Syntactic predictions and asyntactic comprehension in aphasia: Evidence from scope relations

People with aphasia (PWA) often fail to understand syntactically complex sentences. This phenomenon has been described as asyntactic comprehension and has been explored in various studies cross-linguistically in the past decades. However, until now there has been no consensus among researchers as to the nature of sentence comprehension failures in aphasia. Impaired representations accounts ascribe comprehension deficits to loss of syntactic knowledge, whereas processing/resource reduction accounts assume that PWA are unable to use syntactic knowledge in comprehension due to resource limitation resulting from the brain damage. The aim of this paper is to use independently motivated psycholinguistic models of sentence processing to test a variant of the processing/resource reduction accounts that we dub the Complexity Threshold Hypothesis. According to this hypothesis, PWA are capable of building well-formed syntactic representations, but, because their resources for language processing are limited, their syntactic parser fails when processing complexity exceeds a certain threshold. The source of complexity investigated in the experiments reported in this paper is syntactic prediction. We conducted two experiments involving comprehension of sentences with different types of syntactic dependencies, namely dependencies that do not require syntactic prediction (i.e. unpredictable dependencies in sentences that require Quantifier Raising) and dependencies whose resolution requires syntactic predictions at an early stage of processing based on syntactic cues (i.e. predictable dependencies in movement-derived sentences). In line with the predictions of the Complexity Threshold Hypothesis, the results show that the agrammatic patients that participated in this study had no difficulties comprehending sentences with the former type of dependencies, whereas their comprehension of sentences with the latter type of dependencies was impaired

Syntactic Frequency and Sentence Processing in Standard Indonesian:Data from agrammatic aphasia and ERP

Aphasia is a language impairment caused by focal brain damage affecting multiple channels of language. Studies have shown that one third of stroke patients show some form of aphasia. One of the key characteristics of aphasia is that in most types, patients show deficits in sentence processing. This is so much so that many aphasia assessment tools utilize sentence comprehension or production tasks to determine aphasia type or severity, or perhaps to provide a more detailed profile on the symptoms. Individuals with aphasia have been known to face difficulties in processing sentences with a derived or non-canonical structure, like the passive. While numerous studies have discussed the morphosyntactic basis of this deficit, other aspects of sentence processing such as frequency of the sentence structures are often neglected. There is considerable possibility of syntactic frequency affecting sentence processing, as a large body of research has shown the impact of word-level frequency towards language processing. Could the impairment of processing non-canonical sentences be related to the low frequency of these sentences?This thesis examines sentence processing in Standard Indonesian, a language where the passive occurs at a rate that is comparable to active sentences. Individuals with aphasia and controls were tested with sentence comprehension and production tasks, and an event-related potential study of sentence processing for healthy adults were conducted. We found the passive to be unimpaired for aphasic individuals, and we also did not find any observable processing differences between the active and the passive in the neuroimaging experiment

The influence of sense-contingent argument structure frequencies on ambiguity resolution in aphasia

Verbs with multiple senses can show varying argument structure frequencies, depending on the underlying sense. When acknowledge is used to mean ‘recognise’, it takes a direct object (DO), but when it is used to mean ‘admit’ it prefers a sentence complement (SC). The purpose of this study was to investigate whether people with aphasia (PWA) can exploit such meaning-structure probabilities during the reading of temporarily ambiguous sentences, as demonstrated for neurologically healthy individuals (NHI) in a self-paced reading study (Hare et al., 2003). Eleven people with mild or moderate aphasia and eleven neurologically healthy control participants read sentences while their eyes were tracked. Using adapted materials from the study by Hare et al., target sentences containing an SC structure (e.g. He acknowledged (that) his friends would probably help him a lot) were presented following a context prime that biased either a direct object (DO-bias) or sentence complement (SC-bias) reading of the verbs. Half of the stimuli sentences did not contain that so made the post verbal noun phrase (his friends) structurally ambiguous. Both groups of participants were influenced by structural ambiguity as well as by the context bias, indicating that PWA can, like NHI, use their knowledge of a verb’s sense-based argument structure frequency during online sentence reading. However, the individuals with aphasia showed delayed reading patterns and some individual differences in their sensitivity to context and ambiguity cues. These differences compared to the NHI may contribute to difficulties in sentence comprehension in aphasia

Investigating Comprehension Differences Between Active and Passive Sentences in a Young and Older Adult Population

The current investigation sought to determine whether normal, non-impaired young and older adults performed differentially on the active and passive sentences of the Computerized Revised Token Test - Active/Passive (CRTT-A/P). Twenty-five young adults (18 to 30 years old) and twenty-five older adults (50 to 80 years old) completed this study.The first purpose of this study was to determine if the two groups (i.e., young and older) differed significantly in their performance (as measured by overall mean scores) on the two sentence types (i.e., active and passive sentences) across each of the four subtests. Significant differences between subtests were found; participants obtained significantly higher scores on Subtest VIII than on Subtest V and Subtest VI.The second purpose of this study was to determine if the two groups differed significantly in their efficiency scores on the two sentence types across each of the four subtests. It was found that (1) participants obtained significantly higher efficiency scores on Subtest VII than on Subtests V and VI and that (2) participants obtained significantly higher efficiency scores on Subtest VIII than on Subtest VI.The final purpose of this study was to determine if the two groups differed significantly in their response times on the two sentence types across each of the four subtests. It was found that: (1) participants responded more quickly to the passive sentence type than to the active sentence type across all four subtests; (2) the older group responded more quickly on Subtest V than on Subtests VI and VIII; and (3) the older group responded more quickly on Subtest VII than on Subtests VI and VIII.When differences between the two groups were examined for all of the measures, only one significant difference was found (the older group performed significantly slower than the young group on Subtests VI and VIII). These findings demonstrate that language comprehension abilities remain relatively constant with age. While the CRTT-A/P did not detect any significant comprehension differences between active and passive sentences in young and older individuals, this test has yet to be administered to various pathological groups (e.g., persons with agrammatic comprehension). This study thus provides preliminary data for future comparisons with pathological populations. Such studies are equally important for advancing our understanding of the way we comprehend language and form grammatical meaning

The on-line processing of unaccusativity in Greek agrammatism

We investigated the on-line processing of unaccusative and unergative sentences in a group of eight Greek-speaking individuals diagnosed with Broca aphasia and a group of language-unimpaired subjects used as the baseline. The processing of unaccusativity refers to the reactivation of the postverbal trace by retrieving the mnemonic representation of the verb’s syntactically defined antecedent provided in the early part of the sentence. Our results demonstrate that the Broca group showed selective reactivation of the antecedent for the unaccusatives. We consider several interpretations for our data, including explanations focusing on the transitivization properties of nonactive and active voice-alternating unaccusatives, the costly procedure claimed to underlie the parsing of active nonvoice-alternating unaccusatives, and the animacy of the antecedent modulating the syntactic choices of the patients

ERP effects of subject-verb agreement violations in patients with Broca's aphasia

Contains fulltext : 13805.pdf (publisher's version ) (Open Access)This article presents electrophysiological data on on-line syntactic processing during auditory sentence comprehension in patients with Broca's aphasia. Event-related brain potentials (ERPs) were recorded from the scalp while subjects listened to sentences that were either syntactically correct or contained violations of subject-verb agreement. Three groups of subjects were tested: Broca patients (n = 10), nonaphasic patients with a right-hemisphere (RH) lesion (n = 5), and healthy agedmatched controls (n = 12). The healthy, control subjects showed a P600/SPS effect as response to the agreement violations. The nonaphasic patients with an RH lesion showed essentially the same pattern. The overall group of Broca patients did not show this sensitivity. However, the sensitivity was modulated by the severity of the syntactic comprehension impairment. The largest deviation from the standard P600/SPS effect was found in the patients with the relatively more severe syntactic comprehension impairment. In addition, ERPs to tones in a classical tone oddball paradigm were also recorded. Similar to the normal control subjects and RH patients, the group of Broca patients showed a P300 effect in the tone oddball condition. This indicates that aphasia in itself does not lead to a general reduction in all cognitive ERP effects. It was concluded that deviations from the standard P600/SPS effect in the Broca patients reflected difficulties with on-line maintaining of number information across clausal boundaries for establishing subject-verb agreement

A neurolinguistic approach to pronominal resumption in Akan focus constructions

The current project explored the phonological and syntactic aspects of Akan pronominal resumption. The grammatical tone features of the resumptive pronoun and the clause determiner were assessed in Akan speakers with agrammatism. We found that the resumptive pronoun worsens wh-question comprehension in agrammatic speakers. However, the production of pronominal resumption was relatively spared. The ERP study investigated Akan native speakers’ sensitivity to the distribution of the resumptive pronoun by creating word-order and animacy violations. Our study represents a novel addition to the sentence processing field, as it looks into the interface between syntax, semantics, and phonology in Akan pronominal resumption