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Grammatical Class Effects across Impaired Child and Adult Populations

Prof. Kleanthes R. Grohmann [1,3] & Prof. Maria Kambanaros[2,3]

[1] University of Cyprus, [2] Cyprus University of Technology, [3] Cyprus Acqusition Team Grammatical Class Effects across Impaired Child and Adult Populations

Background and Aims: Evidence for any particular language disorder can come from either of two sources: (i) structural and/or functional damage to (a) particular brain area(s) related to language or (ii) a complex combination of gene and/or chromosomal mutations and environmental risk factors (see Benítez-Burraco, to appear, for an overview). For example, verb naming deficits in aphasia, dementia of the Alzheimer’s type (DAT), and schizophrenia (SCZ) involve damage to left frontal-temporal cortical regions (Kambanaros, 2009; Kambanaros et al., in press and references within). Conversely, SLI, dyslexia, and autism are strongly genetically influenced with a wide range of different genes being associated (Fisher & Francks, 2006; Fisher & Scharff, 2009; Benítez-Burraco, to appear). Similarly, language-impaired children with the above-mentioned conditions have difficulties with lexical knowledge and access (Bishop, 2008), including verb retrieval. It is well known that grammatical class plays a crucial role in language processing. For example, during language production, grammatical class affects all types of errors made by normal and language-impaired speakers. Nouns and verbs are highly variable in meaning. Verbs denote events i.e. what happens to things, including actions, while nouns typically denote entities such as people, animals and objects. Since verb processing requires an understanding of relational concepts, whereas nouns are normally non-relational and only need single object reference, verbs appear semantically more complex. Explanations for this cross-linguistic noun advantage in impairment focus on a number of factors including the variability in verb and noun meanings, the complex relationship between verbs and nouns (e.g., instrumentality, name relation, transitivity), the differing linguistic levels of processing, the neurophysiological substrates supporting verb and noun processing, and methodological issues (Kambanaros, 2009). Potential grammatical word class deficits in language-impaired children and adults have been investigated using picture confrontation naming. Moreover, key psycholinguistic variables, such as lexical frequency, age of acquisition, imageability, picture complexity, and syllable length, may exert a stronger influence than grammatical class per se on action and object naming performances. The aims of this study are to:

1. compare quantitative and qualitative differences for action names across all language-impaired groups and between their control groups respectively

2. examine naming errors with reference to psycholinguistic models of word processing

3. establish whether error types differentiate language-impaired children from language-impaired adults

4. determine effects of lexical/psycholinguistic variables on naming accuracies

5. link results to genetic mechanisms and/or neural circuitry in the brain

Method: 110 language-impaired participants have taken part in this study so far: four groups each of Greek-speaking children and adults. Specifically, (i) 17 adults with anomic aphasia (5 monolingual, 12 bilingual), (ii) 7 adults with Broca’s aphasia, (iii) 20 adults with schizophrenia, (iv) 15 adults diagnosed with DAT, (v) 16 monolingual children with SLI, (vi) 10 bilingual children with SLI, (vii) 10 children with autism, and (viii) 15 children with dyslexia. Each language-impaired group has been matched with a non-impaired control group.The Greek Object and Action Test (GOAT; Kambanaros, 2003) and its Cypriot Greek adaptation (COAT; Kambanaros et al., submitted), designed to assess verb and noun access and retrieval, were used for all populations. Object names are single, concrete inanimate nouns and include manipulated instruments, such as garage tools, garden equipment, kitchen utensils, household items, office and personal implements, used for activities of daily living. Object names were not controlled for gender. All verbs were monotransitive with either simple internal word structures of [root + affix] or more complex ones of [root + affix + affix]. Actions were restricted to past stereotypical roles, that is, a woman is shown performing household activities (e.g. sweeping), for example, and a man is performing more “manly” duties (e.g. hammering). These stereotypical roles depicted in the pictures are deemed to be appropriate for ages and cultural group. All action names correspond either to an instrumental verb (where an instrument is part of the action, e.g. cutting) or to a non-instrumental verb (e.g. climbing). All target nouns in object naming were also items in the noun comprehension task. All target verbs in action naming were also targets in the verb comprehension task. On the comprehension task, the participants were asked to point to the correct photograph from a set comprising the target object or action and the two semantic distracters for each target object or action. For word production, the participants were asked to name the object or action represented in the photograph using one word.

Results: The results of two sub-tests, object/noun naming and action/verb naming for all eight language-impaired groups, will be reported. The results of simultaneous multiple regression analyses for the errors in action naming compared to the psycholinguistic variables for all language-impaired groups will be reported and discussed in relation to (adult) models of lexical processing (in particular, Levelt 1989 compared with Caramazza 1997) and genetic and/or neurobiological underpinnings (taking our cue from Benítez-Burraco, to appear).

Conclusions: A verb retrieval deficit is common to both developmental and acquired language impaired groups.

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