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The processing of nonverbal auditory stimuli has not yet been sufficiently investigated in patients with aphasia. On the basis of a duration discrimination task, we examined whether patients with left-sided cerebrovascular lesions were able to perceive time differences in the scale of approximately 150ms. Further linguistic and memory-related tasks were used to characterize more exactly the relationships in the performances between auditory nonverbal task and selective linguistic or mnemonic disturbances. All examined conduction aphasics showed increased thresholds in the duration discrimination task. The low thresholds on this task were in a strong correlative relation to the reduced performances in repetition and working memory task. This was interpreted as an indication of a pronounced disturbance in integrating auditory verbal information into a long-term window (sampling disturbance) resulting in an additional load of working memory. In order to determine the lesion topography of patients with sampling disturbances, the anatomical and psychophysical data were correlated on the basis of a voxelwise statistical approach. It was found that tissue damage extending through the insula, the posterior superior temporal gyrus, and the supramarginal gyrus causes impairments in sequencing of time-sensitive information.
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.