition, low language (n59)
• NLI - low cognition, low language (n80)
• NL - normal cognition, normal language (n316)
• LC - low cognition, normal language (n72)

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Sample(N504) 10th grade diagnosis

• LI - language impairment, SLI NLI (n139)
• NL - normal language (n365)

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• Do adolescents with LI (SLI/NLI) exhibit
  limitations in verbal WM?

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Processing Capacity Tasks

• Verbal WM
• - WJ-III Auditory Working Memory subtest
• - Nonword Repetition Task, NRT
• - Competing Language Processing Task, CLPT
• - Grammatical Judg Listening Span
• Spatial WM
• - Spatial working memory task

• Sentence Discourse Processing
• - Complex Sentence Comprehension Task
• - Discourse Processing Task

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Auditory Working Memory Test 9Woodcock-Johnson
III

• Series of digits and words (e.g., dog, 1, shoe,
  8, 2, apple)
• Presented via audio recording
• Participants first report the objects, then the
  digits, in sequential order

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Nonword Repetition Task(Dollaghan Campbell,
1998)

• 16 nonsense words (1- 4 syllables)
• Characteristics of nonwords
• Consist of early developing phonemes
• Do not follow English metrical stress patterns
• Syllables do not correspond to English words
• Children repeat nonword immediately following
  each stimulus

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Nonword Repetition Task

• 1 syllable /doif/
• 2 syllable /vae?aip/
• 3 syllable /doitauvaeb/
• 4 syllable /daevounoi?ig/

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Competing Language Processing Task(CLPT, Gaulin
Campbell, 1994)

• Sets of 1 to 6 short sentences after each
  sentence child responds true or false
• Concurrently, the child is asked to recall the
  last word in each sentence after the set has been
  presented

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CLPT(Gaulin Campbell, 1994)
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Grammatical Judgment Listening Span Task

• Concurrent tasks consist of sentence
  grammaticality judgments and final word recall
  for each set of sentences (2-6 sentences in
  length)
• Judgments include optional infinitive (OI) and
  non-optional infinitive (NOI) morphemes
• Optional infinitive morphemes are regular
  past/third person singular Non-optional
  infinitives are plurals and possessives

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Grammatical Judgment Listening Span Task
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• Is verbal WM distinguishable from language
  comprehension and production?
• Does verbal WM contribute unique variance to
  language outcomes?

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CLPT
.46
Listening Span OI
.73
.57
.66
Working Memory
.93
Listening Span NOI
.64
.45
.58
.81
Spatial WM
.60
.31
Confirmatory Factor Analysis Normal Language
Group
.45
NRT
.64
.88
WJ Aud WM
.56
.15
.18
PPVT
.85
.48
Language Comp/Prod
1.28
.51
CELF Following Directions
.84
.76
CELF Sentence Repetition
.43
Chi-Square147.2, df63, plt.001, GFI.90,
CFI.96, RMSEA.07
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CLPT
.50
Listening Span OI
.54
.73
Working Memory
.66
1.20
Listening Span NOI
.99
.64
.58
.87
Spatial WM
.85
.31
Confirmatory Factor Analysis LI Group
.45
NRT
1.29
.45
WJ Aud WM
.85
.15
.18
PPVT
.55
Language Comp/Prod
.48
.22
CELF Following Directions
.51
.45
.57
CELF Sentence Repetition
.44
Chi-Square147.2, df63, plt.001, GFI.90,
CFI.96, RMSEA.07
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Does 2nd grade verbal WM contribute unique
variance (beyond early language scores) to the
prediction of 10th grade language outcomes?
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R2.43
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R2.51
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R2.68
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Do WM limitations extend beyond the verbal
domain?
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Visuospatial WM in SLI

• Mixed evidences for deficits
• Archibald Gathercole (2006)
• Hoffman Gillam (2004)
• Hick, Botting, Conti-Ramsden (2005)
• Bavin, Wilson, Maruff, Sleeman (2005)

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Spatial Working Memory Task

• Complex odd-one-out paradigm adapted from a
  measure developed by Russell, Jarrold, Henry
  (1996) to investigate WM in autism
• Similar measure used by Nation and colleagues
  (Nation, Adams, Bowyer-Crane Snowling, 1999) to
  examine memory in normal readers and poor
  comprehenders

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Spatial Working Memory Task

• Presentation of a series of shapes contained
  within a divided rectangle
• Children point to the shape that is different
  from the other two
• Number of rectangles presented at one time ranges
  from 2-6

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Spatial Working Memory Task

• After each exposure trial, a blank grid is
  displayed
• Children point to location in each rectangle
  where oddball shape occurred
• Taps storage capacity

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Examination of Strategy Use
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Summary

• Consistent, replicated group differences across a
  variety of verbal WM measures
• Deficits remain when indices of extant language
  abilities used as covariates/when language
  impairment has resolved
• Structure of measures suggests that verbal WM and
  Language are two distinct factors

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Summary

• Verbal WM provides unique prediction to language
  outcomes
• WM difficulties in visuospatial domain indicate
  general processing limitations

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Theoretical Implications

• Findings support notion of phonological storage
  deficit in WM, but deficits in spatial WM do not
  support Baddeleys model
• Results suggesting domain-general deficits are
  consistent with generalized speed of processing
  account, in the capacity domain
• Findings do not show the expected interplay
  between LTM and WM predicted by Cowan

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Issues for Alternate View of MacDonald
Christensen (2002) as Applied to SLI

• Robust syllable length effect on NRT
• Lack of interaction between grammatical deficits
  (OI) in SLI and recall performance for sentences
  containing those forms
• Dissociations between language and WM in
  individual cases
• Evidence for domain-general WM limitations

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InterpretationInteractive-Multiple Path Account

• WM appears to play a role in SLI, but other
  cognitive processes have also been implicated
• Other research has indicated that cognitive
  stressors involving either reduced speed of
  processing or memory capacity can elicit SLI
  profiles (Hayiou-Thomas, Bishop, Plunkett,
  2004)
• Important to determine relation among various
  cognitive processes

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Speed of Processing and WM Leonard,
Ellis Weismer, Miller, Francis, Tomblin, Kail
(in review)

• Examined construct of processing limitations in
  SLI using measures from 8th grade Iowa dataset
• Speed and WM function as separable factors in
  SLI, with separate verbal/nonverbal dimensions
• Verbal WM nonverbal cognitive speed OR general
  processing speed ? 62 variance in concurrent
  language composite scores
  

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InterpretationInteractive-Multiple Path Account

• Consideration of individual data as well as group
  findings
• As is the case for WM, not all children with SLI
  exhibit speed of processing deficits (Miller et
  al., 2001)
• Multiple language emergence routes that can lead
  to poor language abilities

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Future Directions

• Conduct detailed studies of additional cognitive
  processes, especially executive function and
  attentional control mechanisms
• Further explore the domain specificity issue
• Gather converging evidence from different sources
  (imaging, ERP, modeling)
• Investigate the relation between different
  cognitive processes relative to their
  contributions to processing limitations

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Le Fin, Merci!
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Nonword RepetitionGrade 2 Grade 8
R.68 R2.47
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CLPT Word RecallGrade 3 Grade 8


R .57 R2.33
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Correlation Between Experimental and Diagnostic
MeasuresDiagnostic Battery Grade 8
plt .01
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Correlation Between Experimental Measures
plt .01
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Alternate View

• MacDonald Christiansen (2002)
• Propose that processing capacity is not distinct
  from long-term linguistic knowledge
• Preliminary study by Mainela-Arnold Evans
  (2005) reports that their findings support this
  view