Articulatory and phonological deficits in short-term memory and their relation to syntactic processing

The relationships between sentence comprehension deficits and deficits in the articulatory or phonological components of short-term memory were investigated. Nonfluent agrammatic patients showed very poor comprehension of syntax while a group of nonfluent patients who were not agrammatic showed good comprehension, despite both groups showing similar degrees of deficits in an articulatory component of memory. The results imply that a disruption of inner rehearsal has little consequence for auditory sentence comprehension, and that the syntactic comprehension deficits of the agrammatic patients could not be attributed to their memory deficit. A patient with a disruption in phonological storage showed good comprehension for many sentences, but was impaired when a difficult syntactic structure was encountered early in a sentence. It was proposed that phonological storage serves to hold words in a phonological form when sentence processing cannot keep pace with sentence input. Although a role for phonological storage was postulated, the impressive degree of syntactic processing that could be carried out by patients with very restricted memory spans implies that there is little overlap between the memory systems disrupted in these patients and the working memory system presumed to be involved in sentence comprehension.     

Sentence comprehension and memory for embedded structure

An experimental simulation technique is introduced to study memory constraints affecting comprehension of embedded sentences. Memory for embedded structure is measured in a pairing task that simulates requirements imposed by sentence comprehension. With increasing memory load (number of embeddings), the rate of performance decline is consistent across all (recall and comprehension) conditions, and reflects a loss of order (as opposed to item) information. Short-term memory overload, rather than linguistic complexity, appears sufficient to account for comprehension difficulty. Performance was imperfect even with singly embedded constructions. Recall showed no abrupt failure with multiple embeddings, indicating that memory constraints are not as discontinuous as English syntax might suggest.     

Syntactic structure building in the anterior temporal lobe during natural story listening

The neural basis of syntax is a matter of substantial debate. In particular, the inferior frontal gyrus (IFG), or Broca’s area, has been prominently linked to syntactic processing, but the anterior temporal lobe has been reported to be activated instead of IFG when manipulating the presence of syntactic structure. These findings are difficult to reconcile because they rely on different laboratory tasks which tap into distinct computations, and may only indirectly relate to natural sentence processing. Here we assessed neural correlates of syntactic structure building in natural language comprehension, free from artificial task demands. Subjects passively listened to Alice in Wonderland during functional magnetic resonance imaging and we correlated brain activity with a word-by-word measure of the amount syntactic structure analyzed. Syntactic structure building correlated with activity in the left anterior temporal lobe, but there was no evidence for a correlation between syntactic structure building and activity in inferior frontal areas. Our results suggest that the anterior temporal lobe computes syntactic structure under natural conditions.     

句子理解的关键——对句法和语义关系的再探讨

对于句子理解中句法和语义的关系,传统的模块化观点认为,句法信息优先于语义信息,句法加工支配着句子的理解过程。近期,这种强调句法优先的理论受到了一系列ERP（Event-related potentials）研究结果的挑战,这些研究从不同角度论证了语义信息对句法加工及句子整合加工的重要作用。基于这些研究发现,研究者提出句子理解过程中句法和语义的关系并非一成不变：一些情况下可能是句法支配语义加工,而另一些情况下则可能是语义引导句法加工     

The Effect of LPC Narrowband Processing and Bit Error Rate on Performance in a Sentence Verification Task

The comprehension of narrowband digital speech with bit errors was tested using a sentence verification task. The difficulty of the verification task was varied by using predicates that were either strongly or weakly related to the subjects (e.g., A toad has warts./A toad has eyes.). The test conditions included unprocessed speech and speech processed using a 2,400 bitdsec linear predictive coding (LPC) voice processing algorithm with random bit error rates of 0%, 2%, and 5%. In general, response accuracy decreased and reaction time (RT) increased with LPC processing and with increasing bit error rates. Weakly related true sentences and strongly related false sentences were more difficult than strongly related true sentences and weakly related false sentences, respectively. Interactions between sentence type and speech processing conditions are discussed. The longer time taken to react to degraded speech has implications for performance in military combat situa- tions where split-second decisions are required. The higher error rates with degraded sentences that contain little contextual information are particularly relevant to policy conversations that use a varied vocabulary.     

Similarity-based interference during language comprehension: Evidence from eye tracking during reading

The nature of working memory operation during complex sentence comprehension was studied by means of eye-tracking methodology. Readers had difficulty when the syntax of a sentence required them to hold 2 similar noun phrases (NPs) in working memory before syntactically and semantically integrating either of the NPs with a verb. In sentence structures that placed these NPs at the same linear distances from one another but allowed integration with a verb for 1 of the NPs, the comprehension difficulty was not seen. These results are interpreted as indicating that similarity-based interference occurs online during the comprehension of complex sentences and that the degree of memory accessibility conventionally associated with different types of NPs does not have a strong effect on sentence processing.     

Role of Working Memory in Typically Developing Children’s Complex Sentence Comprehension

The influence of three mechanisms of working memory (phonological short-term memory (PSTM capacity), attentional resource control/allocation, and processing speed) on children's complex (and simple) sentence comprehension was investigated. Fifty two children (6-12 years) completed a nonword repetition task (indexing PSTM), concurrent verbal processing-storage task (indexing resource control/allocation), auditory-visual reaction time (RT) task (indexing processing speed), and a sentence comprehension task that included complex and simple sentences. Correlation and regression analyses were run to determine the association between the memory variables and sentence comprehension accuracy. Results revealed: (1) none of the memory variables correlated with simple sentence comprehension, (2) resource control/allocation and processing speed correlated significantly with complex sentence comprehension, even after covarying for age, and (3) attentional functioning and processing speed predicted complex sentence comprehension (after accounting for age). Results were interpreted to suggest that working memory is significantly involved in school age children's comprehension of familiar complex sentence structures.     

汉语句子理解中语义分析与句法分析的关系

两个实验研究了中文句子理解中句法分析与语义分析的关系。实验1采用被试者自控阅读速度的方法,要求被试者对每个句子(合理句或不合理句)进行语法判断。结果表明,在歧义词(AW)和解歧词(DAW)上,合理句与不合理句的错误率存在显著差异,而反应时差异不显著。实验2研究了语境对句子理解的作用。结果表明,在有语境和无语境条件下,两类句子在歧义词和解歧词上的反应时,均有明显的差异。这些结果支持了句子理解中句法与语义加工的弱相互作用模型。     

Automatic evaluation of syntactic learners in typologically-different languages

Human syntax acquisition involves a system that can learn constraints on possible word sequences in typologically-different human languages. Evaluation of computational syntax acquisition systems typically involves theory-specific or language-specific assumptions that make it difficult to compare results in multiple languages. To address this problem, a bag-of-words incremental generation (BIG) task with an automatic sentence prediction accuracy (SPA) evaluation measure was developed. The BIG–SPA task was used to test several learners that incorporated n-gram statistics which are commonly found in statistical approaches to syntax acquisition. In addition, a novel Adjacency–Prominence learner, that was based on psycholinguistic work in sentence production and syntax acquisition, was also tested and it was found that this learner yielded the best results in this task on these languages. In general, the BIG–SPA task is argued to be a useful platform for comparing explicit theories of syntax acquisition in multiple languages.     

Semantic facilitation across sensory modalities in the processing of individual words and sentences

The effect of semantic priming upon lexical decisions made for words in isolation (Experiment 1) and during sentence comprehension (Experiment 2) was investigated using a cross-modal lexical decision task. In Experiment 1, subjects made lexical decisions to both auditory and visual stimuli. Processing auditorily presented words facilitated subsequent lexical decisions on semantically related visual words. In Experiment 2, subjects comprehended auditorily presented sentences while simultaneously making lexical decisions for visually presented stimuli. Lexical decisions were facilitated when a visual word appeared immediately following a related word in the sentential material. Lexical decisions were also facilitated when the visual word appeared three syllables following closure of the clause containing the related material. Arguments are made for autonomy of semantic priming during sentence comprehension.     

Executive control is shared between sentence processing and digit maintenance: Evidence from a strictly timed dual-task paradigm

We investigated whether the comprehension of syntactically difficult sentences taxes the executive control component of working memory more than the comprehension of their easier counterparts. To that end, we tested the effect of sharing executive control between sentence comprehension and the maintenance of a digit load in two dual-task experiments with strictly controlled timing (Barrouillet, Bernardin, & Camos, 2004). Recall was worse after participants had processed one (Experiment 2) or two (Experiment 1) difficult sentences than after they had processed one or two easy sentences, respectively. This finding suggests that sentence processing and the maintenance of a digit load share executive control. Processing syntactically difficult sentences seems to occupy executive control for a longer time than processing their easy counterparts, thereby blocking refreshments of the memory traces of the digits so that these traces decay more and recall is worse. There was no effect of the size of the digit load on sentence-processing performance (Experiment 2), suggesting that sentence processing completely occupied executive control until processing was complete.     

Syntactic complexity does not necessarily make sentences harder to understand

Researchers studying language comprehension have assumed that, all else being equal, more complex sentence constructions will take longer to process. However, results from experiments, such as the one presented in this paper, which use reading rates as the dependent measure suggest that it is the interaction of specific types of deep structure representations with their surface structure forms that accounts for fluctuations in readers' on-line processing of various sentence types. In particular, those sentences in which the deep structure direct object immediately precedes the verb in the surface structure sequence are easier for comprehenders to process. These data support a dual, parallel processing model of sentence comprehension in which lexical and morphological/relational information are processed independently.Johns Hopkins University.     

Planning units and syntax in sentence production

The study was conducted to determine, first, whether it is the deep or the surface clause that is more important as a speech planning unit, and second, whether syntactic decisions are made during sentence production. Subjects, while talking, heard tones to which they had to respond by pressing a button; reaction times to these tones were taken as an index of processing load during production. It was found that there were increased RTs at the ends compared with the beginnings of deep structure clauses. No difference was found between RTs at the beginnings and ends of surface clauses not corresponding to a deep clause. The results were interpreted as showing that deep clauses are major planning units and that some planning for clauses occurs at the end of the preceding clause. Differences were found between RTs during clauses of different syntactic structure. These results were interpreted as indicating that syntax influences production and were discussed in relation to previous studies of pausing and speech disruption.     

The preservation of verb subcategory knowledge in a spoken language comprehension deficit

Patient WBN has a lexical-semantic deficit resulting in impaired performance on language comprehension tasks that require access to verb meanings in both single-word and sentence contexts. However, WBN shows no such comprehension impairment with respect to lexical syntax. Specifically, he performs without error on comprehension tasks that rely on knowledge of lexical-specific verb subcategory requirements. This performance pattern supports theories of lexical representation and processing in which lexical syntactic information may be encoded and retrieved independently from lexical semantic information.     

Intonational marking of given and new information: Some consequences for comprehension

The role of intonation in conveying discourse relationships in auditory sentence comprehension was investigated in two experiments. Using the simple comprehension time paradigm, Experiment 1 found that sentences with accented new information were understood faster than sentences with a neutral intonation contour and that the presence of accent in context sentences facilitated comprehension of subsequent targets. Both experiments showed faster comprehension times in conditions in which accent placement was appropriate for the information structure of the sentence. In Experiment I, comprehension times were faster when the accent fell on the information focus than when it fell elsewhere in the sentence. In Experiment 2, faster times resulted when new information was accented and given information was not, compared to conditions in which this accent pattern was reversed. This effect held for both active and passive sentences, and whether the new information occurred in the subject or object position.     

Brain potentials elicited by prose-embedded linguistic anomalies

Linguistic theories distinguish between syntax (sentence form) and semantics (sentence meaning). Correspondingly, recent studies have shown that syntactic and semantic anomalies elicit distinct changes in the event-related brain potential (ERP). However, these results have been obtained with highly artificial methodologies and have not yet been generalized to more natural reading conditions. Here, we recorded ERPs while subjects read a naturalistic prose passage. The subjects either read for comprehension with no other task being assigned or read for comprehension and made acceptability judgments after each sentence. Consistent with prior work and regardless of the subjects' assigned task, syntactic anomalies elicited a large positive wave (P600), whereas semantic anomalies elicited a large increase in N400 amplitude. These results demonstrate that the qualitatively distinct ERP responses elicited by syntactic and semantic anomalies are not artifacts of unnatural aspects of previously used stimuli, thereby providing additional evidence that separable syntactic and semantic processes exist.     

Evoked potentials and the study of sentence comprehension

Evoked brain potentials were used to monitor moment-by-moment decisions during language comprehension. Subjects read sentences containing temporary syntactic ambiguities for which one of the possible interpretations was semantically implausible. The N400 component of the evoked potential, which is sensitive to implausibility, was used to discover when during a sentence subjects made a decision about the ambiguity. The results demonstrate that readers try to interpret a syntactic ambiguity early in a sentence rather than waiting for disambiguating information. This introduces a new way to use brain activity to study sentence comprehension processes.     

Structural priming: a critical review

Repetition is a central phenomenon of behavior, and researchers have made extensive use of it to illuminate psychological functioning. In the language sciences, a ubiquitous form of such repetition is structural priming, a tendency to repeat or better process a current sentence because of its structural similarity to a previously experienced ("prime") sentence (J. K. Bock, 1986). The recent explosion of research in structural priming has made it the dominant means of investigating the processes involved in the production (and increasingly, comprehension) of complex expressions such as sentences. This review considers its implications for the representation of syntax and the mechanisms of production and comprehension and their relationship. It then addresses the potential functions of structural priming, before turning to its implications for first language acquisition, bilingualism, and aphasia. The authors close with theoretical and empirical recommendations for future investigations.     

The temporal structure of spoken sentence comprehension in Chinese

Three experiments with 60 native Chinese speakers were conducted to examine the temporal structure of spoken sentence comprehension in Chinese. In the two sentence-gating experiments, listeners heard sentence fragments of various sizes, either successively or individually, and decided on the agent role of the sentence. In the agent-naming experiment, listeners repeated aloud the sentence agent upon hearing the sentence. Converging evidence was derived from these experiments indicating the usefulness of sentence gating in tapping into the temporal structure of comprehension and in evaluating listeners’ comprehension on the basis of partial information. Results from these experiments show that partial sentence information plays a very important role in Chinese sentence comprehension, and that Chinese listeners integrate incomplete and ungrammatical sentence fragments by reference to complete and grammatical models in the language. It is argued that these processing characteristics reflect properties of the Chinese language in which few morphological, grammatical, and syntactic constraints are placed on the relationships between sentence constituents.     

The Emperor's Psycholinguistics

We discuss and debunk five common assumptions about the interrelation of semantics, syntax, and frequency during sentence processing. In the course of this, we explore the implications of the view that syntax is assigned as the last stage of comprehension rather than the first: Statistically based perceptual strategies propose an initial semantic representation, which then constrains the assignment of syntactic representations. This view accounts for a variety of facts, as well as suggesting some surprising new ones.