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Noun-verb dissociations-evidence from acquisition and developmental and acquired impairments Maria Kambanaros PhD CSP MSPA Speech Pathologist Assistant Professor of Speech-Language Therapy ATEI Patras Key issue Grammatical class seems to be a universal linguistic feature, since the difference between nouns and verbs is present in all languages. Introduction People with language impairments often show word class effects or differential impairments for nouns and verbs. In the case of children, verbs are typically the impaired class (Rice & Bode, 1984, Chiat, 2001, Schultz et al., 2001, Black & Chiat, 2002) SLI children For example, children with SLI had reduced verb (but not noun) production and made heavy use of uninflected verbs. That were highly input dependent in their use of verbs, in that verbs, which featured in their speech had often been previously used by their parents in the same session. Conti-Ramsden & Jones, 1997 Verb deficits are also common in acquired language disorders Several reports of 3 different patterns Verbs < Nouns Verbs > Nouns Verbs = Nouns What’s in a word? Phonological information: the sound pattern of the word Semantic information:the meaning to which the sound pattern can refer Syntactic information: the position which the word may occupy in relation to other words Mapping To acquire words: Need to segment The stream of speech separating out the sound pattern of each word The scenes in which the speech occurs, separating out the aspects of the scene which are picked out by the words Map the one onto the other, making connections between the sound patterns they have segmented and the aspects of scenes they have segmented Evidence from normal acquisition Work by Black and Chiat, 2002 Verbs: world to word mappings-the child has to learn which features of an event map onto the specific meaning of the verb. Many features of verb meaning cannot be grasped at all from the perceived event, such as the difference between “buy” and “sell”. Buy vs Sell The contrastive meanings cannot be derived simply by observing buying and selling events The structures in which they occur do offer clues about their particular focus Buy: describes the event from the point of view of the purchaser maps goal onto subject Sell: focuses on the seller, maps source onto subject Hearing many examples of these verbs in sentences can help the child derive this opaque information Work by Black and Chiat, (2002) for English Verbs have difficult phonological properties. In bisyllabic words, nouns normally stress the first syllable, while verbs often stress the second e.g. honey vs attract A listener assuming the typical pattern in which stressed syllables mark word onsets, may confront particular difficulties in segmenting verbs from the speech stream Verbs typically occupy sentence medial, rather than final or initial positions, which again makes them less salient than nouns. “Motherese” or infant directed speech(Aslin et al., 1996) English speaking mothers were asked to teach their 12 month children three verbs and three nouns. The nouns and verbs had very different distributions in the mothers’ speech. Target nouns-overwhelmingly located at the end of utterances, suggesting that mothers knew intuitively that this position favoured acquisition. Target verbs-more variable locations, but most were used in sentence medial positions. It seemed that the mothers were bound by the constraints of English, even when they were consciously teaching vocabulary to their infants. Conclude Verbs entail semantic and phonological complexities, which are not easily compensated for in motherese Verbs have an argument structure while nouns, especially those referring to concrete entities, often do not Given these contrasts, we would expect verbs to be acquired later than nouns in normal acquisition. There is substantial evidence that this is the case Exceptions to the typical noun bias Children learning Korean (Choi & Gopnick, 1995) and Mandarin (Tardiff, 1996) have shown earlier verb acquisition than their English speaking peers Explanations: ?different patterns of parental input (Tardiff et al., 1997) Common view: the noun bias is moderated in languages which allows verbs to appear more in isolation or sentence final positions = greater phonological prominence Evidence from German (De Bleser & Kauschke, 2002) Q: Does the sentence position adopted by verbs influence order of access? German = a verb final language Children ranging from 2;6 to 4;11 years were tested in naming nouns and transitive and intransitive verbs Despite the characteristics of the language, the children showed a consistent noun advantage and across all age groups A: Not always the case What affects acquisition? Nouns and Verbs have Require different different semantic and learning styles phonological properties Evidence (Goldfield, 2000) Source: Parental input 44 mother child interactions at 1;8y.o Parental input aiming to elicit production typically targeted nouns While verbs typically occurred in utterances aiming to elicit behaviours Children have to perform different functions with nouns and verbs Asked to produce nouns, but comprehend verbs Implications 1. studies focussing purely on production may underestmate children’s verbal skills in comprehension - children in the study demonstrated good verb understanding in carrying out mothers’ requests 2 to the encoding of lexical information: early learning of verbs is strongly associated with non- verbal action while nouns are associated with contexts in which an utterance accompanies attention to an object Learning of nouns and verbs may be qualitatively different Verb meanings are linked to Knowledge about action and function Noun meanings are linked to Sensory inputs e.g. the shape or appearance of the item Verb learning Through the linguistic structures in which they appear Supported by richer linguistic input Child provided with many exemplars of each item May compensate for the opaque mappings between verbs and their real world referents in that the repeated linguistic context provides children with evidence about verb meaning Example: buy and sell Lexical-semantic complexity The complexity of the semantic representations of verbs also influences retrieval accuracy Verb meanings = √ describe relational concepts √ structured entities that vary in type and number of constituents √Linked to thematic role assignment and argument structure √ Organised in matrices √ Multiple meanings (e.g. break a glass, break the news, break up a marriage) Evidence from impaired acquisition Definition Children can be described as having language disorders if they have a significant deficit in learning to talk, understand, or use any aspect of language appropriately, relative to both environmental and norm-referenced expectations of similar developmental level (Paul, 2003) Are Verbs more vulnerable in cases of developmental language disorder? Because of semantic and phonological complexities which delay normal verb learning If language is one route to verb meaning, a vicious circle may be established: a child who cannot segment phonology or retain word order will be unable to identify verb arguments or their sentence order = lack the information needed to unravel the meaning of many verbs..without verbs..unable to build linguistic contexts Evidence from SLI (English) Dockrell et al, (2001) 31 children with word finding difficulties (WFD) in their naming of verbs and nouns and compared performance to chronological and language age matched controls WFD children did not show a particular disadvantage with verbs in naming accuracy or latency Dockrell et al, (2001) WFD children were worse than chronological controls with nouns, but not with verbs (accuracy). Like the control groups children with WFD made a higher proportion of “other” errors with verbs e.g. Inappropriate verbs Dockrell et al, (2001) Explanations: 1. Group results obscure individual children who were showing such an effect 2. WFD are not the group in which to expect verb deficits i.e. showed better comprehension than production suggesting that semantic knowledge was intact and this may minimise the likelihood of a verb deficit 3. Picturable actions: being concrete and with observable world to word mapping are relatively easy for language impaired children Evidence from normal acquisition and SLI (Cypriot-Greek) Kambanaros & Grohmann (work in progress) 30 6y.o monolingual Cypriot-Greek Grade 1 children in naming action and object pictures 2 chidren with SLI 4;1 y.o boy = 33 action names incorrect (/42), 27 object names incorrect (/42) 9 y.o girl = 13 action names incorrect (/42) and 11 object names incorrect (/42) Evidence from SLI (Greek) Stavrakaki, S. (1996) Verb production 4 SLI children: 2 boys and 2 girls MA 6;1 years, Mean RA 3;7 years, Mean EA 2;8 years 12 controls: 6 boys and 6 girls MA 6;1 years SLI children have difficulties in verb production, whereas AM controls exhibit high level of correct performance An independent-sample T test carried out indicated that SLI children perform significantly below AM controls on the verb production task [t (3.057)=-8.083 p=.004] Evidence from SLI (Greek) Kambanaros et al., (work in progress) 8 children with SLI: 3 boys and 5 girls MA 5;6 years and LA 3;0yrs 8 normal language developing children : 3 boys and 5 girls who were matched on chronological age with the SLI group (MA 5;06). 8 normal language developing children 3 boys and 5 girls who were matched on language age with the SLI group (MA 3;06). Object name Action name Γενικός Μέζος Όρος Λαθών Παπακάηω αναθέπεηαι ο ζςνολικόρ μέζορ όπορ ηων λαθών ηόζο ζηην καηηγοπία ηων οςζιαζηικών όζο και ζε αςηή ηων πημάηων ΠΙΝΑΚΑΣ 1: Παροσσίαση τοσ Μέσοσ Όροσ των Λαθών στις σποκατηγορίες τοσ τεστ: Οσσιαστικά και Ρήματα. ΜΕΣΟΣ ΟΡΟΣ ΛΑΘΩΝ ΚΑΤΗΓΟΡΙΑ SLI NL CA NL LA Ουσιαστικά 53% 30% 49% Ρήματα 54% 41% 54% Μέσος όρος λαθών ανά κατηγορία Σηο ζύνολο ηος ηεζη ηα παιδιά με SLI έσοςν ηον ίδιο μέζο όπο λαθών με ηα παιδιά θςζιολογικήρ γλωζζικήρ ανάπηςξηρ ίδιαρ γλωζζικήρ ηλικίαρ με ηα SLI. ΜΕΣΟΣ ΟΡΟΣ ΛΑΘΩΝ ΣΤΟ ΣΥΝΟΛΟ ΤΟΥ ΤΕΣΤ 60% 53% 52% 50% 40% 35% 30% υνολικό τεστ 20% 10% 0% SLI NL CA NL LA Είδος λαθών Η πιο ζςσνή καηηγοπία λαθών ζε παιδιά με SLI είναι ηο καμία απάνηηζη με μέζο όπο 43% και ηςπική απόκλιζη 0,15 Διάγραμμα: Σστνόηηηα λαθών ζε παιδιά με SLI 50% 43% 45% 40% 35% 30% 23% 25% ειρά1 20% 12% 15% 10% 10% 5% 6% 5% 0% 1% 0% ΤΥΕΣΙΗ ΜΗ ΥΕΣΙΚΟ ΟΤΙΑΣΙΚΟΤ ΠΕΡΙΓΡΑΦΗ ΗΜΑΙΟΛΟΓΙΚΗ ΑΚΑΣΑΛΗΠΣΟ ΑΠΑΝΣΗΗ ΡΗΜΑΣΟ ΥΡΗΗ ΟΠΣΙΚΗ ΚΑΜΙΑ ΤΥΕΣΙΗ ΥΡΗΗ Τα παιδιά φυσιολογικής γλωσσικής ανάπτυξης που ταιριάζουν ως προς τη χρονολογική ηλικία (CA) με τα παιδιά με SLI παρουσιάζουν κυρίως περιγραφή με μέσο όρο 39% και τυπική απόκλιση 0,09. Διάγραμμα: Συχνότητα λαθών σε παιδιά NL CA 45% 39% 40% 35% 30% 25% 21% 18% ειρά1 20% 14% 15% 7% 10% 5% 0% 1% 0% 0% ΤΥΕΣΙΗ ΜΗ ΥΕΣΙΚΟ ΟΤΙΑΣΙΚΟΤ ΠΕΡΙΓΡΑΦΗ ΗΜΑΙΟΛΟΓΙΚΗ ΑΚΑΣΑΛΗΠΣΟ ΑΠΑΝΣΗΗ ΡΗΜΑΣΟ ΥΡΗΗ ΟΠΣΙΚΗ ΚΑΜΙΑ ΤΥΕΣΙΗ ΥΡΗΗ Η συχνότητα των λαθών των παιδιών φυσιολογικής γλωσσικής ανάπτυξης που ταιριάζουν ως προς τη γλωσσική ηλικία με τα παιδιά με SLI (NL LA) και παρατηρούμε ότι εμφανίζονται με την ίδια συχνότητα η μη σχετική απάντηση και το σημασιολογικά συσχετιζόμενο λάθος Συχνότητα λαθών σε παιδιά NL LA 30% 27% 27% 25% 20% 20% 15% 13% ειρά1 10% 10% 5% 0% 1% 1% 0% ΤΥΕΣΙΗ ΜΗ ΥΕΣΙΚΟ ΟΤΙΑΣΙΚΟΤ ΠΕΡΙΓΡΑΦΗ ΗΜΑΙΟΛΟΓΙΚΗ ΑΚΑΣΑΛΗΠΣΟ ΑΠΑΝΣΗΗ ΡΗΜΑΣΟ ΥΡΗΗ ΟΠΣΙΚΗ ΚΑΜΙΑ ΤΥΕΣΙΗ ΥΡΗΗ Evidence from acquired language disorders Acquired Language disorders as a result of Stroke-Aphasia Syndromes Right Hemisphere Brain Injury Traumatic Brain Injury Dementia of the Alzheimer Type Schizophrenia Aphasia A disorder of language due to brain damage, most commonly stroke. It often affects language production and comprehension, compromising both spoken and written language. Problems can arise at linguistic levels such as semantics, syntax, morphology and phonology. Aphasia may range from mild to severe, but it almost universally affects the ability to find words, nouns and verbs in particular What aphasia is Neurogenic Acquired Language Specific Not modality bound Not a speech problem Not a problem of sensation or intellect Affects psycholinguistic processes Treating patients with aphasia involves more than remediating the language disorder Grammatical word class differences were the first to Goodglass, Klein, Carey, and Jones (1966) report differential noun and verb production in aphasia: individuals with fluent aphasia showed more difficulty naming objects (nouns) whereas individuals with non-fluent (Broca’s) aphasia more impaired in naming action pictures (verbs) The (double) dissociation between noun and verb processing in aphasic individuals has been studied in a number of different languages Previous research:Double dissociation English: (Berndt et al., 1997; Breedin et al., 1998; Breen & Warrington, 1994; Kim & Thompson, 2000; Manning & Warrington, 1996; McCarthy & Warrington, 1985; Marshall, Pring & Chiat, 1998; Shapiro et al., 2000; Zingeser & Berndt, 1990). Chinese (Bates, Chen, Tzeng, Li & Opie, 1991), Danish (Jensen, 2000), Dutch (Bastiaanse, 1991; Jonkers, 1998; Jonkers & Bastiaanse, 1996), Finnish (Laine, Kujala, Niemi, & Uusipaikka, 1992), German (De Bleser & Kauschke, 2002), Hungarian (Osman-Sagi, 1987), Italian (Daniele, Guistolisi, Silveri, Colosimo & Gainotti, 1994; Luzzati, Raggi, Zonco, Pistarini, Contardi et al., 2002; Miceli, Silveri, Villa & Caramazza, 1984; Miceli, Silveri, Noncentini & Caramazza, 1988; Silveri & Di Betta, 1997) Greek (Tsapkini, Jarema & Kehayia, 2002). Previous research: nouns<verbs in fluent aphasia Individuals with posterior lesions of the left hemisphere, fluent aphasia, that of, impaired noun retrieval with relatively spared verb naming. Again this has been demonstrated in a number of languages: English (Berndt et al., 1997; Berndt, Haendiges & Wozniak, 1997; Breen & Warrington, 1994; Caramazza & Hillis, 1991; Shapiro, Shelton & Caramazza, 2000; Zingeser & Berndt, 1990), Chinese (Bates, Chen, Tzeng, Li & Opie, 1991; Chen & Bates, 1998), French (Bachoud-Levi & Dupoux, 2003), Italian (Daniele et al., 1994; Luzzatti et al., 2002; Miceli et al., 1984; Miozzo, et al., 1994) and Hungarian (Osman-Sagi, 1987). Action and Object Naming in anomia Verbs more difficult Nouns more difficult Berndt et al, 1997 Basso et al., 1990 Kohn et al, 1989 Marshall et al., 1996 Jonkers, 1998 Zingeser & Berndt, 1990 Jonkers & Bastiaanse, Miceli et al, 1984, 1988 1996 Luzzatti et al., 2002 Osman-Sagi, 1987 Williams & Canter, 1987 Berndt et al., 2002 Equal Difficulties Luzzatti et al., 2002 Luzzatti et al., 2002 Previous research: nouns>verbs in fluent aphasia Findings suggest that selective verb impairments are not exclusively found in non-fluent, Broca’s patients, but can also be observed in fluent patients with Wernicke’s aphasia (Berndt, Mitchum, Haendiges & Sanderson, 1997) and anomia (Bastiaanse, 1991; Berndt et al., 1997; Breedin & Martin, 1996; Jonkers & Bastiaanse, 1998; Luzzatti et al., 2002). Grammatical word class deficits in fluent aphasia Impaired noun retrieval with fluent aphasia. Impaired verb retrieval with fluent aphasia. No differential impairment for verbs and nouns in aphasia. Verb retrieval in fluent aphasia Edwards (2002) has claimed that access to grammar of the language and the implementation of grammatical rules and processes could be faulty in fluent aphasia or anomia leading to a deficit in processing/retrieving verbs. Contrastingly, other aphasic subjects with anomia have demonstrated impaired knowledge of verb meanings (semantics) rather than syntax (Breedin & Martin, 1994, 1996; Breedin, Saffran & Schwartz, 1998; Manning & Warrington, 1996). For example, some anomic subjects have shown difficulties processing core meanings of verbs despite preserved syntactic knowledge of how the verb is used in a sentence (Breedin & Martin, 1994). Bilingual aphasia research 1980-2004 Nouns Verbs and Nouns Kremin & De Agostini Kremin & De Agostini (1995) (1995) Sasanuma & Park Junque et al., (1989) (1995) Stadie et al., (1995) No study investigating verb/ noun processing in L1 and L2 Recent Bilingual aphasia research Hernandez, Costa, Sebastian-Galles, Juncadella, & Rene (2006) 1 female anomic (BDAE-Cookie theft picture) Alzheimer’s disease Catalan (L1)Spanish (L2) Early bilingual Highly proficient Nouns < Verbs in picture naming Recent Bilingual aphasia research Hernandez, Cano, Costa, Sebastian-Galles, Juncadella & Gascon-Bayarri, (2008) 1 male non-fluent agrammatic (BDAE-Cookie theft picture) Primary Progressive Aphasia Spanish (L1) - Catalan (L2) Late bilingual Highly proficient Nouns > Verbs in picture naming: verbal and written Recent Bilingual aphasia research Kambanaros & van Steenbrugge (2006) 12 bilingual aphasic participants: 8 males and 4 females anomic aphasia (Left CVAs) Greek (L1) - English (L2) Late bilinguals Highly proficient Results: ?? Research Question Do bilingual aphasic subjects have difficulties comprehending and or retrieving verbs and/ nouns ? Why is this study important ? Theory: one lesion-two languages Models of bilingual language organization can be developed further (Lalor & Kirsner, 2001; Roberts, 1998) Previous research-descriptive case-studies with little hypothesis testing, Studies fail to include a non- aphasic bilingual control group Little research so far Modern Greek vs English Modern Greek English Highly inflected Minimally inflected Stems-representational Stems-real words units e.g sweep (s, ing) e.g. a) /skoup/ broom (s) Inflected –a Inflected-izo Subjects Anomic aphasics (N=12) BDAE profiles- One unilateral lesion in the left hemisphere anomic in both Bilingual pre-morbidly- languages Greek native language No reported hearing or 8 males, 4 females visual problems Mean age: 60y.o Right- handed Controls (N=12) Method Research Materials The Greek Object and Action Test (GOAT) developed for this study. 110 coloured photographs (10cms x 15cms) 55 objects 55 actions Verb comprehension subtest ( 55 items) Noun comprehension subtest (55 items) All Greek tests = English tests Language/Subtests were counterbalanced Language Tasks Action/verb comprehension/naming Object/noun comprehension/naming Analysis Repeated measures analysis of variance Within subject factors (L1 and L2 verbs/ nouns) Question 1: Verb/Noun comprehension Do bilingual anomic aphasic subjects have more difficulties comprehending verbs and /or nouns in a comprehension task ? Comprehension: verbs versus nouns 100 95 90 85 80 75 70 COMPVALL COMPNALL Comprehension: verbs and nouns in L1 and L2 100 96 92 88 84 80 COMPVAGR COMPNAGR COMPVENG COMPNENG Question 2: Verb/Noun production Do bilingual anomic aphasic subjects have more difficulties producing verbs and /or nouns in a naming task ? Production: verbs versus nouns 80 70 60 50 TOTVEBAL TOTNNALL Verbs and nouns within languages 70 65 60 55 50 45 40 TOTVEGRE TOTNNGRE TOTVEENG TOTNNENG Verb Errors 1.4 0.5 5.5 Verb Error semantic other c/s 23 gram.class 14.5 phonemic Noun Errors 0.5 0.5 noun 9.4 15.3 other semantic c/s gram.clas 11 phonemic Pictures Level of breakdown Visual Object. recognition system Semantic LEMMA System LEXEME Phono Output Lexicon Phono Output Buffer Results-summary Verbs were more difficult to retrieve compared to nouns. Conclusions: Verbs were more difficult to retrieve than nouns between and within languages language specific Comprehension problems = retrieving the (morpho) phonological representation (lexeme) Semantic accounts of word class effects A number of individuals exhibit verb difficulties which are attributed to a semantic problem either in the context of aphasia, dementia etc Verbs are suggested to be particularly vulnerable to semantic damage, e.g., because they are less imageable than nouns. Semantic disorders affecting nouns but sparing verbs has also been described. Such cases suggest that nouns and verbs are distinguished by different distributions of semantic features. For example, verbs may be defined predominantly by functional, thematic or action related features and nouns more by sensory/perceptual features. = word class effects can arise from impairments to these different domains of meaning Conclusion Semantic Hypothesis provides a convincing explanation for some individuals. Whether it can explain all word class effects is much more disputed Modality specific deficits and non-semantic accounts A number of people have been described with impaired verb production but intact comprehension. Kim & Thompson (2000) tested 7 people with agrammatism on: Noun/verb naming Noun/verb comprehension Grammatical judgements (with anomalous sentences violating the argument properties of verbs) Noun/verb categorisations Results (Kim and Thompson, 2000) Grammaticality 93.6% judgement Noun comprehension 99.8% Verb comprehension 97.5% Noun naming 92.6% Verb naming 71.2% Noun categorisation 99.4% Verb categorisation 66.1% Subjects had good input skills with verbs i.e. They could comprehend them and perform grammaticality judgements. In contrast poor production. There was a clear hierarchy of difficulty which was determined by the number of arguments required by the verb (i.e. One place verbs were produced more successfully than two place and two place more successfully than three). Striking examples-problems confined to one modality of output. Individuals that show focal impairments Caramazza & Hillis, (1991) 2 individuals with excellent comprehension for verbs 1 had difficulties with verbs in speech only and for the other only in writing. Striking examples-problems confined to one modality of output. Marshall et al., (1998) Patient EM- had agrammatic speech which lacked verbs Naming: significant noun advantage but only in speech Written naming: nouns=verbs Comprehension: good for verbs and nouns Could access verbs; thematic properties to distinguish reverse role verbs like buy and sell Striking examples-problems confined to one modality of output. Individuals who have word class effects in one direction in production, and another in comprehension Shapiro et al., (2000) Patient JR Named verbs significantly better than nouns In comprehension verbs were significantly more impaired than nouns Explanations Reflect a lexical rather than semantic deficit Nature of the deficit is disputed-different theories of lexical access 2-stage theory of lexical access (Levelt and colleagues) Stage 1 Lemmas: amodal representation carrying grammatical information e.g. Relating to grammatical class, subcategorisation, gender Stage 2 Lexeme: retrieving the phonological/orthographic form Greek Verb lemma KEY Vt = Transitive Verb pres = Present Tense prog = Progressive MG = Modern Greek x,y = 2 argument position Vt Lexical to hammer x,y Category karfoni pres prog Serial model of word processing (Levelt et al., 1999). Kim & Thompson (2000) attribute their results to a breakdown at the level of the lemma. EM: Lexeme level of breakdown JR: input and output lexicons are marked for word class and that he has a deficit here for verbs. Pictures Visual Object. recognition system Semantic LEMMA System agrammatism LEXEME Phonol Anomia Output Lexicon Phonol. Output Buffer The relationship between lexical and grammatical knowledge Lemma model argues that lexical access entails access to lexical syntactic properties ? Relationship between lexical and syntactic deficits Deficits in verb access = profound consequences for sentence building i.e. Lemma level breakdown Marshall et al., (1998) suggest that even lexeme level verb deficits can impair sentence generation EM: had agrammatic speech coupled with impaired verb production. Problem specific to phonological retrieval in that comprehension and written production were intact. Despite this it seemed a major contributor to her sentence deficit. Sentence production improved when verbs were provided and lexical therapy with verbs substantially improved sentence production. The relationship between verb and syntactic impairments is far from clear cut. One problem is that not all individuals with verb deficits have syntactically impoverished speech. Jensen, (2000) IB: impaired in both producing and understanding verbs = lemma level deficit. BUT able to produce canonical sentence structures, either with a realised verb or with an empty verb slot Could also map agent and theme nouns appropriately onto these structures (even with reversible sentences) It seemed that he had a basic sentence schema, and its associated mapping routines, in the absence of verb specific information. Shapiro and Caramazza, (2002) HG: showed impaired verb access in naming and description Yet morpho-syntactic processes involved with verbs were intact i.e. He could inflect verbs to mark tense or number even pseudo verbs. She could also draw upon her morphological skills to generate novel verbs (like laddering) from instrument names. These results suggest that morpho-syntactic processes are functionally separable from lexical access. HG: dissociations with verbs in an odd one out comprehension task. Did ok on: Manner information (e.g. To mutter, to whimper, to mumble) Non-relational semantic oppositions (e.g. To open, to close, to shut) BUT not ok on: Relational oppositions (e.g. To eject-to exit-to expel) = could not access verbs’ thematic/argument structures It seems that morpho-syntactic information is not only seperable from word forms, but also from thematic/argument information. Shapiro & Caramazza suggest that thematic/argument information is stored at the semantic level, and separately from more perceptual features of verb meaning. An impairment in accessing such information gives rise to a word class effect, given that verbs are much more dependent than nouns on thematic properties Both HG and PB indicate that thematic information is dissociable from morpho-syntactic properties. Shapiro & Caramazza suggest the latter are stored in an independent syntactic network. Impairment to the network generates a morpho-syntactic deficit, which can be specific to nouns or verbs. In contrast, preservation of the network allows for morpho-syntactic skills, even in the face of impaired word retrieval. Some concluding comments Why are verbs Picture more difficult ? Linguistically more complex Visual Object recognition system Semantic LEMMA System LEXEME Phonological Output Lexicon Phonological Output Buffer VERBS Less imageable More complex world mappings More complex syntactic-morphological forms Less phonologically salient Unlikely to show an advantage in developmental disorders and are more vulnerable in aphasia Dissociations can be modality specific i.e. confined to output, or to speech or writing. Dissociations can also occur within the classes (noun-verbs), in that strengths or weaknesses or nothing at all Conclusion According to Marshall (2002: 77), [t]hese different accounts need not be mutually exclusive. Rather, it seems that individuals show word class effects for different reasons. In other words, despite some common symptoms, people with word class effects are probably a very disparate group, a situation which is not at all unfamiliar in aphasia. Thankyou for your attention Questions??
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