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Examining the Role of Processing Limitations in SLI

Examining the Role of Processing Limitations in SLI

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Examining the Role of Processing Limitations in SLI

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  1. Examining the Role of Processing Limitations in SLI Susan Ellis Weismer University of Wisconsin-Madison

  2. 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)

  3. 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 O’Shea, Erin Green, Jordan Scheid, Nicole Schad UW-Madison Statistical Consultants • Associate Professor Daniel Bolt • Professor Mary Lindstrom

  4. Theoretical Accounts of SLIProcessing Limitation Deficit • Temporal Processing • Generalized Slowing hypothesis • Phonological Storage • Limited Processing Capacity in Working Memory • Executive Function deficit

  5. 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)

  6. 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)

  7. 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/suppression, generativity

  8. 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,Christiansen) Propose that processing capacity is not distinct from long-term linguistic knowledge

  9. 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)

  10. 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)

  11. 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)

  12. 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)

  13. 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)

  14. Processing Capacity Limitations in SLI: Part II

  15. Midwest Collaboration on Specific Language ImpairmentNIH P50 DC02746J. Bruce Tomblin, Director Project 2 Limitations in Processing Capacity

  16. 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

  17. Sample(N=527) 8th grade diagnosis SLI - normal cognition, low language (n=59) NLI - low cognition, low language (n=80) NL - normal cognition, normal language (n=316) LC - low cognition, normal language (n=72)

  18. Sample(N=504) 10th grade diagnosis LI - language impairment, SLI + NLI (n=139) NL - normal language (n=365)

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

  20. 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 Processing Capacity Tasks

  21. 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

  22. 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

  23. 1 syllable: /doif/ 2 syllable: /vaeaip/ 3 syllable: /doitauvaeb/ 4 syllable: /daevounoiig/ Nonword Repetition Task

  24. 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

  25. CLPT(Gaulin & Campbell, 1994)

  26. 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

  27. Grammatical Judgment Listening Span Task

  28. Is verbal WM distinguishable from language comprehension and production? • Does verbal WM contribute unique variance to language outcomes?

  29. 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-Square=147.2, df=63, p<.001, GFI=.90, CFI=.96, RMSEA=.07

  30. CLPT .50 Listening Span OI .54 .73 .66 Working Memory 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 .48 Language Comp/Prod .22 CELF: Following Directions .51 .45 .57 CELF: Sentence Repetition .44 Chi-Square=147.2, df=63, p<.001, GFI=.90, CFI=.96, RMSEA=.07