Non-aphasic Speakers Research Articles

Grammatical Morphology in Aphasia: Evidence from Cantonese Classifiers

Grammatical Morphology in Aphasia: Evidence from Cantonese Classifiers

Cognitive correlates of narrative impairment in moderate traumatic brain injury

Traumatic brain injuries (TBIs) are often associated with communicative deficits. The incoherent and impoverished language observed in non-aphasic individuals with severe TBI has been linked to a problem in the global organization of information at the text level. The present study aimed to analyze the features of narrative discourse impairment in a group of adults with moderate TBI (modTBI). 10 non-aphasic speakers with modTBI and 20 neurologically intact participants were recruited for the experiment. Their cognitive, linguistic and narrative skills were thoroughly assessed. The persons with modTBI exhibited normal phonological, lexical and grammatical skills. However, their narratives were characterized by lower levels of Lexical Informativeness and more errors of both Local and Global Coherence that, at times, made their narratives vague and ambiguous. Significant correlations were found between these narrative difficulties and the production of both perseverative and non-perseverative errors on the WCST. These disturbances confirm previous findings which suggest a deficit at the interface between cognitive and linguistic processing rather than a specific linguistic disturbance in these patients.

Verb use in aphasic and non-aphasic personal discourse: What is normal?

Sentence and discourse analysis research provides evidence of both impaired and intact ability in verb production in aphasia, based on comparisons made within aphasic subtypes, and between aphasic and control speakers. Comparisons are complicated due to variation in elicitation tasks and genre, participant sample size, and aphasia subtype, as well as methodological differences in determining fluency. In this study, we examined the impact of aphasia on speakers' capacity to talk about their quality of life, applying three analytical methods to 58 speakers' discourse (29 predominantly fluent aphasic speakers; 29 non-aphasic speakers). Both speaker groups produced similar quantity, weight, and type of verbs, with substantial overlap in verb tokens. Relational, material and mental verbs were prevalent. Aphasic speakers had significantly lower predicate argument structure scores, and produced significantly more 0 argument structures, more [Aux + 0] constructions, fewer 1 argument structures in general and fewer 1 argument structures with clausal embedding, compared to non-aphasic speakers. This study provides evidence for intact (semantic weight and type) and impaired (PAS) verb production in aphasia. The heterogeneity within both participant samples challenges assumptions of normality and typicality.

Patterns of impairment of narrative language in mild traumatic brain injury

Mild traumatic brain injury (mTBI) represents a condition whose cognitive and behavioral sequelae are often underestimated, even when it exerts a profound impact on the patients' every-day life. The present study aimed to analyze the features of narrative discourse impairment in a group of adults with mTBI. 10 mTBI non-aphasic speakers (GCS > 13) and 13 neurologically intact participants were recruited for the experiment. Their cognitive, linguistic and narrative skills were thoroughly assessed. The group of mTBIs exhibited normal phonological, lexical and grammatical skills. However, their narratives were characterized by the presence of frequent interruptions of ongoing utterances, derailments and extraneous utterances that at times made their discourse vague and ambiguous. They produced more errors of global coherence [ F (1; 21) = 24.242; p = .000; η p 2 = 0. 536] and fewer Lexical Information Units [ F (1; 21) = 7.068; p = .015; η p 2 = .252]. The errors of global coherence correlated negatively with non-perseverative errors on the WCST ( r = −.755; p < .012). The macrolinguistic problems made their narrative samples less informative than those produced by the group of control participants. These disturbances may reflect a deficit at the interface between cognitive and linguistic processing rather than a specific linguistic disturbance. These findings suggest that also persons with mild forms of TBI may experience linguistic disturbances that may hamper the quality of their every-day life. • We analyzed narrative discourse in mild TBI non-aphasic speakers. • They had adequate microlinguistic skills. • They could identify a good amount of information. • They couldn't organize it at the macrolinguistic level of narrative processing. • A deficit at the interface between cognitive and linguistic processing is postulated.

Compound nouns in spoken language production by speakers with aphasia compared to neurologically healthy speakers: An exploratory study

Compounds are words that are made up of at least two other words (lexemes), featuring lexical and syntactic characteristics and thus particularly interesting for the study of language processing. Most studies of compounds and language processing have been based on data from experimental single word production and comprehension tasks. To enhance the ecological validity of morphological processing research, data from other contexts, such as discourse production, need to be considered. This study investigates the production of nominal compounds in semi-spontaneous spoken texts by a group of speakers with fluent types of aphasia compared to a group of neurologically healthy speakers. The speakers with aphasia produce significantly fewer nominal compound types in their texts than the non-aphasic speakers, and the compounds they produce exhibit fewer different types of semantic relations than the compounds produced by the non-aphasic speakers. The results are discussed in relation to theories of language processing.

Narrative language in traumatic brain injury

Persons with traumatic brain injury (TBI) often show impaired linguistic and/or narrative abilities. The present study aimed to document the features of narrative discourse impairment in a group of adults with TBI. 14 severe TBI non-aphasic speakers (GCS < 8) in the phase of neurological stability and 14 neurologically intact participants were recruited for the experiment. Their cognitive, linguistic and narrative skills were thoroughly assessed. The group of non-aphasic individuals with TBI had normal lexical and grammatical skills. However, they produced narratives with increased errors of cohesion and coherence due to the frequent interruption of ongoing utterances, derailments and extraneous utterances that made their discourse vague and ambiguous. They produced a normal amount of thematic units (i.e. concepts) in their narratives. However, this information was not correctly organized at micro- and macrolinguistic levels of processing. A Principal Component Analysis showed that a single factor accounted for the production of global coherence errors, and the reduction of both propositional density at the utterance level and proportion of words that conveyed information. It is hypothesized that the linguistic deficits observed in the participants with TBI may reflect a deficit at the interface between cognitive and linguistic processing rather than a specific linguistic disturbance.

Towards a quantitative measure of verbal effectiveness and efficiency in the Amsterdam-Nijmegen Everyday Language Test (ANELT)

Background: A well-known test for measuring verbal adequacy (i.e., verbal effectiveness) in mildly impaired aphasic speakers is the Amsterdam-Nijmegen Everyday Language Test (ANELT; Blomert, Koster, & Kean, 1995). Aphasia therapy practitioners score verbal adequacy qualitatively when they administer the ANELT to their aphasic clients in clinical practice. Aims: The current study investigated whether the construct validity of the ANELT could be further improved by substituting the qualitative score by a quantitative one, which takes the number of essential information units into account. The new quantitative measure could have the following advantages: the ability to derive a quantitative score of verbal efficiency, as well as improved sensitivity to detect changes in functional communication over time. Methods & Procedures: The current study systematically compared a new quantitative measure of verbal effectiveness with the current ANELT Comprehensibility scale, which is based on qualitative judgements. A total of 30 speakers of Dutch participated: 20 non-aphasic speakers and 10 aphasic patients with predominantly expressive disturbances. Outcomes & Results: Although our findings need to be replicated in a larger group of aphasic speakers, the main results suggest that the new quantitative measure of verbal effectiveness is more sensitive to detect change in verbal effectiveness over time. What is more, it can be used to derive a measure of verbal efficiency. Conclusions: The fact that both verbal effectiveness and verbal efficiency can be reliably as well as validly measured in the ANELT is of relevance to clinicians. It allows them to obtain a more complete picture of aphasic speakers' functional communication skills.

Comparison of machine learning methods for classifying aphasic and non-aphasic speakers

Abstract The performance of eight machine learning classifiers were compared with three aphasia related classification problems. The first problem contained naming data of aphasic and non-aphasic speakers tested with the Philadelphia Naming Test. The second problem included the naming data of Alzheimer and vascular disease patients tested with Finnish version of the Boston Naming Test. The third problem included aphasia test data of patients suffering from four different aphasic syndromes tested with the Aachen Aphasia Test. The first two data sets were small. Therefore, the data used in the tests were artificially generated from the original confrontation naming data of 23 and 22 subjects, respectively. The third set contained aphasia test data of 146 aphasic speakers and was used as such in the experiments. With the first and the third data set the classifiers could successfully be used for the task, while the results with the second data set were less encouraging. However, based on the results, no single classifier performed exceptionally well with all data sets, suggesting that the selection of the classifier used for classification of aphasic data should be based on the experiments performed with the data set at hand.

Semantic interference during blocked-cyclic naming: Evidence from aphasia

Nonaphasic speakers are known to take longer to name pictures when they are blocked by semantic category and repeated multiple times. We replicated this “semantic blocking effect” in older controls and showed that in aphasia, the effect is manifested in increased error rates when naming semantically homogeneous, compared to mixed blocks. We further showed that semantic blocking affects Broca’s aphasics more than a matched group of NonBrocas, and that the effect increases with repetition of the blocked sets. Error analysis undermines the inhibition-based account of the blocking effect by showing that errors arise from competition among increasingly activated items within the homogeneous set. The consequent slowing of naming latencies is due at least in part to the intervention of a controlled selection mechanism, and the disruption of this mechanism in anterior aphasia accounts for the increase in error vulnerability.

Facilitation and interference in phonological blocked-cyclic naming

The semantic blocking effect refers to the detrimental effect on naming latencies (nonaphasic speakers; e.g., Damian, Vigliococco, & Levelt, 2001) and accuracy (aphasic speakers) when targets are blocked by semantic category, compared with mixed-category presentation. The effect is most reliable when blocked sets are repeated multiple times in succession (i.e., for multiple ‘‘cycles’’). Schnur, Brecher, Rossi, and Schwartz (2004) recently showed that anterior aphasics are particularly vulnerable to the semantic blocking effect, as indexed by error rate in blocked-cyclic naming. They argued that the increased difficulty exhibited by their Broca’s group, compared to a matched group of fluent aphasic speakers, Non-Broca’s, is consistent with the theory that the left inferior frontal lobe subserves selection during high competition (Thompson-Schill, et al., 1998). Less well understood is the effect of phonological blocking. For nonaphasic speakers, naming sets of phonologically related words generally facilitates latencies (e.g., Damian, 2003), but sometimes it has the opposite effect (O’Seaghdha & Marin, 2000). Phonemic cueing paradigms used with aphasic patients have also produced mixed results, with some patients responding favourably, whereas others do not (Croot, Patterson, & Hodges, 1999). The present study investigated phonological blocking in aphasic and nonaphasic speakers, using the blocked-cyclic naming paradigm.

When lexical selection gets tough, the LIFG gets going: A lesion analysis study of interference during word production

Nonaphasic speakers take longer to name a repeated series of pictures from the same semantic category vs. mixed categories, due to semantically mediated competition for lexical selection (Damian, Vigliocco, & Levelt, 2001). Thompson-Schill et al. (1998) argued that damage to the left inferior frontal gyrus (LIFG) compromises selection when competition is high. Consistent with this, anterior (Broca) aphasics showed a larger blocking effect (more errors in semantically homogeneous vs. mixed blocks) compared to posterior aphasics, and this effect linearly increased across repetitions (Schnur, Brecher, Rossi, & Schwartz, 2004). In this study, we analyzed high-resolution structural MRI and CT scans, collected from a subgroup of aphasics reported by Schnur et al., to directly examine the relationship between the LIFG and the semantic blocking effect.

How abstract is language?

Linguists typically argue in favor of abstract representations for language, but many recent approaches to language within the cognitive science framework have stressed the importance of surface forms. In these approaches, abstract representations emerge as secondary properties at best, and at worst, are absent entirely. One domain in which linguists invoke a particularly abstract level of representation is Semitic word formation. In Semitic languages (e.g. Arabic, Hebrew), a word consists of a three-consonant root (e.g. Arabic /ktb/ signifies the semantic domain of writing) which gets interleaved into fixed templates: KaTaB means ‘wrote’, KuTiB means ‘was written’ and maKTaB means ‘desk’. Many of the templates themselves bear consistent meaning of the sort associated with inflectional morphology in English (e.g. Arabic /a-a/ signifies the perfective, /u-i/ the passive). Additional grammatical meanings can be added through prefixes and suffixes. This analysis requires at least three abstract elements in the representation of even a simple word: the root, the template, and the rules (phonological and semantic) for combining the two. An alternative analysis is simply to say that people who speak these languages know the words katab, kutib, maktab, etc. as independent units and the abstract analysis reflects a level of meta-analysis necessary for linguists but not the average speaker.In a recent paper, Prunet et al.1xThe mental representation of Semitic words. Prunet, J.-F et al. Linguist. Inq. 2000; 31: 609–648CrossrefSee all References1 address the question of the psychological validity of abstract roots by examining the speech errors of an Arabic–French bilingual aphasic patient. Using a variety of different production tasks (including reading aloud, repetition and picture naming), they found that their subject made a large number of root errors in Arabic in which he re-ordered root consonants, but almost no errors in the ordering of the template. Thus, if the target word were ‘kutib’, he might say ‘tukib’, but would not say ‘kitub’. Similarly, he showed almost no re-ordering errors involving consonants from the prefixes or suffixes; only consonants from the root were affected. Thus, if the target were ‘maktab’ (ma is a prefix), he might say ‘matkab’ but not ‘kamtab’. When the same patient was tested in French, he showed over 10 times fewer errors of any sort, and the re-orderings most often involved switches between adjacent elements as opposed to the discontinuous switches found in Arabic. The authors note that there are other known instances of root consonant re-ordering in Semitic languages: in speech errors of non-aphasic speakers, in childrens language games, and in the historical development of the Semitic languages. Moreover, they review parallel evidence from a different aphasic patient, normal speech errors, and language games showing disruptions to the template that leave the root consonants intact. Taken together, the evidence favors an analysis of Semitic languages that includes the root and template as psychologically real parts of the grammar. This article demonstrates, therefore, the importance of such abstract representations, not only for accounts of language itself, but for understanding how human beings represent and access their language.

Lexical access in aphasic and nonaphasic speakers.

Lexical access in aphasic and nonaphasic speakers.

Referential Communication by Aphasic and Nonaphasic Adults

Nonaphasic and nonfluent, mixed, and anomic aphasic adults participated in a referential communication task in which they described pictures to a nonaphasic listener so that the listener could point to the picture being described from an array of four. Both aphasic and nonaphasic subjects were able to determine what information was crucial for identifying pictures and communicate that information to a listener. The major differences between nonaphasic and aphasic subjects were in efficiency and accuracy of communication. Nonaphasic and nonfluent aphasic subjects were more efficient in communicating information than mixed or anomic aphasic subjects were. Nonfluent aphasic subjects were as efficient as nonaphasic speakers in this respect. Aphasic subjects communicated significantly more inaccurate information than nonaphasic speakers did. However, no more than 5% of the information communicated by aphasic subjects was inaccurate. Finally, aphasic speakers modified their descriptions in response to apparent communication failure in the same way that nonaphasic speakers did.