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Background: The issue of production and perception of lexical tone in patients with brain lesions has been investigated mainly through East Asian languages and Norwegian. The present study investigated the lateralisation of lexical tone in Shona, a Bantu language. Van Lancker (1980) proposed a continuum scale of the levels of functional pitch in the speech signal. According to the functional lateralisation account (FLH), the left hemisphere (LH) is associated with highly structured pitch contrasts, such as phonological tone, whereas the right hemisphere (RH) is specialised for the least structured pitch functions cueing emotional and personal information. The extant data show that the ability to produce and identify lexical tone is frequently more impaired as a result of lesions to the LH than RH lesions.
Aims: The present investigation focused on the lateralisation of lexical tone in Shona speakers. The study sought to validate if the scale of hemispheric lateralisation as proposed by Van Lancker (1980) is also valid for Shona, a Bantu language.
Methods & Procedures: We examined five LH damaged (LHD) patients and five RH (RHD) damaged patients using a confrontational picture-naming task and a lexical tone identification task of Shona lexical tone. The first experiment investigated the ability of LHD patients and RHD patients to identify Shona lexical tone in 60 disyllabic minimal pairs. The second experiment examined the ability of Shona brain-damaged patients to produce lexical tone using a confrontational picture-naming task with 120 lexical items.
Outcomes & Results: We observed a dissociation in the performance of both the LHD and RHD patients in the two tasks. Both groups were impaired in the tone identification task relative to the non-brain-damaged controls. However, RHD patients performed significantly better than the LHD patients in the tone identification task. On the other hand, both LHD and RHD groups were equally impaired in the tone production task in comparison to the controls.
Conclusions: The discrepancy in the production and perception of Shona lexical tone for this group of brain-damaged patients shows that, although the two modes are related, they do not always get disrupted at the same level after brain damage. The results from the tone identification task suggest to a certain extent that the FLH is also valid for Shona. In order to account for all the data there is need to carefully consider alternative accounts like the acoustic cue hypothesis (Van Lancker & Sidtis, 1992).
Background: Research on language comprehension in aphasia has primarily focused on comprehension of isolated words and sentences. Even though previous studies have provided insights into comprehension abilities of individuals with aphasia at the word and grammatical level, our understanding of the nature and extent of their language comprehension (dis)abilities is not yet complete. In contrast to the highly restricted semantic and syntactic interpretation of sentences, discourse comprehension requires additional pragmatic and non-linguistic skills.Aims: The purpose of this study was to assess language comprehension in individuals with and without aphasia at the discourse level. In particular, it addressed the question of whether the use of direct speech, compared to indirect speech, affects comprehension of narrative discourse in Dutch aphasic and non-brain-damaged (NBD) listeners.Methods & Procedures: The Direct Speech Comprehension (DISCO) test was developed to examine the effects of manipulating direct vs. indirect speech on discourse comprehension. Twenty-three individuals with aphasia and 20 NBD participants were presented with spoken narratives that contained either direct or indirect speech reports. The narratives were presented audio-visually on an iPad, and comprehension was assessed with yes/no questions.Outcomes & Results: The performance of the participants with aphasia was significantly poorer than that of the NBD participants. Moreover, a main effect for condition type was found, indicating that narratives with direct speech reports were better understood than narratives with indirect speech reports by listeners with and without aphasia. There was no interaction between group and condition type indicating that this main effect held for both the aphasic and the NBD listeners. However, for the participants with aphasia, there was an interaction between condition and Token Test error score indicating that the positive effect of direct speech constructions diminishes for individuals with poorer comprehension.Conclusions: Direct speech constructions facilitate language comprehension in listeners with and without aphasia. One explanation for this finding is the occurrence of additional layers of communication, such as intonation and facial expression, often accompanying direct speech constructions. An alternative account is the degree of grammatical complexity: In Dutch, the syntactic construction of indirect speech requires embedding, whereas in direct speech the introductory sentence and the quote are both main clauses. The finding that the beneficial effect of direct speech on language comprehension diminishes for individuals with severe aphasia may indicate that the DISCO is too difficult for them to reveal an effect of a subtle manipulation such as that of condition type.
Background: Individuals with agrammatic aphasia (IWAs) have problems with grammatical decoding of tense inflection. However, these difficulties depend on the time frame that the tense refers to. Verb morphology with reference to the past is more difficult than with reference to the non-past, because a link needs to be made to the past event in discourse, as captured in the PAst Discourse Linking Hypothesis (PADILIH; Bastiaanse, R., Bamyaci, E., Hsu, C., Lee, J., Yarbay Duman, T., Thompson, C. K., 2011. Time reference in agrammatic aphasia: A cross-linguistic study. J. Neurolinguist. 24, 652-673). With respect to reference to the (non-discourse-linked) future, data so far indicate that IWAs experience less difficulties as compared to past time reference (Bastiaanse, R., Bamyaci, E., Hsu, C., Lee, J., Yarbay Duman, T., Thompson, C. K., 2011. Time reference in agrammatic aphasia: A cross-linguistic study. J. Neurolinguist. 24, 652-673), supporting the assumptions of the PADILIH. Previous online studies of time reference in aphasia used methods such as reaction times analysis (e.g., Faroqi-Shah, Y., Dickey, M. W., 2009. On-line processing of tense and temporality in agrammatic aphasia. Brain Lang. 108, 97-111). So far, no such study used eye-tracking, even though this technique can bring additional insights (Burchert, F., Hanne, S., Vasishth, S., 2013. Sentence comprehension disorders in aphasia: the concept of chance performance revisited. Aphasiology 27, 112-125, doi:10.1080/02687038.2012.730603).
Aims: This study investigated (1) whether processing of future and past time reference inflection differs between non-brain-damaged individuals (NBDs) and IWAs, and (2) underlying mechanisms of time reference comprehension failure by IWAs.
Results and discussion: NBDs scored at ceiling and significantly higher than the IWAs. IWAs had below-ceiling performance on the future condition, and both participant groups were faster to respond to the past than to the future condition. These differences are attributed to a pre-existing preference to look at a past picture, which has to be overcome. Eye movement patterns suggest that both groups interpret future time reference similarly, while IWAs show a delay relative to NBDs in interpreting past time reference inflection. The eye tracking results support the PADILIH, because processing reference to the past in discourse syntax requires additional resources and thus, is problematic and delayed for people with aphasia. (C) 2014 Elsevier Ltd. All rights reserved.
Background: Agrammatic speakers have problems with grammatical encoding and decoding. However, not all syntactic processes are equally problematic: present time reference, who questions, and reflexives can be processed by narrow syntax alone and are relatively spared compared to past time reference, which questions, and personal pronouns, respectively. The latter need additional access to discourse and information structures to link to their referent outside the clause (Avrutin, 2006). Linguistic processing that requires discourse-linking is difficult for agrammatic individuals: verb morphology with reference to the past is more difficult than with reference to the present (Bastiaanse et al., 2011). The same holds for which questions compared to who questions and for pronouns compared to reflexives (Avrutin, 2006). These results have been reported independently for different populations in different languages. The current study, for the first time, tested all conditions within the same population.
Aims: We had two aims with the current study. First, we wanted to investigate whether discourse-linking is the common denominator of the deficits in time reference, wh questions, and object pronouns. Second, we aimed to compare the comprehension of discourse-linked elements in people with agrammatic and fluent aphasia.
Methods and procedures: Three sentence-picture-matching tasks were administered to 10 agrammatic, 10 fluent aphasic, and 10 non-brain-damaged Russian speakers (NBDs): (1) the Test for Assessing Reference of Time (TART) for present imperfective (reference to present) and past perfective (reference to past), (2) the Wh Extraction Assessment Tool (WHEAT) for which and who subject questions, and (3) the Reflexive-Pronoun Test (RePro) for reflexive and pronominal reference.
Outcomes and results: NBDs scored at ceiling and significantly higher than the aphasic participants. We found an overall effect of discourse-linking in the TART and WHEAT for the agrammatic speakers, and in all three tests for the fluent speakers. Scores on the RePro were at ceiling.
Conclusions: The results are in line with the prediction that problems that individuals with agrammatic and fluent aphasia experience when comprehending sentences that contain verbs with past time reference, which question words and pronouns are caused by the fact that these elements involve discourse linking. The effect is not specific to agrammatism, although it may result from different underlying disorders in agrammatic and fluent aphasia.
Comprehension of non-canonical sentences can be difficult for individuals with aphasia (IWA). It is still unclear to which extent morphological cues like case marking or verb inflection may influence IWA's performance or even help to override deficits in sentence comprehension. Until now, studies have mainly used offline methods to draw inferences about syntactic deficits and, so far, only a few studies have looked at online syntactic processing in aphasia. We investigated sentence processing in German-speaking IWA by combining an offline (sentence-picture matching) and an online (eye-tracking in the visual-world paradigm) method. Our goal was to determine whether IWA are capable of using inflectional morphology (number-agreement markers on verbs and case markers in noun phrases) as a cue to sentence interpretation. We report results of two visual-world experiments using German reversible SVO and OVS sentences. In each study, there were eight IWA and 20 age-matched controls. Experiment 1 targeted the role of unambiguous case morphology, while Experiment 2 looked at processing of number-agreement cues at the verb in caseambiguous sentences. IWA showed deficits in using both types of morphological markers as a cue to non-canonical sentence interpretation and the results indicate that in aphasia, processing of case-marking cues is more vulnerable as compared to verbagreement morphology. We ascribe this finding to the higher cue reliability of agreement cues, which renders them more resistant against impairments in aphasia. However, the online data revealed that IWA are in principle capable of successfully computing morphological cues, but the integration of morphological information is delayed as compared to age-matched controls. Furthermore, we found striking differences between controls and IWA regarding subject-before-object parsing predictions. While in case-unambiguous sentences IWA showed evidence for early subjectbefore-object parsing commitments, they exhibited no straightforward subject-first prediction in case-ambiguous sentences, although controls did so for ambiguous structures. IWA delayed their parsing decisions in case-ambiguous sentences until unambiguous morphological information, such as a subject-verbnumber-agreement cue, was available. We attribute the results for IWA to deficits in predictive processes based on morphosyntactic cues during sentence comprehension. The results indicate that IWA adopt a wait-and-see strategy and initiate prediction of upcoming syntactic structure only when unambiguous case or agreement cues are available. (C) 2015 Elsevier Ltd. All rights reserved.
Age of acquisition (AOA) has frequently been shown to influence response times and accuracy rates in word processing and constitutes a meaningful variable in aphasic language processing, while its origin in the language processing system is still under debate. To find out where AOA originates and whether and how it is related to another important psycholinguistic variable, namely semantic typicality (TYP), we studied healthy, elderly controls and semantically impaired individuals using semantic priming. For this purpose, we collected reaction times and accuracy rates as well as event-related potential data in an auditory category-member-verification task. The present results confirm a semantic origin of TYP, but question the same for AOA while favouring its origin at the phonology-semantics interface. The data are further interpreted in consideration of recent theories of ageing. (C) 2016 Elsevier Ltd. All rights reserved.
Individuals with agrammatic Broca's aphasia experience difficulty when processing reversible non-canonical sentences. Different accounts have been proposed to explain this phenomenon. The Trace Deletion account (Grodzinsky, 1995, 2000, 2006) attributes this deficit to an impairment in syntactic representations, whereas others (e.g., Caplan, Waters, Dede, Michaud, & Reddy, 2007; Haarmann, Just, & Carpenter, 1997) propose that the underlying structural representations are unimpaired, but sentence comprehension is affected by processing deficits, such as slow lexical activation, reduction in memory resources, slowed processing and/or intermittent deficiency, among others. We test the claims of two processing accounts, slowed processing and intermittent deficiency, and two versions of the Trace Deletion Hypothesis (TDH), in a computational framework for sentence processing (Lewis & Vasishth, 2005) implemented in ACT-R (Anderson, Byrne, Douglass, Lebiere, & Qin, 2004). The assumption of slowed processing is operationalized as slow procedural memory, so that each processing action is performed slower than normal, and intermittent deficiency as extra noise in the procedural memory, so that the parsing steps are more noisy than normal. We operationalize the TDH as an absence of trace information in the parse tree. To test the predictions of the models implementing these theories, we use the data from a German sentence—picture matching study reported in Hanne, Sekerina, Vasishth, Burchert, and De Bleser (2011). The data consist of offline (sentence-picture matching accuracies and response times) and online (eye fixation proportions) measures. From among the models considered, the model assuming that both slowed processing and intermittent deficiency are present emerges as the best model of sentence processing difficulty in aphasia. The modeling of individual differences suggests that, if we assume that patients have both slowed processing and intermittent deficiency, they have them in differing degrees.
Agrammatic speakers of languages with overt grammatical case show impaired use of the morphological cues to establish theta-role relations in sentences presented in non-canonical word orders. We analysed the effect of word order on the sentence comprehension of aphasic speakers of Basque, an ergative, free word order and head-final (SOV) language. Ergative languages such as Basque establish a one-to-one mapping of the thematic role and the case marker. We collected behavioural and gaze-fixation data while agrammatic speakers performed a picture-matching task with auditorily presented sentences with different word orders. We found that people with aphasia (PWA) had difficulties in assigning theta-roles in Theme-Agent order. This result is in line with processing accounts. Contrary to previous findings, our data do not suggest a systematic delay in the integration of morphological information in the PWA group, but strong reliance on the ergative case morphology and difficulties assigning thematic roles into the determiner phrases.
Comparative research on aphasia and aphasia rehabilitation is challenged by the lack of comparable assessment tools across different languages. In English, a large array of tools is available, while in most other languages, the selection is more limited. Importantly, assessment tools are often simple translations and do not take into consideration specific linguistic and psycholinguistic parameters of the target languages. As a first step in meeting the needs for comparable assessment tools, the Comprehensive Aphasia Test is currently being adapted into a number of languages spoken in Europe. In this article, some key challenges encountered in the adaptation process and the solutions to ensure that the resulting assessment tools are linguistically and culturally equivalent, are proposed. Specifically, we focus on challenges and solutions related to the use of imageability, frequency, word length, spelling-to-sound regularity and sentence length and complexity as underlying properties in the selection of the testing material.
The cross-linguistic finding of greater demands in processing object relatives as compared to subject relatives in individuals with aphasia and non-brain-damaged speakers has been explained within the Relativized Minimality approach. Based on this account, the asymmetry is attributed to an element intervening between the moved element and its extraction site in object relatives, but not in subject relatives. Moreover, it has been proposed that processing of object relatives is facilitated if the intervening and the moved elements differ in their internal feature structure. The present study investigates these predictions in German-speaking individuals with aphasia and a group of control participants by combining the visual world eye-tracking methodology with an auditory referent identification task. Our results provide support for the Relativized Minimality approach. Particularly, the degree of featural distinctness was shown to modulate the occurrence of the effects in aphasia. We claim that, due to reduced processing capacities, individuals with aphasia need a higher degree of featural dissimilarity to distinguish the moved from the intervening element in object relatives to overcome their syntactic deficit. (C) 2017 Elsevier Ltd. All rights reserved.