Syntactic processing of auditory and visual sentences in a learning‐disabled child: Relation to short‐term memory

The nature of a short‐term memory deficit and its relation to syntactic processing were investigated in a learning‐disabled child. The child showed reduced short‐term memory span for both auditorily and visually presented lists. The short‐term memory deficit was attributed to a disruption of phonological storage on the basis of several lines of evidence: No phonological similarity effect was obtained for visual presentation, the recency effect was absent for auditory presentation, and memory was normal for item information but poor for order information. On several syntactic tests, the child showed normal performance for visual presentation but impaired performance for auditory presentation. The deficit for auditory presentation was most obvious for syntactically complex sentences. The child's normal performance for visual presentation suggests that phonological short‐term memory does not play a critical role in reading comprehension. For auditory presentation, we hypothesize that phonological short‐term memory serves to hold subsequent words in a sentence while the syntactic analysis of earlier parts is completed.     

Treatment of thematic mapping in sentence comprehension: implications for normal processing

Abstract

The inability of some aphasic patients to interpret semantically reversible sentences has been hypothesised to arise from failure to link the grammatical roles of nouns (e.g. subject, object) to their corresponding thematic roles (e.g. agent, patient). Several previous attempts to improve patients' thematic mapping abilities have demonstrated a range of treatment effects of considerable relevance to the development of cognitive models of sentence processing. This study reports a new treatment approach to thematic mapping impairment; it succeeded in improving auditory sentence comprehension in a chronic aphasic patient with a long-standing comprehension deficit. Generalisation of improvement to auditory comprehension of sentences with untreated verbs, to comprehension of written sentences, and to tests using pictorial and videotaped materials not used in treatment, place constraints on the range of possible interpretations of the functional locus of treatment effects. Two areas that did not show significant improvement following treatment included auditory comprehension of sentences lengthened with modifiers, and spoken production of active and passive sentences that express correct thematic roles. These null effects are also interpreted as providing information relevant to models of sentence processing, including the role of working memory in sentence comprehension and the nature of thematic mapping procedures in comprehension and production.     

The mani left ti without a trace: A case study of aphasic processing of empty categories

We present the case of an aphasic patient who shows a selective impairment in interpreting syntactic structures on a test of sentence comprehension involving object manipulation. KG makes errors in assigning the antecedents of phonologically empty NPs called traces (Chomsky, 1982 a,b) in sentences like John seems to Bill to be shaving. He is significantly better at choosing the correct antecedent of another type of empty NP, namely subject- and object- controlled PRO (John persuaded Bill to shave, John promised Bill to shave). He has no trouble choosing the correct antecedents of overt pronouns and reflexives and shows no difficulty with syntactic structures that do not contain an empty category. His difficulty with trace is apparent in sentences which have a certain degree of complexity. He also misassigns the antecedent of subject-controlled PRO under one condition: when an overt reflexive or pronoun has PRO as its antecedent (John promised Bill to shave himself). The pattern of impairment suggests that KG cannot utilise one part of a parser/interpreter specifically devoted to the identification and co-indexation of empty categories when other processing demands are high, due to a specific impairment to this component, a capacity limitation, or both. The data support a theory of syntactic structure and parsing which incorporates different types of empty categories.     

Wh- questions and passive sentences in non-fluent variant PPA and semantic variant PPA: Longitudinal findings of an anagram production task

Using an anagram task, we investigated longitudinal syntactic production by individuals with semantic variant primary progressive aphasia (svPPA) and non-fluent variant PPA (nfvPPA), compared to controls. The accuracy of the production of active and passive, and reversible and non-reversible sentences, as well as of wh- questions was compared across the three groups. Results showed a different pattern of syntactic impairment across the two patient groups. The nfvPPA group showed difficulty with wh- questions at Time 1 and impairment with the passive structure approximately one year later, at Time 2. Surprisingly, the svPPA group also showed difficulty with wh- questions from Time 1, but still no difficulty on passive sentences, two years later, at Time 3. Neither group had difficulty with reversibility. The results of the nfvPPA patients were as expected, and the results of the svPPA patients suggest that this group may exhibit a greater syntactic impairment than is typically recognized.     

Processing of syntactically complex sentences relies on verbal short-term memory: Evidence from a short-term memory patient

The role of the phonological loop in auditory sentence comprehension was examined in a 35-year-old woman with a selective deficit of verbal short-term memory (STM). More specifically, the objective of the experiment was to test whether sentence comprehension is limited by number of propositions, as suggested by Rochon, Waters, and Caplan (2000), or whether it depends on syntactic complexity. In an offline task, severe impairment was present on cleft objects and centre-embedded structures; the deficit on object relatives in right peripheral position was less relevant, and the patient was able to handle sentential coordination easily. In an online task, her processing of centre-embedded structures and object relatives in right peripheral position was significantly slower than that in controls. She was also significantly slower in processing the verb of the object relative in centre-embedded structures. The results obtained do not support the claim that the difficulties encountered by patients with limited working-memory resources are due to the number of propositions in the sentence; they do, however, suggest a direct involvement of the phonological loop in processing syntactically complex sentences.     

Processing of syntactically complex sentences relies on verbal short-term memory: evidence from a short-term memory patient

The role of the phonological loop in auditory sentence comprehension was examined in a 35-year-old woman with a selective deficit of verbal short-term memory (STM). More specifically, the objective of the experiment was to test whether sentence comprehension is limited by number of propositions, as suggested by Rochon, Waters, and Caplan (2000), or whether it depends on syntactic complexity. In an offline task, severe impairment was present on cleft objects and centre-embedded structures; the deficit on object relatives in right peripheral position was less relevant, and the patient was able to handle sentential coordination easily. In an online task, her processing of centre-embedded structures and object relatives in right peripheral position was significantly slower than that in controls. She was also significantly slower in processing the verb of the object relative in centre-embedded structures. The results obtained do not support the claim that the difficulties encountered by patients with limited working-memory resources are due to the number of propositions in the sentence; they do, however, suggest a direct involvement of the phonological loop in processing syntactically complex sentences.     

Magnetic Field Tomography Analysis of Continuous Speech

In this article we investigate MEG correlates of syntactic violations in continuous speech. An early left anterior negativity (ELAN) has been reported in previous EEG studies and has been related to syntactic processing. We used Magnetic Field Tomography (MFT) to extract a 3D estimate of the current density distribution J, from MEG data recorded while subjects listened to continuous speech. Separate estimates were obtained from the activity associated with the first word of the sentence, and the last words of the sentence which signified syntactic violation, semantic violation or correct sentences. In each case independent 3D MFT estimates of activity were obtained 2 ms apart. After converting the solutions into a PET-like format we perform a statistical analysis on a voxel-by-voxel basis. Visual inspection of the power of J at the time of the ELAN component and the statistical maps overlaid on the individual anatomical MRI suggests generators in the vicinity of the auditory cortex and in left frontal regions. Directional activation curves are computed to show the variation of activity as a function of time, from well circumscribed areas. The activation curve for the auditory cortex has a characteristic pattern consisting of three peaks, seen in the average time-locked to the onset of the first word, and the critical word of the syntactic violation. The left auditory cortex shows a delay of about 30 ms in the syntactic violation condition compared to the first word condition. No such delay is seen in the right auditory cortex.     

Mechanisms underlying syntactic comprehension deficits in vascular aphasia: new evidence from self-paced listening

Sixty-one people with aphasia (pwa) and 41 matched controls were tested for the ability to understand sentences that required the ability to process particular syntactic elements and assign particular syntactic structures. Participants paced themselves word-by-word through 20 examples of 11 spoken sentence types and indicated which of two pictures corresponded to the meaning of each sentence. Sentences were developed in pairs such that comprehension of the experimental version of a pair required an aspect of syntactic processing not required in the corresponding baseline sentence. The need for the syntactic operations required only in the experimental version was triggered at a “critical word” in the experimental sentence. Listening times for critical words in experimental sentences were compared to those for corresponding words in the corresponding baseline sentences. The results were consistent with several models of syntactic comprehension deficits in pwa: resource reduction, slowed lexical and/or syntactic processing, abnormal susceptibility to interference from thematic roles generated non-syntactically. They suggest that a previously unidentified disturbance limiting the duration of parsing and interpretation may lead to these deficits, and that this mechanism may lead to structure-specific deficits in pwa. The results thus point to more than one mechanism underlying syntactic comprehension disorders both across and within pwa.     

Sentence comprehension in Alzheimer's disease

A visual sentence‐picture matching task was used to clarify the nature of the comprehension deficit in Alzheimer's Disease (AD). Test sentences varied according to how crucial the processing of syntax was in computing a correct interpretation. Half the sentences could be understood through the comprehension of semantic cues alone; the other half required the processing of syntactic cues. In the first experiment, sentences were removed from view before the test pictures were presented; in the second, sentences and pictures were presented together to decrease demands on working memory. Two factors determined the accuracy of sentence comprehension: whether a syntactic analysis was needed and whether additional working‐memory resources were needed for temporary storage. When storage demands were minimized, patients were able to use semantic cues to guide comprehension. When semantic cues were unavailable, comprehension was impaired, regardless of whether or not there were additional storage requirements, providing evidence for a genuine syntactic deficit that is not due to coexisting semantic impairment or working‐memory dysfunction.     

Functional segregation of the inferior frontal gyrus for syntactic processes: a functional magnetic-resonance imaging study

We used functional magnetic resonance imaging in 18 normal volunteers to determine whether there is separate representation of syntactic, semantic, and verbal working memory processing in the left inferior frontal gyrus (GFi). We compared a sentence comprehension task with a short-term memory maintenance task to identify syntactic and semantic processing regions. To investigate the effects of syntactic and verbal working memory load while minimizing the differences in semantic processes, we used comprehension tasks with garden-path (GP) sentences, which require re-parsing, and non-garden-path (NGP) sentences. Compared with the short-term memory task, sentence comprehension activated the left GFi, including Brodmann areas (BAs) 44, 45, and 47, and the left superior temporal gyrus. In GP versus NGP sentences, there was greater activity in the left BAs 44, 45, and 46 extending to the left anterior insula, the pre-supplementary motor area, and the right cerebellum. In the left GFi, verbal working memory activity was located more dorsally (BA 44/45), semantic processing was located more ventrally (BA 47), and syntactic processing was located in between (BA 45). These findings indicate a close relationship between semantic and syntactic processes, and suggest that BA 45 might link verbal working memory and semantic processing via syntactic unification processes.     

Mirrored EMG activity during unimanual rhythmic movements

The present study investigated the relationship between two different syntactic information types, namely word category and morphosyntax. The event-related brain potential (ERP) pattern of acoustically presented sentences containing two syntactic anomalies (word category and subject-verb agreement) was compared to the ERP response to sentences containing a single violation. The ERPs for the agreement violation revealed a left anterior negativity (LAN) indicating the detection of the morphosyntactic error, followed by a P600 reflecting processes of reanalysis. The ERPs for both the category and the combined violation showed an early negativity reflecting processes of phrase structure building, followed by a P600 indicating syntactic reanalysis. Additionally, a broadly distributed negativity following the early negativity and preceding the P600 was observed. This ERP component is suggested to reflect reference specification processes arising from the specific sentence structure used in the present study. The ERP pattern for the combined violation suggests no additivity or interaction between the two syntactic anomalies in the early time windows (early negativity, reference-related negativity, and LAN), whereas interactive effects are observed in a late time range (P600).     

Active maintenance of sentence meaning in working memory: evidence from EEG coherences.

The active maintenance of sentence meaning in working memory was investigated using event-related electroencephalogram (EEG) coherences. Participants read a sentence, retained it for 2.5 s, and then verified a statement about its meaning. The sentences contained either three semantically related nouns or unrelated nouns and started either with a what phrase (WH sentences) or not (non-WH sentences), imposing either a high or low demand on verbal working memory. Comprehension accuracy showed an interaction of semantic relatedness and sentence type due to the presence of a relatedness effect (lower accuracy in the unrelated condition) in WH sentences but not in non-WH sentences. During the post-sentence retention interval, EEG coherences also displayed this interaction of relatedness and sentence type. A semantic relatedness effect was obtained in the WH sentences (high demand) but not in the non-WH sentences (low demand). In addition, compared to a pre-sentence baseline and sentence presentation, coherences increased in the 10-14 Hz band during retention and decreased in the 4-6 Hz band. These coherence changes spanned prefrontal and posterior brain regions, possibly reflecting increased synchronization in projection loops between attention control systems in prefrontal cortex and activated meaning representations in semantic memory in posterior cortex. These findings suggest that short-term retention of the meaning of a sentence involves active maintenance in a capacity-limited working memory, accompanied by a heightened inner direction of attention after sentence presentation.     

MEG study on neural activities associated with syntactic and semantic violations in spoken Korean sentences

We carried out an magnetoencephalography (MEG) study to record cortical responses elicited in the left hemisphere by ending verb phrases, which had syntactic or semantic anomalies, in Korean sentences of subject-object-verb order. Using the high temporal and spatial resolution of MEG, the study was aimed at identifying neural activities that occur during a latency course associated with the syntactic or semantic process in the spoken sentence. Major responses, distinct from the responses to normal sentences, were observed in two latency periods of about 400 and 600 ms following the onset of the verb phrase. Source localization of the grand average fields indicated separate activities in the inferior frontal region and the vicinity of the auditory cortex for the first 400-ms response to the syntactic anomaly. The region around the auditory cortex was indicated for the response to the semantic anomaly in a similar latency. The second 600-ms response indicated activity around the middle temporal gyrus inferior to the auditory cortex for both syntactic and semantic anomalies. The results are discussed with reference to the ERP components established for Indo-European languages, and the possibility of concurrent processing of syntactic and semantic aspects is suggested.     

Phonological short-term store and sentence processing

The grammatical and semantic processing of auditorily presented sentences and passages of prose was investigated in a left brain-damaged patient (PV), who has a reduced auditory memory span, interpreted in terms of a selective deficit of the phonological short-term store component of working memory. In the case of short sentences the patient's performance is well within the normal range, whether tested by sentence-picture matching or by the detection of syntactic or semantic anomalies.

She retains an intact capacity to detect semantic anomalies whether tested using short sentences, long sentences, or prose passages. She retains some capacity for detecting syntactic anomalies even in long sentences, provided these are tested under conditions where such mismatches are very frequent; when they are embedded in more varied material, however, her performance deteriorates. Finally, when the syntactic anomaly involves an anaphoric mismatch across sentences, her performance drops to chance level. These results are consistent with the view that the short-term phonological store serves as a “mnemonic window” that facilitates certain aspects of the comprehension of sentential material.     

The active‐passive test: An age‐referenced clinical test of syntactic discrimination

The construction and use of a test of syntactic discrimination are described. Fifty children (10 each at 6, 8,10,12, and 14 years of age), selected for median scholastic class performance, were tested. The number of correct syntactic discriminations and response latencies were calculated for each of the four sentence forms: active affirmative, passive affirmative, active negative, and passive negative. Comprehension of the sentences improved with age, although even the youngest children identified forms like the passive affirmative at a better‐than‐chance level. Age‐related improvements in test performance were nonlinear and varied with sentence form. Several factors influenced test performance: the semantic relations expressed by different verbs, surface syntactic features, and the degree of syntactic complexity. The effect of a given factor varied with both the age of the child and the performance measure. After age 6, increased skill was associated with the selective allocation of processing time to sentences on the basis of syntactic complexity.     

Dissociations of lexical function: Semantics,syntax, and morphology

Abstract

Aphasic patients who exhibit “asyntactic comprehension” show poor performance on a sentence-picture matching task with semantically unconstrained sentences, such as “The cow bit the horse,” but good performance, when the sentences are semantically constrained, such as “The boy threw the ball.” The assumption has been that such patients are able to interpret these latter sentences by relying solely on the meanings of the individual words, and that their intact lexical semantics can support some amount of sentence processing. We test this claim by investigating, in detail, the lexical semantics of an aphasic patient (JG), whose speech production is severely agrammatic and whose sentence-picture matching in asyntactic. We explore the semantics of JG's lexicon for both morphologically simple and complex words. We find that word meanings are represented normally in his mental lexicon, and he is able to use this information to integrate words into phrases. In contrast, lexical syntactic and morphological processes are severely impaired. This pattern confirms that lexical semantics can support some limited amount of sentence processing in patients with asyntactic comprehension, and that different lexically based processes can be impaired differentially following brain damage.     

Rasch models of aphasic performance on syntactic comprehension tests

Responses of 42 people with aphasia to 11 sentence types in enactment and sentence–picture matching tasks were characterized using Rasch models that varied in the inclusion of the factors of task, sentence type, and patient group. The best fitting models required the factors of task and patient group but not sentence type. The results provide evidence that aphasic syntactic comprehension is best accounted for by models that include different estimates of patient ability in different tasks and different difficulty of all sentences in different groups of patients, but that do not include different estimates of patient ability for different types of sentences.     

Agrammatism as a variable phenomenon

Abstract

With a group of 11 Dutch agrammatic speakers, the studies on production and comprehension of word order by Saffran et al. (1980) and Schwartz et al. (1980) were replicated. We found a pattern of errors that was qualitatively the same as observed by these authors. However, the absolute number of errors was much lower: as a group our agrammatics performed highly above chance. In a second study, we asked seven patients to order various types of sentences in which the position of the verb varied. Again the level of performance was highly above chance. There was no effect of sentence type with respect to verb position (VSO or SOV). Another effect of sentence type, however, was apparent. If the position of the verb could be determined by processing a cue that was within the clause to be ordered, the sentences elicited few errors. Sentences with out-of-clause cues were much more difficult. It seems that there is variability, both between patients and between sentences. A series of possible accounts of this variability is discussed. It is concluded that only some accounts are adequate, in particular those that assume the involvement of memory limitation due to restrictions in space or time. However, even these accounts cannot explain telegraphic speech. Therefore, to supplement them, a new theory of Broca's aphasia is proposed.     

Immediate integration of prosodic information from speech and visual information from pictures in the absence of focused attention: A mismatch negativity study

Language is often perceived together with visual information. Recent experimental evidences indicated that, during spoken language comprehension, the brain can immediately integrate visual information with semantic or syntactic information from speech. Here we used the mismatch negativity to further investigate whether prosodic information from speech could be immediately integrated into a visual scene context or not, and especially the time course and automaticity of this integration process. Sixteen Chinese native speakers participated in the study. The materials included Chinese spoken sentences and picture pairs. In the audiovisual situation, relative to the concomitant pictures, the spoken sentence was appropriately accented in the standard stimuli, but inappropriately accented in the two kinds of deviant stimuli. In the purely auditory situation, the speech sentences were presented without pictures. It was found that the deviants evoked mismatch responses in both audiovisual and purely auditory situations; the mismatch negativity in the purely auditory situation peaked at the same time as, but was weaker than that evoked by the same deviant speech sounds in the audiovisual situation. This pattern of results suggested immediate integration of prosodic information from speech and visual information from pictures in the absence of focused attention.     

Rasch models of aphasic performance on syntactic comprehension tests

Responses of 42 people with aphasia to 11 sentence types in enactment and sentence-picture matching tasks were characterized using Rasch models that varied in the inclusion of the factors of task, sentence type, and patient group. The best fitting models required the factors of task and patient group but not sentence type. The results provide evidence that aphasic syntactic comprehension is best accounted for by models that include different estimates of patient ability in different tasks and different difficulty of all sentences in different groups of patients, but that do not include different estimates of patient ability for different types of sentences.